PIPING AND COMPONENTS INSPECTION.pdf

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3.5 Piping and Component Inspection • API RP 574 • API Std. Std 570

Major Piping Inspection Codes API 570 Piping Inspection Code Underlying Design Standards New Construction

Corrosion Mitigation Standards

ASMEB16.34 Valves - Flanged Threaded and Welding ends

API 651 Cathodic Protection of Aboveground Storage Tanks

ASME BPVC Sec VIII, Division 1 & 2 Pressure Vessels

R:0170 Protection of Austenitic Stainless Steels from Polythionic Acid Stress Corrosion Cracking During Sh d Shutdown off Refinery Equipment

ASME B31.3 Process Piping

NACE RP0169 Control of External Corrosion on Underground or Submerged Metallic Piping Systems

NACE RP0274 High-Voltage Electrical Inspection of Pipeline Coatings Prior to Installation

Application of Organic Coatings to the External Surface of Steel Pipe for Underground Piping

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Safety

Other Inspection Codes / Documents

ASME BPVC Sec IX, "Welding and Brazing Qualifications"

API RP 750 Management of Process Hazards Of Materials

API 510 Pressure Vessel Inspection Code

CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel

NFPA 704 Identification of the Fire Hazards of Materials

API RP 574 Inspection of Piping System Components

Quality

SNT-TC-1A

API 598 Valve 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 API Standards are revised, reaffirmed, or withdrawn at least every 5 years. 4.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 API 570 covers inspection inspection, repair repair, alteration, alteration and rerating procedures for metallic piping systems that have been in-service. • Intent API 570 was developed for the petroleum refining and chemical process industries but may be used, practical,, for anyy piping p p g system. y where p It is intended for use by organizations that maintain or have access to an authorized inspection agency, a repair organization, and technically qualified piping engineers, inspectors, and examiners, all as defined in Section 3.

API 570 Framework • Section 9 of API 570 recognizes two distinctions regarding g g buried pipe: pp • Significant External Deterioration, • Inaccessibility.

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API 570 Framework • Subsections of Section 9 are: • Types yp and Methods of Inspection. p • 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 inspection practices for piping, tubing, 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 inspector in fulfilling their role implementing 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: comparable or duplicate replacement; the addition of any reinforced branch connection equal to or less than the size of existing reinforced branch connections; and the addition of branch connections not requiring reinforcement.

API RP 574 - Definitions condition monitoring locations CMLs • Designated areas on piping systems where periodic inspections and thickness measurements are conducted.

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API RP 574 - Definitions 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 d dummy supportt legs, l stagnant t t control t l valve l bypass b 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.

API RP 574 - Definitions minimum alert thickness • A thi thickness k greater t th than th the minimum i i allowed ll d thickness thi k 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 • The larger of the pressure design thickness or the structural minimum thickness at a CML. It does not include thickness for corrosion allowance or mill tolerances.

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API RP 574 - Definitions piping circuit • C Complex l process units it or piping i i systems t are divided di id d into i t 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 g conditions and construction which is of similar design material. • When establishing the boundary of a particular piping circuit, the Inspector may also size it to provide a practical package for recordkeeping and performing field inspection.

API RP 574 - Definitions 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 rerating ti also l shall h ll should h ld be b satisfied. ti fi d • 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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API RP 574 - Definitions 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 d i conditions design diti is i a means to t provide id increased i d 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 standard t d d chart h t or engineering i i calculations. l l ti It does d nott include 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 through 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, and exchanger h t b tubing tubes, t bi is i similar i il to t piping, i i but b t is i 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. (3 2 mm) less than the actual outside diameter.) (3.2 diameter ) • 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. • Valve V l bbodies di can be b cast, forged, f d machined hi d from f bar b stock, k 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 using appropriate techniques necessary to identify 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. • By developing a database of inspection history, history the user may 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 i inspection ti 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 for piping systems within the scope API 570. 570 • Other piping systems may also be included in the inspection program and accordingly have an inspection plan. • An inspection plan should contain the – inspection tasks tasks, – 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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API 574 - Inspection Plans • 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, e) describe any surface cleaning requirements needed for 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.

API 574 - Inspection Plans • Other common details in an inspection plan include: – ddescribing ibi the th types t off damage d mechanisms h i anticipated ti i t d or experienced in the equipment; – defining the location of the damage; – defining any special access requirements.

