Ch 8 Corrosion

bull Introduction bullTypes of corrosion (pitting inter granular crevice Galvanic etc)

bullCorrosion prevention methods (selection of materials heat treatment design)

bull casting method inhibitors etc

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 1

bull High cost incurred by countries toward the protection of surface degradation

Cost of corrosion It is defined and dangerous enemybull in India ~ 5 of GDP gtgtgt $ 30 billion ( in 2013 data)bull In USA ~ $ 260 Billion

bull Drinking water and sewage system ~ $ 36 Billion

9142019

EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 2

Why to study surface damage (degradation)

DIRECT COST OF CORROSIONExpensive material applicationOver designCost of repair (replacement)Application of anti corrosion means treatments

INDIRECT COST OF CORROSIONPoor design and unrepairable damageCost of labourLoss of productivityCost of equipment used in relation to corrosion inspection and prevention activities

2016 IMPACT study in which it estimates the global cost of corrosion to be US$25 trillion equivalent to roughly 34 percent of the global Gross Domestic Product (GDP)

bullchemicals

bullgases

bullliquid metals

bullcorrosive media

bullWood damage

by termites

bullMicrobes

Physical interactionChemical interaction

Biological interaction

bullStress

bullHeat

bullRadiation

Physical + chemical interaction

o The fracture or deformation of

materials due to stress under sea water

Chemical + Biological

interaction

o Bacteria action on the

surface of materials

Physical + biological

interaction

o The fracture or

deformation of materials

implanted in the human

body

Surface Degradation

(damage)

Mechanisms

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 3

DAMAGED CAUSED BY CORROSION

bullWhy Study Corrosion Metals

bullTo understand of the mechanisms and causes of corrosion

Take measures to prevent them from occurringbullEnvironment (fluid velocity temperatureand composition) - controlbullMaterial - selectionbullMaterial - protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 4

Damage due to corrosion on the bridge

Corrosion failures

often relate to the

material selection

and the

environment

Understanding the mechanisms of corrosion is the key to the development of a knowledge-

based design of corrosion resistant alloys and to the prediction of the long-term behavior of

metallic materials in corrosive environments9142019 5EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

bull High cost incurred by countries toward the protection of surface degradation

Cost of corrosion It is defined and dangerous enemybull in India ~ 5 of GDP gtgtgt $ 30 billion ( in 2013 data)bull In USA ~ $ 260 Billion

bull Drinking water and sewage system ~ $ 36 Billion

9142019

EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 2

Why to study surface damage (degradation)

DIRECT COST OF CORROSIONExpensive material applicationOver designCost of repair (replacement)Application of anti corrosion means treatments

INDIRECT COST OF CORROSIONPoor design and unrepairable damageCost of labourLoss of productivityCost of equipment used in relation to corrosion inspection and prevention activities

2016 IMPACT study in which it estimates the global cost of corrosion to be US$25 trillion equivalent to roughly 34 percent of the global Gross Domestic Product (GDP)

bullchemicals

bullgases

bullliquid metals

bullcorrosive media

bullWood damage

by termites

bullMicrobes

Physical interactionChemical interaction

Biological interaction

bullStress

bullHeat

bullRadiation

Physical + chemical interaction

o The fracture or deformation of

materials due to stress under sea water

Chemical + Biological

interaction

o Bacteria action on the

surface of materials

Physical + biological

interaction

o The fracture or

deformation of materials

implanted in the human

body

Surface Degradation

(damage)

Mechanisms

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 3

DAMAGED CAUSED BY CORROSION

bullWhy Study Corrosion Metals

bullTo understand of the mechanisms and causes of corrosion

Take measures to prevent them from occurringbullEnvironment (fluid velocity temperatureand composition) - controlbullMaterial - selectionbullMaterial - protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 4

