Why Ammonium Nitrate Needs Safety Measures

The most recent ammonium nitrate (AN) disaster within the U.S. occurred on April 17, 2013, at West, Texas. A West Fertilizer Company (WFC) storage and distribution facility storing 30 tons of AN exploded after a fire broke out. This explosion left 15 people dead and around 200 hospitalized.

The explosion also led people to question: “How can An disasters be prevented?”

Vyto Babrauskas, Ph.D., has asked the same question for 20 years. He has spent the last two decades focusing on electrical fires and explosions. Babrauskas spearheaded the fire investigation and litigation of the WFC disaster. He shares his knowledge and discoveries in an SFPE webinar titled, “Ammonium Nitrate: Why We Are on the Course to Blow up More Firefighters and First-Responders.”

In this webinar, Babrauskas explains the past will repeat itself if there continues to be unchanging prognoses and a lack of AN safety procedures executed.

What is Ammonium Nitrate (AN)?

AN is not a new theory. Nor is it a substance the world isn’t familiar with. AN is one of the older known chemical compounds first synthesized in the 1600s. It has since evolved into a key ingredient for agricultural fertilizers.

“AN disasters have overwhelmingly been due to fire or being stored in propinquity to other explosible substances,” explains Babrauskas in the webinar. “And even though these disasters continue to occur, no lessons have been learned, when the solutions can be simple.”

Prevention is Possible

According to Babrauskas, when storing AN, companies must rule out the possibilities for fires. Danger occurs when there are combustibles in the area, which may ignite and burn. But by itself, AN is non-combustible, and therefore, cannot ignite.

“An example of a cost-effective, simple way of building a specialized AN warehouse is through a pre-designed concrete dome. They are inexpensive and wholly not combustible,” he says.

Babrauskas suggests five additional safety measures in the webinar.

• Store the AN in a detached, noncombustible building or bin,
• Prohibit the sitting of AN in facilities within the proximity of explosives,
• Install an automatic fire sprinkler system fully conformed to NFPA 13,
• Place a fire or smoke alarm system monitored by a central station, and
• Prohibit pits, drains and other features where molten AN can collect.

For transporting AN safely, even though fuel cannot be excluded, there are AN alternatives.

“In order to solve this problem, it’s required to migrate from straight-AN to a replacement fertilizer, which is not prone to detonation. Several alternatives include calcium ammonium nitrate (CAN), ammonium sulfate nitrate (ASN-26), and AN with specialized inorganic coatings,” says Babrauskas.

The most common alternative is CAN—a chemical that has been in commercial production since the 1920s. There are many countries that ban AN fertilizer use and replace it with CAN. But the U.S. has resisted its introduction, and CAN currently is only obtainable as an import product.

Insignificant Changes Lead to an Unstable Future

Though U.S. regulations for AN safety exist, many companies still haven’t implemented them, even after the WFC explosion.

There are only two companies within the U.S. that manufacture AN fertilizer grade: CFI and EDC. These manufacturers can improve safety by upholding a Product Stewardship responsibility. This program prohibits sales to establishments that cannot safely store or handle dangerous products. However, this program is not being executed.

“After the WFC disaster, the fertilizer industry responded by establishing a product stewardship initiative (ResponsibleAg). But I am not aware of a single unsafe AN storage facility that has been remediated due to the ResponsibleAg program,” says Babrauskas.

Building codes also are not being executed, he says. NFPA offers building codes, but treats AN as one topic within NFPA 400, the Hazardous Materials Code.

After the WFC disaster, NFPA revised the code that mandates automatic sprinklers. However, the association still permits “grandfathering.” There’s also a lack of local authorities looking to make changes. 

“There has been no further indication that any of the 1,300 or so critically hazardous storage facilities have been upgraded with automatic sprinkler systems. The codes and standards are only as good as their enforcement,” states Babrauskas.

On the state level, the Office of Texas State Chemist (OTSC) was the main regulatory agency subject to WFC. This agency makes sure customers are not being cheated nor sold adulterated products.

In response to WFC, the State took two regulatory actions. The state legislature passed House Bill 942, allowing the State Fire Marshal and the local fire departments to inspect AN storage facilities and require owners to abate identified hazards.

Babrauskas sums up the second regulatory action in two sentences: “Store ammonium nitrate or ammonium nitrate material in a separate structure. Combustible or flammable material must be separated by at least 30 feet.”

Currently, there are no significant changes that exist from these regulatory actions, he says.

Moreover, OSHA is the main Federal agency in charge of safeguarding workers in the workplace, and the last OSHA inspection at WFC was 28 years prior to the explosion. Their response to the explosion was a letter explaining how WFC did not comply with 29 CFR 1910.109, even though OSHA does not include AN on its dangerous chemicals list.

Current OSHA regulations fail to require a monitored alarm or automatic sprinkler system and allow wood for construction and storage material. The organization follows this with a “grandfathering” clause that enables owners to avoid remediation, even if the inspector finds constructional violations.

Other regulatory organizations such as the Department of Homeland Security, Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF); U.S. Chemical Safety and Hazard Investigation Board (CSB); U.S. Environmental Protection Agency (EPA); and the Emergency Response Guidebook (ERG) are following suit with failure of acknowledging AN danger and implementing safety regulations.

If government officials are not enforcing AN safety, there will be little to no change in storage and transportation facilities.

According to the Government Accountability Office (GAO) survey, within the U.S., there are around 1,300 facilities at the same risk level of an AN explosion similar to WFC. Not only are the establishments unsafe, but he says people’s lives are at risk.

“The fact that nothing is being done is of great concern,” concluded Babrauskas.

For Further Reading

There is a plethora of information readily available and accessible for further AN study.

Médard, L. A., Accidental Explosions, 2 vols., Ellis Horwood, Chichester, England (1989). This is the most extensive reference on AN hazards.

Babrauskas, V., Ignition Handbook, Fire Science Publishers/Society of Fire Protection Engineers, Issaquah WA (2003). Has a section on AN.

Kiiski, H., Properties of Ammonium Nitrate Based Fertilisers (Ph.D. dissertation), Univ. Helsinki, Finland (2009).

“Ammonium Nitrate: Why We Are on the Course to Blow up More Firefighters and First-Responders” is part of a five-part webinar series that members can take to further their education. Organizations can access all SFPE webinars and training by becoming a member. Visit https://www.sfpe.org/home to learn more.