I just had an interesting conversation with a television
news person who contacted me about some research he was doing about the
explosion the day before yesterday at the West Fertilizer Company facility in
West, TX. He had apparently talked to someone at ISCD earlier who told him that
(so this is now third hand information that I have not verified) that the
facility had not filed a top screen reporting the anhydrous ammonia stored in
two storage tanks on site. The facility has (according
to rtknet.org) had filed Risk Management Plan (RMP) reports with the EPA
documenting 54,000 lbs of anhydrous ammonia on site.
CFATS Coverage
I was asked if I thought that it would be unusual for a
facility of this type not to have filed a Top Screen. My reply was essentially
yes and no. I mentioned that ISCD had done considerable outreach to chemical
facilities in the years since the introduction of the program in 2007. I know
that agricultural supplier organizations were one of their target audiences in
the early days; so one would like to think that the word had gotten down to
facilities like West Fertilizer.
But the CFATS program is the Chemical Facility
Anti-Terrorism Standards and I would bet that many owners of facilities like
this ignored the information pushed their way because they knew that they weren’t
‘chemical companies’; they were agricultural supply retailers. That plus the
fact that no terrorist worthy of the name would waste their time in an attack
on a rural facility like the one in West, TX would tend to reinforce the view
in the minds of many owners of this type of facility that the CFATS program
couldn’t possibly apply to them.
Anhydrous Ammonia
Explosion?
I was also asked if I though an anhydrous ammonia bleve
(Boiling Liquid Expanding Vapor Explosion) could have been responsible for the
catastrophic explosion at the facility. Now I am hardly an expert on bleves,
but I do know that they are typically preceded by a hot fire outside of the
tank (and videos and news reports certainly show a fire before the explosion) and
can produce spectacular explosions. Now anhydrous ammonia is hardly a flammable
chemical, but a fire hot enough to cause the combination of tank softening and
increased pressure necessary for a bleve would certainly be hot enough to
ignite an anhydrous ammonia cloud. So you certainly have a potential for a
fuel-air explosion.
There are other possible explosion sources at a fertilizer company.
An Ag retail facility like this could typically be expected to store/sell
ammonium nitrate and urea fertilizers. Both of these types of fertilizers can
also produce spectacular explosions. So why the immediate focus on the
anhydrous ammonia? It is the only chemical that a news organization can readily
confirm was located at the site by searching an on-line source like rtknet.org;
neither ammonium nitrate nor urea are required to be reported to the EPA under
the RMP program.
Google Map®
Investigation
This conversation peaked my interest enough that I did a map
investigation of the facility using Google Maps®. If you look at the facility
from the satellite view you will see four
good size tanks; three to the north of the two main buildings and one to the south.
None of these tanks would be holding anhydrous ammonia; they are not pressure
tanks.
I can’t tell what is actually in them, but the large
diameter piping going to the smaller three of these tanks would be typical of a
solids handling system similar to the type used to handle ammonium nitrate or
urea.
Again, I can’t see any tank markings in these satellite images,
but I think that we’ll find that the two anhydrous ammonia tanks are among the
four horizontal tanks south of the larger building along the railroad siding.
These horizontal tanks are commonly used for storing anhydrous ammonia.
Now there are a number of smaller vertical tanks between the
building and the horizontal tanks. If these tanks contained some sort of
flammable or combustible liquid and they released their contents to the ground
you could get the type of fire that could cause a partially filled anhydrous
ammonia tank to bleve. Of course this is also the type fire that we would
expect a responding fire crew to be flooding with water and that would
effectively prevent a bleve.
No, I think that we will find that one or more of the three
intermediate size tanks held ammonium nitrate and that was what caused the devastatingly catastrophic explosion.
Chemical Safety Board
Starting Investigation
The Chemical Safety Board investigators started
arriving on site yesterday. They are deploying a large contingent because
of the number of deaths and the amount of property damage that certainly places
this chemical accident among the most deadly in recent memory. There is no
telling how long it will take for them to complete their investigation, but we
should start to hear some definitive information being provided by the CSB to
the national media.
5 comments:
I highly doubt that the explosion was caused by a bleve. For the shockwave to travel the distance it travelled, it had to have had sustained deflegration from the source of the explosion, which I believe to be ammonium nitrate. Under intense heat form the fire, in a confined space, the AN in the storage bins pictured in the GE imagery (BTW, Bing birds eye view provides much better perspective) would have exploded. The hole in my analysis is what caused the fire? Was their propane present? (A product often times found at such sites)Reports stated that there were 12 gallon AA tanks on site. These are no where near the size required to send a shock wave that far.
There is not enough space for a chemistry lesson but AN will decompose into oxides of N2 and water when heated. This reaction is very exothermic. In bulk storage situations the heat cannot dissipate faster than it is being produced and a runaway decomposition can occur. This is different from the ANFO situation we often hear about. Even open piles of material can be "bulky" enough to have this occur. I also wonder if the CFATS emphasis on AN is mostly directed towards theft and diversion because of the history of its use in IED's.
For some more information on the problem that Jim describes see:
http://laws-lois.justice.gc.ca/eng/regulations/C.R.C.,_c._1145/page-11.html
Here is a link to the Bing View that Jim described: http://tinyurl.com/brjeoc4
This will be a very interesting case to follow for all communities that have anhydrous ammonia as well as fertilizer facilities. I agree that ammonia is not characterized as a flammable gas but it has a long history of impressive explosions under the right circumstances but most if not all are related to situations where the ammonia was contained in a structure. I would not rule out a NH3 vessel bleve and would be interested to know if a bleve provided the heat necessary to set off nearby storage vessels or bins.
I am also curious about the local infrastructure in regards to fire protection. I wonder if the local fire department had the ability to flow enough water to prevent exposure to any part of the facility. I am not familiar with Texas but many rural parts of may state cannot flow the gallons per minute necessary to perform industrial firefighting adequately.
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