Dow worker death likely due to reaction of trimethylindium with cleaning fluid

On Oct. 9, 2013, an explosion and fire at a Dow Chemical electronic materials facility in North Andover, Mass., led to the death of production operator Carlos A. Amaral, 51. According to a statement released by Dow and dated the end of January, the company’s investigation into the incident concluded that:

• An employee sustained injuries as a result of the overpressure of a small stainless steel manufacturing vessel during an operation associated with a Trimethylindium (TMI) manufacturing batch.
• An undesired and unexpected reactive chemical event occurred within the vessel as the employee was transporting the vessel from the glove box to the next manufacturing unit for further processing.
• The overpressure resulted in a release of reacted and unreacted materials and a fire.

The most highly probable cause of the unplanned event was the ingress of cleaning liquid from the cavity space of the ball valve into the crude TMI. Due to the nature of the event, it is impossible to completely validate this conclusion.

I asked Jeremy Cole, business communications manager at Dow Electronic Materials, whether Dow is changing anything regarding cleaning or other handling of the reaction vessel. He said yes, but so far he has declined to provide additional details.

The federal Occupational Safety & Health Administration is investigating the incident, because Massachusetts does not have its own occupational safety and health program. OSHA currently lists the case as open.

Feb. 26 update–Some more information from Dow’s Cole:

the following is the facility’s action plan:
• Prior to TMI production restart, the facility will consider alternate cleaning processes that use cleaning materials that do not react with TMI. If an alternate cleaning process is not feasible, the facility will define a means to confirm the absence of cleaning materials in void spaces and the vessel prior to addition of raw materials.
• The facility will consider modifications to the manufacturing process to increase the tolerance of intrusion of small amounts of cleaning materials as well as variability of raw materials.
• The facility will conduct a review of its Process Hazard Analyses and determine whether any improvements are recommended. Improvements will be captured in appropriate process documentation.

Author: Jyllian Kemsley

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  1. OK, so I see two issues here:

    1. Why was a reactive cleaning solvent used? Did the operator know the vessel was full?
    2. Is Dow saying they had a faulty ball valve? If so, the model of the ball valve would sure be helpful.

  2. I do not work for Dow nor do I know how they make the material but I am failure with this family of compounds. Trimethylindium is a pyrophoric solid. From what was explained above it would seem that the reaction mixture vessel was brought into the dry box. After removing the vessel from the dry box and moving it the fire resulted. Officials at Dow claim an over pressurization of the vessel caused the fire. I am sure that they can only guess at what caused the over pressurization since sadly there is no living witness. As for the “cleaning solution” I would guess they make the product from the indium halide and the methyl Grignard or methyl lithium both would make salts that would need to be cleaned with protic solvents after all of the reactive material has been extracted from the reaction mixture. What bothers me with their explanation is that you do not open valves while transporting the material. When removing the vessel from the dry box all the valves would be closed and would stay closed while transporting the vessel. When you attach it to the next process then you would open the valves. So when did the “cleaning solution” get delivered to the vessel, in the dry box? Why would you open a valve just to close it so you can bring it out? Again I do not know what happened but if I was making the product the only reason I would be going into the dry box is to sample the material or prepare the crude material for sublimation unless something unusual happened. If I had to guess that is the root of the problem. Something different happened and the standard procedures did not work to solve the problem. They needed to try something new.

  3. For people watching the comments feed, I got some more information from Dow this morning.

    @Chemjobber–No answers for you, sorry, although I’d hope that Amaral knew whether there was TMI in the vessel. Dow doesn’t seem to be pointing a finger at the ball valve itself.

    @silane–It does seem hard to envision a probable sequence here. If the valve was open when the vessel was taken into the box, then wouldn’t any residual cleaning agent have evaporated? If it was closed, you’re right, why open it just to close it again? Unless TMI was added through that valve? Or Amaral knocked it open while working in the box?

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