Damage due to corrosion on the bridge

Corrosion failures

often relate to the

material selection

and the

environment

Understanding the mechanisms of corrosion is the key to the development of a knowledge-

based design of corrosion resistant alloys and to the prediction of the long-term behavior of

metallic materials in corrosive environments9142019 5EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

bullchemicals

bullgases

bullliquid metals

bullcorrosive media

bullWood damage

by termites

bullMicrobes

Physical interactionChemical interaction

Biological interaction

bullStress

bullHeat

bullRadiation

Physical + chemical interaction

o The fracture or deformation of

materials due to stress under sea water

Chemical + Biological

interaction

o Bacteria action on the

surface of materials

Physical + biological

interaction

o The fracture or

deformation of materials

implanted in the human

body

Surface Degradation

(damage)

Mechanisms

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 3

DAMAGED CAUSED BY CORROSION

bullWhy Study Corrosion Metals

bullTo understand of the mechanisms and causes of corrosion

Take measures to prevent them from occurringbullEnvironment (fluid velocity temperatureand composition) - controlbullMaterial - selectionbullMaterial - protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 4

Damage due to corrosion on the bridge

Corrosion failures

often relate to the

material selection

and the

environment

Understanding the mechanisms of corrosion is the key to the development of a knowledge-

based design of corrosion resistant alloys and to the prediction of the long-term behavior of

metallic materials in corrosive environments9142019 5EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

DAMAGED CAUSED BY CORROSION

bullWhy Study Corrosion Metals

bullTo understand of the mechanisms and causes of corrosion

Take measures to prevent them from occurringbullEnvironment (fluid velocity temperatureand composition) - controlbullMaterial - selectionbullMaterial - protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 4

Damage due to corrosion on the bridge

Corrosion failures

often relate to the

material selection

and the

environment

Understanding the mechanisms of corrosion is the key to the development of a knowledge-

based design of corrosion resistant alloys and to the prediction of the long-term behavior of

metallic materials in corrosive environments9142019 5EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

Damage due to corrosion on the bridge

Corrosion failures

often relate to the

material selection

and the

environment

Understanding the mechanisms of corrosion is the key to the development of a knowledge-

based design of corrosion resistant alloys and to the prediction of the long-term behavior of

metallic materials in corrosive environments9142019 5EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

CORROSION FUNDAMENTALS

Scientific definition

bull Electrochemical deterioration of materials by chemical interaction with their environmentbull The term corrosion is sometimes also applied to the degradation of plastics

concrete and wood but generally refers to metals

bull Degradation implies deterioration of physical properties of the material

o weakening of the material due to a loss of cross-sectional area

o shattering of a metal due to hydrogen embrittlement

o cracking of a polymer due to sunlight exposure

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 6

Practical definition Tendency of metal to reverting back to its natural startPure iron (Fe) to iron ore (Fe2O3)

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

Causes of Corrosion

bull It involves four factors

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 7

Mechanical factor (Stress)

Thermodynamics factor (Material)

Metallurgical factor (Material)

Electrochemical factor(rate)

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

Causes of Corrosion

bull Three conditions must exist simultaneously in order for the corrosion to occur

1 The presence of an anode and a cathode This occur when two dissimilar metals or two regions of differential electrolyte concentration create a difference in electrical potential

2 A metallic connector between the anode and the cathode

3 An electrolyte such as water

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 8

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

How corrosion occurbull The source of all corrosion is an electrochemical cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 9

electrochemical cell

930min ndash 1955min

Corrosion - Classifications

bull Direct chemical attack

bull Battery acid residual flux deposits entrapped caustic cleaning solutions

bull Electrochemical attack

bull Requires a medium (usually water) that conducts tiny current of electricity

bull More active metal becomes anodic amp less active metal becomes cathodic

bull The greater the difference in electrical potential (dissimilar metals) the greater the corrosion

bull Most common cause of corrosion

bull Environment causing degradation

bull Gas and Vapor environment

bull Aqueous environment

bull Stress corrosion9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 10

Environmental severity factors that influence corrosion

These include but are not limited to

bullTemperature

bullTime-of-Wetness

bullPresence of chloride

bullPH

bull Industrial pollutants

bullUV radiation

bullMicrobiological activity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 11

