NFPA Gas Purging Rules Updated

The Kleen Energy Systems plant in Connecticut was purging fuel supply piping with natural gas indoors on February 7 when an explosion claimed five lives and injured 27 workers. Even at the time “Natural Gas Piping: It’s Time for Better Risk Control” was published in our May issue, indoor purging of natural gas systems was not prohibited under the National Fuel Gas Code, a key consensus code of the National Fire Protection Association (NFPA) that has been adopted by many states and localities across the country. In that article, we called for industry action to prevent a repeat of the Kleen Energy Systems tragedy: “It’s time the industry understood the unique design and safety requirements for working with and purging natural gas piping.”

The CSB has since made urgent recommendations to the NFPA and the International Code Council to prohibit indoor purging and require companies and installers to purge flammable fuel gases to safe locations outdoors, away from workers and ignition sources. On August 5, the NFPA Standards Council gave final approval to an emergency code change, known as a Tentative Interim Amendment, that prohibits indoor purging of industrial gas lines operating at greater than 2 psig or meeting certain pipe size criteria. According to the NFPA, the new requirements are designed to require outdoor purging for industrial, large commercial, and large multifamily buildings. In addition, purging must be monitored using appropriate detection equipment to prevent a significant release of flammable gas.

Expect these interim rules to be permanently incorporated into the National Fuel Gas Code in the near future. The text of the amendment can be found at http://www.nfpa.org; search for TIA54-09-3.

—Edited by Dr. Robert Peltier, PE