piping and components inspection.pdf

7/28/2019 PIPING AND COMPONENTS INSPECTION.pdf

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N. Al-Khirdaji, AZTech, Sr. Consultant

3.5 Piping and Component

Inspection

API RP 574

.

Major Piping Inspection CodesAPI 570

Piping Inspection Code

Design StandardsNew Construction

MitigationStandards

Quality SafetyOther Inspection

Codes / Documents

ASMEB16.34Valves - Flanged

Threaded andWelding ends

API 651Cathodic Protection ofAboveground Storage

Tanks

NACE RP0169Control of External

Corrosion onUnderground or

Submerged MetallicPiping Systems

ASME BPVC Sec IX,"Welding and Brazing

Qualifications"

API RP 750Management ofProcess Hazards

Of Materials

API 510Pressure VesselInspection Code

ASME BPVC Sec VIII,Division 1 & 2

Pressure Vessels

R:0170Protection of

Austenitic StainlessSteels from PolythionicAcid Stress Corrosion

Cracking During

NACE RP0274High-Voltage ElectricalInspection of Pipeline

Coatin s Prior to

CP-189Standard for Qualification

and Certification ofNondestructive Testing

Personnel

NFPA 704Identification ofthe Fire Hazards

of Materials

API RP 574Inspection of Piping

SystemComponents

ut own o

Refinery Equipment

InstallationASME B31.3Process Piping

Application of OrganicCoatings to the

External Surface ofSteel Pipe for

Underground Piping

SNT-TC-1A API 598Valve Inspection

and Testing

Notes:

1. The source of this data is from API Standard 570 "Piping Inspection Code", Second

Edition October 1998, Section2 "References";

2. API 570 references directly all of the standards shown on this diagram and they are

applicable and mandatory under the appropriate conditions as indicated in API 570.

3. API Standards are revised, reaffirmed, or withdrawn at least every 5 years.

4. API Standards, revision or addenda are effective 6 months after the date of issuance


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API 570 - Piping Inspection Code

Coverage

, , ,rerating procedures for metallic piping systems thathave been in-service.

Intent

API 570 was developed for the petroleum refiningand chemical process industries but may be used,where ractical for an i in s stem.

It is intended for use by organizations that maintain

or have access to an authorized inspection agency, arepair organization, and technically qualified pipingengineers, inspectors, and examiners, all as defined inSection 3.

API 570 Framework Section 9 of API 570 recognizes two distinctions

re ardin buried i e:

Significant External Deterioration,

Inaccessibility.


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API 570 Framework

Subsections of Section 9 are:

T es and Methods of Ins ection.

Direct and indirect monitoring (limited reference).

Frequency and Extent of Inspection.

Repairs to Buried Piping System.

Records.

API RP 574 - Inspection Practices For

Piping System Components

This recommended practice describes to the inspector on

describes ins ection ractices for i in tubin valves other

than control valves), and fittings used in petroleum refineries

and chemical plants.

Common piping components, valve types, pipe joining

methods, inspection planning processes, inspection intervals

and techniques, and types of records are described to aid the

ins ector in fulfillin their role im lementin API 570.

This publication does not cover inspection of specialty items,

including instrumentation and control valves


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API RP 574 - Definitions

alteration

A physical change in any component that has design

implications affecting the pressure containing

capability or flexibility of a piping system beyond the

scope of its design.

NOTE The following are not considered alterations:

compara e or up ca e rep acemen ; e a on o any

reinforced branch connection equal to or less than the size

of existing reinforced branch connections; and theaddition of branch connections not requiring

reinforcement.


condition monitoring locations

CMLs

Designated areas on piping systems where

periodic inspections and thickness

measurements are conducted.


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deadlegs

Components of a piping system that normally have no

significant flow.

Examples of deadleg locations include: blanked

branches, lines with normally closed block valves,

lines which have one end blanked, pressurized

ummy suppor egs, s agnan con ro va ve ypass

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.


minimum alert thickness

c ness grea er an e m n mum a owe c ness

that provides for early warning from which the future

service life of the piping is managed through further

inspection and remaining life assessment.

minimum allowed thickness

structural minimum thickness at a CML. It does not

include thickness for corrosion allowance or mill

tolerances.


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piping circuit

omp ex process un s or p p ng sys ems are v e n o

piping circuits to manage the necessary inspections,

calculations, and recordkeeping.

A piping circuit is a section of piping of which all points

are exposed to an environment of similar corrosivity and

which is of similar desi n conditions and construction

material.

When establishing the boundary of a particular pipingcircuit, the Inspector may also size it to provide a

practical package for recordkeeping and performing field

inspection.


repair

A repair is the work necessary to restore a piping

system to a condition suitable for safe operation at the

design conditions.

