nrf-032-pemex-2012 - piping systems in industrial plants

8/19/2019 Nrf-032-Pemex-2012 - Piping Systems in Industrial Plants

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NRF-032-PEMEX-2012

STANDARDS COMMITTEE OF PETROLEOS MEXICANOS AND SUBSIDIARIES

August 14, 2012

PAGE 1 of 100PEMEX REFINACI N

TECHNICAL STANDARDS SUBCOMMITTEE

PIPING SYSTEMS IN INDUSTRIAL PLANTSDESIGN AND MATERIAL SPECIFICATIONS

(This standard cancels and replaces NRF-032-PEMEX-2005 published on March 18, 2006, Specifications

P.2.0371.01, P.2.0370.01, K-101 and GPEI-IT-2001; GNT-SNP-T001-2003, GNT-SNP-T002-2003, GNT-

SNP-T003-2003 and GNT-SNP-T004-2004)


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PIPING SYSTEMS ININDUSTRIAL PLANTS -

DESIGN AND MATERIALSPECIFICATIONS

NRF-032-PEMEX-2012Rev: 0

PAGE 2 OF 104

This Reference Standard was approved by the Standards Committee ofPetróleos Mexicanos and Subsidiaries at Regular Meeting 87

held on May 24, 2012.


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TABLE OF CONTENTS

CHAPTER PAGE0. INTRODUCTION ................................................................................................................ 4

1. OBJECTIVE ....................................................................................................................... 5

2. SCOPE ............................................................................................................................... 5

3. FIELD OF APPLICATION .................................................................................................. 6

4. UPDATING ......................................................................................................................... 6

5. REFERENCES ................................................................................................................... 6

6. DEFINITIONS ....................................................................................................................10

7. SYMBOLS AND ABBREVIATIONS ..................................................................................13

8. DEVELOPMENT................................................................................................................14

8.1 Service requirements ...............................................................................................14

8.1.1 Mechanical design of piping ................................................................................................ 14

8.1.2 Design of piping arrangements ........................................................................................... 33

8.1.3 Piping flexibility and supports .............................................................................................. 56

8.1.4 Service Index and Piping Material Specifications (PMS) .................................................... 63

8.2 Information to be provided by PEMEX ....................................................................65

8.3 Information to be provided by the Contractor ........................................................65 8.4 Acceptance cr iteria ...................................................................................................68

9. RESPONSIBILITIES ..........................................................................................................70

10. ADAPTATION TO MEXICAN OR INTERNATIONAL STANDARDS..............................71

11. BIBLIOGRAPHY ............................................................................................................72

12. ANNEXES ......................................................................................................................80

12.1 Annex 1. Forms ........................................................................................................80

12.2 Annex 2. Index of offshore Piping Material Specif ications (PMS) .........................84

12.3 Annex 3. Index of onshore Piping Material Specif ications (PMS) .........................89

12.4 Annex 4. Requirements to be met by an " or equivalent" document ..................101


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0. INTRODUCTION

Among the main activities carried out at Petróleos Mexicanos and Subsidiaries are oil and gas extraction,collection, primary processing, refining, basic petrochemical production, storage, metering, distribution,repumping and transportation, as well as the design, construction, commissioning, operation andmaintenance of the facilities and procurement of the materials and equipment needed to efficiently andeffectively accomplish the company's objectives.

Operating conditions such as pressure, temperature and environmental effects, among others, have adirect impact on processes for handling fluids such as crude oil, gas, intermediate and finished petroleumproducts and gas, as well as cryogenic fluids, fluidized solids (catalysts), vents and utilities such assteam, air, water and fuel gas, among others, calling for stringent design and material specifications forthe selection of piping, valves, connections and fittings for use in the piping systems at the onshore andoffshore industrial plants of Petróleos Mexicanos and Subsidiaries.

With the aim of unifying criteria, taking advantage of diverse experiences and combining the results ofresearch in domestic and international standardization, Petróleos Mexicanos and Subsidiaries has issuedthis technical document to be used in the design and material specification of piping systems in industrialplants.

This regulatory document was prepared in observance of and compliance with:

Federal Standards and Measures Act and RegulationsPetróleos Mexicanos Act and RegulationsPublic Works and Related Services Act and RegulationsGovernment Procurement, Leases and Services Act and RegulationsGeneral Ecological Equilibrium and Environmental Protection Act and RegulationsRegulatory Act for Article 17 of the Constitution in the Oil Industry and Regulations

Administrative contracting provisions for procurement, leases, works and services in the substantiveproduction activities of Petróleos Mexicanos and Subsidiaries.Supply Policies, Bidding Terms of Reference and General Guidelines in Procurement, Leases andServices for Petróleos Mexicanos, Subsidiaries and Affiliates.Guide for Issuing Reference Standards (CNPMOS-001 Rev. 1, September 30, 2004).

The following took part in the preparation of this document:

Petróleos Mexicanos:PEMEX-Exploración y ProducciónPEMEX-RefinaciónPEMEX-Gas y Petroquímica BásicaPEMEX-Petroquímica

External participants:

Mexican Petroleum Institute Alpha Solutions S.A. de C.V.Cameron Valves & MeasurementCPI, Ingeniería y Administración de Proyectos, S.A. de C.V.Engineering de México, S. de R.L. de C.V.Equipos y Servicios VICA, S.A. de C.V.


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George Fischer Piping SystemsGrupo Norgam de México, S.A. de C.V.

ICA Fluor Daniel, S. de R.L. de C.V.InnovationsPerformance PipeTLM Troquelados y Laminados de Monterrey, S.A. de C.V.Tyco Flow ControlUPC Interpipe, Inc.Vacoisa International, S.A. de C.V.VictaulicViega LLCVTC Servicios S. de R.L.

1. OBJECTIVE

To establish the technical and documentation requirements that must be met in the engineering andmaterial specifications for piping at the industrial plants and offshore facilities of Petróleos Mexicanos andSubsidiaries.

2. SCOPE

This reference standard establishes the minimum requirements applicable to the design engineering andmaterial specifications for piping used in the processes involved at the onshore and offshore industrialfacilities of the work centers of Petróleos Mexicanos and Subsidiaries.

It establishes the technical specifications for piping materials, connections and fittings used in processes

that include crude oil and gas as raw materials, intermediate and finished products from petroleum andgas processing, as well as cryogenic fluids, fluidized solids (catalysts), vents and utilities such as steam,air, water and fuel gas, among others.

This standard does not cover:

a) Piping for radioactive services.b) Piping for power or force covered by ASME B31.1:2010 or equivalent. See 8.1.4.1.5 for particular

cases.c) Piping covered by ASME B31.4:2009 or ASME B31.8:2010 or equivalents (onshore surface or

buried pipelines, marine or undersea pipelines).d) Piping for heat transfere) Piping in ground or maritime transportation vehicles, such as tank trucks and vessels, among

others.f) Tie-in piping between industrial and maritime facilities (ships, wharves, among others) covered by

other standards.g) Piping for drillingh) Plumbing systems

This standard cancels and replaces NRF-032-PEMEX-2005 published on March 18, 2006, Specifications

P.2.0371.01, P.2.0370.01, K-101 and GPEI-IT-2001; GNT-SNP-T001-2003, GNT-SNP-T002-2003, GNT-

SNP-T003-2003 and GNT-SNP-T004-2004.


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3. FIELD OF APPLICATION

This reference standard is generally applicable and mandatory in the procurement, leasing or contractingof services covered hereunder at the work centers of Petróleos Mexicanos and Subsidiaries. Therefore, itmust be included in public bidding procedures, invitations to at least three parties (restricted invitation inthe Petróleos Mexicanos Act) and direct awards involving contracts for purchases, services and publicworks or related services, as part of the requirements to be met by the vendor, contractor or bidder.

In repairs, modifications or expansions of existing industrial facilities, the requirements established in thisreference standard must be met in the following cases:

− If the original design's Piping Material Specifications are not available.

− If the original design's Piping Material Specifications are obsolete.

− If repairs, modifications or expansions of existing facilities change the original design's operatingconditions.

When any parts of existing facilities are substituted or replaced and the requirements for the originaldesign are retained, such parts shall be considered as within specification.

4. UPDATING

This reference standard must be reviewed and, if appropriate, modified at least every 5 years or earlier ifthe suggested and recommended changes so warrant.

Proposed and suggested changes should be submitted on form CNPMOS-001-A01 of the Guide forIssuing Reference Standards CNPMOS-001 Rev. 1 dated September 20, 2004, and sent to:

Standards Committee of Petróleos Mexicanos and Subsidiaries Avenida Marina Nacional, No. 329, 35th Floor, Executive TowerColonia Petróleos Mexicanos, Postal Code 11311, Mexico, Federal DistrictDirect phone: 19-44-92-40; Switchboard: 19-44-25-00, Ext. 5-47-81E-mail: [email protected]

5. REFERENCES

5.1 NOM-008-SCFI-2002. General system of units of measure.

5.2 NOM-011-STPS-2001. Safety and health conditions at work centers where noise is generated.

5.3 NOM-018-STPS-2000. System for identifying and reporting hazards and risks arising fromhazardous chemical substances at work centers.

