NFPA 400 Updated in Response to West Explosion

The new 2016 edition says existing AN storage facilities of non-combustible construction should be retrofitted with automatic fire sprinklers.

• By Jerry Laws
• Aug 01, 2015

The National Fire Protection Association recently made the 2016 edition of NFPA 400, its Hazardous Materials Code, available on its website. This edition contains a revised Chapter 11 with significant changes for the design, construction, and fire suppression systems of new facilities built to house ammonium nitrate (AN), two NFPA staffers reported during a June 1 session at the AIHce 2015 conference in Salt Lake City. Nancy Pearce, CIH, a senior fire protection engineer at NFPA who is the staff liaison to the NFPA Hazardous Chemicals Committee, and Guy Colonna, P.E., an NFPA division manager, explained how a task group was formed following the West, Texas, fire and explosion at an AN storage facility in April 2013, with the mission of updating Chapter 11 in light of the lessons from that incident.

Fifteen people died in the explosion, 12 of whom were firefighters attempting to quench the fire at the West Fertilizer Company when 30 tons of stored AN exploded. With a middle school and a two-story apartment building located near the facility and heavily damaged, the toll could have been much worse, Colonna said. "The good news, if there's any, is that it occurred at 7:30 [p.m.] rather than at 2 p.m., when kids would've been in that school," he explained.

One lesson from the incident is the importance of maintaining adequate separation distances between hazardous processes and between facilities housing them and the greater community, he said, explaining that the nearby school and apartment building were erected after the storage facility was built.

The West Fertilizer fire occurred inside a wooden warehouse that lacked fire sprinklers and had no automatic fire detection or suppression systems, the U.S. Chemical Safety Board (CSB) reported in its preliminary findings on the explosion, which occurred only 20 minutes after the West Volunteer Fire Department received the first notification of the fire. "Not only were the warehouse and bins combustible, but the building also contained significant amounts of combustible seeds, which likely contributed to the intensity of the fire," CSB reported.

NFPA 400 was not applicable to the West plant because it was built in 1962, and Chapter 11 of the code originated in 1963, Colonna said, adding that NFPA standards generally are not applied retroactively. However, a significant provision of the 2016 edition has been written to apply to existing AN storage facilities of non-combustible construction: The revised Chapter 11 indicates they should be retrofitted with automatic fire sprinklers, Pearce said.

After what she described as heated debate over the question among the task group members, the threshold amount of AN to which the chapter's new provisions apply is 1,000 pounds of 60 percent solid AN or 70 percent liquid AN. "Below those levels, it is believed that ammonium nitrate will not explode," she said.

Pearce said the 2016 edition calls for new AN storage facilities to be of non-combustible construction, with separation of the material from contaminants, as well as automatic fire sprinklers and a one-hour fire barrier floor to roof required. The minimum separation distance in the code for outdoor storage has been doubled from 15 feet to 30 feet.

The previous edition of NFPA 400 required automatic fire sprinklers only for facilities storing more than 2,500 tons of AN, far more than the amount involved in the powerful explosion in West. The Dallas Morning News’ Marissa Barnett reported June 8 that Texas Gov. Greg Abbott had signed legislation that week that would prohibit AN from being stored together with combustible material. Taking effect immediately, the measure gives the state fire marshal authority to inspect AN storage facilities and moves oversight from the state health department to the Texas Commission on Environmental Quality, she reported.

Pearce explained that one of the new elements in Chapter 11 is intended to provide clear guidance to emergency responders when an AN storage facility is burning. It calls for placing warning signs on the facility's exterior that state:

DO NOT FIGHT FIRE

EXPLOSION HAZARD

For security reasons, the standard does not specify that the signs say the facility contains AN, she said.

AN Containment the Common Denominator for Higher Risk
"After two years, we actually are going to be releasing the new edition with these changes," Pearce told their audience. "The good news is, everybody [serving on the task group] had really the same goal, which was to prevent something like this from ever happening again, with the associated loss of life."

