Garner, NC, blast investigation, video

Thursday, May 6, 2010 @ 02:05 PM gHale

It was almost one year ago, during the afternoon of June 9, 4 workers were killed and close to 40 others were injured when an explosion occurred at the ConAgra Foods facility in Garner, NC.
Workers had been installing a new, natural gas-powered industrial water heater in an interior utility room, and they ended up purging a new gas line before commissioning the heater. As you can see from the animation below, the purged gasses vented directly into the utility room where the deadly vapors concentrated enough to explode, which brought part of the building down.
The explosion led to the collapse of a large part of the building and the release of about 18,000 pounds of ammonia from the plant’s refrigeration system. [private]
Following the incident, ConAgra Foods agreed to pay a $106,440 fine and take steps to improve safety at its Slim Jim plant. The state Department of Labor found 26 serious health and safety violations at the plant and initially fined the company nearly $135,000.
Donald Holmstrom, who led the Chemical Safety Board’s (CSB) investigation, said during a meeting in Raleigh, NC, in February purging natural gas inside is common practice in plants across the country.
While the CSB’s investigation remains open, the board did vote 2-1 to approve urgent safety recommendations on gas purging safety.
The draft recommendations urged the National Fire Protection Association (NFPA), American Gas Association (AGA), and the International Code Council (ICC) to strengthen the national fuel gas code provisions on purging.
Proper gas purging procedures
The following are the recommendations:
Enact a Tentative Interim Amendment as well as permanent changes to the National Fuel Gas Code (NFPA 54/ANSI Z223.1) to require that during the purging of fuel gas piping at industrial, commercial, and public facilities:
(a) Purged fuel gases shall be directly vented to a safe location outdoors, away from personnel and ignition sources
(b) If it is not possible to vent purged gases outdoors, purging gas to the inside of a building shall be allowed only upon approval by the authority having jurisdiction of a documented risk evaluation and hazard control plan. The evaluation and plan shall establish that indoor purging is necessary and that adequate safeguards are in place such as:
• Evacuating nonessential personnel from the vicinity of the purging;
• Providing adequate ventilation to maintain the gas concentration at an established safe level, substantially below the lower explosive limit; and
• Controlling or eliminating potential ignition sources
(c) Combustible gas detectors are used to continuously monitor the gas concentration at appropriate locations in the vicinity where purged gases are released
(d) Personnel are trained about the problems of odor fade and odor fatigue and warned against relying on odor alone for detecting releases of fuel gases
At the same time, the ICC International Fuel Gas Code Committee Chair and the International Code Council made their recommendations:
Incorporate the revised gas purging provisions of the National Fuel Gas Code, consistent with CSB recommendation 2009-12-I-NC-R1, into the International Fuel Gas Code.[/private]

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