Corrosion classification Manner in which it is manifest

bull Metallic corrosion is sometimes classified into eight forms

bulluniform

bullPitting

bullcrevice

bullgalvanic

bull intergranular

bullselective leaching

bullerosionndashcorrosion and

bullstress corrosion9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 12

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 13

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 14

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Environmental severity factors that influence corrosion

These include but are not limited to

bullTemperature

bullTime-of-Wetness

bullPresence of chloride

bullPH

bull Industrial pollutants

bullUV radiation

bullMicrobiological activity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 11

Corrosion classification Manner in which it is manifest

bull Metallic corrosion is sometimes classified into eight forms

bulluniform

bullPitting

bullcrevice

bullgalvanic

bull intergranular

bullselective leaching

bullerosionndashcorrosion and

bullstress corrosion9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 12

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 13

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 14

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Corrosion classification Manner in which it is manifest

bull Metallic corrosion is sometimes classified into eight forms

bulluniform

bullPitting

bullcrevice

bullgalvanic

bull intergranular

bullselective leaching

bullerosionndashcorrosion and

bullstress corrosion9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 12

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 13

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 14

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 13

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 14

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 14

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

15

Forms of Corrosion Uniform Attack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Galvanic

bull Two metals or alloys having different compositions are electrically coupled while exposed to an electrolyte

bull The less noble or more reactive anode in the particular environment will experience corrosion

bull The more inert metal the cathode will be protected from corrosion

bull Eg Steel screws corrode when in contact with brass in a marine environment

Copper and steel tubing are joined in a domestic water heater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 16

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Galvanic Cell

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 17

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 18

Galvanic Corrosion

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Recommend on the connection in the photo

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 19

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Galvanic Corrosion Demetallification amp Concentration Cell

bull Alloy or a metal containing impurities

bull Brass Zinc = anode Copper = cathodebull Zinc corrode [Dezincification]

bull Pearlitic steel Ferrite = anode Cementite=cathodebull Ferrite corroded

bull Cast Iron iron = anode graphite = cathodebull Iron corroded [Graphitisation]

Drop of

H2O

Greatest

amount of

dissolved

oxygen

AnodeCathode

bull More concentrated electrolyte

bull Least concentration of oxygen

bull Dilute electrolyte

bull High concentration of oxygen

Demetallification

Concentration Cell

bullAnode end

bullCathode end

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 20

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

21

Forms of Corrosion Pitting corrosion

bull Localized nature

bull Coring mixture of phases and residual stress

bull Different electrical potential occur at metal surface

bull Thus presence of electrolyte established galvanic cell with more anodic portion of the surface is attacked at localized site

Corrosion pits can also be harmful by acting as

stress risers Fatigue and stress corrosion cracking

may initiate at the base of corrosion pits

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

22

Forms of Corrosion Pitting

Pitting Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Microscopic Image of Pitting corrosion Once the corrosion products are cleaned away from the metal surface

It has a great impact on the structural integrity

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 23

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Crevice

bull Describes two modes of localized corrosionsbull 1The physical situation where electrolyte

is trapped and not drained out

bull 2 Difference in the concentration of ions in the electrolyte

consequence of concentration

differences of ions or dissolved

gases in the electrolyte solution and

between two regions of the same

metal piece

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 24

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

The chronology of a Crevice

Stage One induction

At time zero the oxygen

content in the water

occupying a crevice is equal

to the level of soluble

oxygen and is the same

everywhere

Stage Two Restricted Convection

Difficult access caused by the crevice

geometry oxygen consumed by

normal uniform corrosion is very soon

depleted in the crevice The corrosion

reactions now specialize in the crevice

(anodic) and on the open surface

(cathodic)

