The National Fire Protection Association’s (NFPA) National Fuel Gas Code Committee moved to strengthen safety requirements for gas purging in NFPA 54, National Fuel Gas Code, at its meeting held February 23-25, 2010. Their action follows urgent recommendations issued by the U.S. Chemical Safety and Hazard Investigation Board (CSB) in the wake of a tragic explosion at the ConAgra Slim Jim plant in Garner, N.C. in June 2009. CSB recommendations acknowledged the hazards involved in this common industry practice and encouraged that indoor gas purging at industrial, commercial, and public facilities be restricted.
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:
1. The point of discharge shall be controlled with a shutoff valve.
2. Discharge point shall be at least 10 ft. from sources of ignition, located a minimum of 10 ft. from building openings and a minimum of 25 ft. from mechanical air intake openings.
3. During discharge, the open discharge point shall be continuously attended and monitored with a combustible gas indicator.
4. Purging operations introducing fuel gas shall be stopped when 90% fuel gas by volume is detected within the pipe at the point of discharge.
5. All persons not involved in the purging operations shall be evacuated from the area within 25 ft. of the point of discharge.
There will now be a letter ballot of the Technical Committee and an expedited public review and comment period on the TIA. NFPA also welcomes public input on this proposed emergency revision. The TIA 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.
In addition to the TIA, the Technical Committee also took first steps to change the next edition of NFPA 54. The Technical Committee’s actions on changes to the 2012 edition will be letter-balloted by all members of the Technical Committee and then be published and made publicly available in the Report on Proposals (ROP). At that point, all changes to NFPA 54 are opened for public review and comment until September 3, 2010. The 2012 edition of NFPA 54 is scheduled for issuance in the summer of 2011.
All relevant information pertaining to the development of the 2012 edition of NFPA 54 and the TIA can be found at http://www.nfpa.org/54.