If any of the restorative changes result in a change of

design temperature or pressure, the requirements for

rera ng a so s a s ou e sa s e . Any welding, cutting, or grinding operation on a

pressure containing piping component not specifically

considered an alteration is considered a repair.


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rerating

Rerating is A change in either or both the design

temperature or the maximum allowable working

pressure of a piping system.

NOTE: A rerating may consist of an increase,

decrease, or a combination. Derating below original

es gn con ons s a means o prov e ncrease

corrosion allowance.

structural minimum thickness

Minimum pipe wall thickness typically needed to

support non-pressure loadings, e.g. weight of pipe,

process fluids, insulation, other live and dead loads,

etc.

NOTE : The thickness is either determined from a

s an ar c ar or eng neer ng ca cu a ons. oes noinclude thickness for corrosion allowance or mill

tolerances


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API RP 574 - Piping

Piping can be made from any material that can be rolled and

welded cast or drawn throu h dies to form a tubular section.

The two most common carbon steel piping materials used in

the petrochemical industry are ASTM A 53 and A 106.

The industry generally uses seamless piping for most services.

Piping of a nominal size larger than 16 in. (406 mm) is usually

made by rolling plates to size and welding the seams.

Centrifugally cast piping can be cast then machined to any

desired thickness.

Steel and alloy piping are manufactured to standard

dimensions in nominal pipe sizes up to 48 in. (1219 mm).

Table 3 Permissible Tolerances in

Diameter and Thickness for Ferritic Pipe


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API RP 574

Tubing - With the exception of heater, boiler, andexc anger u es, u ng s s m ar o p p ng, u s

manufactured in many outside diameters and wall thicknesses.

Tubing is generally seamless, but may be welded. Its stated

size is the actual outside diameter rather than nominal pipe

size. (ASTM B 88 tubing, which is often used for steam

tracing, is an exception in that its size designation is 1/8 in.

. . Tubing is usually made in small diameters and is mainly used

for heat exchangers, instrument piping, lubricating oil services,

steam tracing, and similar services.


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API RP 574

Valves

The basic types of valves are gate, globe, plug, ball,

diaphragm, butterfly, check, and slide valves. Valves are made

in standard pipe sizes, materials, body thickness, and pressure

ratings that permit them to be used in any pressure-temperature

service in accordance with ASME B16.34 or API 599, API

600, API 602, API 603, API 608, or API 609, as applicable.

a ve o es can e cast, orge , mac ne rom ar stoc , or

fabricated by welding a combination of two or more materials.

The seating surfaces in the body can be integral with the body,

or they can be made as inserts. The insert material can be the

same as or different from the body material.

API 574 - Reasons for Inspection

The primary purpose of inspection is to perform activities

usin a ro riate techni ues necessar to identif active

deterioration mechanisms and to specify repair, replacement,

or future inspections for affected piping.

This requires developing information about the physical

condition of the piping, the causes of its deterioration, and its

rate of deterioration.

,

predict and recommend future repairs and replacements, and

act accordingly, to prevent or retard further deterioration and

most importantly, prevent loss of containment.


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API 574 - Reasons for Inspection

(continued)

This should result in

increased operating safety,

reduced maintenance costs, and

more reliable and efficient operations.

API 570 provides the basic requirements for such an

nspec on program.

This recommended practice supplements API 570 by

providing piping inspectors with information that can

improve skill and increase basic knowledge and practices

API 574 - Inspection Plans

An inspection plan is often developed and implemented

.

Other piping systems may also be included in the

inspection program and accordingly have an inspection

plan.

An inspection plan should contain the

,

scope of inspection, and

schedule required to monitor damage mechanisms and

assure the mechanical integrity of the piping components in

the system.


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The plan will typically

a) define the type(s) of inspection needed, e.g. external,

b) identify the next inspection interval and date for each

inspection type,

c) describe the inspection and NDE techniques,

d) describe the extent and locations of inspection and NDE,

inspection and examinations,

f) describe the requirements of any needed pressure test, e.g.type of test, test pressure, and duration, and

g) describe any required repairs.


Other common details in an inspection plan include:

escr ng e ypes o amage mec an sms an c pa e or

experienced in the equipment;

defining the location of the damage;

defining any special access requirements.

Inspection plans for piping may be maintained in

,

inspection software databases. Proprietary software,

typically used by inspection groups, often assists in

inspection data analysis and record keeping.


