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Experts work to find cause of Texas fertilizer blast

04.18.2013  | 

It's not clear what occurred at the West facility. The fire which preceded the blast could have heated up the storage tanks and set off the explosion. For now, though, "that is still speculation", officials say.

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(Our initial story on the West plant explosion and its aftermath can be read by clicking here.)

By GAUTAM NAIK

Experts are still trying to pin down the chain of events that triggered the mammoth explosion at a Texas fertilizer plant on Wednesday night, but such explosions are unusual because of the high temperatures required to ignite them.

The facility, run by West Fertilizer Co., appears to be a place where agricultural fertilizer was likely stored, rather than manufactured. One of the main chemicals at the facility likely was ammonia -- a colorless, pungent gas that's stored in liquid form under high pressure in steel containers.

But because ammonia is relatively stable and only ignites at a temperature of 1562 degrees Fahrenheit, such events are rare.

"This is pretty new to us," said Kathy Mathers, spokeswoman for The Fertilizer Institute, or TFI, a US trade association for the fertilizer industry. "It's not something we are familiar with in our business."

While nitrogen is found widely in the environment, many plants aren't especially efficient at using it for growth. Fertilizer provides nitrogen in a form that's easier for plants to take up.

Mined minerals such as potash and phosphates are a type of fertilizer that can be spread. Another fertilizer is ammonia gas, a combination of nitrogen and hydrogen. In the US, ammonia gas is often directly injected into the soil.

Nitrogen fertilizers are often made with a century-old technique known as the Haber-Bosch process. The process takes nitrogen out of the air and combines it with hydrogen obtained from natural gas.

When ammonia is heated, it expands. "Traditionally, that's our concern," said Ford West, president of TFI. "That's why tanks [that store ammonia] have safety release valves" that get triggered if the pressure inside rises past a certain point.

It's not clear what occurred at the Texas facility. The fire which preceded the blast could have heated up the storage tanks and set off the explosion. For now, though, "that is still speculation," said Mr. West.

Another fertilizer is ammonium nitrate, which is easy to spread and often used for specialty crops, fruits and vegetables. The product is highly combustible but requires a fuel booster before it can ignite. Ammonium nitrate is also to make explosive and was the material used in the deadly Oklahoma City bombing of April 19, 1995.

It is not known if ammonium nitrate was stored at the Texas facility.


Dow Jones Newswires



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abdolreza foolad
05.01.2013

Ammonium Nitratrate in a closed container or warehouse , if heated up, is disintegrated and emits a lot of gases. these gases , when can not evacuate from the closed warehouse,as in the above case, may triger a great explosion.

Masoud
04.24.2013

Bill,
Safety rules dictates following a disaster all the credible scenarios to be considered and discussed and then ruled out if not relevant. Anhydrous Ammonia BLEVE can happen. Pls. refer to page 220 -Storage Requirements-Rural Rescue and Emergency Care published by American Academy of Orthopaedic Surgeons ISBN 0-89203-075-5. WACO Police Seargent William Patrick Swanton in HCP April 2013 issue states that the fire and blast appeared to involve a railroad tanker carrying anhydrous Ammonia. So I believe we can not rule out this possibility and ofcourse risk of Ammonium Nitrate explosion .

Masoud Sadra
Tech. Safety &Risk Principal Engineer

peter R Wigley
04.22.2013

If they had ammonium nitrate stored there that is the cause. I still remember as a boy seeing the photos of bodies resulting from the explosion of a French ship "The Grandcamp" loaded with Ammonium nitrate at Texas City,it must have been back in the 1940s. I also remember that on 10/11,a fertilizer plant in Toulouse,owned by Total was completely demolished by an Ammonium Nitrate explosion. This event did not make much news being the day after 9/11 in New York,but I heard all about it because I was working for an Exxon/Total JV in Antwerp at the time.The cause of the explosion in Toulouse was never fully established, except that it was not a terrorist attack

Bill Arnold
04.20.2013

Forget the anhydrous ammonia. The plant was storing more than 270 tons of ammonium nitrate, a compound known to be unstable and much used in terrorist bombs where it is mixed with fuel oil. The Oklahoma bomb was such a device and was estimated to use about half the amount stored at West fertilizer. The TFI must be extraordinarily ill informed not to be looking in the direction of ammonium nitrate instead of anhydrous ammonia!

Masoud
04.20.2013

Could it be what is called a Boiling Liquid Expanding Vapor Explosion (BLEVE) which is very commn in industries. It happens when a pressurized storage tank full of liquid is exposed to external fire (Cryo liquids like LPG are specially prone to this phenomenon).

Mohammad Nasir Khan
04.19.2013

I am chemical Engineer working in the Ammonia / urea Fertilizer industry for last 20 years. In my whole career I haven't heard this kind of incident. this was really tragic one costing mass causalities. All such facilities have very effective process safety management in place. Nevertheless, sometimes some unsafe conditions or acts may cause catastrophic failure. It is always a good idea that utmost importance should be given to Safety Management.

mansour balavar
04.19.2013

AT ACCCIDENT IS OCCURED FREESING SO ?

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