API 570 Course Notes- Joshi

8/11/2019 API 570 Course Notes- Joshi

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API 570 PAPI 570 PIPINGIPING

IINSPECTORNSPECTOR

PPREPARATORYREPARATORY CCOURSEOURSE

COURSE NOTES

Conducted by

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API 570 PAPI 570 PIPINGIPING IINSPECTORNSPECTOR

PPREPARATORYREPARATORY CCOURSEOURSE

TABLE OF CONTENTSTABLE OF CONTENTS

CHAPTERCHAPTER DESCRIPTIONDESCRIPTION

1.1. Overwew o! API "#$Overwew o! API "#$

%.%. Overvew o! RP& API "#'Overvew o! RP& API "#'

(.(. Overwew o! AS)E B (1.(Overwew o! AS)E B (1.(

'.'. Overvew o! AS)E B 1*."Overvew o! AS)E B 1*."

".". Overvew o! AS)E Secton I+Overvew o! AS)E Secton I+

*. Overvew o! AS)E Secton ,*. Overvew o! AS)E Secton ,

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CHAPTER&1

"#$ PIPIN- INSPECTION CODE

1. INTRODUCTION TO API&"#$

1.1 SCOPE

1.1.1 Cover/e 0

API 570 covers inspection, repair, alteration, and rerating procedures for metallic

piping systems that have been in service.

Rer ; The or! necessary to restore a piping system to a condition suitable

for safe operation at the design condition.

A2terton3 " A physical change in any component that has design implications

affecting the pressure containing capability or fle#ibility of a piping system

beyond the scope of its design.

Rertn/ " A change in either or both the design temperature or the ma#imum

alloable or!ing pressure of a piping system. A rerating may consist of an

increase, a decrease, or a combination of both. $erating belo original design

conditions is a means to provide increased corrosion alloance.

1.1.% LI)ITATIONS 0

API 570 shall not be used as a substitute for the original construction

re%uirements governing a piping system before it is placed in service.

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1.% SPECIFIC APPLICATIONS

1.%.1 Inc2uded F2ud Servce3 0

API 570 applies to piping systems for process fluids, hydrocarbons, and

similar flammable or to#ic fluid services, such as the folloing.

a. $a, intermediate, and finished petroleum products.

b. $a intermediate, and finished chemical products.

c. &atalyst lines.d. 'ydrogen, natural gas, fuel gas, and flare systems.

e. (our ater and ha)ardous aste streams above threshold limits, as

defined by *urisdictional regulations.

f. 'a)ardous chemicals above threshold limits, as defined by

*urisdictional regulations.

1.%.% E4c2uded nd Oton2 Pn/ Sy3te53 "

The fluid services and classes of piping systems listed belo are e#cluded from the

specific re%uirements of API 570 but may be included at the oner+s or user+s

oner-user+s option.

a. /luid services that are e#cluded or optional include the folloing.

. 'a)ardous fluid services belo threshold limits, as defined by

*urisdictional regulations.

1. 2ater including fire protection systems , steam, steam3condensate,

boiler feed ater, and &ategory 4 fluid services, as defined in A(6

8.8

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b. &lasses of piping systems that are e#cluded or optional are as follos "

. Piping systems on movable structures covered by *urisdictional

regulations, including piping systems on truc!s, ships, barges, andother mobile e%uipment.

1. Piping systems that are an integral part or component or rotating or

reciprocating mechanical devices, such as pumps, compressors,

turbines, generators, engines, and hydraulic or pneumatic cylinders

here the primary design considerations and-or stresses are derived

from the functional re%uirements of the device.

8. Internal piping or tubing of fired heaters and boilers, including tubes,

tube headers, return bends, e#ternal crossovers, and manifolds.

9. Pressure vessels, heaters, furnaces, heat e#changers, and other fluid

handling or processing e%uipment, including internal piping and

connections for e#ternal piping.

5. Plumbing, sanitary seers, process aste seers, and storm seers.

:. Piping or tubing ith an outside diameter not e#ceeding that of P(


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%. DEFINITIONS

%.1 APPLICATION CODE 0

The code, code section, or other recogni)ed and generally accepted engineering

standard or practice to hich the piping system as built or hich is deemed by

the oner or user or the piping engineer to be most appropriate for the situation,

including but not limited to the latest edition of A(6 8.8

%.% AUTHORI6ED INSPECTION A-ENC7 0

4efined as any of the folloing. "

a. The inspection organi)ation of the *urisdiction in hich the piping system is

used.

b. The inspection organi)ation of an insurance company that is licensed or

registered to rite insurance for piping systems.

c. An oner or user of piping systems ho maintains an inspection

organi)ation for activities relating only to his e%uipment and not for piping

systems intended for sale or resale.

d. An independent inspection organi)ation employed by or under contract to

the oner or user of piping systems that are used only by the oner or

user and not for sale or resale.

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e. An independent inspection organi)ation licensed or recogni)ed by the

*urisdiction in hich the piping system is used and employed by or under

contract to the oner or user.

%.( AUTHORI6ED PIPIN- INSPECTOR 0

An employee of an authori)ed inspection agency ho is %ualified and certified to

perform the functions specified in API 570. A nondestructive 46 e#aminer is

not re%uired to be an authori)ed piping inspector. 2henever the term inspector

is used in API 570, it refers to an authori)ed piping inspector.

%.' AU+ILLAR7 PIPIN- 0

Instrument and machinery piping, typically small3bore secondary process piping

that can be isolated from primary piping systems. 6#amples include flush lines,

seal oil lines, analy)er lines, balance lines, buffer gas lines, drains and vents.

%." CUI 0

&orrosion under insulation, including stress corrosion crac!ing under insulation.

%.* DEADLE-S "

&omponents of a piping system that normally have no significant flo. 6#amples

include the folloing " blan!ed branches, lines ith normally closed bloc!

valves, lines ith one end blan!ed, pressuri)ed dummy support legs, stagnant

control valve bypass piping, spare pump piping, level bridles, relief valve inlet

and outlet header piping, pump trim bypass lines, high point vents, sample

points, drains, bleeders, and instrument connections.

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%.# DEFECT "

An imperfection of a type or magnitude e#ceeding the acceptable criteria.

%.8 E+A)INER "

A person ho assists the inspector by performing specific nondestructive

e#amination 46 on piping system components but does not evaluate the

results of those e#aminations in accordance ith API 570, unless specifically

trained and authori)ed to do so by the oner or user. The e#aminer need not be%ualified in accordance ith API 570.

%.9 HOLD POINT 0

A point in the repair or alteration process beyond hich or! may not proceed

until the re%uired inspection has been performed and documented.

%.1$ I)PERFECTIONS "

/las or other discontinuities noted during inspection that may be sub*ect to

acceptance criteria during an engineering and inspection analysis.

%.11 INDICATION "

A response or evidence resulting from the application of a nondestructive

evaluation techni%ue.

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%.1% IN:ECTION POINT "

=ocations here relatively small %uantities of materials are in*ected into process

streams to control chemistry or other process variables. In*ection points do not

include locations here to process streams *oin.

%.1( IN&SER,ICE "

$efers to piping systems that have been placed in operation, as opposed to ne

construction prior to being placed in service.

%.1' INSPECTOR "

An authori)ed piping inspector.

%.1" LE,EL BRIDLE "

A level gauge glass piping assembly attached to a vessel.

1.: A>I? A==@2A=6 2@$IB P$6((?$6 A2P

The ma#imum internal pressure permitted in the piping system for continued

operation at the most severe condition of coincident internal or e#ternal pressure

and temperature ma#imum and minimum e#pected during service. It is the

same as the design pressure, as defined in A(6 8.8 and other code

sections, and is sub*ect to the same rules relating to alloances for variations of

pressure or temperature or both.

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%.1# ON&STREA) "

Piping containing any amount of process fluid.

%.18 PIPIN- CIRCUIT "

A section of piping that has all points e#posed to an environment of similar

corrosivity and that is of similar design conditions and construction material.

%.19 PRI)AR7 PROCESS PIPIN- "

Process piping in normal, active service that cannot be valved off or, if it ere

valved off, ould significantly affect unit operability. Primary process piping

normally includes all process piping greater than P( 1.

1.10 $6PAI$ @$BAICATI@ "

Any of the folloing "

a. An oner or user of piping systems ho repairs or alters his or her on

e%uipment in accordance ith API 570.

b. A contractor hose %ualifications are acceptable to the oner or user of

piping systems and ho ma!es repairs or alterations in accordance ith

API 570.

c. @ne ho is authori)ed by, acceptable to, or otherise not prohibited bythe *urisdiction and ho ma!es repairs in accordance ith API 570.

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%.%* TE)PORAR7 REPAIRS "

$epairs made to piping systems in order to restore sufficient integrity to continue

safe operation until permanent repairs can be scheduled and accomplished

ithin a time period acceptable to the inspector or piping engineer.