5.4 NOM-093-SCFI-1994. Steel and bronze spring-loaded and pilot-operated pressure relief valves(safety, safety-relief and relief valves).

5.5 NMX-CC-9001-IMNC-2008. Quality management systems - Requirements (ISO 9001:2008 withISO 9001:2008/Cor 1:2009).

5.6 NMX-CC-9004-IMNC-2009. Managing for the sustained success of an organization - a qualitymanagement approach (ISO 9004:2009).


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5.7 NMX-CC-10005-IMNC-2006. Quality management systems - guidelines for quality plans (ISO10005-2005).

5.8 NMX-E-018-SCFI-2002. Plastics industry – high-density polyethylene (HDPE) pipe forpressurized water - Specifications.

5.9 NRF-009-PEMEX-2004. Identification of products transported by piping or contained in storagetanks.

5.10 NRF-015-PEMEX-2008. Protection of inflammable or combustible product storage areas andtanks.

5.11 NRF-016-PEMEX-2010. Design of firefighting systems.

5.12 NRF-026-PEMEX-2008. Anticorrosion coating protection for buried and/or submerged pipe.

5.13 NRF-027-PEMEX-2009. Alloy steel and stainless steel studs and bolts for high and lowtemperature service.

5.14 NRF-028-PEMEX-2010. Design and construction of pressure vessels.

5.15 NRF-031-PEMEX-2011. Venting and flaring systems in facilities.

5.16 NRF-034-PEMEX-2011. Thermal insulation for high temperatures in equipment, vessels andsurface piping.

5.17 NRF-035-PEMEX-2005. Piping systems in industrial plants - installation and testing.

5.18 NRF-049-PEMEX-2009. Inspection and supervision of movable property leases and services.

5.19 NRF-053-PEMEX-2006. Coating-based anticorrosion protection systems for surface facilities.

5.20 NRF-107-PEMEX-2010. Intelligent 2D and 3D electronic models for facilities.

5.21 NRF-127-PEMEX-2007. Seawater-based firefighting systems at fixed offshore facilities.

5.22 NRF-139-PEMEX-2012. Piping supports - Design.

5.23 NRF-140-PEMEX-2011. Drainage systems.

5.24 NRF-142-PEMEX-2011. Plug valves.

5.25 NRF-156-PEMEX-2008. Joints and gaskets.5.26 NRF-158-PEMEX-2012. Metal expansion joints.

5.27 NRF-171-PEMEX-2007. Rubber expansion joints.

5.28 NRF-204-PEMEX-2102. Emergency shutoff valves (remotely actuated isolation valves)

5.29 NRF-211-PEMEX-2008. Gate and ball valves in oil and gas transportation lines.


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5.30 NRF-248-PEMEX-2010. Electrical trace heating systems - Design.

5.31 NRF-268-PEMEX-2010. Articulated platforms with electric motors or internal combustion engines.

5.32 NRF-271-PEMEX-2011. Composition of the project book for delivery of works and services.

5.33 NRF-281-PEMEX-2012. Anticorrosion protection based on hot-dip galvanizing.

5.34 ISO 3183:2007. Petroleum and natural gas industries - Steel pipe for pipeline transportationsystems.

5.35 ISO 5208:2008. Industrial valves - Pressure testing metal valves.

5.36 ISO 7005-1:2011. Pipe flanges Part 1: Steel flanges for industrial and general service pipingsystems.

5.37 ISO 10434:2004. Bolted bonnet steel gate valves for the petroleum, petrochemical and allied

industries (ISO 10434:1998 is parallel to API Std 600:2001).

5.38 ISO/TS 10465-1:2007 Underground installation of flexible glass-reinforced pipe based onunsaturated polyester resin (GRP-UP) - Part 1. Installation procedures.

5.39 ISO 10497:2010. Testing of valves - Fire type-testing requirements.

5.40 ISO 13703:2002 wi th ISO 13703:2002 Cor 1:2002. Petroleum and natural gas industries. Designand installation of piping systems on offshore production platforms.

5.41 ISO 14313:2007 wi th ISO 14313 Cor 1:2009. Petroleum and natural gas industries - Pipelinetransportation systems - Pipeline valves. This international standard is the result of harmonizing therequirements in ISO 14313:1999 and API Spec 6D-2002).

5.42 ISO 14692-1:2002 Petroleum and natural gas industries - Glass-reinforced plastic (GRP) piping -Part 1: Vocabulary, symbols, applications and materials.

5.43 ISO 14692-2:2002 wi th ISO 14692-2:2002/Cor 1:2005 Petroleum and natural gas industries -Glass-reinforced-plastic (GRP) piping - Part 2: Qualification and manufacture.

5.44 ISO 14692-3:2002. Petroleum and natural gas industries. Glass-reinforced-plastic (GRP) piping -Part 3: System design.

5.45 ISO 14692-4:2002 wi th ISO 14692-4:2002/Cor 1:2006 Petroleum and natural gas industries -Glass-reinforced-plastic (GRP) piping - Part 4: Fabrication, installation and operation.

5.46 ISO 15156-1:2009. Petroleum and natural gas industries. Materials for use in H 2S-containing

environments in oil and gas production - Part 1: General principles for selecting cracking-resistantmaterials.

5.47 ISO 15156-2:2009. Petroleum and natural gas industries. Materials for use in H2S-containingenvironments in oil and gas production - Part 2: Cracking-resistant carbon and low-alloy steels and theuse of cast irons.

[In 2003, the publication of the three parts of ISO 15156 and NACE MR0175/ISO 1516 were completed.These technically identical documents used the [same] sources to maintain requirements and


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recommendations for material qualification and selection in environments containing wet H 2S inpetroleum and gas production systems. They are supplemented by NACE TM0177 and NACE TM0284).

5.48 ISO 15156-3:2009. Petroleum and natural gas industries. Materials for use in H2S-containingenvironments in oil and gas production - Part 3: Cracking-resistant CRA’s (corrosion-resistant alloys) andother alloys.

5.49 ISO 15649:2001. Petroleum and natural gas industries - Piping.

5.50 ISO 15761:2002. Steel gate, globe and check valves for sizes DN 100 and smaller for thepetroleum and natural gas industries. (Parallel to the specifications found in API Std 602).

5.51 ISO 15848-1:2006. Industrial valves - Measurement, test and qualification procedures for fugitiveemissions - Part 1: Classification system and qualification procedures for type testing of valves.


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6. DEFINITIONS

For the purposes of this standard, the following definitions apply:

6.1 Support: Element on which the piping rests and is fixed.

6.2 Zero leaks (in valve seats): No visible leak (dripping or bubbling) for the duration of the test inaccordance with ISO 5208:2008.

6.3 Piping circui ts: Set of piping and equipment that handle a substance with the samecomposition, in which operating conditions may vary in its different parts.

6.4 Class: Non-dimensional designation for classifying piping components that relates a pressure-temperature range based on the mechanical properties of the materials, as well as the necessarydimensions for coupling between piping components; in the American system.

6.5 Pipeline. The components through which hydrocarbons and their derivatives are collected andtransported between stations and/or facilities, including pipes, piping components, pig traps, fittings,isolation and sectioning valves.

6.6 Piping components: Any element that forms or assembles (by welding or another type ofconnection) a piping system, piping circuit or piping.

6.7 Constructability: Technique as a system to achieve an optimum integration of knowledge andconstruction experience in planning, engineering and construction operations; aimed at dealing with theparticularities of the project and the restrictions of the surrounding area for the purpose of reaching theproject's objectives.

6.8 Service Specification (SS): Document that describes, indicates and establishes the minimumcharacteristics which the piping must have, as well as the user's particular requirements, service life,

design and operating conditions, environment, material safety data sheets, physical and chemicalproperties of the fluids (substances), safety, operating flexibility and applicable rules and regulations, inconformance with this reference standard.

6.9 Piping Material Specification (PMS): Document establishing the group of piping components,their materials, Class, characteristics and construction requirements for handling one or more serviceswithin a given operating range (pressure-temperature).

6.10 Equivalent: Per Annex 12.4 of this reference standard.

6.11 Water hammer: Sudden and unexpected pressure increase in the piping due to a change in thedynamic state of the fluid, like the pressure increase caused by the abrupt closing of a valve, among otherthings.

6.12 Process data sheets: Document containing the basic information on equipment or vessels orinstruments. This information may consist of: dimensions, form, type, connection ends, service, operatingconditions, material specifications, and components, among others.

6.13 Basic engineering: State of a project that consists of defining the layouts, designs and generalspecifications, material and energy balances, piping and equipment diagrams, among others, which areprepared on the basis of design concepts and technology selected during the conceptual engineeringphase. The specifications are prepared for quoting equipment and defining the service and constructionor fabrication requirements.


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6.14 Detail Engineering: Final design stage of a project, which includes the final detail drawings forconstruction and/or fabrication prepared on the basis of the basic engineering and extended basicengineering if available. Detail engineering includes updated specifications for equipment procurementand complete definition of the construction requirements and supplies.

