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ASME B31.8-2016(Revision of ASME B31.8-2014)Gas Transmissionand DistributionPiping SystemsASME Code for Pressure Piping,B31AN INTERNATIONAL PIPING CODEThe American Society ofMechanical EngineersASME B31.8-2016(Revision of ASME B31.8-2014)Gas Transmissionand DistributionPiping SystemsASME Code for Pressure Piping,B31AN INTERNATIONAL PIPING CODEThe American Society ofMechanical EngineersTwo Park AvenueNew York,.NY1O016UsADate of Issuance:October 19,2016The next edition of this Code is scheduled for publication in 2018.This Code will become effective6 months after the Date of Issuance.ASME issues written replies to inquiries concerning interpretations of technical aspects of this Code.Interpretations are published on the Committee Web page and under go.asme.org/Interpretations.Periodically certain actions of the ASME B31 Committee may be published as Cases.Cases arepublished on the ASME Web site under the B31 Committee Page at go.asme.org/B31committee asthey are issued.Errata to codes and standards may be posted on the ASME Web site under the Committee Pages ofthe associated codes and standards to provide corrections to incorrectly published items,or to correcttypographical or grammatical errors in codes and standards.Such errata shall be used on the dateposted.The B31 Committee Page can be found at go.asme.org/B31committee.The associated B31 CommitteePages for each code and standard can be accessed from the main page.There is an option availableto automatically receive an e-mail notification when errata are posted to a particular code or standard.This option can be found on the appropriate Committee Page after selectingErratain the PublicationInformationsection.ASME is the registered trademark of The American Society of Mechanical Engineers.This international code or standard was developed under procedures accredited as meeting the criteria for AmericanNational Standards and it is an American National Standard.The Standards Committee that approved the code orstandard was balanced to assure that individuals from competent and concerned interests have had an opportunity toparticipate.The proposed code or standard was made available for public review and comment that provides anopportunity for additional public input from industry,academia,regulatory agencies,and the public-at-largeASME does not approve,rate,or endorseany item,construction,proprietary device,or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with anyitems mentioned in this document,and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent,nor assumes any such liability.Users of a code or standard are expresslyadvised that determination of the validity of any such patent rights,and the risk of infringement of such rights,isentirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted asgovernment or industry endorsement of this code or standard.ASME accepts responsibility for only those interpretations of this document issued in accordance with the establishedASME procedures and policies,which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersTwo Park Avenue,New York,NY 10016-5990Copyright2016byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword.viniCommittee Roster.XIntroduction.xivSummary of ChangesxviGeneral Provisions and Definitions.18011802Scope and Intent1803Piping Systems Definitions.2804Piping Systems Component Definitions.805Design,Fabrication,Operation,and Testing Terms andDefinitions.3806Quality Assurance.12807Training and Qualification of Personnel.12Chapter IMaterials and Equipment.14810Materials and Equipment.14811Qualification of Materials and Equipment14812Materials for Use in Low-Temperature Applications.14813Marking.15814Material Specifications.15815Equipment Specifications.16816Transportation of Line Pipe.16817Conditions for the Reuse of Pipe.16Table817.1.3-1Tensile Testing17Chapter llWelding19820Welding19821General19822Preparation for Welding.19823Qualification of Procedures and Welders.19824Preheating.20825826Stress Relieving.0Weld Inspection Requirements.21827Repair or Removal of Defective Welds in Piping Intendedto Operate at Hoop Stress Levels of 20%or More ofthe Specified Minimum Yield Strength.22Chapter IllPiping System Components and Fabrication Details.3830Piping System Components and Fabrication Details.2831Piping System Components.23832Expansion and Flexibility.0833Design for Longitudinal Stress.31834Supports and Anchorage for Exposed Piping.33835Anchorage for Buried Piping4Tables831.4.2-1Reinforcement of Welded Branch Connections,SpecialRequirements,28832.2-1Thermal Expansion or Contraction of PipingMaterials.30i进832.5-1Modulus of Elasticity for Carbon and Low AlloySeel,31Chapter IVDesign,Installation,and Testing.35840Design,Installation,and Testing.35841Steel Pipe37842Other Materials。1843Compressor Stations.58844Pipe-Type and Bottle-Type Holders.845Control and Limiting of Gas Pressure.62846Valves847Vaults6848CustomersMeters and Regulators.849Gas Service Lines.71Tables841.1.6-1Basic Design Factor,F.39841.1.6-2Design Factors for Steel Pipe Construction.40841.1.7-1Longitudinal Joint Factor,E.841.1.8-1Temperature Derating Factor,T,for Steel Pipe.41841.1.11-1Pipeline Cover Requirements.43841.2.3-1Pipeline Field Cold Bend Requirements.45841.3.2-1Test Requirements for Steel Pipelines and Mains toOperate at Hoop Stresses of 30%or More of theSpecified Minimum Yield Strength of the Pipe.49841.3.3-1Maximum Hoop Stress Permissible During an Air or Gas.50842.1.1-1Standard Thickness Selection Table for Ductileron Pipe.52842.2.9-1Nominal Values for Coefficients of Thermal Expansionof Thermoplastic Pipe Materials.56844.3-1Design Factors,F62844.3-2Minimum Clearance Between Containers and FencedBoundaries,.,.,.,.,.,.,.,.62845.2.2-1Maximum Allowable Operating Pressure for Steel orPlastic Pipelines or Mains.63845.2.3-1Maximum Allowable Operating Pressure for PipelinesOperating at 100 psig(690 kPa)or More.63845.2.3-2Maximum Allowable Operating Pressure for PipelinesOperating at Less Than 100 psig(690 kPa)64Chapter VOperating and Maintenance Procedures.75850Operating and Maintenance Procedures Affecting theSafety of Gas Transmission and DistributionFacilities.75851Pipeline Maintenance.77852Distribution Piping Maintenance。4.4.4。83853Miscellaneous Facilities Maintenance.854Location Class and Changes in Number of BuildingsIntended for Human Occupancy89855Pipeline Service Conversions.98560 dorization.857Uprating.92iv