%.%# TEST POINT "

An area defined by a circle having a diameter not greater than 1 inches 50 mm

for a line diameter not e#ceeding 0 inches 150 mm or not greater than 8

inches 75 mm for larger lines. Thic!ness readings may be averaged ithin thisarea. A test point shall be ithin a thic!ness measurement location.

%.%8 THIC>NESS )EASURE)ENT LOCATIONS ;T)L3


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(.1 API AUTHORI6ED PIPIN- INSPECTOR @UALIFICATION AND

CERTIFICATION 0

Authori)ed piping inspectors shall have education and e#perience in accordance

ith Appendi# A of this inspection code. Authori)ed piping inspectors shall be

certified by the American Petroleum Institute in accordance ith the provisions of

Appendi# A. 2henever the term inspector is used in this document, it refers to

an authori)ed piping inspector.

8.1 $6(P@(II=ITI6( "

(.%.1 An oner-user organi)ation is responsible for developing, documenting,

implementing, e#ecuting, and assessing piping inspection systems and

inspection procedures that ill meet the re%uirements of this inspection code.

These systems and procedures ill be contained in a %uality assurance

inspection manual or ritten procedures and shall include "

a. @rgani)ation and reporting structure for inspection personnel.

b. 4ocumenting and maintaining inspection and %uality assurance

procedures.

c. 4ocumenting and reporting inspection and test results.

d. &orrective action for inspection and test results.

e. Internal auditing for compliance ith the %uality assurance inspection

manual.

f. $evie and approval of draings, design calculations, and specifications

for repairs, alterations, and re3ratings.

g. 6nsuring that all *urisdictional re%uirements for piping inspection, repairs,

alterations, and re3rating are continuously met.

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h. $eporting to the authori)ed piping inspector any process changes that

could affect piping integrity.

i. Training re%uirements for inspection personnel regarding inspection tools,

techni%ues, and technical !noledge base.

*. &ontrols necessary so that only %ualified elders and procedures areused for all repairs and alterations.

!. &ontrols necessary so that only %ualified nondestructive e#amination

46 personnel and procedures are utili)ed.

l. &ontrols necessary so that only materials conforming to the applicable

section of the A(6 &ode are utili)ed for repairs and alterations.

m. &ontrols necessary so that all inspection measurement and test

e%uipment are properly maintained and calibrated.

n. &ontrols necessary so that the or! of contract inspection or repair

organi)ations meet the same inspection re%uirements as the oner-user

organi)ation.

o. Internal auditing re%uirements for the %uality control system for pressure3

relieving devoices.

(.%.% PIPIN- EN-INEER "

The piping engineer is responsible to the oner-user for activities involving

design, engineering revie, analysis, or evaluation of piping systems covered by

API 570.

(.%.( REPAIR OR-ANI6ATION "

The repair organi)ation shall be responsible to the oner-user and shall provide

the materials, e%uipment, %uality control, and or!manship necessary to

maintain and repair the piping systems in accordance ith the re%uirements of

API 570.

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(.%.' AUTHORI6ED PIPIN- INSPECTOR 0

2hen inspections, repairs, or alterations are being conducted on piping systems,

an API authori)ed piping inspector shall be responsible to the oner-user for

determining that the re%uirements of API 570 on inspection, e#amination, andtesting are met, and shall be directly involved in the inspection activities. The API

authori)ed piping inspector may be assisted in performing visual inspections by

other properly trained and %ualified individuals, ho may or may not be certified

piping inspectors. Personnel performing nondestructive e#aminations shall meet

the %ualifications identified in 8.1, but need not be API authori)ed piping

inspectors. 'oever, all e#amination results must be evaluated and accepted by

the API3 authori)ed piping inspector.

(.%." OTHER PERSONNEL "

@perating, maintenance, or other personnel ho have special !noledge or

e#pertise related to particular piping systems shall be responsible for promptly

ma!ing the inspector or piping engineer aare of any unusual conditions that

may develop and for providing other assistance, here appropriate.

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INSPECTION AND TESTIN-

1. RIS> BASED INSPECTION ;RBIIN- 0

/atigue crac!ing of piping systems may result from e#cessive cyclic stresses that

are often ell belo the static yield strength of the material. The onset of lo3

cycle fatigue crac!ing is often directly related to the number of heat3up and cool3

don cycles e#perienced. 6#cessive piping system vibration such as machine

or flo3induced vibrations also can cause high3cycle fatigue damage.

/atigue crac!ing can typically be first detected at points of high3stressintensification such as branch connections. =ocations here metals having

different coefficients of thermal e#pansion are *oined by elding may be

susceptible to thermal fatigue. Preferred 46 methods of detecting fatigue

crac!ing include li%uid3penetrant testing PT or magnetic3particle testing T.

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Acoustic emission also may be used to detect the presence of crac!s that are

activated by test pressures of stresses generated during the test.

It is important that the oner-user and the inspector understand that fatigue

crac!ing is li!ely to cause piping failure before it is detected ith any 46methods. @f the total number of fatigue cycles re%uired to produce a failure, the

vast ma*ority are re%uired to initiate a crac! and relatively feer cycles are

re%uired to propagate the crac! to failure. Therefore, proper design and

installation in order to prevent the initiation of fatigue crac!ing are important.

'.%.1% CREEP CRAC>IN- "

&reep is dependent on time, temperature, and stress. &rac!ing is accelerated by

creep and fatigue interaction hen operating conditions in the creep range are

cycle. If e#cessive temperatures are encountered, mechanical property and

microstructural changes in metals also may ta!e place.

46 methods of detecting creep crac!ing include li%uid3penetrant testing,

magnetic3particle testing, ultrasonic testing, radiographic testing, and in3situ

metallography. Acoustic emission testing also may be used to detect the

presence of crac!s that are activated by test pressures or stresses generated

during the test.

'.%.1( BRITTLE FRACTURE 0

&arbon lo3alloy, and other ferritic steels may be susceptible to brittle failure at

or belo ambient temperatures. rittle fracture usually is not a concern ith

relatively thinall piping. ost brittle fractures have occurred on the first

application of a particular stress level that is, the first hydrotest or overload

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unless critical defects are introduced during service. The potential for a brittle

failure shall be considered hen rehydrotesting.

'.%.1' FREE6E DA)A-E "

At subfree)ing temperatures, ater and a%ueous solutions in piping systems may

free)e and cause failure because of the e#pansion of these materials. After

une#pectedly severe free)ing eather, it is important to chec! for free)e damage

to e#posed piping components before the system thas. If rupture has occurred,

lea!age may be temporarily prevented by the fro)en fluid. =o points, riplegs,

and deadlegs of piping systems containing ater should be carefully e#amined for

damage.

'.( T7PES OF INSPECTION AND SUR,EILLANCE "

4ifferent types of inspection and surveillance are appropriate depending on the

circumstances and the piping system . These include the folloing "

a. Internal visual inspection.

b. Thic!ness measurement inspection.

c. 6#ternal visual inspection.

d. ibrating piping inspection

e. (upplemental inspection.

'.(.1 INTERNAL ,ISUAL INSPECTION 0

Internal visual inspections are not normally performed on piping. 2hen possible

and practical, internal visual inspections may be scheduled for systems such as

large3diameter transfer lines, ducts, or other large3diameter piping systems.

(uch inspections are similar in nature to pressure vessel inspections and should

be conducted ith methods and procedures similar to those outlined in API 50.

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'.(.% THIC>NESS )EASURE)ENT INSPECTION "

A thic!ness measurement inspection is performed to determine the internal

condition and remaining thic!ness of the piping components. Thic!ness

measurements may be obtained hen the piping system is in or out of operation

and shall be performed by the inspector or e#aminer.

'.(.( E+TERNAL ,ISUAL INSPECTION "

In addition to these scheduled e#ternal inspections that are documented in

inspection records, it is beneficial for personnel ho fre%uent the area to reportdeterioration or changes to the inspector.

'.(.' SUPPLE)ENTAL INSPECTION "

@ther inspections may be scheduled as appropriate or necessary. 6#amples of

such inspections include periodic use of radiography and-or thermography to

chec! for fouling or internal plugging, thermography to chec! for hot spots inrefractory lined systems, or inspection for environmental crac!ing. Acoustic

emission, acoustic lea! detection, and thermography can be used or remote lea!

detection and surveillance. ?ltrasonics and-or radiography can be used for

detecting locali)ed corrosion.

'.' THIC>NESS )EASURE)ENT LOCATIONS "

'.'.1 -ENERAL "

Thic!ness measurement locations T=+s are specific areas along the piping

circuit here inspections are to be made. The nature of the T= varies

according to its location in the piping system. The selection of T=+s shall

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consider the potential for locali)ed corrosion and service3specific corrosion as

described in 5.8

'.'.% T)L )ONITORIN- "

6ach piping system shall be monitored by ta!ing thic!ness measurements at

T=+s. Piping circuits ith high potential conse%uences if failure should occur

and those sub*ect to higher corrosion rates or locali)ed corrosion ill normally

have more T=s and be monitored more fre%uently.