• Inspection plans for piping may be maintained in spreadsheets hard copy files and proprietary spreadsheets, inspection software databases. Proprietary software, typically used by inspection groups, often assists in inspection data analysis and record keeping.

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API 574 - Inspection Plans • For piping systems, inspection plans should address the following: 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;

API 574 - Inspection Plans – i) positive material identification; – j) auxiliary piping; – 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 likelihood of failure and the consequence of failure of a 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 has all of the key elements defined in API RP 580

Minimum Alert Thickness • The alert thickness signals the inspector that it is timely for a remaining 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 the default limit.

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Table 6—Minimum Thicknesses for Carbon and Low Alloy Steel Pipe Default Minimum Structural Thickness for Temperatures p o < 400 F (205 oC) in. (mm)

Minimum Alert Thickness for Temperatures < 400oF (205 oC) in (mm)

½ to 1

0.07 (1.8)

0.08 (2.0)

1½

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)

NPS

API 570 SECTION 5 - Inspection, Examination and Pressure Testing Practices • An inspection plan shall be established for all piping systems within the scope of this code code. – 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 developing the 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 and schedule required to monitor identified damage 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); – identify the next inspection date for each 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 NDE at CMLs; – describe the surface cleaning requirements needed for inspection and examinations for each type of inspection; – describe the requirements of any needed pressure test e.g. test, e g type of test test, test pressure, pressure test temperature 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 Mechanisms Damage Type General and local metal loss

Damage Mechanism Sulfidation Oxidation Mi bi l i ll influenced Microbiologically i fl d corrosion i Organic acid corrosion Erosion / erosion-corrosion Galvanic corrosion Corrosion under insulation

Surface connected cracking

Fatigue Caustic stress corrosion cracking Sulfide stress corrosion cracking Chloride stress corrosion cracking Polythionic acid stress corrosion cracking Other forms of environmental cracking

Subsurface cracking Microfissuring/microvoid formation

Hydrogen induced cracking High temperature hydrogen attack Creep Graphitization Temper embrittlement Hydrogen blistering Creep and stress rupture Thermal Brittle fracture

Metallurgical changes Blistering Dimensional changes Material properties changes

API 570 Table 5-1 – Some Typical Piping Damage Types and Mechanisms Damage Type General and local metal loss

Surface connected cracking

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Damage Mechanism Sulfidation Oxidation Microbiologically influenced corrosion Organic acid corrosion Erosion / erosion-corrosion Galvanic corrosion Corrosion under insulation Fatigue Caustic stress corrosion cracking Sulfide 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 S b f Subsurface cracking ki Microfissuring/microvoid formation Metallurgical changes Blistering Dimensional changes Material properties changes

Damage Mechanism H d Hydrogen induced i d d cracking ki High temperature hydrogen attack Creep Graphitization Temper embrittlement Hydrogen blistering Creep and stress rupture Thermal Brittle fracture

API 570 Areas of Deterioration for Piping Systems • Each owner/user shall provide specific attention to the need for inspection of piping systems that are 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 Systems f. Erosion and corrosion/erosion. g.Environmental E i l cracking. ki 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 appropriate depending on the circumstances and the 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 Surveillance d.Corrosion under insulation (CUI) inspection. e. Vibrating Vib i piping i i inspection. i i f Supplemental inspection. Note: See Section 6 for interval/frequency and extent of inspection. Imperfections identified during i inspections i andd examinations i i should h ld be b characterized, sized, and evaluated per Section 7.

API 570 - Vibrating Piping and Line Movement Surveillance • Operating personnel should report vibrating or swaying piping to engineering or inspection personnel for 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, periodic i di MT or PT should h ld be b considered id d to check h k for f the h onset 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 along the piping circuit where inspections 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 CMLs include – – – –

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 circuits depend on the forms of degradation that can 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 consequence of failure is defined in 6.2. 62 • 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 • S Services i with ith th the hi highest h t potential t ti l off resulting lti in i an immediate i di t 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. • Pressurized services that may rapidly vaporize during release, release creating vapors that may collect and form an explosive mixture, such as C2, C3, and C4 streams.