6.15 Responsible engineer: Engineer with technical and legal authority and a professional I.D.issued by the Mexican Government or its international equivalent and with at least five years of provenexperience in the engineering of piping of the same magnitude and importance, who signs, initials andendorses the documents with his professional I.D.

6.16 Piping Isometric: Drawing with the orthogonal representation of a piping design showing itsroute, components, dimensions, location, characteristics and construction requirements.

6.17 Nominal: A numerical identification for dimensions, capacities, stresses, Classes and othercharacteristics that are used as a property, not an exact measurement.

6.18 Series (of flanges or "flange series"): Classification system for flange design, resulting in Class

series and PN series in accordance with ISO 7005:2011.

6.19 Cryogenic service: Service at temperatures below -196°C (-320°F).

6.20 Low-temperature service: Service at temperatures between -28°C (-20°F) and -196°C(-320°F).

6.21 Saddle: Support for adjusting piping elevation and transferring the actions to the piping support;formed by a 120° to 180° segment of a cylinder or pipe with structural fastening elements.

6.22 Piping system: Interconnected piping subject to the same design conditions.

6.23 Piping support : Structure designed to support the piping, such as piping racks, surface piping

supports and support blocks, among others.

6.24 Hazardous substances (or hazardous chemical substances): Substances whose physicaland/or chemical properties may entail health, inflammability, reactivity or special risks when beinghandled, transported, stored or processed, and can affect the health of persons exposed to them orcause physical damage to facilities. They are classified by their hazard levels in accordance with NOM-018-STPS-2000.

6.25 Non-hazardous subs tances: Chemical substances that are not inflammable, toxic or reactiveand do not cause damage to human tissue or the environment; substances with a design pressure lowerthan 686 kPa (7 kg/cm

2) and/or a design temperature of -29°C to 50°C (-20°F to 122°F).

6.26 Licensor: Contractor owning the technology or the licensed rights to use the technology.

6.27 Trim: Name for the valve internals, which in include the description and characteristics of thematerial specifications for:

a) Stemb) Surface of the seat for gate or discc) Surface of the seat for the body (rings)d) Stem guide bushingse) Bolt or pin joining the stem with the gate, if applicablef) Other elements specified in the Piping Material Specification


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6.28 Piping. Assembly of pipes and piping components used to transport, distribute, mix, separate,discharge, meter, control or deter the flows of a fluid or substance (piping system, piping circuits and/orpiping, as applicable).

6.29 Piping: Piping system, piping circuit and/or piping.

6.30 Pipe: Leak-tight hollow cylinder used to transport a fluid or move a pressurized fluid.


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7. SYMBOLS AND ABBREVIATIONS

CS Carbon Steel AWWA American Water Works AssociationBSI British Standard InstituteW/S SeamedCGA Compressed Gas AssociationDN Nominal DiameterEEMUA Engineering Equipment and Materials Users AssociationW/T Pipe wall thicknessEj Joint efficiencyPMS Piping Material SpecificationSS Service SpecificationFM Factory Mutual Insurance CompanyFF Flat face

Gr. Material gradeRF Raised faceLFMN Federal Standards and Measures Act and Regulations (for its initials in Spanish)MSS Manufacturers Standardization Society of the Valve and Fittings IndustryN/A Not applicableNDT Non-destructive testsNPT National Pipe ThreadNPS Nominal Pipe SizeNRF Reference StandardNSF National Sanitation FoundationHDPE High-density polyethylenePFI Pipe Fabrication InstitutePTFE Polytetrafluoroethylene (Teflon®).

PSV Safety, safety-relief, relief, pressure relief valves.Stress Rel. Stress reliefRF Raised faceRPTFE Reinforced polytetrafluoroethyleneRT Radiographic testRJ Ring jointRTJ Ring-type joint gasketRTRP Reinforced thermosetting resin pipeRx X-raysN/S SeamlessUL Underwriters Laboratories Inc.UT Ultrasound test

For the purposes of this reference standard with regard to symbols and units of measure, see NOM-008-SCFI-2002.


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8. DEVELOPMENT

8.1 Service requi rements

Piping design and material specifications at onshore and offshore industrial facilities must comply withthis reference standard. Cases not covered by this standard must comply with ISO 15649:2001 and ISO13703:2002, respectively, and are subject to the requirements of ASME B 31:3:2010.

The figures in this reference standard are schematic and should not be interpreted as construction ordesign drawings.

8.1.1 Mechanical design of piping

The mechanical design of piping must be prepared on the basis of design and service conditions andcomply with ASME B31:3:2010 Chapter II, including but not limited to the following:

a) Maximum and minimum temperatures, both for the process and the environment.b) Maximum and minimum pressures of the piping circuit.c) Physical and chemical properties of the substances and their hazard levels.d) Compatibility between the materials of the piping components, the contained substance and the

environment.e) Compatibility between the materials of the piping components and their mechanical strength.f) Constructability and operation and maintenance facilities.g) Environmental effects that impact the piping.h) Effects resulting from the service, installation, supports and geographical location that impact the

piping.

i) Required minimum service life (corrosion and erosion) j) Permissible stresses and other stress limitsk) Variations in pressure/temperature conditionsl) Tolerances and mechanical strength.

8.1.1.1 Piping dimensions and requirements

8.1.1.1.1 General requirements

For the pressure design of the piping, ASME B31.3:2010 Paragraphs 303 and 304 must be observed inaccordance with the requirements of this reference standard.

The minimum nominal diameter for piping in all services must be DN 20 (NPS ¾); in exceptional cases,nipples may be DN 15 (NPS ½) in arrangements for instruments.

8.1.1.1.2 Carbon, intermediate- and low -alloy steel pip ing

8.1.1.1.2.1 Carbon, intermediate- and low-alloy steels and other alloys, with the exception of stainlesssteels, must comply with the dimensions and requirements of ASME B36.10M:2004 or equivalent.

8.1.1.1.2.2 DN 20 to 50 (NPS ¾ to 2) carbon, intermediate- and low-alloy steel piping must be at leastSchedule 80, even when calculations give smaller thicknesses.


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8.1.1.1.2.3 DN 80 (NPS 3) to DN 600 (NPD 24) carbon steel piping must be at least standard schedule(STD), even when calculations give smaller thicknesses.

8.1.1.1.2.4 DN 65 (NPS 2½) piping must only be specified for firefighting systems. DN 125 (NPS 5)piping only applies to drilling packages and should not be specified in other cases.

8.1.1.1.3 Stainless steel pip ing

8.1.1.1.3.1 Stainless steel piping must comply with the dimensions and requirements of ASMEB36.19M:2004 or equivalent. When dimensions not covered by ASME B36.19M:2004 or equivalent arenecessary, the requirements of ASME B36.10M:2004 or equivalent must be met.

8.1.1.1.3.2 For DN 20 to 40 (NPS ¾ to 1½) stainless steel piping, the minimum schedule must be 80S.For DN 50 (NPS 2), the minimum schedule must be 40S. Even when calculations give smallerthicknesses, they should not be specified.

8.1.1.1.3.3 For DN 80 (NPS 3) and larger stainless steel piping, the minimum schedule must be 10S.

Even when calculations give smaller thicknesses, they should not be specified.

8.1.1.1.4 Non-ferrous metal pip ing

8.1.1.1.4.1 Pipe dimensions must comply with the dimensions and requirements of ASME B36.19M:2004or ASME B36.10M:2004 or equivalents; for pipes fabricated from plate, the minimum thickness must beexpressed according to the ASTM specification for the plate given in the relevant Piping MaterialSpecification.

8.1.1.2 Seamless and longitudinally seamed piping

8.1.1.2.1 Pipes may be seamless or seamed. The Piping Material Specifications forming part of thisstandard indicate when seamed or seamless pipe must be used.

8.1.1.2.2 Seamed piping for services with hazardous substances must have a joint efficiency of 1. Fornon-hazardous substances, the minimum joint efficiency must be 0.85.

8.1.1.2.3 Piping for severe cyclical service must be seamless up to DN 600 (NPS 24) and seamed forlarger DN’s in compliance with ASME B31.3:201 Paragraph 305.2.3.

8.1.1.3 Unions between piping components

8.1.1.3.1 In corrosive fluids, piping and piping components with beveled ends for butt welding must beused in all diameters.

8.1.1.3.2 Socket weld unions are not permissible for piping in any of the following services:

a) Risk of or substances that induce corrosion, crevice corrosion, or erosion.b) Severe mechanical vibrationc) Hydrogen

8.1.1.3.3 The minimum separation between contiguous circumferential welds in piping arrangementsmust be as follows:

For onshore facilities:


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a) 90 mm (3.5 in) for ND 50 (NPS 2) and smallerb) 1.5 times the DN for DN 80 to 100 (NPS 3 to 4)c) 1.0 times the DN for DN 150 to 500 (NPS 6 to 20)d) 0.5 times the DN for DN 600 (NPS 24) and larger

For offshore facilities:

a) 90 mm (3.5 in) for ND 50 (NPS 2) and smallerb) 1.5 times the DN for DN 80 to 100 (NPS 3 to 4)c) 1.0 times the DN for DN 150 (NPS 6) and larger

8.1.1.3.4 The separation between pipe-pipe circumferential seams in straight piping must be no less than6 m for non-ferrous metal pipe or 12 m for carbon, intermediate- and low-alloy steel pipe. Except incontinuous straight piping runs where an adjustment spool is specified by design, only one should beused.

