Bab 03 Linepipe Material Selection

7/27/2019 Bab 03 Linepipe Material Selection

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BAB 3

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Bab 3 Linepipe Material SelectionBab 3 Linepipe Material Selection

sign

Parameter Design Enviromental DataRouteSurvey

Pip

eline

De

PIPELINE DESIGN

Route

Buckling

Wall Thickness

Cathodic

Fatigue

ThermalExpansion

Pipeline Codes & StandardsPipeline Codes & Standards

MaterialSelection

On Bottom-Stability

e ec on

Spanning

ro ec on


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Linepipe Material SelectionLinepipe Material Selection

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1. Spec. and Req. of Linepipe1. Spec. and Req. of Linepipe

z The following properties :

9 Strength9 Toughness

9 Ductility


9 e a y

9 Corrosion Resistance


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1. Spec. and Req. of Linepipe (cont)1. Spec. and Req. of Linepipe (cont)

z Steel pipe are manufactured to particular

specifications :

Chemical composition

Strength data

Tolerance


z The well-known spec. for pipeline = API 5L

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2. Linepipe Metallurgy and Pipe2. Linepipe Metallurgy and PipeGradesGrades

HISTORY

9Mid 1950 API 5LA, B and 5L X42, X52, and X56.

Wall thickness less than 0.50

The ield stren th of the X52/X56 steel were


obtained by use of relatively rich alloy content,

and cold working.


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2. Linepipe Metallurgy and Pipe Grades2. Linepipe Metallurgy and Pipe Grades(cont)(cont)

9 Late 1950 The importance of good weldability become recognized

because of frequent of hydrogen cracking in the HAZ ingirth weld.

Increased strength from microalloying addition ofNiobium (0.04%) and/or Vanadium (0.08%).

The strength of first fine grained High Strength Low Alloy


of grain size control and normalizing after hot rolling.

The normalized steel plates contained :

Level of Nb & V with C = 0.2

Carbon Equivalent = 0.45

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9 1960 : The steel plate process route develop from normalizing to

controlled rolling (CR). This practice consisted of low temperature finishing of the

plates during hot rolling on the plate mill and thus producinga finer ferrite pearlite microstructure

The implementation of CR can reduce cost, because :


CR was being practiced from 1968 to produce pipe havingSMYS up to X65 (1968)

Avoiding normalizing

Reduction in C level, from 0.20 % to 0.12%


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9 Mid 1960s : The early higher steel pipes, as the strength increased,

failure resulted in fractures over long distance.

Research showed that the distance a fracture wouldpropagate was a function of temperature and toughness

The requirement designed The fracture wasductile at operating temperature or operating temperature


was higher than brittle-ductile toughness transition

temperature of the steel Research showed that a reduction of pearlite fraction and

additional grain refinement was needed to meet thetransition temperature requirement

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9 1970 Laboratory and industrial investigation showed that with a

proper choice of chemical composition & CR schedules,finer-grained acicular ferrite (AF) steel, could be producedwith guaranteed superior weldability & yield strength levelsup to X70

In the development of the accelerated cooling (AC)


ec no ogy, ue o e g er coo ng ra es nrolling, leaner compositions can be used to obtain finestructure

Low sulphur (S) contents (


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9 1980

This finding together with the need of lower C

level (Weldability and SCC) influenced the steel

making and rolling practice

This led to steelmaking practices with very strict


con ro o res ua e emen s , , , , an

and a gradual switch from Controlling Rolling(CR) to Thermo-Mechanically Controlled Rolling

(TMCP)

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2. Linepipe Metallurgy and Pipe2. Linepipe Metallurgy and PipeGrades (cont)Grades (cont)

9 For thick wall thickness (t>30 mm), homogeneous

through thickness properties cant met by TMCP,

met by quenching and tempering process (Q &T).

9 Q & T pipe steel have both high yield strength and

good toughness without necessity for high


.

9 Currently, For strength up to X52, rolled normalized

carbon-manganese steel is commonly used.


