CSB welcomes change in gas code

Author : Paul Gay

11 August 2010

The US National Fire Protection Association (NFPA) has introduced an emergency change to the National Fuel Gas Code following last year’s fatal blast at ConAgra’s Slim Jim Plant in North Carolina. The accident occurred during an operation to purge air from a new steel gas-supply pipe that was connected to a newly installed industrial water heater.

Extensive sections of ConAgra's facility collapsed

The pipe was connected at the other end to the building’s natural gas distribution system and 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.
Back in February this year, John Bresland, board member of the Chemical Safety Board (CSB) presided at a public meeting in Raleigh, North Carolina, to present the CSB’s findings on the natural gas explosion at the ConAgra Slim Jim manufacturing plant in the nearby community of Garner.
The NFPA has made CSB’s recommendation a high priority and has taken immediate steps to improve the National Fuel Gas Code. Last week 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 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.
The tragic and preventable accident at ConAgra’s Slim Jim Plant 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.