8.1.1.3.5 Threaded connections should only be specified in piping for the following services:

a) Non-hazardous substancesb) Non-erosive substancesc) Substances that do not induce corrosion or crevice corrosiond) Operating pressure below 2 MPa (300 psi), ande) Drains or vents downstream from shutoff valves with nipples and threaded plugs.

8.1.1.3.6 Piping with a grooved connection system must comply with ASME B31.3:2010 and AWWAC606-2011 or equivalent. It should only be specified in offshore facilities or temporary onshore facilitiesfor service with non-hazardous, non-polluting substances where, in the event of failure, it does not putcontinuous operation of the facilities at risk, and at the specific request of PEMEX in the ServiceSpecification and with the respective Piping Material Specification. It should not be specified forpermanent industrial refining, petrochemical or gas-processing facilities.

8.1.1.4 Radiographic testing in welded joints

8.1.1.4.1 Welded circumferential joints in piping must be inspected with radiographic testing (X-ray orgamma-ray, as applicable) by design in compliance with ASME B31.3:2010, and with at least thefollowing percentage per service, which applies when at least one of the following conditions is met:

a) 100 percent for service with:- Hazardous substances with level 4 health risk according to NOM-018-STPS-2000- Piping in severe cyclical conditions as defined in ASME B31.3:2010 Paragraph 302.3.5- Design temperatures 25°C or 50°F below the temperature limit established for the material

specification (Numbers P4 and P5) according to ASME B31.3:2001, Table A-1- Hydrogen service

- Class 1500 or larger

b) 50 percent for service with:- Hazardous substances with level 3 health risks according to NOM-018-STPS-2000.- Class 900.

c) 33 percent for service with:- Hazardous substances with level 2 health risk according to NOM-018-STPS-2000.- Class 600.


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d) 20 percent for service with:- Hazardous substances with level 1 health risk according to NOM-0180-STPS-2000.- Class 300.

e) 10 percent for service with:- Hazardous substances with level 0 health risk according to NOM-018-STPS-200 in Class 150

f) 5 percent for services with:- Non-hazardous substances in Class 150.

Note 1: When a substance is not classified in NOM-018-STPS-2000, the safety datasheet should beconsulted, and in the absence thereof, a risk analysis should be performed.

Note 2: For inspection of fillet welds that cannot be inspected with radiographic testing (X-ray or gamma-ray), see NRF-035-PEMEX-2005.

8.1.1.4.2 The percentage of radiographic testing for piping in service with hazardous substances with

any degree of inflammability, reactivity or special risk must be at least that indicated in the precedingsubparagraphs by Class.

8.1.1.4.3 In the case of piping in service with substances to which two or more radiographic testingpercentages apply, the higher percentage must be used.

8.1.1.4.4 The specified percentage of welds or joints to be tested applies for butt-welds or butt-welded orsocket-weld joints made by each of the welders or welding machine operators using the same weldingprocedure (WPS). These connections must be X-rayed over the entire circumference.

8.1.1.4.5 When the percentage results in a fraction of a joint, the results should be rounded up to thenext highest number of joints.

8.1.1.4.6 For the detection of defects in the welds selected within the radiographic testing percentagesdescribed in this reference standard, the number of joints to be inspected must be increased based onthe requirements of ASME B31.3:2010 Paragraph 341.3.4.

8.1.1.4.7 Circumferential welds in firefighting system piping must only be inspected by radiography.

8.1.1.5 Heat Treatment

8.1.1.5.1 When piping system pipes and components require heat treatment in addition to the standardtreatment for manufacture of the material according to the requirement of the service to be handled, suchtreatment must be indicated in the respective Piping Material Specification.

8.1.1.5.2 Piping fabricated in the field or shop must be heat-treated and/or stress-relieved as established

in ASME B31:3.2010 for the respective material, thickness and fabrication process. This requirementmust be indicated as a supplement in the respective Piping Material Specification.

8.1.1.5.3 Piping that requires heat treatment and/or stress relief due to the service must comply with thePiping Material Specifications of this reference standard. The respective requirements indicated in thefollowing documents must be met for services not included in the Piping Material Specifications:

a) NACE SP0403:2008 or equivalent for caustic service.b) ISO 1516:2009 for sour service in oil and gas, as well as for natural gas treatment plants.


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c) NACE MR0103:2010 or equivalent for hydrosulfuric acid in oil refining and related processingcontaining H2S in gas or dissolved in the aqueous phase, with or without hydrocarbon processes.

d) NACE SP0472:2008 or equivalent and API RP945:2008 or equivalent for amine service.e) API RP 941:2008 "Nelson Chart" or equivalent for material selection in hydrogen service where

any combination of operating conditions plus 30°C or 54°F in addition to the correspondingtemperature must remain under the material's curve.

f) API RP 934-A:2008/934-C:2001 or equivalent for hydrogen service at high temperatures.g) API RP 751:2007 or equivalent, NACE SP0472:2008 or equivalent and NACE 5A171:2007 or

equivalent for hydrofluoric acid (HF) or anhydrous hydrogen fluoride (AHF) service.h) NACE RP0170:2004 or equivalent.

8.1.1.6 Corrosion and erosion tolerance

8.1.1.6.1 Corrosion and erosion tolerance is the additional thickness that must be included for wear dueto corrosion and erosion. For carbon or low- and intermediate-alloy steels, it must be equal to or greaterthan the fluid wear rate for the piping material as given in NACE 37519:1985 or equivalent, supplementedwith API RP 581:2008 or equivalent for a service life of 20 years (unless specified otherwise for the

project), but no less than the following:

a) 1.6 mm (0.0625) for service that generate uniform wear less than 0.076 mm/year (0.003 in/year).b) 3.2 mm (0.125 in) for service that generate uniform wear between 0.076 mm/year (0.003 in/year)

and 0.152 mm/year (0.006 in/year).

8.1.1.6.2 For piping that must handle substances with a wear rate requiring a corrosion tolerance greaterthan those indicated in 8.1.1.6.1(b), corrosion-resistant materials for uniform wear lower than those givenin NACE 37519:1985 or equivalent should be selected when economically feasible.

8.1.1.6.3 For piping made of stainless steel, non-ferrous materials and/or their alloys (nickel, titanium andtantalum, among others) that handles non-corrosive fluids, the corrosion tolerance must be zero.

8.1.1.7 Piping components

8.1.1.7.1 Nipples

8.1.1.7.1.1 The length of nipples for piping with no thermal insulation system must be from 90 mm (3.5mm) to 100 mm (4 in.); and for piping with a thermal insulation system, 150 mm (6 in.) to 170 mm (6.5in.).

8.1.1.7.1.2 The permissible minimum diameter is DN 20 (NPS ¾). For instrument connections, it may beND 15 (NPS ½).

8.1.1.7.1.3 Concentric or eccentric reducing nipples (swage nipples) must be fabricated in accordance

with the requirements of MSS SP-95:2006 or equivalent. Reducers (swage nipples) are only permissiblewhen they are a particular requirement of the Piping Material Specification covered by this standard.

8.1.1.7.1.4 In concentric or eccentric reducing nipples (swage nipples), the permissible smaller diameteris DN 15 to 50 (NPS ½ to 2) and the permissible larger diameter is DN 20 to 80 (NPS ¾ to 3). They mustbe specified with both ends flat or flat-threaded ends, as applicable. In the case of DN 80 (NPS 3), theymust be joined to the piping with bevels and butt welding.

8.1.1.7.2 Threaded connections


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8.1.1.7.2.1 Threaded connections are only permissible for DN 20 to 50 (NPS to 2), except whereindicated in the Piping Material Specifications of this reference standard.

8.1.1.7.2.2 Threaded connections must be NPT in accordance with ASME B1.20.1:1983 and ASMEB16.11:2009 or equivalents.

8.1.1.7.2.3 Threaded connections must be Class 3000 or 6000. The carbon steel pipes to be joined mustbe schedule 160 for Class 3000 and schedule XXS for Class 6000, in accordance with ASMEB16.11:2009, Table 7, or equivalent.

8.1.1.7.2.4 Bull plugs must be solid bar with a hex head or a round head.

8.1.1.7.2.5 Cap plugs and street elbows (female-male thread) must be Class 6000; see Fig. 1.

8.1.1.7.2.6 Plugs with square heads, bushing-type reducers, coupling nuts or hollow plugs should not bespecified.

8.1.1.7.2.7 Threaded connections should not be specified for thermowells.

Solid bar bullplug

Street elbow Cap plug

Fig. 1. Bull plug, street elbow and cap plug .

8.1.1.7.2.8 Threaded ends in service with hazardous substances must be sealed with continuous weldingand no exposed threads must remain.