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3. Philosophy of Materials Selection3. Philosophy of Materials Selection

z The fundamental criteria for the selection of

material :

9 Mechanical properties

9 Corrosion resistance


9 Cost

9 Availability

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3. Philosophy of Materials Selection3. Philosophy of Materials Selection(cont)(cont)

z The basic information to evaluate pipelinematerial selection :

1) Maximum operating pressure

2) Preliminary determination diam. & wallthickness


3) Material strength requirements to containpressure

4) Max & min design temperature

5) Method of production in special condition


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6) Composition of gasses and fluids

7) Erosion problems (i.e. the presence of

sand)

8) Corrosive media (i.e. H2S, CO2, O2, etc)


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3.1. Material Selection Based on Corrosion

Resistance :1) Low Alloy Steels

2) High Alloy Steels



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z Low Alloy Steel

Basis for low alloy steels:

Maximum hardness limitation

Maximum nickel content of 1%


ea rea men con on

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z Low Alloy Steel

Hydrogen induced cracking (HIC) is a further formof hydrogen sulphide corrosion which may occur,

especially in low alloy material.

Today, considered only to be a problem at partial


pressure o 2 over . ps w en precau on

against SSC must be adopted.


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z Low Alloy Steel

Precaution to minimize the risk of corrosion:

1) Material compositional control

2) Specialized corrosion testing


3) omp ance w - -

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z High Alloy Steel

A chloride containing environment, the finalchoice of Corrosion Resistant Alloys (CRA)

should be on the basis of its resistance to pitting

and crevice corrosion.


s can e es a s us ng e ng es s ance

Equivalent (PRE)

NMCPREOR

%16%3.3% ++=


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z Application of High Alloy Material

1) Duplex Stainless Steel Austenite : Ferrite = 50 : 50

There are 2 types : one based on 22% chromium, and theother based on 25% chromium (called super duplexstainless steel)

=


,

resistant to pitting up to 30 C, but susceptible to crevicecorrosion at lower temperatures

25 % chromium super duplex stainless steel has a PRE >34, resistant to pitting & crevice corrosion up to T = 60 C.

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2) Austenitic Stainless Steel (typically 316 L)

Excellent corrosion resistance to CO2 dan H2S PRE = 27

At T > 60 C, austenitic stainless steel are liable

to stress corrosion cracking by chloride.



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3) High Nickel Alloys Containing up to 25-65 % Ni

No limitation are given for CO2 corrosion,whereas H2S corrosion resistance is determineby nickel content

For nickel content of 25 52 % tem erature


limitation are 160 C 275 C Incoloy alloy 825 & inconel alloy 625 are

probably most widely used in pipeline

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4) High Nickel Alloys

Containing up to 25-65 % Ni No limitation are given for CO2 corrosion,

whereas H2S corrosion resistance is determineby nickel content

For nickel content of 25 52 % tem erature


limitation are 160 C 275 C

Incoloy alloy 825 & inconel alloy 625 areprobably most widely used in pipeline


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5) CRA Clad Carbon Steel

Where high nickel alloys are selected,

consideration should be given to the use of clad

materials due to high cost of solid alloy pipes

The use of duplex stainless steel clad pipes is


m e ue o e cu y n ma n a n ng e

required duplex structure of the cladding duringheat treatment of carbon steel pipe following

pipe manufacture.

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3.2. Selection Based on Mechanical Requirement :

1) Yield Strength2) Fracture Control Design Requirement

3) Weldability requirement



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3.2.1. Yield Strength :

Low Al loy Steels

Yield Strength of 70 ksi are now feasible provide that installation

& operation condition are satisfied.

Controlled rolled steels and normalized steel used additions of

Titanium, Vanadium, and/or Niobium to give enhanced yield


strength capability through precipitation hardening & grain

refinement

Satisfactory properties have been obtained for pipe grades up to

X65, using controlled rolled steel & normalized steels,

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Low Alloy Steels (cont)z For higher strength steel (i.e. X70 & X80) development have

been centered around the use of thermomechanical treatmentcoupled with accelerated cooling

z These process have enabled the production of higher strengthsteels with reduced quantities of alloying elements, in particularwith low carbon contents (less than 0.01%)


z For optimum strength/toughness combination, acceleratedcooling should be started around Ac3 transformationtemperature.


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High Alloy Steels Only duplex (austenitic/ferritic) stainless steel can be used

for high strength requirement

Duplex stainless steel is normally supplied in the following

form solution annealed (typically at 1050 C).

High nickel stainless steels & austenitic stainless steel


have to be used in the clad form, as they have limited yield

strength used as internal cladding o conventionalhigh strength low alloy steel.

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3.2.2. Fracture Control Design Requirement

In large diameter pipe, fracture control must consider not

only base material but also weld seam and Heat Affected

Zone (HAZ)

The principal demands placed on pipe materials for gas

transmission lines is that toughness properties remain


Fracture mechanics has been constantly improved andupdated as research and testing have highlighted the

controlling parameters.