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For piping systems, inspection plans should address

a) condition monitoring locations (CMLs) for specific

damage mechanisms;

b) piping contact points at pipe support

c) welded pipe supports;

d CUI

e) injection points;

f) process mix points;g) soil-to-air (concrete-to-air) interfaces;

h) deadleg sections of pipe;


i) positive material identification;

k) critical utility piping as defined by owner-user;

l) vents/drains;

m) threaded pipe joints;

n) internal linings;

o critical valves

p) expansion joints;

Inspection plans may be based upon various criteria but should

include a risk assessment or fixed intervals as defined in API

570.


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API RP 574: Risk Based Inspection

Inspection plans based upon an assessment of the

piping system or circuit is RBI.

RBI may be used to determine inspection intervals and

the type and extent of future inspection/examinations.

API RP 580 details the systematic evaluation of both the

likelihood of failure and consequence of failure for

establishing RBI plans.

API Publication 581 details an RBI methodology that hasall of the key elements defined in API RP 580

Minimum Alert Thickness

The alert thickness signals the inspector that it is timely for a

remainin life assessment. This could include a detailed

engineering evaluation of the structural minimum thickness,

fitness-for-service assessment, or developing future repair

plans. In addition, when a CML reaches the alert thickness, it

raises a flag to consider the extent and severity at other

possible locations for the corrosion mechanism. Alert

minimum thicknesses are usually not intended to mean that

pipe components must be retired when one CML reaches thedefault limit.


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Table 6Minimum Thicknesses for

Carbon and Low Alloy Steel PipeDefault Minimum Structural

Thickness for Tem eratures Minimum Alert Thickness for

NPS< 400oF (205 oC)

in. (mm)

Temperatures < 400oF (205 oC)

in (mm)

to 1 0.07 (1.8) 0.08 (2.0)

1 0.07 (1.8) 0.09 (2.3)

2 0.07 1.8 0.10 2.5

3 0.08 (2.0) 0.11 (2.8)

4 0.09 (2.3) 0.12 (3.1)

6-18 0.11 (2.8) 0.13 (3.3)

20-24 0.12 (3.1) 0.14 (3.6)

API 570 SECTION 5 - Inspection,Examination and Pressure Testing Practices

An inspection plan shall be established for all piping

.

The inspection plan shall be developed by the inspector

and/or engineer.

A corrosion specialist shall be consulted as needed to

clarify potential damage mechanisms and specific locations

where degradation may occur.

A corrosion specialist shall be consulted when developingthe inspection plan for piping systems that operate at

elevated temperatures (above 750oF (400oC)) and piping

systems that operate below the ductile-to-brittle transition

temperature.


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API 570 - Minimum Contents of an

Inspection Plan The inspection plan shall contain the inspection tasks

mechanisms and assure the pressure integrity of the

piping systems. The plan should:

define the type(s) of inspection needed, e.g.

internal, external, on-stream (non-intrusive);

inspection type;

describe the inspection methods and NDE

techniques;

API 570 - Minimum Contents of an

Inspection Plan

describe the extent and locations of inspection and

describe the surface cleaning requirements needed

for inspection and examinations for each type of

inspection;

describe the requirements of any needed pressure

, . . , ,and duration; and,

describe any required repairs if known or

previously planned before the upcoming

inspection.


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API 570 Table 5-1 Some Typical

Piping Damage Types and MechanismsDamage Type Damage Mechanism

General and local metal loss SulfidationOxidation

cro o og ca y n uence corros onOrganic acid corrosionErosion / erosion-corrosionGalvanic corrosionCorrosion under insulation

Surface connected cracking FatigueCaustic stress corrosion crackingSulfide stress corrosion crackingChloride stress corrosion crackingPolythionic acid stress corrosion crackingOther forms of environmental cracking

Subsurface cracking Hydrogen induced crackingMicrofissuring/microvoid formation High temperature hydrogen attack

Creep

Metallurgical changes GraphitizationTemper embrittlement

Blistering Hydrogen blisteringDimensional changes Creep and stress rupture

Thermal

Material properties changes Brittle fracture

API 570 Table 5-1 Some TypicalPiping Damage Types and Mechanisms

Damage Type Damage Mechanism

Oxidation

Microbiologically influenced corrosion

Organic acid corrosion

Erosion / erosion-corrosion

Galvanic corrosion

Corrosion under insulation

Surface connected cracking Fatigue

Caustic stress corrosion crackingSulfide stress corrosion cracking

Chloride stress corrosion cracking

Polythionic acid stress corrosion cracking

Other forms of environmental cracking


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API 570 Table 5-1 Some Typical

Piping Damage Types and Mechanisms

Damage Type Damage Mechanism

u sur ace crac ng y rogen n uce crac ng

Microfissuring/microvoid

formation

High temperature hydrogen attack

Creep

Metallurgical changes Graphitization

Temper embrittlement

Blistering Hydrogen blistering

Dimensional changes Creep and stress rupture

Thermal

Material properties changes Brittle fracture

API 570 Areas of Deterioration for

Piping Systems

Each owner/user shall provide specific attention to

susceptible to the following specific types and areas

of deterioration:

a. Injection points and mix points.

b. Deadlegs.

c. Corrosion under insulation CUI .

d. Soil-to-air (S/A) interfaces.

e. Service specific and localized corrosion.