Stage Three Obstruction

and Electro migration

bullThe metal ions produced by the

anodic corrosion reaction readily

hydrolyze giving off protons (acid)

and forming corrosion products

The pH in a crevice can reach

very acidic values sometimes

equivalent to pure acids 9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 25

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of corrosion Erosion

bull Flow removes protective layer

bull New protective layer forms using up metal

bull Promoted bybull High flow

bull Turbulent conditions

bull Particulates in fluid

bull Erosionndashcorrosion is commonly found in piping especially at bends elbows and abrupt changes in pipe diametermdashpositions where the fluid changes direction or flow suddenly becomes turbulent

bull Propellers turbine blades valves and pumps are also susceptible to this form of corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 26

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Erosion corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 27

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of corrosion Erosion

bull Four Categories

bull 1 Solid particle erosion

bull Solid particle carried by gas

bull Corrosion rate = f(velocity size shape strike angle) of particle

bull Ductile materials 20 to 30 OC

bull Brittle materials 90 OC

bull 2 Slurry erosion

bull Liquid stream carry particle against metal surface

bull 3 Liquid droplet erosion

bull Liquid droplets striking metal surface causing plastic depressions

bull Stream turbines and AC flying at high speed through rainstorm

bull 4 Cavitation

bull Propellers and impellers turbine blades valves and pumps at (suction end) also susceptible to this form of corrosion

Sever deterioration

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 28

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of corrosion Erosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 29

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Cavitation Erosion

Cavitation occurs when a fluids

operational pressure drops below its

vapor pressure causing gas pockets

and bubbles to form and collapse

This form of corrosion will eat out the volutes and impellers of centrifugal

pumps amp valve seats It will contribute to other forms of erosion corrosion

such as found in elbows and tees

Cavitation should be designed out by reducing hydrodynamic pressure

gradients and designing to avoid pressure drops below the vapor pressure of

the liquid and air ingress

bull Mechanically Aided Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 30

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Fretting corrosion

bull It refers to corrosion damage at the asperities under the category of erosion corrosion

bull of contact surfaces

bullMechanically Aided Corrosion

bullOccurs when mating parts have little relative motion

bullSplined shaft Keyed shaft pressed fittings

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 31

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Fretting corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 32

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Intergranular

bullDue to difference in the electrical potential with in the metal itself ( Similar to pitting)

bullThe electrical difference is between the grain boundary and the grain ndash causing the higher corrosion rate at the grain boundaries

bullThis potential difference is because of difference in composition between the two areas

bull Improperly heat treated stainless steel

bullMore chromium precipitation at the grain boundary and not enough chromium within the grain

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 33

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Forms of Corrosion Intergranular Corrosion

Intergranular Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 34

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

35

SL = Short longitudinal

ST = Short transverse

LT = Longitudinal transverse

Wrought

aluminum

alloys

Forms of Corrosion Intergranular

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

36

Forms of Corrosion Intergranular

Intergranular corrosion is an especially severe problem in the

welding of stainless steels when it is often termed weld decay

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Selective leaching

bull Is found in solid solution alloys and occurs when one element or constituent is preferentially removed as a consequence of corrosion processes

bullDealloying

bull intragranular Dealloying

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 37

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Environmental cracking

bull A corrosion cracking caused by a combination of conditions

bull Stress Corrosion Cracking (SCC) - Results from the combined action of an applied tensile stress and a corrosive environment

bull SCC = Tensile stress + corrosive environment bull Corrosion fatigue - Result of the combined action of an alternating or

cycling stresses and a corrosive environmentbull Hydrogen embrittlement

bull Stress that cause environmental cracking arise from

bull Residual cold work welding grinding thermal treatment or may be externally applied during service and to be effective must be tensile (as opposed to compressive)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 38