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3.2.2. Fracture Control Design Requirement (cont)

This is true as long as welds and base material are virtuals

free from defects, the weld treating cycle has not affected

the transition temperature, and large stress concentration

factor dont exist.

For high strength ductile material, these condition dont


,

developed.

Full scale experiment have led to the development of

semi-empirical formulae for determining the critical flaw

size in pipelines


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3.2.2. Fracture Control Design Requirement (cont)For fracture initiation, if the pipe material is ductile with anestablish minimum toughness level and the crack go throughwall. Formula is given by :

E

ARC C

2

HV

=


i

Where :

CV = Charpy energy at 100% shear(ft/lbs)H = nominal hoop stress (ksi)

R = Pipe radius (inch)

AC = Cross sectional area of Charpy

impact specimen (inch2)

E = Youngs modulus (103 ksi)

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3.2.2. Fracture Control Design Requirement (cont)

It has been long known that for very toughmaterials crack can propagate over large distance

in gas transmission pipelines.

From semi-empirical formulae developed by the


a e e emor a ns u e, corre a on as ma e

between Charpy energy & the arrest of fracture

propagation.


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Where :

CV = Charpy energy required

(ft/lbs)H = nominal hoop stress (ksi)

R = Pipe radius (inch)t = Wall thickness (inch)

z Formula :

C3

1

t

2

HV A)(R0.0873C =


AC = Cross sectional area of

Charpy impact specimen(inch2)

NOTE : These formula werent developed using

The high strength pipeline materials (i.e. X65)

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3.2.3. Weldability Requirement :

1) Low Alloys Steels2) High Alloy Steels



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3.2.3. Weldability Requirement :

A pre-requisite of competent pipeline construction &

installation, which can often be undertaken in adverse

weather condition, is that the pipeline steels show good

weldability

The following welding processes available for field welding


z Shield manual metal arc welding, using cellulosic electrodesz Shield manual metal arc welding, using basing, low hydrogen

electrodes.

z Fully mechanised gas shielding arc welding

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z Low Alloy Steels Field weldability of high strength low alloy steels is greatly

enhanced by the use of low carbon content :

++

+++

+=

1556

NiCuVMoCrMnCCE


,weldable the steel

This formula was originally developed for higher carbonsteel (i.e. above 0.12 %) which achieved strength mainly bycarbon & manganese and by heat treatment


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z Low Alloy Steels The quantitative statements given using this formula to

calculate weld hardenability cant really be considered

accurate for modern large diameter pipe steel with low

carbon, vanadium, and nickel addition.

E uation should be considered for determinin if


preheating is necessary:

BVNiMoCrCuCrSi

CPcm

51060152030

+

+

+

+

+++

+=

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z High Alloy Steels

High alloy steels are weldable using:

a) Gas tungsten Arc Welding (GTAW)

b) Shielding Metal Arc Welding (SMAW)

c) Gas Metal Arc Welding (GMAW)

Thermal conductivity of high alloy steels (e.g. duplex


stainless steel) = 1.5 carbon steel

Problem of carbide precipitation & sigma phase formation

caused by heat retention, can lead to enhanced

susceptibility to corrosion & embrittlement


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z High Alloy Steels Microalloying with V and Nb to achieve a more

fine grained structure is used for strength classesup to X60.

Thermomechanically treated low-carbon steel isused for strength classes X60 X70 and above


For strength above X70, quenched & tempered,or in certain cases, TMCP steel may be used toobtain necessary toughness while maintainingweldability

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Non Metallic PipeNon Metallic Pipe


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Non Metallic PipeNon Metallic Pipe

Thermoplastic (PVC) :Thermoplastic (PVC) : Corrosion resistanceCorrosion resistance

m e pressure an empera urem e pressure an empera ure

Shall be buried or supportedShall be buried or supported

Resistance to UVResistance to UV

Composite (Fiber Reinforced Plastic)Composite (Fiber Reinforced Plastic)

Higher pressure resistance than PVCHigher pressure resistance than PVC Resistance to vibrationResistance to vibration

Resistance to ultravioletResistance to ultraviolet

Fitting methods ?Fitting methods ?

NDT methods ?NDT methods ?


