1、Gas Transmission and Distribution Piping SystemsASME Code for Pressure Piping, B31AN INTERNATIONAL PIPING CODEASME B31.8-2014(Revision of ASME B31.8-2012)ASME B31.8-2014(Revision of ASME B31.8-2012)Gas Transmissionand DistributionPiping SystemsASME Code for Pressure Piping, B31AN INTERNATIONAL PIPIN
2、G CODETwo Park Avenue New York, NY 10016 USADate of Issuance: September 30, 2014The next edition of this Code is scheduled for publication in 2016. This Code will become effective6 months after the Date of Issuance.ASME issues written replies to inquiries concerning interpretations of technical aspe
3、cts of this Code.Interpretations, Code Cases, and errata are published on the ASME Web site under the CommitteePages at http:/cstools.asme.org/ as they are issued. Interpretations and Code Cases are also includedwith each edition.Errata to codes and standards may be posted on the ASME Web site under
4、 the Committee Pages toprovide corrections to incorrectly published items, or to correct typographical or grammatical errorsin codes and standards. Such errata shall be used on the date posted.The Committee Pages can be found at http:/cstools.asme.org/. There is an option available toautomatically r
5、eceive 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 selecting “Errata” in the “PublicationInformation” section.ASME is the registered trademark of The American Society of Mechanical Engineers.This inte
6、rnational 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 interest
7、s 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-large.ASME does not “approve,” “rate,” or “endorse” any item
8、, 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 app
9、licable 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
10、 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 o
11、f 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 10016-5990Copyright 2014 byTHE AMERIC
12、AN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword viiiCommittee Roster . xIntroduction . xivSummary of Changes xviGeneral Provisions and Definitions 1801 General . 1802 Scope and Intent 1803 Piping Systems Definitions 2804 Piping Systems Component Definitions 480
13、5 Design, Fabrication, Operation, and Testing Terms andDefinitions . 6806 Quality Assurance 12807 Training and Qualification of Personnel 12Chapter I Materials and Equipment . 14810 Materials and Equipment . 14811 Qualification of Materials and Equipment . 14812 Materials for Use in Low-Temperature
14、Applications 15813 Marking 15814 Material Specifications 15815 Equipment Specifications 16816 Transportation of Line Pipe . 16817 Conditions for the Reuse of Pipe 16Table817.1.3-1 Tensile Testing 17Chapter II Welding . 19820 Welding 19821 General . 19822 Preparation for Welding . 19823 Qualification
15、 of Procedures and Welders . 19824 Preheating 20825 Stress Relieving . 20826 Weld Inspection Requirements . 21827 Repair or Removal of Defective Welds in Piping Intendedto Operate at Hoop Stress Levels of 20% or More ofthe Specified Minimum Yield Strength 22Chapter III Piping System Components and F
16、abrication Details. 23830 Piping System Components and Fabrication Details 23831 Piping System Components . 23832 Expansion and Flexibility . 30833 Design for Longitudinal Stress . 31834 Supports and Anchorage for Exposed Piping 33835 Anchorage for Buried Piping 34Tables831.4.2-1 Reinforcement of We
17、lded Branch Connections, SpecialRequirements . 28832.2-1 Thermal Expansion or Contraction of PipingMaterials . 30iii832.5-1 Modulus of Elasticity for Carbon and Low AlloySteel . 31Chapter IV Design, Installation, and Testing 35840 Design, Installation, and Testing . 35841 Steel Pipe . 37842 Other Ma
18、terials . 51843 Compressor Stations 59844 Pipe-Type and Bottle-Type Holders 62845 Control and Limiting of Gas Pressure 63846 Valves 68847 Vaults 69848 Customers Meters and Regulators 70849 Gas Service Lines . 71Tables841.1.6-1 Basic Design Factor, F . 39841.1.6-2 Design Factors for Steel Pipe Constr
19、uction . 40841.1.7-1 Longitudinal Joint Factor, E . 41841.1.8-1 Temperature Derating Factor, T, for Steel Pipe . 41841.1.11-1 Pipeline Cover Requirements 43841.2.3-1 Pipeline Field Cold Bend Requirements 45841.3.2-1 Test Requirements for Steel Pipelines and Mains toOperate at Hoop Stresses of 30% or
20、 More of theSpecified Minimum Yield Strength of the Pipe . 49841.3.3-1 Maximum Hoop Stress Permissible During an Air or GasTest 50842.1.1-1 Standard Thickness Selection Table for DuctileIron Pipe . 52842.2.2-1 Wall Thickness and Standard Dimension Ratio forThermoplastic Pipe . 54842.2.3-1 Diameter a