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Environmental cracking

Stress Corrosion Cracking

Fatigue stress

corrosion Cracking

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 39

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

40

Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

41

Hydrogen embrittlement

bull Hydrogen-induced cracking and hydrogen stress cracking

bull Various metal alloys specifically some steels experience a significant reduction in ductility and tensile strength when atomic hydrogen (H) penetrates into the material

bull Hydrogen in its atomic form (H) diffuses interstitially through the crystal lattice

bull Concentrations as low as several parts per million can lead to cracking

bull Hydrogen embrittlement does not affect all metallic materials equally The most vulnerable are high-strength steels titanium alloys and aluminium alloys

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Hydrogen embrittlement

bull Favorable conditions

bull pickling of steels in sulfuric acid

bull electroplating

bull presence of hydrogen-bearing atmospheres (including water vapor) at elevated temperatures such as during welding and heat treatments

bull presence of what are termed ldquopoisonsrdquo such as sulfur (ieH2S) and arsenic compounds

bull these substances retard the formation of molecular hydrogen and thereby increase the residence time of atomic hydrogen on the metal surface

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 42

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

43

RECAP Fatigue limit load in corrosion-assisted fatigue

bull Fracture is brittle and the cracks are most often transgranular as in stress-corrosion cracking but not branched

Corrosion-fatigue crack

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

RECAPhellipMain

forms of corrosion regrouped

by their ease of

recognition

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 44

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

gtgtgtgt GROUP ASSIGNMENT 01

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 45

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

bull Pitting helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR1

bull crevice helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR2

bull galvanichelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR3

bull intergranularhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR4

bull erosionndashcorrosion helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR5

bull Cavitation helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR6

bull FrettinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR7

bull stress corrosionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR8

bull selective leachinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR9

bull uniform helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipGR10

GROUP ASSIGNMENT 04 Sub date 21st September 19Write short note with practical example from the industryManner in which the corrosion is manifest and prevention methods

DIRECT COPY AND PASTE FROM ANY SOURCE9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 46

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Corrosion Prevention method

1 Selection of appropriate material for the environment concerned

bull Dissimilar metals not to form a cellbull Sacrificial protection ndash Mg or Zn

2 Selection of appropriate designbull Avoid potential crevicesbull Avoid Stress concentration

3 Modification of the environmentbull Corrosion inhibitors in liquids (chromate or phosphate

ions)bull Removing residual water vapor in packagebull include desiccant such as Silica gel within package

4 Use of protective coatingsbull Paintsbull Metallic coatings ndash Zinc coated steelbull Electroplating ndash Cr or Ni plating

Mg++

Fe pipeMg

e-

concrete

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 47

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Prevention of Corrosion-Related Failures of Metals

bull Material Selection

bull Corrosion allowance

bull Change in the environment

bull Change in the alloy or heat treatment

bull Design change

bull Use of galvanic protection (cathodic protection amp anodic potection)

bull Use of inhibitors

bull Use of nonmetallic coatings and liners

bull Application of metallic coatings

bull Use of surface treatments thermal spray or other surface modifications

bull Corrosion monitoring9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 48

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

bull R amp D on corrosion focus o four area of corrosion pretension control methods

1 Prevent ndash The chance of occurrence 2 Detect ndash Analyze the type of corrosion3 Predict - Intensity of damage4 Manage ndash take corrective action accordingly

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 49

Prevention of Corrosion

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 50

Prevention of Corrosion-Retard corrosion (Stop corrosion cell activity)

Use of inhibitors

Materialselection

Highly resistance to

corrosion

Design system

Any of the corrosion cell can not exist

New material

Manufacturing

method

Surface treatment

bullPaints

bullCPC

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Corrosion Prevention method Cathodic Protection

One of the most common methods of corrosion mitigation in the pipeline and storage tank industry mitigates corrosion by eliminating all anodic areas on an underground metallic structure

bull Two methodsbull Connect a

sacrificial metal bull Impressed current

cathodic protection

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 51

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Impressed current cathodic protection(ICCP)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 52

