NFPA amends the Fuel Gas Code to prevent purging of pipelines using natural gas after Kleen explosion

Industrial Accidents
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Aug 11, 2010– The National Fire Protection Association (NFPA), through an emergency revision to the NFPA 2009 code, has prohibited the purging of gas pipelines by using natural gas. This is a direct fallout of the Kleen Energy accident investigation, after the US Chemical Safety Board concluded that the purging by natural gas led to the accident. The CSB had also appealed to standards and regulatory bodies like OSHA and NFPA to amend the codes that regulate natural gas piping and operations in view of these findings. We had reported all about it here.

The NFPA has now responded by issuing aTentative Interim Amendment to Section 54 of the Natural Gas Code. This can be downloaded from here.
(Note: The code specifically talks about installing a gas detector to detect the presence of natural gas-if you would like to know how to specify, select, install, calibrate and maintain these gas detectors, please click here)

The CSB was glad to hear about this and the agency has issued a statement reproduced below.

Here’s the CSB statement (in Italics)


Emergency Change to National Fuel Gas Code Addresses Cause of Fatal June 2009 Blast at ConAgra Slim Jim Plant in North Carolina

On February 4, 2010, I presided at a Chemical Safety Board public meeting in Raleigh, North Carolina, to present the CSB’s findings on the June 9, 2009, natural gas explosion at the ConAgra Slim Jim manufacturing plant in the nearby community of Garner.

That tragic and preventable accident cost four lives, injured 67 others, and led to a decision to close the plant, with the loss of hundreds of jobs in the region.  The accident occurred during an operation to purge (or clear air) from a new steel gas-supply pipe that was connected to a newly installed industrial water heater.  The pipe was connected at the other end to the building’s natural gas distribution system.  During the purging operation, gas was allowed to flow through the pipe and exit through an open valve inside the utility room where the water heater was located.  Due to difficulties in lighting the water heater, the purging operation was continued for an unusually long time, eventually causing gas to accumulate above the lower explosive limit inside the building.  The gas contacted an ignition source and exploded, causing extensive sections of the large facility to collapse.

The CSB noted that the accident at ConAgra was but one of a number of similar explosions caused by an intentional, planned work activity that inadvertently led to a large and unsafe release of natural gas into a workplace.

At the time of the accident, 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.  At the February 4 public meeting, the Board voted to make urgent recommendations to 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.

I am pleased that the NFPA made our recommendation a high priority and took immediate steps to improve the National Fuel Gas Code.  Last week, on August 5, the NFPA Standards Council gave final approval to an emergency code change, known as a Tentative Interim Amendment, that will prohibit indoor purging of industrial gas lines operating at greater than two pounds per square inch gauge (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.

These new provisions would have required the gas pipe at ConAgra to be purged outdoors, away from personnel and ignition sources.  Under the new requirements, purging must be monitored using appropriate detection equipment to prevent a significant release of flammable gas.  The new requirements are similar to new safety procedures developed and implemented by both ConAgra and the State of North Carolina in the months following the tragedy.

Outdoor purging is inherently safer than venting gas into a building.  Had the gas pipe at ConAgra been safely purged outdoors, the explosion and resulting deaths and injuries could have been avoided.

I encourage all companies to study the new code recommendations and to purge flammable gases outdoors whenever possible.  I urge the NFPA to ensure that a prohibition on indoor purging and other safeguards are permanently incorporated into the National Fuel Gas Code, and I thank the NFPA leadership and members for their positive actions to promote worker safety.