1、NFPA56 Standard for Fire and Explosion Prevention During Cleaning and Purging of Flammable Gas Piping Systems 2014 Edition NFPA, 1 Batterymarch Park, Quincy, MA 02169-7471 An International Codes and Standards Organization IMPORTANT NOTICES AND DISCLAIMERS CONCERNING NFPADOCUMENTSNOTICE AND DISCLAIME
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29、 Rights Reserved.NFPA56Standard forFire and Explosion Prevention During Cleaning and Purging ofFlammable Gas Piping Systems2014 EditionThis edition of NFPA 56, Standard for Fire and Explosion Prevention During Cleaning andPurging of Flammable Gas Piping Systems, was prepared by the Technical Committ
30、ee on GasProcess Safety. It was issued by the Standards Council on May 28, 2013, with an effective dateof June 17, 2013, and supersedes all previous editions.ThiseditionofNFPA56wasapprovedasanAmericanNationalStandardonJune17,2013.Origin and Development of NFPA 56In February 2010, an explosion occurr
31、ed at a power plant construction site as the result ofan uncontrolled release of flammable gas that was being used to clean the interior of the fuelpiping system. The incident investigation resulted in urgent recommendations being issuedby the U.S. Chemical Safety Board (CSB) for NFPA to develop req
32、uirements for the “safeconduct of fuel gas piping cleaning operations.” In response, the NFPA Standards Councilestablished the Technical Committee on Gas Process Safety and tasked that committee withdeveloping a standard to address piping system cleaning and purging operations. As a resultof the CSB
33、s urgent recommendation, NFPAissued provisional standard NFPA56 (PS), Stan-dard forFire and Explosion Prevention During Cleaning and Purging of Flammable Gas Piping Systems,which prohibits the use of flammable gas as an agent for the interior cleaning of pipingsystems. NFPA 56 (PS) expanded on the C
34、SB recommendations by including cleaning andpurgingofallflammablegaspipingsystemsatanyinletpressureforelectric-generatingplantsand for industrial, commercial, and institutional applications.In addition to the use of flammable gas for cleaning and purging, the provisional standardaddressedtrainingreq
35、uirementsforpersonnelaswellasnotificationofhazardsforpersonnelnot directly involved in cleaning or purging procedures.The standard required developmentof written procedures for cleaning and purging activities and that all such written proceduresundergo a safety validation performed by a competent pe
36、rson. The definition of competentperson was extracted directly from federal Occupational Safety and Health Administration(OSHA) regulations. NFPA 56 (PS) also adopted terminology commonly used by the petro-chemical industry for those procedures: purging into service for the process of replacing air
37、in apipingsystemwithinertorflammablegasand purging out of service fortheprocessofreplacingflammable gas in the piping system with inert gas or air.In accordance withANSI requirements for provisional standards, NFPA56 (PS) was imme-diately submitted for revision in accordance with the NFPA Regulation
38、s Governing Commit-tee Projects. As a result, NFPA 56 is no longer a provisional standard and will no longer bedesignated with the suffix “PS.”In the 2014 edition, new requirements have been added to address the use of pressurerelief valves and their associated piping in purging and cleaning process
39、es. NFPA 55, Com-pressed Gases and Cryogenic Fluids Code, is exempted from the scope of NFPA56 in recognitionof new requirements added to NFPA 55 to address cleaning and purging of flammable gaspiping systems within the NFPA 55 scope. Also, the term source valve has been defined andadded to the scop
40、e because it is the term used in the compressed/industrial gas industry todemarcate the point of delivery to the piping system. The 2014 edition also includes addi-tional annex text to further clarify existing and new requirements.561NFPAand National Fire ProtectionAssociation are registered tradema
41、rks of the National Fire ProtectionAssociation, Quincy, Massachusetts 02169.Technical Committee on Gas Process SafetyGlenn Mahnken, ChairFM Global, MAIDonald W. Bairley, Alstom Power Inc., CT UMichael W. Bethany, Eclipse/CEC Combustion Safety,Inc., OH MLeon A. Bowdoin, Jr., Hess LNG, MAUWilliam M. B
42、radshaw, ABSG Consulting Inc., TN SEChristopher S. Buehler, Exponent, Inc., TX SEPaul W. Cabot, American GasAssociation, DC IMTherese Cirone, The Chlorine Institute, VAMRep. The Chlorine Institute, Inc.Richard A. Craig, Compressed GasAssociation, VAMRep. Compressed GasAssociationLawrence M. Danner,
43、General Electric, Energy, SC MLouis A. Donsbach, Jr., U.S. Steel Corporation, IN UDan Dorran, Atlas Copco Rental, OR URob Early, Praxair, NY MKevin W. Gordon, NextEra Energy/Florida Powerpropelledbyair,water,or another medium; or driven by the product flow.3.3.10 Purge. To free a gas conduit of air
44、or gas, or a mixtureof gas and air. 54, 20123.3.10.1 Purge into Service. To replace the air or inert gasin a closed system by a flammable gas.3.3.10.2 Purge out of Service. To replace the normal flam-mable content of a closed system by inert gas, air, or water.3.3.11 SourceValve. Ashutoffvalveonthep
45、ipingsystemserv-ing a gas supply system where the gas supply, at service pres-sure, first enters the supply line.Chapter 4 General Requirements4.1 Piping System Construction. Flammable gas piping sys-tems shall be designed, constructed, inspected, and tested inaccordance with ASME B31.1, Power Pipin
46、g; ASME B31.3, Pro-cess Piping; ASME B31.12, Hydrogen Piping and Pipelines;NFPA 55, Compressed Gases and Cryogenic Fluids Code; NFPA 54,National Fuel Gas Code; or other approved codes or standards.4.1.1 The requirement of Section 4.1 shall not be required tobe applied retroactively.4.1.2* Pressure T
47、esting and Inspection. Prior to cleaning orpurging, piping systems shall be inspected and pressure testedtodeterminethatthematerials,design,fabrication,andinstal-lation practices comply with the requirements of this standardand the intended application.4.1.2.1 Pressure testing and inspection procedu
48、res shall bedocumented.4.1.2.2 Where piping is designed and installed in accordancewith NFPA 54, National Fuel Gas Code, pressure testing and in-spection shall be in accordance with NFPA54, Chapter 8.4.1.2.3 Where piping is designed and installed in accordancewithASMEB31.1,PowerPiping,pressuretestin
49、gandinspectionshall be in accordance with Chapter VI ofASME B31.1.4.1.2.4* Where piping is designed and constructed in accor-dance withASME B31.3, Process Piping, leak testing and inspec-tion shall be in accordance with Chapter VI ofASME B31.3.4.1.2.5* Where pneumatic testing is conducted in accordancewith ASME B31.1, Power Piping, paragraph 137.5.2, or withASME B31.3, Process Piping, paragraph 345.5.3, the test me-dium shall be air or an inert gas. Oxygen shall never be used.4.2* Temperature and Pressure. The delivered temperatureand pressure of clea