The minimum thic!ness at each T= can be located by ultrasonic scanning or

radiography. 6lectromagnetic techni%ues also can be used to identify thin areas

that may then be measured by ultrasonics or radiography. 2hen accomplished

ith ultrasonics, scanning consists of ta!ing several thic!ness measurement at

the T= searching for locali)ed thinning. The thinnest reading or an average of

several measurement readings ta!en ithin the area of a test point shall be

recorded and used to calculate corrosion rates, remaining life, and the ne#t

inspection date.

2here appropriate, thic!ness measurements should include measurements at

each of the four %uadrants on pipe and fittings, ith special attention to the inside

and outside radius of elbos and tees here corrosion-erosion could increase

corrosion rates. As a minimum, the thinnest reading and its location shall be

recorded.

T=+s should be established for areas ith continuing &?I, corrosion at (-A

interfaces, or other locations of potential locali)ed corrosion as ell as forgeneral uniform corrosion.

T=s should be mar!ed on inspection draings and on the piping system to

allo repetitive measurements at the same T=s. This recording procedure

provides data for more accurate corrosion rate determination.

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'.'.( T)L SELECTION 0

In selecting or ad*usting the number and locations of T=s the inspector should

ta!e unto account the patterns of corrosion that ould be e#pected and havebeen e#perienced in the process unit.

ore T=s should be selected for piping systems ith any of the folloing

characteristics "

a. 'igher potential for creating a safety or environmental emergency in the

event of a lea!.

b. 'igher e#pected or e#perienced corrosion rates.

c. 'igher potential for locali)ed corrosion.

d. ore comple#ity in terms of fittings, branches, deadlegs in*ection points,

and other similar items.

e. 'igher potential for &?I

/eer T=s can be selected for piping systems ith any of the folloing three

characteristics "

a. =o potential for creating a safety or environmental emergency in the

event of a lea!.

b. $elatively non3corosive piping systems.

c. =ong, straight3run piping systems.

T=s can be eliminated for piping systems ith either of the folloing to

characteristics "

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a. 6#tremely lo potential for creating a safety or environmental emergency

in the event of a lea!.

b. on3corrosive systems, as demonstrated by history or similar service, and

systems not sub*ect to changes that could cause corrosion.

'." THIC>NESS )EASURE)ENT )ETHODS 0

?ltrasonic thic!ness measuring instruments usually are the most accurate mean

for obtaining thic!ness measurements on installed pipe larger than P( .

$adiographic profile techni%ues are preferred for pipe diameters of P( and

smaller. $adiographic profile techni%ues may be used for locating areas to be

measured, particularly in insulted systems or here non3uniform or locali)edcorrosion is suspected.

2here practical , ultrasonics can then be used to obtain the actual thic!ness of

the areas to be recorded. /olloing ultrasonic readings at T=s, proper repair of

insulation and insulation eather coating is recommended to reduce the potential

for &?I.

$adiographic profile techni%ues, hich do not re%uire removing insulation, may

be considered as an alternative.

2hen ultrasonic measurements are ta!en above 50o/ :5o&, instruments,

couplants, and procedures should be used that ill result in accurate

measurements at the higher temperatures.

easurements should be ad*usted by the appropriate temperature correction

factor.

a. Improper instrument calibration.

b. 6#ternal coatings or scale.

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c. 6#cessive surface roughness.

d. 6#cessive Lroc!ingM of the probe on the curved surface

e. (ubsurface material flas, such as laminations.

f. Temperature effects Eat temperatures above 50o/ :5o&F

g. (mall fla detector screens.

h. Thic!ness of less than -J inch 8.1 mm for typical digital thic!ness

gauges.

In addition, it must be !ept in mind that the pattern of corrosion can be non3

uniform.

/or corrosion rate determinations to be valid, it is important that measurements

on the thinnest point be repeated as closely as possible to the same location.

Alternatively, the minimum reading or an average of several readings at a test

point may be considered.

2hen piping systems are out of service, thic!ness measurements may be ta!en

through openings using calipers. &alipers are useful in determining appro#imate

thic!nesses of castings, forgings, and valve bodies, as ell as pit depth

appro#imations from &?I on pipe.

Pit depth measuring devices also may be used to determine the depth of

locali)ed metal loss.

'.* PRESSURE TESTIN- OF PIPIN- S7STE)S "

Pressure tests are not normally conducted as part of a routine inspection.

6#ceptions to this include re%uirements of local *urisdictions, after elded

alterations or hen specified by the inspector or piping engineer. 2hen they are

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conducted , pressure tests shall be performed in accordance ith the

re%uirements of A(6 8.8

If a pressure test is to be maintained for a period of time and the test fluid in the

system is sub*ect to thermal e#pansion, precautions shall be ta!en to avoide#cessive pressure.

2hen a pressure test is re%uired, it shall be conducted after any heat treatment.

A pneumatic pressure test may be used hen it is impracticable to hydrostatically

test due to temperature, structural, or process limitations. 'oever, the potential

ris!s to personnel and property of pneumatic testing shall be considered hen

carrying out such a test. As a minimum, the inspection precautions contained in

A(6 8.8 shall be applied in any pneumatic testing.

4uring a pressure test, here the test pressure ill e#ceed the set pressure of

the safety valve on a piping system, the safety relief valve or valves should be

removed or blan!ed for the duration of the test. As an alternative, each valve

dis! must be held don by a suitably designed test clamp.

The application of an additional load to the valve spring by turning the ad*usting

scre is not recommended. @ther appurtenances that are incapable of

ithstanding the test pressure, such as gage glasses, pressure gages,

e#pansion *oints, and rupture dis!s, should be removed or blan!ed. =ines

containing e#pansion *oints that cannot be removed or isolated may be tested at

a reduced pressure in accordance ith the principles of A(6 8.8. If bloc!

valves are used to isolate a piping system for a pressure test, caution should beused to not e#ceed the permissible seat pressure as described in A(6 :.89

or applicable valve manufacturer data.

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?pon completion of the pressure test, pressure relief devices of the proper

settings and other appurtenances removed or made inoperable during the

pressure test shall be reinstalled or reactivated.

'.# )ATERIAL ,ERIFICATIONS AND TRACEABILT7 0

4uring repairs or alterations of lo3 to high alloy piping systems, the inspector

shall verify the installation of the correct ne materials. At the discretion of the

oner-user or the inspector, this verification can be either by 00 percent

chec!ing or testing in certain critical situations or by sampling a percentage of the

materials.

Testing can be accomplished by the inspector or the e#aminer ith the use of

suitable portable methods, such as chemical spot testing, optical spectrographic

analy)ers, or >3ray fluorescent analy)ers. &hec!ing can involve verifying test

reports on materials, mar!ings on piping components and bolting, and !ey

dimensions.

If a piping system component should fail because an incorrect material as

inadvertently substituted for the proper piping material, the inspector shall

consider the need for further verification of e#isting piping materials.

The e#tent of further verification ill depend upon circumstances such as the

conse%uences of failure and the li!elihood of further material errors.

'.8 INSPECTION OF ,AL,ES "

ormally, thic!ness measurements are not routinely ta!en on valves in piping

circuits. The body of a valve is normally thic!er than other piping components for

design reasons. 'oever, hen valves are dismantlted for servicing and repair,

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the shop should be attentive to any unusual corrosion patterns or thinning and,

hen noted, report that information to the inspector.

If gate valves are !non to be or are suspected of being e#posed to

corrosion-erosion, thic!ness readings should be ta!en beteen the seats, sincethis is an area of high turbulence and high stress.

&ontrol valves or other throttling valves, particularly in high pressure drop3and3

slurry services, can be susceptible to locali)ed corrosion-erosion of the body

donstream of the orifice. If such metal loss is suspected, the valve should be

removed from the line for internal inspection. The inside of the donstream

mating flange and piping also should be inspected for local metal loss.

&ritical chec! valves should be visually and internally inspected to ensure that they

ill stop flo reversals.

An e#ample of a critical chec! valve may be the chec! valve located on the outlet of

a multistage, high head hydro3processing charge pump. /ailure of such a chec!

valve to operate correctly could result in over pressuring the piping during a flo

reversal. The normal visual inspection method should include "

a. &hec!ing to insure that the flapper is free to move, as re%uired, ithout

e#cessive looseness from ear.

b. The flapper stop should not have e#cessive ear. This ill minimi)e the

li!elihood that the flapper ill move past the top dead central position and

remain in an open position hen the chec! valve is mounted in a verticalposition.

c. The flapper nut should be secured to the flapper bolt to avoid bac!ing off in

service.

=ea! chec!s of critical chec! valves are normally not re%uired.