While the conditions that lead to AN explosions aren't yet fully known, containment of the fertilizer seems to be the common denominator for higher risk, Pearce said. Ammonium nitrate is an oxidizer that is classified as both a blasting agent and a fertilizer. Solid AN will explode when it becomes molten, decomposes, and the molten material is contained and confined in a drain, pit, bin, or similar enclosure—and so ventilation of AN storage and having storage areas with sloped floors, so the molten AN can run off in the event of a fire, can help to prevent explosions, she said.

CSB Called for Review of Fire Codes
The 2016 edition of the code makes progress on one of CSB's chief concerns following the explosion. The board's preliminary findings said many AN safety provisions in the NFPA and International Code Council (ICC) fire codes "are quite old and appear to be confusing or contradictory, even to code experts, and are in need of a comprehensive review in light of the West disaster and other recent accidents."

CSB noted that other forms of AN have been developed to reduce or eliminate the risk of accidental detonation, such as compounding the ammonium nitrate with calcium carbonate (limestone), a method widely used in Europe. Its findings stated that OSHA';s 29 CFR 1910.109 Explosives and Blasting Agents standard does not prohibit wooden bins or wooden construction and does not require sprinklers unless more than 2,500 tons of AN are present, and that when OSHA last inspected the West Fertilizer facility in 1985, no citations were issued under the 1910.109 standard.

McLennan County, where the West facility was located, had not adopted a fire code prior to the explosion, and thus the facility was thus not required to follow any of NFPA's or ICC's recommendations for the storage of ammonium nitrate, the safety board reported.

Federal, Industry Actions on AN
President Obama issued Executive Order 13650, "Improving Chemical Facility Safety and Security," on Aug. 1, 2013, in response to the West explosion. It directed several federal agencies to identify ways to increase the safety and security of chemical facilities and reduce risks associated with hazardous chemicals such as ammonium nitrate. His order established a Chemical Facility Safety and Security Working Group to oversee the effort, chaired by EPA, DOL, and DHS, and leaders of those organizations on June 6, 2014, released a 121-page report titled "Actions to Improve Chemical Facilities' Safety and Security—A Shared Commitment," laying out a blueprint for actions that include revising OSHA’s Process Safety Management regulation and EPA's Risk Management Program regulation.

OSHA recently posted a fact sheet updating the participating agencies' actions to date. It says OSHA has issued guidance to its regional administrators on enforcement of the 1910.109 standard and is in the process of developing both regional and local emphasis programs "to more effectively enforce standards for the safe storage of ammonium nitrate."

Other actions listed in the sheet include these:

• In June 2015, OSHA, EPA, and ATF issued an updated Chemical Advisory: Safe Storage, Handling, and Management of Solid Ammonium Nitrate Prills (www2.epa.gov/sites/production/files/2015-06/documents/an_advisory_6-5-15.pdf).
• OSHA issued a letter and additional materials to major fertilizer industry stakeholders to emphasize current requirements for AN storage.
• The Fertilizer Safety and Health Partners Alliance was created in February 2015, with representatives of OSHA, EPA, the Agricultural Retailers Association, the Ammonia Safety and Training Institute, The Fertilizer Institute, the International Association of Fire Fighters, and the National Volunteer Fire Council signing. The alliance partners agreed to work together to raise awareness of OSHA and EPA rulemaking and enforcement activities and to develop and distribute fact sheets, case studies, presentations at partners' conferences and local meetings, best practice seminars/webinars, and a pilot training program for OSHA and EPA staffers.
• OSHA initiated the small business review panel in June 2015 to get feedback on the proposed PSM revisions.
• An interagency work group that has completed the integration of chemical facility data sets, a compendium of more than 300,000 records, with the goal of creating a unified chemical facility data clearinghouse. Each facility has been given a single EPA identifier, allowing stakeholders to search nearly all chemical facility safety and security information that has been submitted to the federal government, according to the fact sheet.

This article originally appeared in the August 2015 issue of Occupational Health & Safety.