21、nd Wall Thickness for ReinforcedThermosetting Plastic Pipe 54842.2.9-1 Nominal Values for Coefficients of Thermal Expansionof Thermoplastic Pipe Materials . 56844.3-1 Design Factors, F . 62844.3-2 Minimum Clearance Between Containers and FencedBoundaries . 62845.2.2-1 Maximum Allowable Operating Pre
22、ssure for Steel orPlastic Pipelines or Mains . 64845.2.3-1 Maximum Allowable Operating Pressure for PipelinesOperating at 100 psig (690 kPa) or More . 64845.2.3-2 Maximum Allowable Operating Pressure for PipelinesOperating at Less Than 100 psig (690 kPa) 64Chapter V Operating and Maintenance Procedu
23、res 75850 Operating and Maintenance Procedures Affecting theSafety of Gas Transmission and DistributionFacilities 75851 Pipeline Maintenance . 77852 Distribution Piping Maintenance 83853 Miscellaneous Facilities Maintenance 86854 Location Class and Changes in Number of BuildingsIntended for Human Oc
24、cupancy 89855 Pipeline Service Conversions 91856 Odorization . 91857 Uprating 92ivFigure851.4.1-1 Allowable Ripple Heights . 80Tables851.4.4-1 Wall Thickness for Unlikely Occurrence ofBurn-Through 81854.1-1 Location Class 90857.4-1 Wall Thickness Allowance for Uprating a Ductile IronHigh-Pressure Ma
25、in or System 94Chapter VI Corrosion Control . 95860 Corrosion Control General 95861 External Corrosion Control for Steel Pipelines 96862 Cathodic Protection Criteria . 98863 Operation and Maintenance of Cathodic ProtectionSystems 98864 Internal Corrosion Control 98865 Steel Pipelines in Arctic Envir
26、onments . 99866 Steel Pipelines in High-Temperature Service . 100867 Stress Corrosion and Other Phenomena 101868 Cast Iron, Wrought Iron, Ductile Iron, and Other MetallicPipelines . 101Chapter VII Intentionally Left Blank . 102Chapter VIII Offshore Gas Transmission 103A800 Offshore Gas Transmission
27、103A801 General . 103A802 Scope and Intent 103A803 Offshore Gas Transmission Terms and Definitions 103A811 Qualification of Materials and Equipment . 104A814 Material Specifications 104A817 Conditions for the Reuse and Requalification of Pipe 105A820 Welding Offshore Pipelines 105A821 General . 105A
28、823 Qualification of Procedures and Welders . 105A825 Stress Relieving . 106A826 Inspection of Welds . 106A830 Piping System Components and Fabrication Details 106A831 Piping System Components . 106A832 Expansion and Flexibility . 106A834 Supports and Anchorage for Exposed Piping 106A835 Anchorage f
29、or Buried Piping 106A840 Design, Installation, and Testing . 107A841 Design Considerations 107A842 Strength Considerations . 108A843 Compressor Stations 111A844 On-Bottom Stability . 112A846 Valves 113A847 Testing . 113A850 Operating and Maintenance Procedures Affecting theSafety of Gas Transmission
30、 Facilities 114A851 Pipeline Maintenance . 114A854 Location Class 115A860 Corrosion Control of Offshore Pipelines 115A861 External Corrosion Control 115A862 Cathodic Protection Criteria . 117A864 Internal Corrosion Control 117vTableA842.2.2-1 Design Factors for Offshore Pipelines, PlatformPiping, an
31、d Pipeline Risers 109Chapter IX Sour Gas Service . 118B800 Sour Gas Service 118B801 General . 118B802 Scope and Intent 118B803 Sour Gas Terms and Definitions . 118B813 Marking 119B814 Material Specifications 119B820 Welding Sour Gas Pipelines . 119B821 General . 119B822 Preparation for Welding . 119
32、B823 Qualification of Procedures and Welders . 119B824 Preheating 119B825 Stress Relieving . 120B826 Welding and Inspection Tests 120B830 Piping System Components and Fabrication Details 120B831 Piping System Components . 120B840 Design, Installation, and Testing . 120B841 Steel Pipe . 120B842 Other
33、 Materials . 121B843 Compressor Stations 121B844 Pipe-Type and Bottle-Type Holders 121B850 Additional Operating and MaintenanceConsiderations Affecting the Safety of Sour GasPipelines . 121B851 Pipeline Maintenance . 122B854 Location Class and Changes in Number of BuildingsIntended for Human Occupan
34、cy 122B860 Corrosion Control of Sour Gas Pipelines . 122B861 External Corrosion Control for Steel Pipelines 124B864 Internal Corrosion Control 124B867 Stress Corrosion and Other Phenomena 124TablesB850.1-1 100-ppm ROE . 123B850.1-2 500-ppm ROE . 123B850.1-3 Metric Example for 100-ppm ROE . 123B850.1
35、-4 Metric Example for 500-ppm ROE . 123AppendicesMandatory Appendix A References 125Mandatory Appendix B Numbers and Subjects of Standards and SpecificationsThat Appear in Mandatory Appendix A . 130Nonmandatory Appendix C Publications That Do Not Appear in the Code orMandatory Appendix A 131Mandator