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'.9 INSPECTION OF ?ELDS IN& SER,ICE 0

Inspection for piping eld %uality is normally accomplished as a part of the

re%uirements for ne construction, repairs, or alterations. 'oever, elds are

often inspected for corrosion as part of a radiographic profile inspection or as part

of internal inspection. 2hen preferential eld corrosion is noted, additional

elds in the same circuit or system should be e#amined for corrosion.

If the noted imperfections are a result of original eld fabrication, inspection

and-or engineering analysis is re%uired to assess the impact of the eld %uality

on piping integrity. This analysis may be one or more of the folloing

a. Inspector *udgment.

b. &ertified elding inspector *udgment.

c. Piping engineer *udgment.

d. 6ngineering fitness3for3service analysis.

Issues to consider hen assessing the %uality of e#isting elds include the

folloing

a. @riginal fabrication inspection acceptance criteria.

b. 6#tent, magnitude, and orientation of imperfections.

c. =ength of time in3service.

d. @perating versus design conditions.

e. Presence of secondary piping stresses residual and thermal

f. Potential for fatigue loads mechanical and thermal.

g. Primary or secondary piping system.

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h. Potential for impact or transient loads.

i. Potential for environmental crac!ing.

*. 2eld hardness.

In many cases for in3service elds, it is not appropriate to use the random or

spot radiography acceptance criteria for eld %uality in A(6 8.8 These

acceptance criteria are intended to apply to ne construction on a sampling of

elds, not *ust the elds e#amined, in order to assess the probable %uality of all

elds or elders in the system.

(ome elds may e#ist that ill not meet these criteria but ill still performsatisfactorily in service.

'.1$ INSPECTION OF FLAN-ED :OINTS 0

The mar!ings on a representative sample of nely installed fasteners and

gas!ets should be e#amined to determine hether they meet the material

specification. The mar!ings are identified in the applicable A(6 and A(T

standards. Nuestionable fasteners should be verified or reneed.

/asteners should e#tend completely through their nuts. Any fastener failing to do

so is considered acceptably engaged if the lac! of complete engagement is not

more than one thread.

/langed and valve bonnet *oints should be e#amined for evidence of lea!age,

such as stains, deposits, or drips. Process lea!s onto flange and bonnetfasteners may result in corrosion or environmental crac!ing.

This e#amination should include those flanges enclosed ith flange or splash3

and3spray guards.

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". FRE@UENC7 AND E+TENT OF INSPECTION

".1 -ENERAL 0

The fre%uency and e#tent of inspection piping circuits depend on the forms of

degradation that can affect the piping and conse%uence of a piping failure.

Inspection strategy based on li!elihood and conse%uence of failure, is referred to

as ris!3based inspection. Piping classification scheme in (ection given belo is

based on the conse%uence of a failure. The classification is used to establish

fre%uency and e#tent of inspection. The oner-user may devise a moree#tensive classification scheme that more accurately assesses conse%uence for

certain piping circuits. The conse%uence assessment ould consider the

potential for e#plosion, fire, to#icity, environmental impact and other potential

effects associated ith a failure.

After an effective assessment is conducted, the results can be used to establish

a piping circuit inspection strategy and more specifically better define thefolloing "

a. The most appropriate inspection methods, scope, tools and techni%ues to

be utili)ed based on the e#pected forms of degradation;

b. The appropriate inspection fre%uency;

c. The need for pressure testing after damage has been incurred or after

repairs or modifications have been completed; and

d. The prevention and mitigation steps to reduce the li!elihood and

conse%uence of a piping failure.

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".% PIPIN- SER,ICE CLASSES 0

All process piping systems shall be categori)ed into different classes. (uch a

classification system allos e#tra inspection efforts to be focused on piping

systems that may have the highest potential conse%uences if failure or loss ofcontainment should occur. In general, the higher classified systems re%uire more

e#tensive inspection at shorter intervals in order to affirm their integrity for

continued safe operation. &lassifications should be based on potential safety

and environmental effects should a lea! occur.

".%.1 CLASS 1 0

(ervices ith the heist potential of resulting in an immediate emergency if a lea!

ere to occur are in &lass . (uch an emergency may be safety or

environmental in nature. 6#amples of &lass piping include, but are not

necessarily limited to, those containing the folloing "

a. /lammable services that may auto3refrigerate and lead to brittle fracture.

b. Pressuri)ed services that may rapidly vapori)e during release, creating

vapors that may collect and form an e#plosive mi#ture, such as &1, &8

and &9 streams.

c. 'ydrogen sulfide greater than 8 percent eight in a gaseous stream.

d. Anhydrous hydrogen chloride.

e. 'ydrofluoric acid.

f. Piping over or ad*acent to ater and piping over public through ays.

".%.% CLASS % 0

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(ervices not included in other classes are in &lass 1. This classification includes

the ma*ority of unit process piping and selected off3site piping . Typical e#amples

of these services include those containing the folloing "

a. @n3site hydrocarbons that ill sloly vapori)e during release.

b. 'ydrogen, fuel gas and natural gas

c. @n3site strong acids and caustics.

".%.( CLASS ( 0

(ervices that are flammable but do not significantly vapori)e hen they lea! and

are not located in high activity areas are in &lass 8 . (ervices that dare

potentially harmful to human tissue but are located in remote areas may be

included din this class. 6#amples of &lass 8 service are as follos "

a. @n site hydrocarbons that ill not significantly vapori)e during release.

b. 4istillate and product lines to and from storage and loading.

c. @ff3site acids and caustics.

".( INSPECTION INTER,ALS 0

The interval beteen piping inspections shall be established and maintained

using the folloing criteria "

a. &orrosion rate and remaining life calculations.

b. Piping service classification.

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c. Applicable *urisdictional re%uirements

d. Oudgment of the inspector, the piping engineer, the piping engineer

supervisor, or a corrosion specialist, based don operating conditions,

previous inspection history, current inspection results, and conditions that

may arrant supplemental inspections covered in 5.9.5 of code.

Thic!ness measurements should be scheduled based on the calculation of not

more than half the remaining life determined from corrosion rates indicated or at

the ma#imum intervals suggested in Table :3, hichever is shorter. (horter

intervals may be appropriate under certain circumstances. Prior to using Table :3

, corrosion rates should be calculated in accordance ith 7.8 of code.

The inspection interval must be revieed and ad*usted as necessary after each

inspection or significant change in operating conditions. Beneral corrosion,

locali)ed corrosion, pitting, environmental crac!ing, and other forms of

deterioration must be considered hen establishing the various inspection

intervals.

".' E+TENT OF ,ISUAL E+TERNAL AND CUI INSPECTIONS "

6#ternal visual inspections, including inspections for corrosion under insulation

&?I, should be conducted at ma#imum intervals listed in Table :3 to evaluate

items such as those in Appendi# 4. The e#ternal visual inspection on bare piping

is to assess the condition of paint and coating systems, to chec! for e#ternal

corrosion, and to chec! for other forms of deterioration. This e#ternal visualinspection for potential &?I is also to assess insulation condition and shall be

conducted on all piping systems susceptible to &?I listed in 5.8.8. of code

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/olloing the e#ternal visual inspection of susceptible systems, additional

e#amination is re%uired for the inspection of &?I. The e#tent and type of the

additional &?I inspection are listed in Table :31 . 4amaged insulation at higher

elevations may result in &?I in loer areas remote from the damage. 46

inspection for &?I should also be conducted as listed in Table :31 at suspectlocations of 5.8.8. e#cluding c meeting the temperature criteria for 5.8.8.

e,f,h.

$adiographic e#amination or insulation removal and visual inspection is normally

re%uired for this inspection at damaged or suspect locations. @ther 46

assessment methods may be used here applicable. If the inspection of the

damaged or suspect areas has located significant &?I, additional area should be

inspected and, here arranted, up to 00 percent of the circuit should be

inspected.

The e#tent of the &?I program described in Table :31 should be considered as

target levels for piping systems and locations ith no &?I inspection e#perience.

It is recogni)ed that several factors may affect the li!elihood of &?I to include "

a. =ocal climatic conditions

b. Insulation design.

c. &oating %uality.

d. (ervice conditions.

/acilities ith &?I inspection e#perience may increase or reduce the &?I

inspection targets of Table :31. An e#act accounting of the &?I inspection target

is not re%uired. The oner-user may confirm inspection targets ith operationalhistory or other documentation.

Piping systems that are !non to have a remaining life of over 0 years or that

are ade%uately protected against e#ternal corrosion need not be included for the

46 inspection recommended in Table :31. 'oever, the condition of the

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insulating system or the outer *ac!eting, such as a cold3bo# shell, should be

observed periodically by operating or other personnel. If deterioration is noted, it

should be reported to the inspector. The folloing are e#amples of these

systems "

a. Piping systems insulated effectively to preclude the entrance of moisture.

b. Oac!eted cryogenic piping systems

c. Piping systems installed in a cold bo# in hich the atmosphere is purged

ith an inert gas.

d. Piping systems in hich the temperature being maintained is sufficiently

lo or sufficiently high to preclude the presence of ater.