8.1.1.7.3 Socket-weld end connections

8.1.7.3.1 Socket-weld end connections must be DN 50 (NPS 2) and smaller and comply with ASMEB16:11:2009 or equivalent.

8.1.1.7.3.2 Socket-weld end connections must be Class 3000, 6000 or 9000, except for nipolets inoffshore Piping Material Specifications, where they must be at least Class 6000. The carbon, low- andintermediate-alloy steel pipes to be joined with these connections must be at least schedule 80 for Class3000, schedule 160 for Class 6000. and schedule XXS for class 9000 in accordance with ASMEB16.11:2009 Table 7 or equivalent.

8.1.1.7.3.3 Socket-weld end connections for stainless steel and non-ferrous metal piping (titanium,aluminum, nickel and other alloys) must be at least Class 3000 with schedule 40S pipes, even whencalculations give smaller thicknesses. For intermediate schedules, the next highest Class and schedulemust be specified in accordance with ASME B16.11:2009, Table 7, or equivalent.

8.1.1.7.4 Butt-weld end connections

8.1.1.7.4.1 Up to DN 1200 (NPS 48), they must comply with ASME B16.9:2007 or equivalent, and forlarger diameters up to DN 1500 (NPS 60), with MSS SP-75:2008 or equivalent.


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8.1.1.7.4.2 They must have the same wall thickness or schedule as the pipe to which they are joined.

8.1.1.7.4.3 Elbows must be long radius regardless of their DN (NPS), except in offshore facilities wherethey may be short radius due to space limitations.

8.1.1.7.4.4 Direction changes must be made with factory connections and not with bent pipe, unlessotherwise indicated in the Piping Material Specifications due to the process technology and/or servicerequirements, in which case ASME B31.3:2010, Paragraph 304.2.1, must be observed.

8.1.1.7.4.5 "Improvised" piping connections such as mitered elbows, sectioned reducers, sectioned plugs,pencil point terminations, and welded flat covers made of plate, among others, should not be used forprocess piping or in service with hazardous substances.

8.1.1.7.4.6 Mitered elbows and "improvised" reducers may only be used in cooling water or utility waterservice in Class 150 with DN larger than 650 (NPS 26) and must be:

a) Long-radius elbows of at least 3 sections with a complete penetration circumferential seam, 100%X-rayed per ASME BN31.3.2010, Paragraph 304.2.

b) Improvised reducers must be rolled, with a complete penetration butt-welded longitudinal seam,100% X-rayed, and with dimensions per MSS SP-75:2008 or equivalent.

c) Elbows must be fabricated from pipe with the same Piping Material Specification as the piping.

8.1.1.7.4.7 The use of direct pipe-to-pipe branch connections should not be specified except foratmospheric drains and as indicated in 8.1.1.7.4.8.

8.1.1.7.4.8 Tie-ins between new and existing facilities in particular cases where the clearance cannot bemade must be implemented with integrally reinforced connections, split tees or branch connectionsreinforced with casing (made of the same material as the piping), and must comply with the requirementsgiven in API RP 2201:2010 or equivalent. In the case of branch connections with a diameter ratio greater

than 2/3 branch/header or Class 300 and up, a split tee must be used.

8.1.1.7.4.9 For tie-ins between new and existing facilities where clearance can be made and a branch isinserted which, by design, requires that such branches be located next to one another, the separationmust be as given in the applicable tables of Figures 2 and 3 in Standard PFI-ES-7:2004 or equivalent,and the branches must have the type of connection indicated in the branch tables of the Pipe MaterialSpecifications.

8.1.1.7.4.10 Lateral 45° Y’s (Fig. 2) must be one-piece construction, seamless, with a uniform wall, andshould not intersect with angled finishes or cutting edges and must comply with the requirements given in

ASME B16.9:0207 or equivalent. No exceptions are permissible, even the exception indicated in Section5 of said standard.

Fig. 2. Y Fittings

Lateral 45° Y fittingReduced lateral 45° Y fitting


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8.1.1.7.5 Integrally reinfo rced connections

8.1.1.7.5.1 May be Threadolet, Sockolet, Weldolet or equivalent, which must comply with the dimensionsand requirements given in MSS SP-97:2010 or equivalent; as well as Latrolet, Nipolet, Elbolet or NipplePipet or equivalent, which must comply with ASME B31.3:2010, Paragraphs 302.2, 304.3 and 326.5.

8.1.1.7.5.2 Integrally reinforced connections must be specified with branch diameter and headerdiameter; see Fig. 3.

8.1.1.7.5.3 Beveled ends must comply with ASME B16.25:2007 or equivalent and the union with theheader should have a maximum gap of 1.6 millimeters (0.0625 in.); see Fig. 4.

Threaded end(NPT) for branch

Beveled end forwelding to header

“Threadolet”

Socket-weld endfor branch


“Sockolet”

Beveled-weld endfor branch


“Weldolet”

Beveled-weldend for 45° Y

branch

Beveled end forwelding to

header“Lateral”

Socket-weld endfor 45° Y branch


“Latrolet”

Fig. 3. Integrally reinforced connections

Figure 4. Minimum gap

8.1.1.7.5.4 When the branch is DN 50 (NPS 2) or smaller, the Sockolet and Threadolet fittings must be inaccordance with dimensions given in ASME B16.11:2009 or equivalent and limited to DN 50 (NPS 2).

8.1.1.7.5.5 In the Sockolets, a minimum gap of 1.16 millimeters (1/16 in.) must be allowed in the socket.

8.1.1.7.5.6 The threaded ends of the Threadolets must be sealed with welding after the nipple or plug isinstalled.

8.1.1.7.6 Flanges

Flatend

Beveledend forwelding

Nipolet or nipple pipet

Integrallyreinforcedconnector

Maximumgap

Minimumgap

Minimumgap

1/16"maximum

gap

Specify minimum header diameter allowing the

connector to be seated on the i e.


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8.1.1.7.6.1 Flanges should not be specified for fabrication from plate, regardless of DN and Class.

8.1.1.7.6.2 Flanges must comply with ISO 7005-1:2001 Class series, with the requirements of ASMEB16.5:2009 for DN’s up to 600 (NPS 24), and with the requirements of ASME B16.47:2011 Class Series

A for DN 650 to 1500 (NPS 26 to 60).

8.1.1.7.6.3 Flanges larger than DN 1520 (NPS 60) must be calculated according to ASME Section VIIIDivision 2:2010 or equivalent, and the dimensions must be listed in the piping isometrics. These flangesmust be supplied with a mating flange, hardware and gasket, unless otherwise specified in the ServiceSpecification.

8.1.1.7.6.4 Flanges must be the weld neck, socket weld, long neck, lap joint, or slip-on or blind type (seeFig. 5) as specified in the respective Piping Material Specification; with raised face (RF) or ring joint (RJ -also known as RTJ) for metal flanges; and flat face (FF) for non-metal or copper-nickel alloy flanges.

SLIP-ON WELDING NECK SOCKET WELD

LAP JOINTLONG WELDING NECK

BLIND


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ORIFICE

Fig. 5. Types of Flanges

8.1.1.7.6.5 The finish on the flange faces must comply with ASME B.16.5:2009 Paragraph 6.4.5, asapplicable for the service and gasket.

8.1.1.7.6.6 Welding neck flanges may be specified in all DN’s and classes.

8.1.1.7.6.7 Welding neck flanges must have the same bore and schedule or thickness as the pipe orpiping component to which they are joined.

8.1.1.7.6.8 Socket weld flanges should not be specified for DN’s larger than 50 (NPS 2).

8.1.1.7.6.9 Lap joint flanges may only be specified for piping made of non-ferrous metal materials and up

to Class 150.

8.1.1.7.6.10 Taps for thermowells must be made with long neck flanges, at least Class 300. The OD ofthe thermowell must pass through the ID of the long-neck flange; see Fig. 6

Fig. 6. Long-neck flanges for thermowell taps

8.1.1.7.6.11 Blind flanges must be factory forged and may be specified in all DN’s and Classes. Flangesfabricated from plate are not permissible, regardless of the DN and Class.

8.1.1.7.6.12. Reducing flanges must be limited to Class 150 and up to DN 600 (NPS 24). Their particularapplication is given in the Piping Material Specifications. Reducing flanges fabricated from blind or plateflanges are not acceptable.

Pressure tap

Seal by welding

Equal bores

flange - pipe

Orifice plate

Dress weld

Thermowell

Long-neck

flange

Pipe wall


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8.1.1.7.6.13 Slip-on flanges may only be specified in Class 150 for service with non-hazardoussubstances or cooling water in limited spaces, in package equipment for offshore services; and foratmospheric rainwater and oily water drainage service.

8.1.1.7.6.14 Threaded flanges may only be specified in Class 150 for service with non-hazardoussubstances and when indicated in the Piping Material Specifications of this reference standard.

8.1.1.7.6.15 Orifice plate flanges must be DN 50 (NPS 2) or larger, at least Class 300 and must complywith ASME 16:36:2009 or equivalent. The flange must have the same bore as the piping on which it isinstalled; see Fig. 5.

8.1.1.7.7. Valves

8.1.1.7.7.1 Valves for piping must comply with the recommended practices in API RP 615:2010 orequivalent, and for offshore facilities, with ISO 13703:2002 Section 6, but the requirements given in thisreference standard shall prevail.