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API 570 Areas of Deterioration for

Piping Systemsf. Erosion and corrosion/erosion.

g. nv ronmenta crac ng.

h.Corrosion beneath linings and deposits.

i. Fatigue cracking.

j. Creep cracking.

k.Brittle fracture.

l. Freeze damage.

m.Contact point corrosion

API 570 - General Types of Inspection

and Surveillance

Different types of inspection and surveillance are

piping system (see note). These include the

following:

a. Internal visual inspection.

b. On-stream inspection.

b.Thickness measurement inspection.

c.External visual inspection.


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API 570 - General Types of Inspection

and Surveillanced.Corrosion under insulation (CUI) inspection.

e. rat ng p p ng nspect on.

f Supplemental inspection.

Note: See Section 6 for interval/frequency and extent

of inspection. Imperfections identified during

nspect ons an exam nat ons s ou e

characterized, sized, and evaluated per Section 7.

API 570 - Vibrating Piping and Line

Movement Surveillance

Operating personnel should report vibrating or swaying

assessment.

Evidence of significant line movements that could have

resulted from liquid hammer, liquid slugging in vapor lines,

or abnormal thermal expansion should be reported.

At locations where vibrating piping systems are restrained,

per o c or s ou e cons ere to c ec or t eonset of fatigue cracking.

Branch connections should receive special attention

particularly unbraced small bore piping connected to

vibrating pipe.


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API 570 - Condition Monitoring

Locations Condition monitoring locations (CMLs) are specific areas

alon the i in circuit where ins ections are to be made.

The nature of the CML varies according to its location in the

piping system.

The selection of CMLs shall consider the potential for

localized corrosion and service-specific corrosion as described

in API 574 and API 571. Examples of different types of

locations for thickness measurement,

locations for stress cracking examinations,

locations for CUI, and

locations for high temperature hydrogen attack examinations.

API 570 SECTION 6 Frequency and

Extent of Inspection

The frequency and extent of inspection on piping

affect the piping and consequence of a piping failure.

The various forms of degradation that can affect

refinery piping circuits are described in 5.3, while a

simplified classification of piping based on the

. .

As described in 5.1, inspection strategy based on

likelihood and consequence of failure, is referred to

as risk-based inspection.


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API 570 SECTION 6 Frequency and

Extent of Inspection The simplified piping classification scheme in Section 6.2 is

based on the consequence of a failure. The classification is

used to establish frequency and extent of inspection.

The owner/user may devise a more extensive classification

scheme that more accurately assesses consequence for certain

piping circuits.

The consequence assessment would consider the potential for

explosion, fire, toxicity, environmental impact, and other

potential effects associated with a failure.

The three classes are recommended

Piping Classes

Class 1

erv ces w e g es po en a o resu ng n an mme a e

emergency if a leak were to occur are in Class 1. Such an

emergency may be safety or environmental in nature.

Examples of Class 1 piping include, but are not necessarily

limited to, those containing the following:

Flammable services that may auto-refrigerate and lead to brittle fracture.

,

vapors that may collect and form an explosive mixture, such as C2, C3, and

C4 streams.


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Piping Classes

Class 1 (contd)

H dro en sulfide reater than 3 ercent wei ht in a aseous stream.

Anhydrous hydrogen chloride.

Hydrofluoric acid.

Piping over or adjacent to water and piping over public throughways.

(Refer to Department of Transportation and U.S. Coast Guard regulations

for inspection of overwater piping.)

Piping Classes

Class 2

Services not included in other classes are in Class 2. This

classification includes the majority of unit process piping and

selected off-site piping. Typical examples of these services

include those containing the following:

On-site hydrocarbons that will slowly vaporize during release.

Hydrogen, fuel gas, and natural gas.

On-site strong acids and caustics.


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Piping Classes

Class 3

erv ces a are amma e u o no s gn can y vapor ze

when they leak and are not located in high-activity areas are in

Class 3. Services that are potentially harmful to human tissue

but are located in remote areas may be included in this class.

Examples of Class 3 service are as follows:

On-site hydrocarbons that will not significantly vaporize

ur ng re ease.