"." E+TENT OF THIC>NESS )EASURE)ENT INSPECTION "

To satisfy inspection interval re%uirements, each thic!ness measurement

inspection should obtain thic!ness readings on a representative sampling of

T=s on each circuit . This representative sampling should include data for all

the various types of components and orientations hori)ontal and vertical found

in each circuit. This sampling also must include T=s ith the earliest reneal

date as of the previous inspection. The more T=s measured for each circuit,

the more accurately the ne#t inspection date ill be pro*ected. Therefore,

scheduled inspection of circuits should obtain as many measurements as

necessary.

The e#tent of inspection for in*ection points is covered in 5.8. of code.

5.: 6>T6T @/ (A==3@$6, A?>I=IA$ PIPIB, A4 T'$6A464 3&@6&TI@( I(P6&TI@( "

".*.1 S)ALL BORE PIPIN- INSPECTION "

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(mall bore piping (P that is primary process piping should be

inspected in accordance ith all the re%uirements of this document.

(P that is secondary process piping has different minimum re%uirements

depending upon service classification. &lass secondary (P shall beinspected to the same re%uirements as primary process piping. Inspection

of &lass1 and &lass 8 secondary (P is optional. (P deadlegs such

das level bridles in &lass 1 and &lass 8 systems should be inspected

here corrosion has been e#perienced or is anticipated.

".*.% AU+ILIAR7 PIPIN- INSPECTION "

Inspection of secondary, au#iliary (P associated ith instruments and

machinery is optional. &riteria to consider in determining hether au#iliary

(P ill need some form of inspection include the folloing "

a. &lassification.

b. Potential for environmental or fatigue crac!ing.

c. Potential for corrosion based on e#perience ith ad*acent primary

system.

d. Potential for &?I.

".*.( THREADED&CONNECTIIONS INSPECTION "

Inspection of threaded connections ill be according to the re%uirements

listed above for small3bore and au#iliary piping. 2hen selecting T=s on

threaded connection, include only those that can be radio3graphed duringscheduled inspection.

Threaded connections associated ith machinery and sub*ect to fatigue

damage should be periodically assessed and considered for possible

reneal ith a thic!er all or upgrading to elded components. The

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schedule for such reneal ill depend on several issues, including the

folloing "

a. &lassification piping

b. agnitude and fre%uency of vibration.c. Amount of unsupported eight.

d. &urrent piping all thic!ness.

e. 2hether or not the system can be maintained on stream.

f. &orrosion rate.

g. Intermittent service.

TABLE *&1&&&&RECO))ENDED )A+I)U) INSPECTION INTER,ALS

Tye3 o! Crcut Tcne33)e3ure5ent3

,3u2 E4tern2

&lass 5 years 5 years&lass 1 0 years 5 years&lass 8 0 years 0 yearsIn*ection points 8 years y &lass

(oil3to3air interfaces 3333 y &lass

Note " Thic!ness measurements apply to systems for hich T=s have beenestablished in accordance ith 5.5

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TABLE D*&% &&& RECO))ENDED E+TENT OF CUI INSPECTIONFOLLO?IN- ,ISUAL INSPECTION

Aro45te A5ount o! Fo22owuE45nton wt NDE or In3u2tonRe5ov2 t Are3 wtD5/ed In3u2ton

Aro45te A5ount o! CUI

In3ecton by NDE t Su3ectAre3 ; ".(.(.% < on Pn/ Sy3te53wtn Su3cetb2e Te5erture

Rn/e3 ; ".(.(.% e.!. NESS DETER)INATION 0

The minimum re%uired pipe all thic!ness, or retirement thic!ness, shall be

based on pressure, mechanical, and structural considerations using the

appropriate design formulas and code alloable stress. &onsideration of both

general and locali)ed corrosion shall be included. /or services ith high

potential conse%uences if failure ere to occur, the piping engineer should

consider increasing the re%uired minimum thic!ness above the calculated

minimum thic!ness to provide for unanticipated or un!non loadings,

undiscovered metal loss, or resistance to normal abuse.

*.' REPORTIN- AND RECORDS FOR PIPIN- S7STE) INSPECTION

Any significant increase in corrosion rates shall be reported to the oner-user for

appropriate action.

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The oner-user shall maintain appropriate permanent and progressive records of

each piping system covered by API 570. These records shall contain pertinent

data such as piping system service; classification; identification numbers;

inspection intervals; and documents necessary to record the name of the

individual performing the testing, the date, the types of testing, the results ofthic!ness measurements and other tests, inspections, repairs temporary and

permanent, alterations, or rerating. 4esign information and piping draings may

be included. Information on maintenance activities and events affecting piping

system integrity also should be included. The date and results of re%uired

e#ternal inspections shall be recorded. see API $P 579 for guidance on piping

inspection records.

The use of a computer based system for storing, calculating, and analy)ing data

should be considered in vie of the volume of data that ill be generated as part

of a piping test3point program. &omputer programs are particularly useful for the

folloing "

a. (toring the actual thic!ness reading.

b. &alculating short and long term corrosion rates, retirement dates, A2P,

and reinspection intervals on a test point by test point basis.

c. 'ighlighting areas of high corrosion rates, circuits over3due for inspection,

close to retirement thic!ness, and other information.

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#. REPAIRS ALTERATIONS RERATIN-

#.1 REPAIRS AND ALTERATIONS 0

The principles of A(6 8.8 or the code to hich the piping system as built

shall be folloed.

#.1.1 AUTHORI6ATION 0

All repair and alteration or! must be done by a repair organi)ation as defined in

(ection 8 and must be authori)ed by the inspector prior to its commencement.Authori)ation for alteration or! to a piping system may not be given ithout

prior consultation ith, and approval by, the piping engineer. The inspector ill

designate any inspection hold points re%uired during the repair or alteration

se%uence. The inspector may give prior general authori)ation for limited or

routine repairs and procedures, provided the inspector is satisfied ith the

competency of the repair organi)ation.

#.1.% APPRO,AL "

All proposed methods of design, e#ecution, materials, elding procedures,

e#amination, and testing must be approved by the inspector or by the piping

engineer, as appropriate. @ner-user approval of on stream elding is re%uired.

2elding repairs of crac!s that occurred in service should not be attempted

ithout prior consultation ith the piping engineer in order to identify and correct

the cause of the crac!ing. 6#amples are crac!s suspected of being caused by

vibration, thermal cycling, thermal e#pansion problems, and environmental

crac!ing.

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The inspector shall approve all repair and alteration or! at designated hold

points and after the repairs and alterations have been satisfactorily completed in

accordance ith the re%uirements of API 570

#.1.( ?ELDIN- REPAIRS ;DDINCLUDIN- ON$STREA)


52/173

Temporary repairs should be removed and replaced ith a suitable

permanent repair at the ne#t available maintenance opportunity.

Temporary repairs may remain in place for a longer period of time

only if approved and documented by the piping engineer.

#.1.(.% PER)ANENT REPAIRS "

$epairs to defects found in piping components may be made by

preparing a elding groove that completely removes the defect and

then filling the groove ith eld metal deposited din accordance

ith 7.1

&orroded areas may be restored ith eld metal deposited din

accordance ith 7.1 (urface irregularities and contamination shall

be removed before elding. Appropriate 46 methods shall be

applied after completion of the eld.

If it is feasible to ta!e the piping system out of service, the defective

area may be removed by cutting out a cylindrical section and

replacing it ith a piping component that meets the applicable

code.

Insert patches flush patches may be used to repair damaged or

corroded areas if the folloing re%uirements are met "

a. /ull penetration groove elds are provided.

b. /or &lass and &lass 1 piping systems, the elds shall be00 percent radio3graphed or ultrasonically tested using

46 procedures that are approved by the inspector.

c. Patches may be any shape but shall have rounded corners

inch 15mm minimum radius

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#.1.' NON&?ELDIN- REPAIRS ;ON STREA)


54/173

(uggested 'ot Tap &hec!listM contained in API Publication 110 for hot tapping

performed on piping components.

#.%.1 PROCEDURES @UALIFICATIONS AND RECORDS 0

The repair organi)ation shall use elders and elding procedures %ualified in

accordance ith A(6 8.8 or the code to hich the piping as built.

The repair organi)ation shall maintain records of elding procedures and elder

performance %ualifications. These records shall be available to the inspector

prior to the start of elding.

#.%.% PERHEATIN- AND POST?ELD HEAT TREAT)ENT "

#.%.%.1 PREHEATIN- "

Preheat temperature used in mas!ing elding repairs shall be in

accordance ith the applicable code and %ualified elding

procedure. 6#ceptions for temporary repairs must be approved by

the piping engineer.