8.1.1.7.7.2 Valves must be specified according to and in conformance with ASME B16:34:2009 A -standard Class series; ASME B16.10:2009 for dimensions between faces; ISO 5208:2008 for inspectionand testing; and with the following standards as applicable, as well as the specifications given in thisreference standard and each particular Piping Material Specification:

a) Socket-weld or threaded- or welded-end gate, globe and check valves up to DN 50 (NPS2), ISO15761:2002.

b) Stainless steel or nickel alloy gate valves from DN 80 (NPS 3) up to DN 600 (NPS 24), API603:2007 or equivalent.

c) Carbon, intermediate- and low-alloy steel gate valves from DN 80 (NPS 3) up to DN 600 (NPS24), ISO 10434:2004.

d) Carbon steel globe valves DN 80 (NPS 3) and larger, ASME B16:34:2009 or equivalent, with

body and stem thickness per ISO 10434:2004.e) Floating ball valves, API 608:2008 or equivalent.f) Trunnion-mounted ball valves, NRF-211-PEMEX-2008.g) Plug valves, NRF-142-PEMEX-2011.h) Butterfly valves DN 80 (NPS 3) and larger, API 609:2009 or equivalent.i) Check valves DN 80 (NPS 3) and larger, ASME B16.34:2009 or API 594:2010 or equivalents, as

specified. j) Sliding solid parallel faced double-expanding gate valves, DN 600 (NPS 24) or larger, NRF-211-

PEMEX 2008.k) Emergency shutoff valves, NRF-204-PEMEX-2012.l) Needle valves, API STD 599:2007 or equivalent.m) Valves not covered by the standards mentioned in the preceding subparagraphs, ASME

B16:34:2009 or equivalent.

8.1.1.7.7.3 The material of the valves' internals (trim) must comply with API Std 600:2009 or equivalentand API Std 602:2010, Table 12, or equivalent, as applicable, except for certain special severe servicesin which the Piping Material Specifications of this reference standard specify special trim materials withcoatings such as chromium carbide and tungsten carbide, among others.

8.1.1.7.7.4 Valves should not have gaskets containing asbestos or materials that pollute the workenvironment.


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8.1.1.7.7.5 Valve materials must be steel or other alloys specified in ASME B16:34:2009 or equivalent,based on the service and as specified in the respective Piping Material Specification. The use of cast ironvalves is not permissible, except for cement and barite service per 8.1.1.7.7.30 of this reference standard.

8.1.1.7.7.6 Valves must be specified as follows:

a) Gate, butterfly, ball or plug valves to isolate or shut offb) Globe or butterfly valves to regulate or throttle flowc) Check valves to prevent backflow

8.1.1.7.7.7. Flanged ends of valves must be built into the body and fabricated by forging or casting in asingle piece (body-flange(s)). Valve flanges must comply with 8.1.1.7.6 of this reference standard.

8.1.1.7.7.8 Valve wheels must be solid.

8.1.1.7.7.9 Valves for service with hazardous substances must be specified for ultra-low emissions,classification C01, and for service with hazardous substances, with health risk level 4 in NOM-018-STPS-

2000 with a classification of at least CO2, in compliance with ISO 15848-1:2006. Valves must be markedas required in ISO 15848-1:2006, Paragraph 6.6.

8.1.1.7.7.10 Class 800 socket-weld or beveled-end gate, globe or check valves from DN 20 to 50 (NPS¾ to 2) must comply with the following:

a) Gate valves must have a fixed wheel, rising stem, bolted bonnet and solid wedge.b) Globe valves must have a wheel, rising stem and bolted bonnet.c) Check valves (no backflow) must be ball, piston or swing valves working in a horizontal or vertical

position, with a bolted cover.

8.1.1.7.7.11 Class 150, 300 and 600 gate valves from DN 15 to 600 (NPS ½ to 24) with flanged orbeveled ends must comply with the requirements of ISO 10434:2004 and must have a fixed wheel, rising

stem, exterior thread, standard yoke and flanged bonnet, with the following requirements for the ends:

a) Flanged ends in DN 15 to 600 (NPS ½ to 24)b) Beveled ends in DN 80 to 600 (NPS 3 to 24) when indicated in the Piping Material Specifications

of this reference standard.

8.1.1.7.7.12 Class 150, 300 and 600 gate valves larger than DN 600 (NPS 24) with flanged or beveledends must comply with the requirements of ASME B16:34:209 or equivalent; and must have a fixedwheel, rising stem, exterior thread and standard yoke, flanged bonnet and ends.

8.1.1.7.7.13 Class 600, 900 or 1,500 pressure seal gate valves with beveled ends must comply with therequirements of ISO 10434:2004 in DN 50 to DN 600 (NPS 2 to NPS 24), with fixed wheel, rising stem,seats with leak-tight seal, and ultralow-emission graphite gaskets. These valves must be specified for

saturated and superheated steam service.

8.1.1.7.7.14 Gate valves for service in temperatures of -45°C (-49°F) must comply with the requirementsindicated in this reference standard for gate valves, have a 3.2 mm (1/8 in) diameter pressure-equalizinghole on the fluid-containing side face of the gate in order to have the same pressure in the bonnet cavitywhen the valve is closed; and the valve body must be marked with an arrow on the side with higherpressure as shown in Fig. 7.


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Figure 7. Pressure-equalizing hole in valve gate.

8.1.1.7.7.15 Extended-bonnet gate and globe valves for service at design temperatures below ‒45°C or ‒49°F must comply with the requirements outlined in this reference standard for gate and globe valves,testing requirements and bonnet type in accordance with BS 6364:1984 or equivalent and the following.PEMEX will specify in the Service Specifications whether it requires the prototype test indicated in BS6364:1984 or equivalent.

a) The extended bonnets of the valves may be one-piece or three-piece, mid-body flange -extension - stuffing box, and in this case they must comply with the following requirements:

- The flange of the bonnet for the extension must have a welding neck (equivalent to a weldingneck reducer flange per ASME B16.5:2009) making it possible to join an extension and pipe ofequal thicknesses. Unions between a flange and an extension without a neck that makes itpossible to join equal thicknesses are not permissible; see Fig. 8.

- The bonnet flange - extension pipe - stuffing box welds must be of the same thickness withbevel, complete penetration and 100 percent X-rayed.

- The wall thickness of the extension must be compatible with the valve Class and within themechanical strength requirements.

b) Gate valves must have a 3.2 millimeter (1/8 in.) diameter pressure-equalizing hole on the fluid-containing side face of the gate in order to have the same pressure in the bonnet cavity when thevalve is closed; and the valve body must be marked with an arrow on the side with higherpressure, as shown in Fig. 7.

Valve with pressure hole inflexible wedge

Depressurizedside

Flow,pressurized side

Flow


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Fig. 8. Bonnet extension for gate and globe valves.

8.1.1.7.7.16 Floating ball valves should only be specified up to DN 300 (NPS 12) in firefighting waterservice or services where hydrocarbons are not handled; or up to DN 50 (NPS 2) in services that handlehydrocarbons.

8.1.1.7.7.17 Unless otherwise specified, plug valves must be anti-static and designed as indicated below:

a) Class 150- Short pattern in DN 50 to DN 300 (NPS 2 to NPS 12)- Venturi pattern in DN 350 to DN 600 (NPS 14 to NPS 24).

b) Class 300- Short pattern in DN 50 to DN 250 (NPS 2 to NPS 10).- Venturi pattern in DN 300 to DN 600 (NPS 12 to NPS 24)

c) Class 600-Regular pattern in DN 50 to DN 300 (NPS 2 to NPS 12).

8.1.1.7.7.18 Butterfly valves for process service must have flanged ends and be triple offset, API Std609:2009 Category B or equivalent, with a wedge disc-stem connection unless otherwise indicated in theService Specification or Piping Material Specification.

8.1.1.7.7.19 Wafer and lug butterfly valves are of limited use as jacketed valves only. These valves arepermitted for DN 80 (NPS 3) and larger.

8.1.1.7.7.20 Jacketed lug butterfly valves must be double offset with a bolt circle, in DN 80 (NPS 3) andlarger.

8.1.1.7.7.21 Pressure seal globe valves with beveled ends for saturated and superheated steam servicemust comply with the requirements of ASME B16:34:2009 or equivalent; the permissible classes are 600,

900 and 1500 in DN 50 to DN 300 (NPS 2 to NPS 12) with a fixed wheel, rising stem and seats with aleak-tight seal. In addition, the stem and the valve body wall thicknesses must comply with therequirements of ISO 10434:2004.

8.1.1.7.7.22 Extended-bonnet globe valves for service at temperatures below -45°C (-49°F) must comply

with the requirements indicated in 8.1.1.7.7.1, 8.1.1.7.7.2 and 8.1.1.7.7.15(a) of this reference standardand with testing and bonnet requirements per BS 6364:1984 or equivalent.

