NFPA 56

Abstract

<strong>Applicability.</strong> This standard shall apply to fire and explosion prevention during cleaning and purging activities for new and existing flammable gas piping found in electricgenerating plants and in industrial, institutional, and commercial applications. <br>Coverage of fuel gas piping systems shall extend from the point of delivery or source valve to the gas-consuming equipment isolation valve. <br>For other than undiluted liquefied petroleum gas (LP-Gas) systems, the point of delivery or source valve shall be the outlet of the service meter assembly or the outlet of the service regulator or service shutoff valve where no meter is provided. [54: 1.1.1.1(A)] <br>For undiluted LP-Gas, the point of delivery shall be considered to be the outlet of the final pressure regulator, exclusive of line gas regulators where no meter is instal Where a meter is installed, the point of delivery shall be the outlet of the meter. [54: 1.1.1.1(A)] <br>For facilities that produce flammable gas for consumption on site, the point of delivery or source valve shall be the discharge isolation valve for the gas-producing equipment. <br>Coverage of flammable gas piping systems other than fuel gas piping systems shall extend from the source valve serving the gas supply system to the gas-consuming equipment isolation valve. <br><strong>Nonapplication of Standard.</strong> This standard shall not apply to the following items: <br>(1)*Piping systems covered by NFPA 2, <em>Hydrogen Technologies Code</em> <br>(2)*Piping systems covered by NFPA 51, <em>Standard for the Design and Installation of Oxygen&#8211;Fuel Gas Systems for Welding, Cutting, and Allied Processes</em> <br>(3)*Piping systems covered by NFPA 51A, Standard for Acetylene Cylinder Charging Plants <br>) Fuel-dispensing facilities covered by NFPA 52, <em>Vehicular Gaseous Fuel Systems Code.</em> <br>(5)*Piping systems covered by NFPA 54, <em>National Fuel Gas Code</em> <br>(6)*Piping systems covered by NFPA 55, <em>Compressed Gases and Cryogenic Fluids Code</em> <br>(7)*Piping systems covered by NFPA 58, <em>Liquefied Petroleum Gas Code</em> <br>(8)*LP-Gas (including refrigerated storage) at utility gas plants (<em>see</em> NFPA 59, <em>Utility LP-Gas Plant Code</em>) <br>(9)*LNG facilities covered by NFPA 59A, <em>Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG)</em> <br>(10)*Vehicle fuel dispensers <br>(11) Commissioning and maintenance of equipment <br>(12) Vent lines from pressure relief valves or devices unless such vent lines are also used for purging of flammable gas piping systems <br>(13)*Systems regulated by U.S. Department of Transportation (DOT) 49 CFR 100&#8211;199 <br><strong>Purpose.</strong> This standard provides minimum safety requirements for the cleaning and purging of flammable gas piping systems, including cleaning new or existing piping systems, and purging piping systems into or out of service, from the point of delivery or source valve to the equipment isolation valve. <br>For the purposes of this document, a piping system shall be understood to mean a complete piping system, including valves, regulators, and other appurtenances, and any segment thereof that can be isolated from the system.