Preheating to not less that 800o/ 50o& may be considered as an

alternative to posteld heat treatment P2'T for alterations or

repairs of piping systems initially posteld heat heated as a code

re%uirement see note. This applies to piping constructed of the P3

steels listed in A(6 8.8. P38 steels , ith the e#ception of

n3o steels, also may receive the 800o

/50o

& minimum preheatalternative hen the piping system operating temperature is high

enough to provide reasonable toughness and hen there is no

identifiable ha)ard associated ith pressure testing , shutdon, and

startup. The inspector should determine that the mKinimum

preheat temperature is measured and maintained. After elding,

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the *oint should immediately be covered ith insulation to slo the

cooling rate.

NOTE" Preheating may not be considered as an alternative to environmentalcrac!ing prevention.

Piping systems constructed of other steel initially re%uiring P2'T normally

are posteld heat treated if alterations or repairs involving pressure

retaining elding are performed. The use of the preheat alternative

re%uires consultation ith the piping engineer ho should consider the

potential for environmental crac!ing and hether the elding procedure

ill provide ade%uate toughness. 6#amples of situations here this

alternative could be considered include seal elds, eld metal buildup ofthin area, and elding support clips.

#.%.%.% POST?ELD HEAT TREAT)ENT "

P2'T of piping system repairs or alterations should be made using

the applicable re%uirements of A(6 8.8 or the code to hich

the piping as built. (ee 7.1.1. for an alternative preheat

procedure for some P2'T re%uirements. 6#ceptions for temporary

repair must be approved by the piping engineer.

=ocal P2'T may be substituted for 8:03 degree banding on local

repairs on all materials, provided the folloing precautions and

re%uirements are applied.

a. The application is revieed, and a procedure is developed

by the piping engineer.

b. In evaluating the suitability of a procedure, consideration

shall be given to applicable factors, such as base metal

thic!ness, thermal gradients, material properties, changes

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resulting from P2'T, the need for full penetration elds, and

surface and volumetric e#aminations after P2'T.

Additionally, the overall and local strains and distortions

resulting from the heating of a local restrained area of the

piping all shall be considered in developing and evaluatingP2'T procedures.

c. A preheat of 800o/ 50o&, or higher as specified by

specific elding procedures, is maintained hile elding.

d. The re%uired P2'T temperature shall be maintained for a

distance of not less than to times the base metal thic!ness

measured form the eld. The P2'T temperature shall be

monitored by a suitable number of thermocouples a

minimum of to based on the si)e and shape of the area

being heat treated.

e. &ontrolled heat also shall be applied to any branch

connection or other attachment ithin the P2'T area.

f. The P2'T is performed for code compliance and not for

environmental crac!ing resistance.

#.%.( DESI-N "

utt *oints shall be full penetration groove elds.

Piping components shall be replaced hen repair is li!ely to be inade%uate. e

connections and replacement s shall be designed and fabricated according to

the principles of the applicable code. The design of temporary enclosures and

repairs shall be approved by the piping engineer.

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e connections may be installed on piping systems provided the design,

location, and method of attachment conform to the principles of the applicable

code.

/illet3elded patches re%uire special design considerations, especially relating toeld3*oint efficiency and crevice corrosion. /illet3elded patches shall be

designed by the piping engineer. A patch may be applied to the e#ternal surfaces

of piping, provided it is in accordance ith 7..8 and meets either of the folloing

re%uirements. "

a. The proposed patch provides design strength e%uivalent to a reinforced

opening designed according to the applicable code.

b. The proposed patch is designed to absorb the membrane strain of the part

in a manner that is in accordance ith the principles of the applicable

code, if the folloing criteria are met "

. The alloable membrane stress is not e#ceeded in the piping part

or the patch.

1. The strain in the patch does not result in fillet eld stresses e#ceeding

alloable stresses for such elds.

8. An overlay patch shall have rounded corners se Appendi# &

#.%.' )ATERIALS "

The materials used in ma!ing repairs or alterations shall be of !non eldable

%uality, shall conform to the applicable code, and shall be compatible ith the

original materials. /or material verification re%uirements see 9.J

#.%." NON&DESTRUCTI,E E+A)INATION "

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Acceptance of a elded repair or alteration shall include 46 in accordance ith

the applicable code and the oner-user+s specification, unless otherise

specified in API 570

#.%.* PRESSURE TESTIN- "

After elding is completed, pressure test in accordance ith 9.7 shall be

performed if practical and deemed necessary by the inspector. Pressure tests

are normally re%uired after alterations and ma*or repairs. 2hen a pressure test

is not necessary or practical, 46 shall be utili)ed in lieu of a pressure test.

(ubstituting special procedures for a pressure test after an alteration or repair

may b e done only after consultation ith the inspector and the piping engineer.

2hen it is not practical to perform a pressure test of a final closure eld that *oins

a ne or replacement section of piping to an e#isting system, all of the folloing

re%uirements shall be satisfied "

a. The ne or replacement piping is pressure tested.

b. The closure eld is a full penetration butt3eld beteen a eld nec! flange

and standard piping component or straight sections of pipe of e%ual

diameter and thic!ness, a#ially aligned not miter cut , and of e%uivalent

materials. Acceptable alternatives are

. slip3on flanges for design cases upto &lass 50 and 500o/,

1:0o& and

1. soc!et elded flanges or soc!et elded unions for si)es P( 1 or

less and design cases upto &lass 50 and 500 o/ 1:0o&. A spacer

designed for soc!et elding or some other means shall be used to

establish a minimum -: inch .: mm gap. (oc!et elds shall

be per A(6 8.8 and shall be a minimum of to passes.

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c. Any final closure butt3eld shall be of 00 percent radiographic %uality;

@$ angle beam ultrasonics fla detection may be used, provided the

appropriate acceptance criteria have been established.

d. T or PT shall be performed on the root pass and the completed eld for

butt3elds and on the completed eld for fillet elds.

#.( RERATIN-

$erating piping systems by changing the temperature rating or the A2P may

be done only after all of the folloing re%uirements have been met "

a. &alculations are performed by the piping engineer or the inspector.

b. All ratings shall be established in accordance ith the re%uirements of the

code to hich the piping system as built or by computation using the

appropriate methods in the latest edition of the applicable code.

c. &urrent inspection records verify that the piping system is satisfactory for the

proposed service conditions and that the appropriate corrosion alloance

is provided.

d. $erated piping systems shall be lea! tested in accordance ith the code

to hich the piping system as built or the latest edition of the applicable

code for the ne service conditions, unless documented records indicate

a previous lea! test as performed at greater than or e%ual to the testpressure for the ne condition. An increase in the rating temperature that

does not affect alloable tenside stress does not re%uire a lea! test.

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e. The piping system is chec!ed to affirm that the re%uired pressure relieving

devices are present, are set at the appropriate pressure, and have the

appropriate capacity at set pressure.

f. The piping system rerating is acceptable to the inspector or pipingengineer.

g. All piping components in the system such as valves, flanges, bolts,

gas!ets, pac!ing, and e#pansion *oints are ade%uate for the ne

combination of pressure and temperature.

. Pn/ !2e4b2ty 3 deGute !or de3/n te5erture cn/e3.

i. Appropriate engineering records are updated.

*. A decrease in minimum operating temperature is *ustified by impact test

results, if re%uired by the applicable code.

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8. INSPECTION OF BURIED PIPIN-

Inspection of buried process piping is different from other process piping inspection

because significant e#ternal deterioration can be caused by corrosive soil conditions.

(ince the inspection is hindered by the inaccessibility of the affected areas of the piping,

the inspection of buried piping is treated in a separate section of API 570.

8.1 T7PES AND )ETHODS OF INSPECTION

8.1.1 Above -rde ,3u2 Surve22nce 0

Indications of lea!s in buried piping may include a change in the surface contourof the ground, discoloration of the soil, softening of paving asphalt, pool

formation, bubbling ater puddles, or noticeable odor. (urveying the route of

buried piping is one method of identifying problem areas.

8.1.% C2o3e Interv2 Potent2 Survey 0

The close interval potential survey performed at ground level over the buried pipecan be used to locate active corrosion points on the pipe+s surface.

&orrosion cells can form on both bare and coated pipe here the bare steel

contacts the soil. (ince the potential at the area of corrosion ill be measurably

different from an ad*acent area on the pipe, the location of the corrosion activity

can be determined by this survey techni%ue.

8.1.( Pe Cotn/ Ho2dy Survey 0

The pipe coating holiday survey can be used to locate coating defects on buried

coated pipes, and it can be used on nely constructed pipe systems to ensure

that the coating is intact and holiday free. ore often it is used to evaluate

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coating serviceability for buried piping that has been in service for an e#tended

period of time.

8.1.' So2 Re33tvty "

&orrosion of bare or poorly coated piping is often caused by a mi#ture of different

soils in contact ith the pipe surface. The corrosiveness of the soils can be

determined by a measurement of the soil resistivity. =oer levels of resistivity

are relatively more corrosive than higher levels, especially in areas here the

pipe is e#posed to significant changers in soil resistivity.