Stuffing

Extension pipe

Equal thicknesses

Bonnet flange with

welding neck. Welding without a neck

is not acceptable


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8.1.1.7.7.23 Swing-type check valves must have flanged ends in Class 150, 300, 600, 900 and 1500 forDN 80 to 600 (NPS 3 to NPS 24); the design must include a stop built into the cover or body that limitsthe disc opening.

a) Valves DN 80 to 600 (NPS 3 to NPS 24) must be Type B per API Std 594:2010 or equivalent.b) Valves larger than DN 600 (NPS 24) and up to DN 1050 (NPS 42) must be Type A per API Std

594:2010 or equivalent.

Fig. 9. Check valve with stop bu ilt into cover or body.

8.1.1.7.7.24 "Non-slam" axial-flow check valves must comply with the requirements of ISO 14313:2007and should be specified for the discharges of centrifugal compressors for process service.

8.1.1.7.7.25 Split-disc (dual-plate) check valves in Classes 150, 300, 600, 900 and 1500 must be Type Aper API Std 594:2010 or equivalent. This type of valve should only be used for the Piping MaterialSpecifications where so specified in this reference standard and its selection must be based on thefollowing:

a) Class 150- Valves with flanged ends in DN 200 (NPS 8) and larger- Lug valves in DN 150 (NPS 6) and larger

b) Class 300, 600, 900 and 1500- Valves with flanged ends in DN 300 (NPS 12) and larger- Lug valves in DN 250 (NPS 10) and smaller

8.1.1.7.7.26 Check valves between flanges (wafer valves) are not permissible.

8.1.1.7.7.27 Pressure seal check valves with beveled ends for saturated or superheated steam servicemust comply with the requirements of ASME B16:34:2009 or equivalent with body wall thickness per ISO10434:2004 in Classes 600, 900 and 1500 and DN 50 to DN 600 (NPS 2 to NPS 24).

8.1.1.7.7.28 Piston-type sampling valves must comply with the requirements of ASME B16:34:2009 orequivalent.

8.1.1.7.7.29 The valves indicated in Table 1 of this reference standard must have a gear and pinionactuator, with opening indicators.

8.1.1.7.7.30 Butterfly and check valves with grooved ends for cementing and barite service must be ND80 to DN 200 (NPS 3 to NPS 8) with ductile iron body made of ASTA A395 Gr. 65-45-15 or ASTM A536Gr. 65-45-12 or equivalents. Their use and application is restricted to these services, as established in thePiping Material Specifications of this reference standard.

8.1.1.7.8 Flanges for gaskets

Flow

Stop

Disc or knuckle

joint

Flow

Stop

Note: These valvesmust be installed in

horizontal position

in any service.


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8.1.1.7.8.1 Gaskets must be specified to ensure leak-tight flanged connections.

8.1.1.7.8.2 Gaskets must comply with NRF-156-PEMEX-2008 and ASME B16:20:2007 or equivalent, andbe of the type and material specified in the Piping Material Specification.

8.1.1.7.8.3 Gaskets must be free of asbestos and environmental pollutants.

8.1.1.7.8.4 Spiral-wound metal gaskets must have a centering (external) ring and, whenever it is aparticular requirement of the Piping Material Specification, a backup (internal) ring. Spiral-wound metalgaskets must be identified as required in NRF-156-PEMEX-2008 with the proper color, both for the metalmaterial and for the fill; see Fig. 10. The backup ring must be made of at least ASTM A240/A240M:2012TP-304 or equivalent; the centering ring must be made of carbon steel, ASTM A36/A36M:2008 orequivalent with anticorrosion coating. Gaskets requiring different materials due to the service or acid,brine or corrosive environments are specified in the Piping Material Specifications of this referencestandard.

8.1.1.7.8.5 R-type (RTJ) octagonal ring gaskets must be specified for hydrogen service and for Class 900and larger, and must comply with NRF-156-PEMEX-2008.

8.1.1.7.8.6 Flat solid-metal gaskets (kammprofile) must have dimensions according to the Class andmaterial specified in the project's Service Specifications, have an external centering ring and be identifiedas indicated in NRF-156-PEMEX-2008, Annex K, Table 1.

8.1.1.7.8.7 Non-metal gaskets should not be specified for metal piping.

Type Valve Diameter ClassDN (NPS)

Globe

200 (8) and larger 300

150 (6) and larger 600100 (4) and larger 900 and 1500

Gate

400 (16) and larger 150

300 (12) and larger 300

250 (10) and larger 600

200 (8) and larger 900

150 (6) and larger 1500

Butterfly 200 (8) and larger 150, 300 and 600

Ball 150 (6) and larger 150, 300, 600, 900 and 1500

Plug, short pattern 200 (8) and larger 150 and 300

Plug, Venturi pattern 350 (14) and larger 150 and 300

Plug, regular pattern 100 (4) and larger 600

Table 1. Use of rack and pinion in valves [sic].


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Figure 10. Spiral-wound metal gasket

8.1.1.7.9 Studs and bol ts

8.1.1.7.9.1 Piping studs, screws, bolts and nuts must comply with the requirements of NRF-027-PEMEX-2009. Flanged connections must be made with studs or bolts and nuts; screws should not be specified forflanged connections.

8.1.1.7.9.2 In addition to 8.1.1.7.9.1, studs, bolts and nuts must comply with ASME B31.3:2010, ASMEB16:5:2009 and ASME B18:31:2:2008 or their equivalents.

8.1.1.7.9.3 Studs and bolts must have conical or round pointed ends for immediate insertion into the

threaded nuts and bolt holes. Bolts must be full body.

8.1.1.7.9.4 The length of the studs or bolts in flanged connections must be specified so that after they aretightened, they protrude by two or three threads on each end, which includes the threads of the pointedends; see Fig. 11.

U = Length of conical orrounded pointed end;not to be tightened pastthis point.

Fig. 11. Pointed end length

8.1.1.7.9.5 Studs, bolts, screws and nuts made of carbon or low- and intermediate-alloy steels withcorrosion-resistant coating as required by PEMEX in the Service Specifications or Piping MaterialsSpecifications included in this reference standard must comply with NRF-027-PEMEX-2007, ASMEB1.1:2003, Section 7, or equivalent and the following maximum working temperature limits:

a) Zinc-based coating, up to 210°C (410°F).b) Cadmium-based coating, up to 160°C (320°F)

Centering

ring

Color marking to identify

material

Metal spiral with fill

material

Optional internal

ring


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c) Polytetrafluoroethylene (PTFE)-based coating, up to 260°C (500°F)

8.1.1.7.10 Figure eights, spacers and blinds

8.1.1.7.10.1 The spacing required for the installation and operation of figure eights, spacers andpermanent blinds to block off piping and equipment must be specified from the design stage.

8.1.1.7.10.2 Figure eights, spacers and blinds must comply with ASME B16:48:2010 or equivalent for thepiping Class in question. The sizes not covered by ASME B16:48:2010 or equivalent must be calculatedin accordance with ASME B31.3:2010 Paragraph 304.5.3 and dimensions must be compatible with thedimensions of the flanges where they are to be installed. Figure eights must be specified for diameters upto DN 300 (NPS 12), and a two-piece spacer and blind for larger diameters.

8.1.1.7.10.3 Cast figure eights, separators and blinds or those made of plate should not be specified forClass 900 and larger.

8.1.1.7.10.4 In figure eights, spacers and blinds, the sealing surface of the gasket must have the samefinish, rise and dimensions as the faces of the flanges where they are installed in accordance with ASMEB16:5.2009 or ASME B16.47:20011, Series A, as applicable. The thickness of the raised face or groove,as applicable, must be added to the required thickness as calculated or indicated in ASME B16.48:2010or equivalent.

8.1.1.7.10.5 Figure eights, spacers and blinds must be stamped on the edges with the DN, Class andmaterial specification; and for those not covered by ASME B16.48:2010 or equivalent, also with thepermissible maximum working pressure and the corresponding temperature. For figure eights, themarking must be on both sides (blind side and free side).

8.1.1.7.10.6 Spacers and blinds must have a pad-eye lifting lug. The lifting lug of the blinds must belocated on the normal axes of the piping (0°, 90°, 180° or 270°) that passes between the space of the

studs or bolts. The lifting lug of the spacers must also have an eye that matches the bolt circle and bolthole diameter of the flanges, which must be located to coincide with the first stud or bolt of the flangedconnection per Fig. 12.

Figure 12. Spacers and blinds

Blind Spacer

Bolt hole matching thebolt circle and bolt holediameter of the flanges.

Blind lifting

lug

Spacer

lifting lug

Stamp the DN, Class and material on

the ed es.


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8.1.1.7.10.7 The lifting lug must protrude at least 10 cm from the flanges and each of its faces must bestamped "CIEGO” (BLIND) for the blinds and "LIBRE” “(FREE) for the spacers. The marks must not behidden by the flanges; see Fig. 12.

8.1.1.7.10.8 When frequent operation of the figure eights is anticipated in service with hazardoussubstances and/or where a leak would put the facilities at risk, manual (lever-operated) or automaticsliding shutters between flanges may be specified at the request of PEMEX and stipulated in the project'sService Specification in order to allow safe changes of plate position without the need to dismantle theflanges. These devices must be flanged and comply with the dimensions given in ASME B16.5:2009 or

ASME B16.47:2001, Series A, as applicable.

