The National Fire Protection Association (NFPA) has adopted the U.S. Chemical Safety Board’s recommendation to prohibit the purging of pipe lines using natural gas. The new standard, National Fuel Gas Code, NFPA 56, states unequivocally that flammable gas shall not be used for internal cleaning of piping. Air, steam, water and inert gas are recommended as substitutes. The standard also includes a detailed list of procedures and training requirements for workers involved in cleaning operations. The action is potentially significant because, although  NFPA is a voluntary consensus standards organization, the codes and standards it develops often are adopted into  law by states.

CSB recommended urgent action to stop the purging practice following the death of six workers and the injury of at least 50 others in a natural gas explosion at the Kleen Energy electric plant construction site in Connecticut. The February 2010 explosion occurred during a “gas blow,” an operation used to clean pipes by forcing large quantities of gas through piping at high pressure. The gas accumulated and was ignited by an undetermined source. Four months after the incident, CSB urged NFPA to revise its National Fuel Gas Code, NFPA 54, to prohibit the pipe- cleaning practice it called “inherently unsafe.”

“We are very pleased to see NFPA 56 also includes requirements for purging fuel gas systems into and out of service, saying gases must be released to a safe outdoor location, or captured inside and further processed before release,” CSB chairman Dr. Rafael Moure-Eraso said.

Noting that a large number of natural gas-fired power plants are planned for construction across the country over the next few years, Moure-Eraso predicted that “the NFPA will be instrumental in preventing further loss of life and property damage.”