8.1." Ctodc Protecton )ontorn/ 0

&athodicallyJ protected buried piping should be monitored regularly to assure

ade%uate levels of protection. onitoring should include periodic measurement

and analysis of pipe to soil potentials by personnel trained and e#perienced in

cathodic protection system operation. ore fre%uent monitoring of critical

cathodic protection components, such as impressed current rectifiers, is re%uired

to ensure reliable system operation.

8.1.* In3ecton )etod3 0

(everal inspection methods are available. (ome methods can indicate the

e#ternal or all condition of the piping, hereas other methods indicate only the

internal condition. 6#amples are as follos "

a. Intelligent pigging. This method involves the movement of adevice pig through the piping either hile it is in service or after it has

been removed from service. (everal types of devices are available

employing different methods of inspection.

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b. ideo cameras. Television cameras are available that cana be

inserted into the piping. These cameras may provide visual inspection

information on the internal condition of the line.

c. 6#cavation. In many cases, the only available inspectionmethod that can be performed is unearthing the piping in order to visually

inspect the e#ternal condition of the piping and to evaluate its thic!ness

and internal condition.

8.% FRE@UENC7 AND E+TENT OF INSPECTION "

8.%.1 Above&-rde ,3u2 Surve22nce "

The oner- user should, at appro#imately : month intervals survey the surface

conditions on and ad*acent to each pipeline path.

8.%.% Pe to So2 Potent2 Survey "

A close interval potential survey on a cathodically protected line may be used to

verify that the buried piping has a protective potential throughout its length. /or

poorly coated pipes here cathodic protection potentials are inconsistent, the

survey may be conducted at 5 year intervals for veritication of continuous

corrosion control.

/or piping ith no cathodic protection or in areas here lea!s have occurred dueto e#ternal corrosion, a pipe to soil potential survey may be conducted along the

pipe route. The pipe should be e#cavated at sites here active corrosion cells

have been located to determine the e#tent of corrosion damage.

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8.%.( Pe Cotn/ Ho2dy Survey "

The fre%uency of pipe coating holiday surveys is usually based on indications

that other forms of corrosion control are ineffective. /or e#ample, on a coated

pipe here there is gradual loss of cathodic protection potentials or an e#ternalcorrosion lea! occurs at a coating defect, a pipe coating holiday survey may be

used to evaluate the coating.

8.%.' So2 Corro3vty "

/or piping buried in lengths greater than 00 feet 80 m and not cathodically

protected, evaluations of soil corrosivity should be performed at 5 year intervals.

(oil resistivity measurements may be used for relative classification of the soil

corrosivity.

8.%." Ctodc Protecton "

If the piping is cathodically protected, the system should be monitored at intervals

in accordance ith (ection 0 of A&6 $P0:K or (ection of API $P :5.

8.%.* E4tern2 nd Intern2 In3ecton Interv23 "

If internal corrosion of buried piping is e#pected as a result of inspection on the

above grade portion of the line, inspection intervals and methods for the buried

portion should be ad*usted accordingly. The inspector should be aare of and

consider the possibility of accelerated internal corrosion in deadlegs.

The e#ternal condition of buried piping that is not cathodically protected should

be determined by either pigging, hich can measure all thic!ness or by

e#cavating according to the fre%uency given in Table K3. (ignificant e#ternal

corrosion detected by pigging or by other means may re%uire e#cavation and

evaluation even if the piping is cathodically protected.

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Piping inspected periodically by e#cavation shall be inspected in lengths of : feet

HJ feet 1.0 m31.5 m at one or more locations *udged to be most suspectible to

corrosion. 6#cavated piping should be inspected full circumference for the type

and e#tent of corrosion pitting or general and the condition of the coating.

If inspection reveals damaged coating or corroded piping, additional piping shall

be e#cavated until the e#tent of the condition is identified. If the average all

thic!ness is at or belo retirement thic!ness, it shall be repaired or replaced.

If the piping is contained inside a casing pipe, the conditional of the casing

should be inspected to determine if ater and- or soil has entered the casing.

The inspector should verify the folloing "

a. both ends of the casing e#tend beyond the ground line;

b. the ends of the casing are sealed if the casing is not self3draining; and

c. the pressure carrying pipe is properly coated and rapped.

8.%.# Le Te3tn/ Interv23 "

An alternative or supplement to inspection is lea! testing ith li%uid at a pressure

atleast 0 percent greater than ma#imum operating pressure at intervals one3half

the length of those shon in Table K3 for piping not cathodically protected and at

the same intervals as shon in Table K3 for cathodically protected piping. The

lea! test should be maintained for a period of J hours.

/our hours after the initial pressuri)ation of the piping system, the pressure

should be noted and, if necessary, the line repressuri)ed to original test pressure

and isolated from the pressure source.

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If, during the remainder of the test period, the pressure decreases more than 5

percent, the piping should be visually inspected e#ternally and- or inspected

internally to find the lea! and assess the e#tent of corrosion. (onic

measurements may be helpful in locating lea!s during lea! testing.

uried piping also may be surveyed for integrity by using temperature3corrected

volumetric or pressure test methods.

Table K3 /re%uency of Inspection for uried Piping

2ithout 6ffective &athodic Protection

So2 Re33tvty; o5&c5 < In3ecton Interv2 ; yer3 33C

directions

- If e#cessive vibrations are observed in a piping elds shall be inspected for

crac!s, especially at points of restraints, anchors

- Additional supports may be considered for poorly supported lines

- (ee! advice of &onsultant - Piping 6ngineer to eliminate - dampen the

vibrations

-

d < E4tern2 Corro3on

- 4ue to defects in &oating, painting or damaged insulation

- (urvey for &?I shall be done in operation to the e#tent possible

- =ines that seat, li%uid spills, condensate relief valves don stream may

cause e#ternal corrosion

- 'ot spots due to damage of internal refractory lining.

- ight glo or balding of pipes may be seen

- To arrest balding e#ternal cooling by ater, air, may be used till system is

removed for maintenance

INSPECTION DURIN- SHUT DO?N

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. isual inspection after pipe is opened at various flanged *oints and valves.

/lash light and e#tension lights and mirrors magnifying glasses may be used

may reveal folloing "

a 6#cessive corrosion - 6rosion, fouling

b &rac!s elds are most prone areas investigate crac!s further by blast

cleaning and et fluorescent PI, =PI and ?T

c Bas!et faces of flanges shall be chec!ed for scratches, cuts, pitting etc

$ef. A(6 :.5 Para :.0

d alves, bodies to be chec!ed for thic!ness, flanged ends for defects X

above and other parts seat stem spring for damage and brea!age, chec!

studs and nuts for deformation, shaving of threads etc.

e &hec! threaded *oints for loose threads, corrosing, cross threading,

ensure ne Teflon tapes are used hile putting bac! in place

f Areas seen as hot spots e#ternally shall be inspected for damage

internally and repaired

g 4amage to internal painting, coating, cladding shall be surveyed and

repaired

PRESSURE TESTS

Piping systems sub*ect to pr. Test include "

a. ?nderground lines and other inaccessible piping

b. 2ater and other non3ha)ardous utility lines

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c. =ong oil3transfer lines in arcas here a lea! or spill ould not be

ha)ardous to personnel or harmful to the environment.

d. &omplicated manifold systems.

e. (mall piping and tubing systems.

f. All systems after a chemical cleaning operation.

1 API 570 sec. 8.7 gives guidelines for preparing piping for pressure Testing.

8 4uring li%uid pressure Test, all air must be e#pelled, or else failure could be

more violent than li%uid3full system.

9 Avod over re33ure

H yield limit may e#ceed. ?se calibrated pressure Bauges gauge range < to 9

times test pressure. 'oever, 1 to 8 times Ptis preferred.

5 F2ud3 u3ed 3

a. ater H preferred

b. =i%uid products normally carried if not to#ic or inflammable

c. (team

d. Air, itrogen, 'elium

: 2ater as test medium may not be suitable for

a. Acid lines

b. acuum lines vertical lines

c. &orrosion of Austentic (teels (&&

d. ay free)e in cold eather

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7 (team may be used particularly if it is used for heating or purging. 'oever,

- difficulty in draining condensate from all areas and

- &ompressibility unsafe

- Inaccessibility and burn to personnel on lea!age could put severe

restrictions. All precautions of pneumatic testing stated in A(6 8.8

must be observed for steam testing as ell.

Pneu5tc te3t30

Pneumatic tests ith soap solutions are permissible. 'oever, best gaseous

mediums ould be inert gases li!e nitrogen 'elium etc.

'elium is ideal as it can detect minutest crac!s hich otherise ould be missed

in ater, air, steam or itrogen testing.

'elium lea!age in ppm levels can be detected by 'elium sniffers.

'ence they are used hen service conditions are particularly critical.

HA))ER TESTIN-

'ammer testing is old method to detect une#pected thin sections.