Distillate and product lines to and from storage and loading.

Off-site acids and caustics.

Inspection Intervals

The interval between piping inspections shall be established

and maintained usin the followin criteria:

Corrosion rate and remaining life calculations.

Piping service classification.

Applicable jurisdictional requirements.

Judgment of the inspector, the piping engineer, the piping

engineer supervisor, or a corrosion specialist, based on

operating conditions, previous inspection history, currentinspection results, and conditions that may warrant

supplemental inspections covered in 5.4.5.


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Table 6-1Recommended Maximum

Inspection Intervals

Type of Circuit Thickness

Measurement

Visual External

Class 1 5 years 5 years



Injection points a 3 years By Class

Soil-to-air interfaces b - By Class

Rerating of Piping Systems

API 570 Piping inspection code: Inspection, repair,-,

covers the inspection, repair, alteration and re-ratingprocedures for in-service metallic piping systems.

The code establishes the requirements and guidelinesthat allow the owners and users of piping systems tomaintain the safety and mechanical integrity of


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Rerating Definition

- definitions that apply to this code. They include thefollowing definitions that pertain to rerating:

Rerating [3.39]: A change in either or both thedesign temperature or the maximum allowableworkin ressure of a i in s stem.

A rerating may consist of an increase, a decrease,

or a combination of both. Derating below originaldesign conditions is a means to provide increasedcorrosion allowance.

MAWP Determination - 1

Maximum Allowable Working Pressure: (MAWP).

the piping system for continued operation at the mostsevere condition of coincident internal or external

pressure and temperature (minimum or maximum)expected during service.

It is the same as the design pressure, as defined in

. ,to the same rules relating to allowances for variationsof pressure or temperature or both


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MAWP for the continued use of piping systems shall.

Computations may be made for known materials if allthe following essential details are known to complywith the principles of the applicable code:

a. Upper and/or lower temperature limits for specificmaterials.

. ua y o ma er a s an wor mans p.

c. Inspection requirements.

d. Reinforcement of openings.

e. Any cyclical service requirements.


For unknown materials, computations may be madeassumin the lowest rade material and oint efficienc inthe applicable code.

When the MAWP is recalculated, the wall thickness usedin these computations shall be the actual thickness asdetermined by inspection (see 5.6 for definition) minustwice the estimated corrosion loss before the date of thenext inspection (see 6.3).

Allowance shall be made for the other loadings inaccordance with the applicable code.

The applicable code allowances for pressure andtemperature variations from the MAWP are permittedprovided all of the associated code criteria are satisfied.


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Retirement Thickness Determination 1

The minimum required pipe wall retirement

minimum required thickness, or retirementthickness, and shall be based on

pressure,

mechanical, and

using the appropriate design formulae and code

allowable stress.

Consideration of both general and localizedcorrosion shall be included

Retirement Thickness Determination 2

For services with high potential consequences if,

consider increasing the required minimum thicknessabove the calculated minimum thickness to providefor unanticipated or unknown loadings, undiscoveredmetal loss, or resistance to normal abuse.

In this case, the retirement thickness shall be used in

. .remaining life calculations


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Rerating Requirements

API 570 - Sub-Section 8.3 Rerating piping systems by changing thetemperature rating or the MAWP may be doneonly after all of the following requirements have

been met:

a. Calculations are performed by the piping engineer or theinspector.

b. All reratings shall be established in accordance with therequirements of the code to which the piping system wasu or y compu a on us ng e appropr a e me o s n

the latest edition of the applicable code.

c. Current inspection records verify that the piping system issatisfactory for the proposed service conditions and thatthe appropriate corrosion allowance is provided.


API 570 - Sub-Section 8.3d. Rerated piping systems shall be leak tested in

accordance with the code to which the piping system

was built or the latest edition of the applicable code for

the new service conditions, unless documented records

indicate a previous leak test was performed at greater

than or equal to the test pressure for the new condition.

An increase in the rating temperature that does not affect

allowable tensile stress does not require a leak test.

e. The piping system is checked to affirm that the requiredpressure relieving devices are present, are set at the

appropriate pressure, and have the appropriate capacity

at set pressure.


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API 570 - Sub-Section 8.3f. The piping system rerating is acceptable to the inspectoror piping engineer.

g. All piping components in the system (such as valves,flanges, bolts, gaskets, packing, and expansion joints)are adequate for the new combination of pressure andtemperature.

h. Piping flexibility is adequate for design temperaturechanges.

. ppropr ate eng neer ng recor s are up ate .

j. A decrease in minimum operating temperature is

justified by impact test results, if required by theapplicable code.