NFPA 56 (PS)
Standard for Fire and Explosion Prevention During Cleaning and Purging of Flammable Gas Piping Systems
|Publication Date:||1 January 2012|
Applicability. 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.
Coverage of piping systems shall extend from the point of delivery to the gas-consuming equipment isolation valve.
For other than undiluted liquefied petroleum gas (LP-Gas) systems, the point of delivery is the outlet of the customer meter or at the connection to a customer's piping, whichever is farther downstream, or if there is no meter at the connection to customer piping.
For undiluted LP-Gas, the point of delivery is the outlet of the final pressure regulator, exclusive of line gas regulators, in the system.
For facilities that produce flammable gas for consumption on site, the point of delivery is the discharge isolation valve for the gas-producing equipment.
Nonapplication of Standard. This standard shall not apply to the following items:
(1)*Piping systems covered by NFPA 2
(2)*Piping systems covered by NFPA 54
(3)*Piping systems covered by NFPA 58
(4)*LP-Gas (including refrigerated storage) at utility gas plants (see NFPA 59)
(5)*LNG facilities covered by NFPA 59A
(6) LP-Gas used with oxygen for cutting, welding, or other hot work
(7)*Vehicle fuel dispensers
(8) Commissioning and maintenance of appliances or equipment
(9) Vent lines from pressure relief valves
(10) Systems regulated by U.S. Department of Transportation (DOT) 49 CFR 191 and 192
Purpose. This standard provides minimum safety requirements for the cleaning and purging of flammable gas piping systems, including cleaning new or existing piping systems, purging piping systems into service, and purging piping systems out of service.
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.