36、y Appendix D Specified Minimum Yield Strength for Steel PipeCommonly Used in Piping Systems . 134Mandatory Appendix E Flexibility and Stress Intensification Factors 137Mandatory Appendix F Extruded Headers and Welded Branch Connections 143Mandatory Appendix G Testing of Welders Limited to Work on Li
37、nes Operatingat Hoop Stresses of Less Than 20% of the SpecifiedMinimum Yield Strength 151Mandatory Appendix H Flattening Test for Pipe . 152Mandatory Appendix I End Preparations for Buttwelding . 153Nonmandatory Appendix J Commonly Used Conversion Factors 162viMandatory Appendix K Criteria for Catho
38、dic Protection . 166Nonmandatory Appendix L Determination of Remaining Strength of CorrodedPipe 168Nonmandatory Appendix M Gas Leakage Control Criteria 169Nonmandatory Appendix N Recommended Practice for Hydrostatic Testing ofPipelines in Place . 176Nonmandatory Appendix O Preparation of Technical I
39、nquiries . 178Nonmandatory Appendix P Nomenclature for Figures . 179Mandatory Appendix Q Scope Diagrams . 180Nonmandatory Appendix R Estimating Strain in Dents 183Index 185viiFOREWORDThe need for a national code for pressure piping became increasingly evident from 1915 to1925. To meet this need, the
40、 American Engineering Standards Committee (later changed to theAmerican Standards Association, now the American National Standards Institute) initiated ProjectB31 in March 1926 at the request of the American Society of Mechanical Engineers and withthat Society as sole sponsor. After several years of
41、 work by Sectional Committee B31 and itssubcommittees, a first Edition was published in 1935 as an American Tentative Standard Codefor Pressure Piping.A revision of the original tentative standard began in 1937. Several more years of effort weregiven to securing uniformity among sections, eliminatin
42、g divergent requirements and discrepan-cies, keeping the Code abreast of current developments in welding technique, calculating stresscomputations, and including reference to new dimensional and material standards. During thisperiod, a new section on refrigeration piping was prepared in cooperation
43、with the AmericanSociety of Refrigeration Engineers and complemented the American Standard Code for MechanicalRefrigeration. This work culminated in the 1942 American Standard Code for Pressure Piping.Supplements 1 and 2 of the 1942 Code, which appeared in 1944 and 1947, respectively, introducednew
44、dimensional and material standards, a new formula for pipe wall thickness, and morecomprehensive requirements for instrument and control piping. Shortly after the 1942 Code wasissued, procedures were established for handling inquiries requiring explanation or interpretationof Code requirements and f
45、or publishing such inquiries and answers in Mechanical Engineeringfor the information of all concerned.By 1948, continuing increases in the severity of service conditions combined with the develop-ment of new materials and designs to meet these higher requirements warranted more extensivechanges in
46、the Code than could be provided from supplements alone. The decision was reachedby the American Standards Association and the sponsor to reorganize the sectional committeeand its several subcommittees and to invite the various interested bodies to reaffirm their represen-tatives or to designate new
47、ones.Because of the wide field involved, between 30 and 40 different engineering societies, govern-ment bureaus, trade associations, institutes, and similar organizations had one or more representa-tives on the sectional committee, plus a few “members at large” to represent general interests.Code ac
48、tivities were subdivided according to the scope of the several sections. General directionof Code activities rested with the Standards Committee officers and an executive committee,membership of which consisted principally of Standards Committee officers and section chairmen.Following its reorganiza
49、tion in 1948, Standards Committee B31 made an intensive review ofthe 1942 Code that resulted in(a) a general revision and extension of requirements to agree with present-day practice(b) the revision of references to existing dimensional standards and material specifications andthe addition of references to the new ones(c) the clarification of ambiguous or conflicting requirementsA revision was presented for letter ballot vote of Standards Committee B31. Following approvalby this body, the project was approved by the sponsor organization and by the American StandardsAssociation. It