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

53

Corrosion-Preventive Maintenance

bullAn adequate cleaning

bullDetailed inspection for corrosion and failure of protective systems

bullPrompt treatment of corrosion and touchup of damaged paint areas

bullKeeping drain holes free of obstruction

bullDaily wipe down of exposed critical areas

bullMaking maximum use of protective covers

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Corrosion ndash Preventive Maintenance

bullElectroplating

bullMetal Spraying (Metallizing)

bullParco Lubrizing

bullAnodizing

bullAnodized surfaces

bullAlodizing

bullSurface Treatment

bullProtective paint finishes

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 54

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 55

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 56

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 57

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Design and assembly can affect localized corrosion by creating crevices and traps where corrosive liquids can accumulate

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 58

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Constructive Uses of Corrosion

bullElectrochemical Machining ndash EDM

bullElectropolishing

bullSacrificial Metal (Cathodic) protection

Corrosion prevents corrosion

bullGalvanic corrosion - used in batteries

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 59

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Validation of corrosion damage in pipes

bull Around 2000 the Royal shell company has launched a program of ldquointelligent pig runsrdquo An intelligent pig is a device that can be sent through a large-diameter pipe to measure corrosion defects

bull The Oil amp gas company is interested in using these runs to calibrate the failure model so that the model can be used to support the selection of pipes to be pigged in the future

bull The data consist of list of defects their position on the pipe and their depth( of wall thickness removed)

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 60

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 61

Fatigue failure

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Fatigue failure

bull Less than 10 of bearing reach their designed lifetime

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 62

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 63

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

DRILL 1 Below is a picture representing one of the corrosion protection

method Discuss in brief what you know about it

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 64

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Drill 2 Galvanic corrosion

If the use of undesirable couple of metal can not be avoided what can be done to minimize the

galvanic corrosion that may result

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 65

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

DRILL 3 Discuss on the sketch below

Galvanic coupling caused by riveting plates9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 66

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

DRILL 3A GALVANIC CORROSION

bull If aluminum rivets were used on steel plates the rivets would corrode extremely rapidly Explain

bull Which one of the following riveting system is advisable Why

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 67

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Drill 4 Forms of corrosion

Discuss what will happen in the fitting

Steel

Copper

Zinc coating

H2O

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 68

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Drill 5 Observe the picture shown below Discuss the type of

failure and the remedial actions

ldquohorseshoerdquo

shape using a

nut-and bolt

assembly-

While

immersed in

seawater

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 69

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

70

DRILL 6 Discuss on the figure shown below

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

RECAP corrosionThe science of corrosion

bull A Silent Pervasive Enemy that destroys the very item we count on every day

bull It occurs naturally (Simple law of physical science)

bull Examplesbull Brake failure in transport systembull Overhead crane cable failure

Cost of corrosionbull Direct costbull Indirect costbull gtgt investing in the prevention of corrosion

reduces total cost by ~ 40USA in 2002 congress director of department of defense developed a program corrosion prevention and controlgtgtgt corrosion education at the university level

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 85

Corrosion Protection

bull Material selection in the designed stage (might not be possible in all cases)

bull Engineers unintentional design and use a manufacturing methods that might promote corrosion

bull Initial corrosion protection procedures and designs might be more costly than the life time maintenance cost of equipment

bull Inspectionbull Treatmentbull Repairsbull combat

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

Todayrsquos challenge

bull Aging infrastructures

bull Simulation of the real corrosion environment to demonstrate in the research area

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 86

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-

EXAMPLES

9142019 EMeng 1081- Sem III 2019 AYLECTURER FANUEAL SAMSON 87

Zn

HCL

CASE 1 NO DISOLVED OXYGEN PURE HCL

Reaction Zn + 2HCL ZnCl2 + H2

Zn Zn ++

Oxidation (anodic reaction)

Two Half cell

Reaction2H++ 2H = H2

reduction (Cathodic reaction)

- 2e-

+ 2e-