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LIMITATION OF THERMOPLASTIC PIPELIMITATION OF THERMOPLASTIC PIPE

Limited P and TLimited P and T

,,

PE : T < 40 C, Stress < 625 psiPE : T < 40 C, Stress < 625 psi

Shall be buried (to protect from sunlight, fire, mechanicalShall be buried (to protect from sunlight, fire, mechanical

damage)damage)

Low resistance to vibrationLow resistance to vibration

Fiberglass Reinforced Plastic (FRP) PipeFiberglass Reinforced Plastic (FRP) Pipe

Excellent corrosion resistance propertiesExcellent corrosion resistance properties

Ease of installationEase of installation

Low maintenance costLow maintenance cost

Applications : Freshwater, potable water, chilled water,Applications : Freshwater, potable water, chilled water,

seawater, chlorinated seawaterseawater, chlorinated seawaterHigher tensile strength than HDPE pipeHigher tensile strength than HDPE pipe

T < 95T < 95 ooC.C. P < 20 barP < 20 bar (LR)(LR)

Not recommended for depressurized systemsNot recommended for depressurized systems

, ,, ,damage)damage)

Low resistance to vibrationLow resistance to vibration


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Linepipe Material Selection

Case Study

MethodologyPreliminary study & Data Collection

Establish Material Criteria

Choose Material Alternatives

Generate material type-properties-operational

criteria matrix

Material

Accepted

?

Material Recommendation

NO

YES

Unrecommended

Material

Back


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Fluid Composition

z Fluid system flow inside the line pipe consist of :

Hydrocarbon

Water

Gas

Impurities

Wax.. etc

Linepipe Material Alternatives

Stainless Steel

Duplex Stainless Steel

Stainless Steel 304

Internally Clad Pipe, Carbon Steel

Outer Material

304L SS - Carbon Steel Clad Pipe

Stainless Steel 316

Nonferrous Alloy

Cu - Ni Alloy Ni Alloy

Aluminum - Magnesium Alloy

Composite Pipe

316L SS - Carbon Steel Clad Pipe

Duplex SS - Carbon Steel Clad

Pipe CuNi Alloy - Carbon Steel Clad

Pipe

Internally Coated Carbon Steel

Fusion Bonded Epoxy (FBE)

(GFRP)

Carbon / Epoxy Composite

High Density Polyethylene

(HDPE)

Coating

Coal Tar Epoxy Coating

Ceramic Epoxy Coating

Carbon Steel


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Stainless Steel

Stainless steel type: Duplex Stainless Steel

Stainless Steel 304

a n ess ee

Material Type Duplex Stainless Steel Stainless Steel 304 Stainless Steel 316

Excelent Corrosion Resistance

High Strength

Weldable by all standard methods

Better stress-corrosion cracking

resistanceExcellent forming

Susceptible to stress cracking Susceptible to stress cracking

Advantages

Excellent in a range of

atmospheric environments and

many corrosive media -

generally more resistant than

304.

Excellent in a wide range of

atmospheric environments

and many corrosive media.

Has lower stiffness comparedto Polypropylene

Susceptible to sensitisation

(grain boundary carbideprecipitation) when heated

until 425-860 0C

High mould shrinkage and

poor UV resistance

Cannot be hardened by

thermal treatment.

ExpensiveDisadvantages

Nonferrous Alloy

Cu Ni alloy type:

90Cu - 10Ni

80Cu - 20Ni

Ni alloy type:

70Ni 30Cu

Inconel

- 70Cu - 30Ni

Material

Type

90Cu - 10Ni 80Cu - 20Ni 70Cu - 30Ni 70Ni - 30Cu Inconel

Aluminum -

Magnesium

Alloy

excellent corrosion

resistance in

reducing chemical

environments and in

sea water

excellent

mechanical

properties and

presents the

desirable

typically

displays

excellent

electrical andAdvantag

excellent electrical and thermal conductivities,

outstanding resistance to corrosion, ease of

fabrication, and good strength and fatigue

resistance . Can be readily soldered and

brazed. Can be welded by various gas, arc,

Alloy

Good resistance to

corrosion and heatLow density

Expensive

Lower strength

than

ferousbased

Metal

com na on o g

strength and good

workability.

erma

conductivity,

exce en uc y an

can be readily

fabricated and

formed into a variety

of shapes.

Very expensivesometimes have limited usefulness in certain environments because

of hydrogen embrittlement or stress-corrosion cracking (SCC).

esand resistance methods. Can be plated,

coated with organic substances, or chemically

colored to further extend the variety of

available finishes.