&ast Irons and &austic lines inside coated lines should not be hammered

$e%uires personal e#pertise

'ammer test shall be folloed up by other methods li!e ?T at suspected areas.

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NSPECTION OF UNDER-ROUND PIPIN-

In addition to product corrosion the ?nderground Piping is e#posed to soil

corrosion. /olloing methods are adopted in inspection of ?nderground Piping "

1. A survey above ground of the piping route could sho discoloration of soil,

pool formation, noticeable odor etc. for hich corrosion and lea! may be

probable cause.

All Pipes are inspected at and *ust belo the point here they enter earth,

concrete, asphalt etc. since these areas are more prone to corrosion.

8. &lose internal potential survey H This techni%ue measures the potential of the

pipe to the soil directly over pipe at fi#ed intervals 5 ft, 0 ft. etc.

Pipe contact can be made at an above ground attachment. (udden change ofP-( potential is location for further scrutiny by e#cavation, if re%uired .

9. 'oliday pipe coating survey is employed to ensure that coating is intact and

holiday free.This techni%ue is used for predicting corrosion activity in specific

area and coating replacement decisions.

5. (oil resistivity testing " This techni%ue is used for relative classification of the

soil resistivity.=oer levels of resistivity are more corrosive than higher levels.

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:. &athodic Protection onitoring " This shall be carried out regularly to assure

ade%uate levels of protection.

Periodic monitoring includes chec!ing condition of sacrifical anodes or rectifier

currents in impressed current system.

7. Intelligent Pigging " This method involves movement of device pig through

piping. 'oever, this techni%ue re%uires line to be free from restrictions i.e. full

bore valves, absence of reduces and five diameter ban!ds. ery effective

techni%ue in long distance piping. 'oever, blant piping has limited use.

J. ideo &ameras " These provide direct visual information on internal

condition of pipe.

K. 6#cavation " (ometimes the only available method is unearthing of piping for

visual inspection of e#ternal condition of piping and evaluate its thic!ness.

0. =ea! testing " IB lines that can not be visually inspected should be

periodically.

a. Pressure decay method " Pressurise the line, bloc! it, remove

source of pressure, monitoring over a period of time ill provide indicating

of pressure tightness. Performance can be confirmed by lea! simulation.

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b. olume in- volume out method uses volumetric measuring meter at

each end of the line. Performance can be determined by lea! simulation.

c. (ingle point volumetric method is similar to pressure decay method

e#cept that a graduated cylinder is employed to chec! level reduction by

lea!age.

d. a!er chemical tracer may be added to line to detect lea! and

soil gas samples near line are tested for presence of ma!er chemicals.

e. Accoustic emission technology detects and locates lea!s by sound

created by lea! and detected by senser.

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RETIRE)ENT THIC>NESS FOR PIPES

API 579 Par. .

Thic!ness formulas from A(6 8.8 shall be used.

t R tmY A

P42here tm R 3333333333333333 Y A or,

1(6 Y1P

P4 tm R 33333333 Z arlo formula

1(6

for t V 4-: or P-(6 V 0.8J5, special considerationsre%uired

In practice t is generally higher due to rounding up of pipe

schedule to higher number.

1 /or lo pressure and temperatures, above thic!nesses could be so small for

sufficient structural strength for span and other ?4= insulation, sno etc.

8 Absolute minimum thic!ness ta shall be determined based on internal

pressure, sag, buc!ling etc.

Pipe should not be permitted to deteriorate belo this thic!ness t a , hich is

called L$etirement Thic!nessM i.e. Pipe shall be retired replaced at this

thic!ness.

9 Above calculations shall be performed by or under direction of Piping 6ngineer.

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RETIRE)ENT THIC>NESSFOR ,AL,ES FLAN-ED FITTIN-S0 API 579 H Para .1

.(tress pattern for valves and flanges in %uite comple# due to simultaneous effects of "

- Internal pressure

- olts load forces and movements

- (tress concentration due to shape

1. A(6 :.89 determines that min. alve all thic!ness tv shall be

tv R .5 # t Z.. for alve classes 50 H 1500

tv R .85 # t Z for alve class 9500

2here, t R Thic!ness of &ylinder ith ( R 7000 psi and Pressure same as that

from P H T ratings

Actual thic!ness ta given in :.89 R tvY 0. In.fi#ed

alve thic!ness per API :00 have additional corrosion and erosion re%uirementover ta from :.89

8. 2here corrosion - erosion is anticipated thic!ness measurements shall be

made to determine metal loss.

9. /ormula for calculating retirement thic!ness of pipe can be used for alves

and flanged fittings using factor .5 and 5 alves from A(6 8.8.

&alculations described above not re%uired for elded fittings. Pipe thic!ness can be

adopted for elded fittings using appropriate corrections for shape, if necessary.

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INSPECTION RECORDS

API 570 H &hapter 1

. Inspection records provide "

- A comprehensive picture of general condition i.e. health of piping

system

- 4ecide on additional - supplementary inspections

- 6valuation of remaining useful life

- 4eciding on probable retirement and replacement programmes and ta!e

advance action for the same.

The data should be arranged on suitable forms so that successive inspection

records furnished a chronological picture.

1. (!etches " @riginal isometric s!etches may be used or ne s!etches made

to sho T=s and other relevant information.

8. Thic!ness 4ata " $ecord of thic!ness data obtained from periodic or

scheduled inspections shall be shon on s!etches and tabulated and attached

s!etches /ig. 89 sample form

9. $evie of $ecords " $ecords of previous inspection shall be revieed soon

after current data is available from field and follo3up action sheets shall be

prepared shoing "

- Approaching retirement thic!ness

- eed of further investigation based on past and present data i.e.

e#cessive corrosion rates on both occasions

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- In other cases specific features to be monitored during on3stream or ne#t

shut don inspection.

- A list for predictable repairs and alterations shall be made so thatmaintenance dept. can obtain materials, !eep components ready, if

nessary, fabricate ell ahead of ne#t shut don. This list ill also help to

plan manpoer for ne#t shut don.

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PLANT PIPIN- CODE & AS)E B (1.(

PIPIN- FUNDA)ENTALS

1. -ener2 0

Prior to study of Plant piping code, a %uic! revie of piping fundamentals is

essential for prper understanding of the code.

A e or tubeis hollo, longitudinal product. [A tube+ is a general term used

for hollo product having circular, elliptical or s%uare cross3section or for that

matter cross3section of any closed perimeter.

A e is tubular product of circular cross3section that has specific si)es and

thic!nesses governed by particular dimensional standard.

%. C233!cton 0

Pipe can be classified based on methods of manufacture or based on their

applications.

(. )etod3 o! 5nu!cture 0

(eamless pipes are manufactured by draing or e#trusion process. 6$2 pipes

6lectric resistance elded pipes are formed from a strip hich is longitudinally

elded along its length. 2elding may be by 6lectric resistance, high fre%uency,or induction elding, 6$2 pipes can also be dran for obtaining re%uired

dimensions and tolerances.

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Pipes in small %uantities are manufactured by 6/2 6lectric fusion elding

process here in instead of electric resistance elding, the longitudinal seam is

elded by manual or automatic electric arc process.

There are spiral seam elded pipes, hich are large dia pipes 500 andabove, and pipes are made by elding a spiral seam produced by forming

continuous steel s!elp into circular shape.

&entrifugally cast pipes are made by spraying molten metal along a rotating die

here the pipes are cast in shape due to centrifugal action.

C233!cton b3ed on end u3e "

Pipes a re classified as "

- Pressure pipes or Process pipes

- =ine pipes

- (tructural pipes

. Pressure pipes are those hich are sub*ected to fluid pressure and or

temperatures. /luid pressure in generally internal pressure due to fluid

being conveyed or may be e#ternal pressure e.g. *ac!ed piping and are

mainly used as plant piping.

1. =ine Pipes are mainly used for long distance conveying of the fluids and

are sub*ected to fluid pressures. These are generally not sub*ected to

high temperatures.

8. (tructural pipes are not used for conveying fluids and therefore not

sub*ected to fluid pressures or temperatures. They are used as structural

components e.g. handrails, columns, sleeves etc. and are sub*ected to

static loads only.

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9. Pe3 D5en3on2 Stndrd3 "

4iameters " Pipes are designated by ominal si)e, (tarting form -JM ominal

si)e, and increasing in steps.

. Pipe si)es increases in steps of -JM fir -JM to


91/173

&ommon pipe schedules are (ch 90, (ch J0, (ch 10, (ch :0, for larger pipe

si)es intermediate schedule numbers (ch10, (ch 80 etc. are also employed

$ef. Pipe 4imension &hart

/or &arbon steel, Pipe all thic!ness tolerance is Y 1


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*.1 Butt&?e2ded Fttn/3

2elded fittings are used primarily in systems meant to be permanent.

They have the same all thic!ness as the mating pipe. Among the many

advantages of butt

Documents

API 570 Course Notes- Joshi