Thursday, August 31, 2017

Harvey Chemplant Explosion – Part I

It looks like this organic peroxide plant situation will be continuing news. It seems that late last night there were two ‘explosions’ at the facility (see here and here for news reports) and a number of police officers are being treated for chemical exposure issues.

NBC News Tweeted® a copy of the Arkema statement about last night’s incident. It makes a very important point: “We want local residents to be aware that product is stored at multiple locations on site, and a threat of additional explosions remains.”

Health Effects

First, we need to remember that the smoke from any fire contains some number of toxic elements and should be avoided. This is especially true when you see thick black smoke; that indicates incomplete combustion and you are going to have a wide variety of chemicals and physical particles that will, at the very least, irritate the lungs.

I am not an industrial health expert, by any stretch of the imagination, but organic peroxides will almost certainly have some level of toxicity due to their chemical nature. The free radicals produced in the initial decomposition are very reactive and will almost certainly react with body tissues. Fortunately, they also react very quickly with oxygen in the air, so this toxicity is typically greatly decreased the further you get from the un-decomposed organic peroxide.

Police officers are always going to be at risk from smoke inhalation injuries due to the nature of their duties since they do not have ready access to necessary personal protective equipment. The standard issue protective mask (used mainly for riot control situations where tear gas may be employed) may not be effective protection against all components of the smoke of an industrial fire. This is why fire fighters carry the heavy and awkward breathing air tanks on their backs.

For more information on the toxicity of organic peroxides you can visit the Arkema web site and find the Safety Data Sheets for the Luperox® line of organic peroxides. I am not sure which of those are manufactured at this particular facility (the local fire department has that list), but you can get an idea of the types of solvents used and the general toxicity information.


Those SDS also contain another interesting bit of information, the temperature at which a self-accelerating decomposition reaction (SADR) begins {referred to as the self-accelerating decomposition temperature (SADT)}. This is the decomposition reaction that I described in last night’s blog post. This is the critical temperature that I talked about. Looking at a random selection of the Luperox products this morning, it would seem that most have a SADT in excess of 100° F.

Unfortunately, even below the SADT some level of decomposition remains, and the exothermic nature of that decomposition reaction will raise the temperature of the mixture. The SADT is the point of no return. When it reaches the SADT there is essentially nothing that can be done to prevent catastrophic decomposition rates.

The higher the SADT, the longer it is going to take for those containers to reach their failure point, prolonging the current problem. Of course, a fire on the site will change all of that as it would quickly raise the temperature well above the SADT point while weakening the structure integrity of the storage containers.

Storage Issues

One last item that needs to be taken into consideration. Organic peroxides are normally shipped in five-gallon plastic containers. I would expect that this facility would store those on pallets with the containers stacked two or three high. The containers at the center of the stack are going to generally be the first to fail as they are insulated from the cooling effects of the air surrounding the stack.

It would not be unusual to expect that, depending on how the pallets are stacked in relation to each other, that we could see several small ‘explosions’ of individual containers before the bulk of a certain product releases. This could also cause a relatively small fire in the storage area that could expedite other products reaching their SADT.

It will be interesting to see how much detail is included in the monitoring of these storage areas. We could get some very important data on failure rates and effects that could be beneficial in preventing future incidents at these types of facilities.

1 comment:

terre said...

We appreciate your succinct and informative input.

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