The National Fire Protection Association's National Fuel Gas Code Committee recently moved to strengthen gas-purging safety requirements in NFPA 54, National Fuel Gas Code. The action followed recommendations issued by the Chemical Safety and Hazard Investigation Board (CSB) in the wake of the 2009 ConAgra Slim Jim plant accident in Garner, N.C. The CSB's recommendations acknowledged the accident was caused by improper indoor gas purging and, therefore, encouraged that the practice be restricted, said Guy Colonna, a NFPA division manager.

"ConAgra highlighted the flaws of the process, but it was not the direct reason for the safety revisions," Colonna said. "NFPA 54 is revised every three years as part of the ongoing revision for the code, so it was already scheduled to do its normal, three-year revision independent of the circumstances surrounding the incidents related to gas purging at ConAgra."

There were several lessons learned from the ConAgra incident and such lessons were considered during the revisions, Colonna said. The event highlighted the dangers of gas purging indoors, which in the past was a common industry practice. Now, the proposed change requires the discharge of gas purging to be directed outdoors and identifies specific requirements that must be met during the purging process. (See sidebar below.)

The second safety requirement mandates that users deploy a portable atmospheric monitoring detector that can detect gas concentrations, instead of personnel's previous reliance on the ability to smell the gas to determine when the purging process had completed, Colonna said.

"One of the changes is that they will now be required, at the dispatch point, to use calibrated atmospheric monitoring devices capable of detecting the appropriate concentrations of purged gas," he said.

The committee put forth a request for an expedited public review and comment period based on the Tentative Interim Amendment (TIA), which asks that the current edition of the code be changed on an emergency basis and enables the lessons learned from the CSB investigation of the ConAgra incident to be implemented without waiting for the complete revision cycle of the 2012 edition of NFPA 54 to be completed, Colonna said.

"The TIA, if approved, would then be an immediate change to the 2009 edition of the code, which is the current edition," he said. "So in the next several months we anticipate, depending on how that schedule moves through — that could happen in the next several months, in which case these technical changes would become effective immediately at that point for the current edition of the code."

However, Colonna said that the technical committee's other actions on changes to the 2012 edition will be letter-balloted by all members of the committee and then be published and publicly available in the report on proposals. At that point, all changes to NFPA 54 are opened for public review and comment until Sept. 3, 2010. The 2012 edition of NFPA 54 is scheduled for issuance in the summer of 2011, he said.

Sidebar: Technical Committee TIA to change to NFPA 54

The Technical Committee initiated a Tentative Interim Amendment (TIA) to change the current edition of the code on an emergency basis. The proposed change requires the discharge of gas purging to be directed outdoors and identifies specific requirements that must be met during the purging process. Specific requirements include:

• The point of discharge shall be controlled with a shutoff valve.
• Discharge point shall be at least 10 feet from sources of ignition, located a minimum of 10 feet from building openings and a minimum of 25 feet from mechanical air intake openings.
• During discharge, the open discharge point shall be continuously attended and monitored with a combustible gas indicator.
• Purging operations introducing fuel gas shall be stopped when 90% fuel gas by volume is detected within the pipe at the point of discharge.
• All persons not involved in the purging operations shall be evacuated from the area within 25 feet of the point of discharge.