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Piping Classes Class 1 (cont’d) • Hydrogen y g sulfide (g (greater than 3 ppercent weight) g ) in a ggaseous 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 • S Services i th t are flammable that fl bl but b t do d nott significantly i ifi tl vaporize i 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 during release. release • 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 using the following 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, current inspection results, and conditions that may warrant supplemental inspections covered in 5.4.5.

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Table 6-1—Recommended Maximum Inspection Intervals Type of Circuit Class 1 Class 2 Class 3 Injection points a Soil-to-air interfaces b

Thickness Measurement 5 years 10 years 10 years 3 years -

Visual External 5 years 5 years 10 years By Class By Class

Rerating of Piping Systems • API 570 Piping inspection code: Inspection, repair, alteration and rerating of in alteration, in-service service piping systems covers the inspection, repair, alteration and re-rating procedures for in-service metallic piping systems. • The code establishes the requirements and guidelines that allow the owners and users of piping systems to maintain the safety and mechanical integrity of systems after they have been placed into service

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Rerating Definition • Section 3 of API 570 - “Definitions” Definitions states the definitions that apply to this code. They include the following definitions that pertain to rerating: “Rerating [3.39]: A change in either or both the design temperature or the maximum allowable working g pressure p of a piping p p g system. y A rerating may consist of an increase, a decrease, or a combination of both. Derating below original design conditions is a means to provide increased corrosion allowance”.

MAWP Determination - 1 Maximum Allowable Working Pressure: (MAWP) [3 21]: The maximum internal pressure permitted in [3.21]: the piping system for continued operation at the most severe 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 ASME B31.3 B31 3 and other code sections sections, and is subject to the same rules relating to allowances for variations of pressure or temperature or both

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MAWP Determination - 2 • MAWP for the continued use of piping systems shall be established using the applicable code. code • Computations may be made for known materials if all the following essential details are known to comply with the principles of the applicable code: a. Upper and/or lower temperature limits for specific materials. b Quality b. Q lit off materials t i l and d workmanship. k hi c. Inspection requirements. d. Reinforcement of openings. e. Any cyclical service requirements.

MAWP Determination - 3 • For unknown materials, computations may be made assumingg the lowest ggrade material and jjoint efficiencyy in the applicable code. • When the MAWP is recalculated, the wall thickness used in these computations shall be the actual thickness as determined by inspection (see 5.6 for definition) minus twice the estimated corrosion loss before the date of the next inspection (see 6.3). • Allowance shall be made for the other loadings in accordance with the applicable code. • The applicable code allowances for pressure and temperature variations from the MAWP are permitted provided all of the associated code criteria are satisfied.

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Retirement Thickness Determination 1 • The minimum required pipe wall retirement thickness shall be equal to or greater than the minimum required thickness, or retirement thickness, and shall be based on – pressure, – mechanical, and – structural considerations using the appropriate design formulae and code allowable stress.

• Consideration of both general and localized corrosion shall be included

Retirement Thickness Determination 2 • For services with high potential consequences if failure were to occur, occur the piping engineer should consider increasing the required minimum thickness above the calculated minimum thickness to provide for unanticipated or unknown loadings, undiscovered metal loss, or resistance to normal abuse. • In this case, the retirement thickness shall be used in lieu of the minimum required thickness in 7.1.1 7 1 1 for remaining life calculations

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Rerating Requirements API 570 - Sub-Section 8.3 • Rerating piping systems by changing the temperature rating or the MAWP may be done only after all of the following requirements have been met: a. Calculations are performed by the piping engineer or the inspector. b. All reratings shall be established in accordance with the requirements of the code to which the piping system was b ilt or by built b computation t ti using i the th appropriate i t methods th d in i the latest edition of the applicable code. c. Current inspection records verify that the piping system is satisfactory for the proposed service conditions and that the appropriate corrosion allowance is provided.

Rerating Requirements API 570 - Sub-Section 8.3 d.

e.

Rerated piping systems shall be leak tested in accordance with the code to which the ppiping p g system y 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. The piping system is checked to affirm that the required pressure relieving devices are present, are set at the appropriate pressure, and have the appropriate capacity at set pressure.

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Rerating Requirements API 570 - Sub-Section 8.3 f. g.

h. ii. j.

The piping system rerating is acceptable to the inspector or ppiping p g 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 and temperature. Piping flexibility is adequate for design temperature changes. A Appropriate i engineering i i records d are updated. d d A decrease in minimum operating temperature is justified by impact test results, if required by the applicable code.

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