Disadvan

tages


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Composite Pipe

Composite type: Glass Fiber Reinforced Plastics (GFRP)

Carbon / Epoxy Composite

Hi h Densit Pol eth lene HDPE

Aliphatic

Amine Cured

Epoxy

Anhydiride

Cured

Epoxy

Aromatic

Amine Cured

Epoxy

Good mechanical

properties

Good low temperature impact

resistance

Good chemicalExcellent chemical resistance

GFRP

Material

Type

Carbon / Epoxy

CompositeHDPE

Advantag

Corrosion Control - Resists corrosion

caused by CO2, H2S and salt water

Reduced cost of the piping and reduced

res s ance

Lowest shrinkage(highest stability).

Exceptional resistance to rapid-crack propagation

Disadvan

tagesExpensive

May react with oxygen and strong

oxidizing agents, such as chlorates,

nitrates, peroxides, etc.

Low performance in high temperature

es man enance cos s

Reduced weight on the platform deck

Internally Clad Pipe, Carbon Steel Outer Material

Internally Clad type:

304L SS - Carbon Steel Clad

pe

316L SS - Carbon Steel Clad

Pipe

Duplex SS - Carbon Steel Clad

Pipe

-

PipeMaterial Type

-

Carbon Steel

-

Carbon Steel

-

Carbon Steel

-

Carbon Steel

Advantages Combining the features of metallurgical & mechanical

DisadvantagesExpensive

Need High Level on joining


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n erna y oa e ar on

Steel Fusion Bonded Epoxy (FBE) Coating

Coal Tar Epoxy Coating

Ceramic Epoxy Coating

Material Type FBE Coating Coa l Tar Epoxy Coating Ceramic Epoxy Coating

Advantages

ease of application,Suitable for intermittent exposure to

300FHoliday (pinhole) testing per applicable ASTM, NACE, And

SSPC Industry standards

less waste of

material,Excellent chemical resistance

Can be applied to the bell and spigot of ductile iron pipe for

total "Wet Area" protection

rapid appl icat ion, Excel lent adhesion

Field repairs are completed with the same product as is

applied at the factory, not coal tar epoxy or "Pipe Joint

Compound

cure schedules,

which means faster

production rates.

Convenient 2A to 3B mix ratio by

volume

Can be stored outside indefinitely without disbondment from

the substrate (some chalking will occur)

Finished coatedpieces can be moved

to the storage area

within minutes after

the application

High build to 40 mils per coatxce ent a ras on res stance p a ase a um na ceram cs -

Hardness just below s diamond)

100% solids, 0.0 lbs. VOC

Superior bonding to the substrate (three times that of any other

ceramic epoxy or polyethylene product)Sprayable, Tough and flexible

Moisture insensitive and Low

temperature curing

Disadvantages

Do not use below 40F

Store material under dry conditions

For best results, applied condition

material to 70F or higher.

Carbon Steel

Material Type Carbon Steel

Advantages

Serviceable under a wide variety of conditions and especially

adaptable to low-cost techniques of mass production.

Ease of fabrication

adequate strengthexcellent finishing characteristics to provide attractive

appearance after fabrication

compatibility with other materials and with various coatings and

processes.

Not expensive

Disadvantages

Low corrosion resistance

Back


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General Matrix

SelectedChemical/corrosion

Resistance

DegradationResistance Construction/Joinability Maintainability

Availability

No Materi al

Resistance

to injection

Fluid

External

Corrosion/

Degradation

Resistance

Stren

gth

Pressure

Containment

Tough

ness

Construction

/ Joinability

Expansion

/ Flexibility

Damage

Due To

Accidental

Load

Maintaina

bility

Life

time

Availabil

ityCost

Final

Score

20% 5% 10% 5% 5% 10% 5% 3% 7% 5% 10% 15% 100%

1 X1 B A A A A C C A A A D E 72

2 X2 C A A A A B A A A A B C 82

3 X3 B A A A A B A A A A B D 83

a e r aMechanical

Strength Cost

5 X5 A A C C C C A C C B D B 74

6 X6 A A C C C B A C C B D B 767 X7 A A B B B C C B C B D B 76.6

8 X8 A A A A A E A A A A E E 72

9 X9 E C C C C C B C C C C C 53

10 X10 B C E E E B A E A D B A 68.6

Note: A: Very good; B: Good; C: Fair; D: Bad; E: Very bad

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Bab 03 Linepipe Material Selection