8.1.1.8 Non-metal piping

8.1.1.8.1 Non-metal piping must only be specified when requested by PEMEX in the Service Specificationwith the pertinent Piping Material Specification.

8.1.1.8.2 The design of non-metal piping must comply with ASME B31.3:2010 and this reference

standard, and include at least the following:

a) The inside diameter must have a cross-section area commensurate with a velocity and flowsimilar to that required for metal piping and use the factory connections required to tie in withmetal piping where specified. Since non-metal piping has a greater thickness than steel pipingunder the same working conditions, it must have a larger diameter to offer with the same velocityand not worsen pressure losses.

b) Necessary service life of the facility and deterioration during that time.c) Expected extreme environmental conditions.d) Long-term shear strength and modulus of elasticity at design temperature that match the lifetime

of the facility.e) Thermal expansion coefficient.f) Flexibility analysis that includes the design of expansion curves and necessary anchors in the

transition zone with the union with metal piping.g) The mechanical transition joint between metal and non-metal piping must be designed withfactory parts. Cast iron piping components should not be specified.

h) In connections with LJ flanges, the stub end material must have the same specification as thenon-metal pipe.

i) Calculate the pipe's long-term resistance to overpressures (water hammer, recurrent andoccasional sudden surges, greater risk conditions for the firefighting system, among others) in thepiping system that matches the service life of the facility.

j) The hydrostatic design stress must be confirmed by the manufacturer with destructive laboratorytests, delivering the results report issued by an accredited laboratory in terms of the FederalStandards and Measures Act.

k) Pipes and piping components must be tested and approved by FM and bear the mark "FM."l) Pipes and piping components for the firefighting system must be listed for firefighting service by

the UL or equivalent.

8.1.1.8.3 Underground piping for firefighting systems

8.1.1.8.3.1 Non-metal piping for underground installation in firefighting systems is only permissible whenrequested by PEMEX in the pertinent Service Specification for the project, and must comply with thisreference standard, applicable Piping Material Specifications and design criteria given in NRF-016-PEMEX-2010.

8.1.1.8.3.2 The installation of fiberglass piping must comply with ISO/TS 10465-1:2007.


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8.1.1.8.3.3 High-density polyethylene piping must have a nominal pressure of 1.72 MPa (250 psi) and aDR (diameter-thickness) ratio of 7.3 per ASTM F2619/F2619M:2011 or equivalent.

8.1.1.8.4 Piping for firefighting sys tems in o ffshore facilit ies.

8.1.1.8.4.1 Non-metal piping for firefighting water in offshore facilities is only permissible when requestedby PEMEX in the pertinent Service Specification for the project and must comply with this referencestandard, the applicable Piping Material Specification and design criteria given in NRF-016-PEMEX-2010.

8.1.1.8.4.2 Any fiberglass piping that is specified must comply with at least the following:

a) A seawater-resistant liner at least 0.0254 mm (0.001 in.) thick.b) Hydrostatic design pressure of 48.26 MPa (7000 psi).c) Exterior intumescent coating for jet fire resistance of at least 5 minutes with the piping empty and

20 minutes with the piping packed, signal red in color.d) The winding angle of the reinforcement fiber must be 54.7°.

e) The piping must comply with ISO 14692-1, 2, 3 and 4:2002.

8.1.2 Design of piping arrangements

8.1.2.1 General requi rements

8.1.2.1.1 When PEMEX so specifies, piping engineering must be prepared with the use of intelligent 3-Delectronic models, which must comply with NRF-107-PEMEX-2010.

8.1.2.1.2 The spacing between onshore facilities or plants and between equipment must comply with theapplicable approved-for-design equipment layout of the project.

8.1.2.1.3. Piping arrangements and distribution must be grouped and ordered so that installation is

functional, simple, safe and economic, and should facilitate constructability, operation and maintenance,as well as provide the necessary space for access and emergency escape routes.

8.1.2.1.4 Provisions for future expansions must be made with an isolation valve (root or shutoff valve) andblind flange downstream; figure eights and blinds should not be used in these cases.

8.1.2.1.5 For splitting streams where figure eights or blinds must be installed, isolation valves should bespecified before them.

8.1.2.1.6 Figure eights and blinds should not be specified for piping terminal points.

8.1.2.1.7 Piping must rest on piping supports; for onshore facilities, supports must comply with NRF-139-PEMEX-2012.

8.1.2.1.8 Piping arrangements should not include dead legs.

8.1.2.1.9 Where purges must be installed, the height between the finished floor level and the bottom spanof the pipe must be at least 40 cm, except as indicated in 8.1.2.6.3 and 8.1.2.1.14.

8.1.2.1.10 The minimum height of the bridges must be as given in NRF-139-PEMEX-2012.


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8.1.2.1.11 The minimum obstruction-free height between the finished floor level or operating level (asapplicable) and the bottom span of the structure must be as shown in Table 2.

8.1.2.1.12 Underground piping is only permissible for drainage, cooling water, utility water, drinking waterand firefighting water service and collection and recovery systems. Any other service must be overhead.Piping for firefighting water must also comply with NRF-015-PEMEX-2008 and NRF-016-PEMEX-2010.Underground metal piping must only be specified with welded joints.

Description Onshorefacilities

Offshorefacilities

Minimum height of elevated supports, piping corridors inside theplant limit.

3.00 m 2.20 m

Over platforms and walkways 2.40 m 2.20 m

Inside buildings (compressor house, pump house, among others) orwithin a common group of equipment

2.40 m 2.10 m

Note: In all cases, sufficient space must be provided to remove and/or access the equipment.

Table 2. Minimum height of structural supports

8.1.2.1.13 Underground piping for gravity collection and recovery of reusable substances such as amine,muriatic acid (HCI), MTBE/TAME and methanol, among others, must be laid in trenches.

8.1.2.1.14 Piping laid in trenches must be supported on blocks that must allow runoff into rainwater drainsand/or the applicable drainage, depending on the service of the lines, with a gap of at least 10 cmbetween both sides of the block and the walls and a minimum height of 15 cm.

8.1.2.1.15 Trenches must have galvanized grates, concrete covers or railings, as specified in the project,in order not to leave hazardous conditions for the personnel. Piping that handles explosive fluids whosevapors are heavier than air should not be laid in trenches.

8.1.2.1.16 When vents and drains are integrated into a closed system in the design, they must includefigure eights.

8.1.2.1.17 Services for the purging and draining of liquids must be piped to oily or chemical drainage or aclosed system; arrangements with purges into the ground or the atmosphere are not permissible.

8.1.2.1.18 Purges, drains or vents of hazardous substances or environmental pollutants must be tied intoclosed systems.

8.1.2.1.19 Piping arrangements must include the interlocks needed to allow safe sectioning or isolationfor shutdown, maintenance and inspection of the facilities, so that blocking off one does not affect theoperation of the others.

8.1.2.1.20 Piping arrangements must allow quick and easy access to equipment and instruments foroperation and maintenance.

8.1.2.1.21 For piping that operates at high temperatures and requires a thermal insulation system, thissystem must comply with NRF-034-PEMEX-2011.


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8.1.2.1.22 For piping that operates at low temperatures and requires a thermal insulation system, thissystem must comply with NOM-009-ENER-1995, ISO 1224 1:2008 and the particular specification for theproject.

8.1.2.1.23 Piping with no thermal insulation system and an operating temperature higher than 59°C(139°F) or colder than -5°C (23°F) in areas where personnel may come in contact with it must have abarrier installed for their protection per NRF-034-PEMEX-2011.

8.1.2.1.24 Barriers in coastal or offshore facilities must be made of aluminum for marine environments, ASTM B928 Alloy 5083 or equivalent.

8.1.2.2 Spacing between piping

8.1.2.2.1 For ease of removal and repair, piping must have at least the following separations (see Fig.13):

a) Onshore facilities; • In flangeless piping, 80 mm between pipe/pipe or pipe/insulation, pipe/wall and insulation/wall

spans.

• In flanged piping, 50 mm between pipe/large diameter flange, pipe/flange insulation orinsulation/flange spans.

• 150 mm between non-insulated flanges and the adjacent wall or equipment, or 80 mmbetween insulated flanges and a wall.

• In hookup piping at onshore industrial plants, 150 mm between piping spans.

b) Offshore facilities: • In flangeless piping, 50 mm between pipe/pipe or pipe/insulation, pipe/wall and insulation/wall

spans.

• In flanged piping, 50 mm between pipe-large diameter flange, pipe-flange insulation orinsulation/flange spans.

• 80 mm between non-insulated flanges and the adjacent wall or equipment, or 50 mmbetween insulated flanges and a wall.

Flanges should not be aligned in parallel piping; they should be staggered.

8.1.2.2.2 In parallel piping subject to thermal expansion or contraction, the minimum separation betweenpiping must be greater, depending on the flexibility analysis in order to prevent contact or interferenceduring operation, startup or shutdown.

8.1.2.2.3 Piping arrangements must includ

nrf-032-pemex-2012 - piping systems in industrial plants

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