West Texas and Ammonium Nitrate: Part 6

Here is what the  Kaufman County LEPC said they would do if one of their ammonium nitrate fertilizer facilities was involved in a fire:

"If it's in the building housing 50,000 pounds of ammonium nitrate we are going to evacuate the area and back off."

Source

I wrote, but did not post this: "Two very simple steps.  Have a community plan and read the ERG and 12 responders would probably - most assuredly - be alive today."

I have changed my mind on this.  I was wrong to conclude along with everyone else that had they only known, had a plan been developed, this tragedy would have been avoided or minimized.  I have changed my mind based on two issues in play that night:

1. The explosion took place within 20 minutes of the call
2. The responders were concerned about the release of anhydrous ammonia - a toxic gas - from the tanks that were at the site.

There is a third factor that plays into this for me as well; ammonium nitrate does not normally explode.

Doreen Strickland, president of the volunteer firefighters from nearby Abbott, pulled up to the plant as it exploded. One of her fire trucks was lifted in the air and slammed back down. Some of her men were inside, and she knew they had to be dead. At least three were killed. But she heard no one discuss ammonium nitrate ahead of the massive blast.

"Our main reason for evacuating at that time was because of the heat and intensity of the fire, and it was so close," Strickland said. The anhydrous ammonia "was a major concern." (1)

I write this blog and these posts as a way of helping me understand something that I should understand (because of my job) or because I am curious.  I write in "real time" meaning I look things up on the fly and have no editor other than maybe a couple of days while I re-write it for clarity and grammar.  The basic premise of these posts is to ask a question and then see if I can answer it.  In the process I end up going down a lot of different paths and looking at a lot of information as I try to bring clarity to the topic I am writing about.

So my question now is this; would discussing the ammonium nitrate with Doreen Strickland have changed anything?  I don't know, no one knows that.  I suspect that it would not for the simple fact that ammonium nitrate used to make fertilizer would not have taken precedence over the anhydrous ammonia tanks.  Ammonium nitrate can explode, but so can a can of gasoline or a propane cylinder.

Basically, and this is where I am willing to go with this, what we know about ammonium nitrate is that it does not explode within 20 minutes of a fire being reported.  We know this now, but we did not understand this at the time.

I train folks to protect themselves.  This is why I give my students instruction on how to use a Material Safety Data Sheet (MSDS), the new Safety Data Sheet (SDS), instruction on how to look up information on the internet using CAMEO or WISER, and how to use the Emergency Response Guidebook (ERG).

Source

So let's start there.  Before the explosion what did we understand about ammonium nitrate that is used to produce a fertilizer?

A good place to start is California.  If you buy into the "Texas businesses can do whatever they please" mindset then you must know that California is the polar opposite.

I was looking up the definition for "ammonitrate" which is the term they use in the 2001 Toulouse, France explosion (it is the French term for "granular ammonium nitrate, used directly in agriculture").  This lead me to the California link:

Clicking on that link brings up the EPA's Chemical Emergency Preparedness and Prevention Office (CEPP) "Alert."

Source

This Alert is dated December of 1997.  I Google'd the name and it still shows 1997.  Here is what the EPA's CEPP says and CalEPA presumably supports:

Ammonium nitrate can be exploded under certain conditions. These must include added energy (heat, shock), especially under conditions of confinement or presence of contaminants. Although ammonium nitrate generally is used safely and normally is stable and unlikely to explode accidentally, accidental explosions of ammonium nitrate have resulted in loss of lives and destruction of property. These accidents rarely occur, but when they do, they have high impacts.

That's what I understood about ammonium nitrate.  I was not alone in that understanding:

Ammonium nitrate, in solid or molten form or in solution, is a stable compound and generally is difficult to explode.

Ammonium nitrate by itself does not burn, but in contact with other combustible materials, it increases the fire hazard. It can support and intensify a fire even in the absence of air. Fires involving ammonium nitrate can release toxic nitrogen oxides and ammonia. A fire involving ammonium nitrate in an enclosed space could lead to an explosion. Closed containers may rupture violently when heated.

It has the potential to exploded, but it takes energy to do so:

Ammonium nitrate may explode, however, when exposed to strong shock or to high temperature under confinement. In a large quantity of ammonium nitrate, localized areas of high temperature may be sufficiently confined by the total quantity to initiate an explosion. The explosion of a small quantity of ammonium nitrate in a confined space (e.g., a pipe) may initiate the explosion of larger quantities (e.g., in an associated vessel).

That's what I understand about ammonium nitrate and that's probably what the plant manager - who died with the responders - also understood as well.

It can explode, but it takes certain conditions to do so.  The explosion happened within 20 minutes of the fire being reported.  History does not show a building holding ammonium nitrate exploding when on fire.  That's not what we have seen in the past:

• 1921 Germany explosion from attempts to break up large piles of solidified ammonium nitrate using blasting explosives.
• 1947 Texas City - explosion in ship cargo holds (confinement).
• 1994 ammonium nitrate solution explodes during manufacturing process.
• 2001 Toulouse, France explosion in process building - unknown cause
• 2009 Bryan, Texas (100 miles south of West) Fire in fertilizer plant with over 200 tons of ammonium nitrate. No explosion took place.

What we see now is something different.  We still do not know what initiated the blast.  It should not have exploded.  It did, and that requires an answer as to why.

We need to, in my opinion, move away from this idea that had a plan been in place or if everyone would have known about the ammonium nitrate that all of this could have been avoided.

Maybe, but I doubt it.  In 20 minutes of the call it exploded.  Concern over the anhydrous ammonia tanks was not a misguided approach at that time.  Even though ammonium nitrate can explode, it usually does not.  It did not in the fire in Bryan 100 miles south of West in 2009 so why would we expect it to explode here?

So where do we take this from here?  What should we do in the future?

Next post: West Texas and Ammonium Nitrate: Part 7

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