A SELF ACCELERATING DECOMPOSITION REACTION KILLS AN OPERATOR

On May 4, 2023, at about 12:40 a.m., a pressure Nutsche filter vessel (“vessel”) exploded at a facility in  Massachusetts. The explosion and fire fatally injured one operator and caused approximately $48 million in loss from property damage, which led to the permanent closure of the facility.

At the time of the incident, the plant was producing a substance called Dekon 139 (“Dekon”). The Dekon had already been synthesized, and excess liquid from the production process had been removed from the solid product (“cake”) within the nitrogen-inerted vessel. The plant used an agitator to smooth the cake and remove lumps that formed during drying to remove the liquid from the cake.                                                                                                                                                                            In post-incident testing, the plant determined that Dekon could undergo exothermic, self-accelerating decomposition when heated to 280 degrees Fahrenheit. The plant learned that Dekon decomposition releases flammable gases, including hydrogen, methane, and carbon monoxide.
In its incident investigation, the plant determined that leading up to the incident, the agitator had loosened and was rubbing a plate at the bottom of the filter dryer vessel, generating heat from friction. The friction likely caused an area of high temperature (“hot spot”) in the Dekon, which likely reached the temperature
necessary for the Dekon to begin decomposition. The decomposition reaction released energy, which increased the temperature of the material in the vessel and caused more Dekon to decompose.                                                                                                                                
The gases produced by the reaction rapidly increased the pressure within the vessel, causing the vessel’s discharge door to open. The released flammable materials (gas and Dekon dust) mixed with atmospheric oxygen and ignited, causing an initial weak explosion. Shortly after that, the vessel’s rupture disc opened, and a second larger explosion occurred when the vessel failed.
One operator was unable to escape the area and was fatally injured.
The CSB estimated that approximately 600 pounds of Dekon decomposed into flammable gases that were consumed during the incident.
Probable Cause
Based on the company's investigation, the CSB determined that the probable cause of the explosion and fire was a self-accelerating decomposition reaction of Dekon, which produced flammable gases and released combustible Dekon dust that ignited upon release. Contributing to the incident was the company's incomplete knowledge of the hazards associated with Dekon, including its ability to undergo a self-accelerating decomposition reaction capable of rupturing the reaction vessel.

Source:CSB.gov

Thermal decomposition incident

At approximately 9:15 p.m., in a sealant adhesive manufacturing plant, a mixer producing an epoxy adhesive overheated causing thermal decomposition. The smoke from the mixer filled most of a 3000 sq. ft. production room. The Fire alarm was pulled by an operator outside of the production room. The fire department arrived on scene and took control as Incident Command and called for a shelter-in-place of surrounding neighborhood. Initially, about a 4-block radius around plant was blocked to any traffic. By about 10:20pm, the fire department reduced the blocked off area to only the plant perimeter. A representative from the Emergency Response section responded to the scene and verified that there were no chemical release issues.
The fire department relieved pressure off the mixer and then set up additional exhaust fans to air out the production room, and after getting readings of less than 10 parts per million Carbon Monoxide the Fire Department gave the all-clear, which was about 12am. There was no explosion, no fire and no environmental release and the fire department did not use any extinguishing agents. 

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Lab accident - the dangers of chemicals

A chemical accident in a lab in India that went wrong has again pointed out the dangers of accidents in labs. Two girls were injured when an uncontrolled reaction took place. Treat your lab and R and D facilities with the same respect as your plant! Read the artcile in this link.

Running blind - the dangers of reactive chemistry

There is a lot of ignorance about reaction hazards in the batch processing industry. As long as incidents do not occur, operators of reactors that handle reactive chemicals seem to think that it will never happen to them. The fallacy is that we seem to think that big reactors are safe as they look strong! It is the other way around in reactive chemistry! If you do not know the sizing basis of your cooling/condensing systems, your vent/scrubber systems and details of the reactions you are handling, you are running blind! Read a basic article on dangers of reactive chemistry in this link.

Water and reactive chemicals = fire

A warehouse with old stored toxic chemicals has reportedly caught fire in Ukraine. The cause of the fire is due to rain water entering the warehouse and reacting with the chemicals stored and causing fire.
How well are your chemical warehouses protected from the elements?
Read the full article in this link.

Dangers of chemical reactions

Unexpected chemical reactions are dangerous and can kill.Whenever a new product is envisaged, it must be taken through a proper management of change process, including understanding of process chemistry.Even though this incident happened in 2008, it underscores the importance of knowing what you are doing. Read about the incident in this link.
More recently, another accident occurred at a chemical factory at Ankleshwar where two people died. Read about the incident in this link.

Safety valves and runaway reactions

I was participating in a HAZOP study of a reactor where a runaway reaction was possible.There was a serious discussion about the reaction kill system, when one of the participants asked what the operators will do if a runaway reaction occurs. The operations chief who was participating immediately answered - run away!He had witnessed an actual runaway reaction in which the reactor started rumbling, gaskets blew, safety valve lifted,and the operators ran away. Know the design basis of your safety valves. This is important for management of change and for writing operating procedures.

Process safety in batch operations

What goes around comes around! As far as process safety incidents in batch process go, I sometimes despair whether we will ever learn from previous incidents. Last year I had investigated some batch process incidents, the causes of which are very very familiar - incompatibility,scale up issues, heat removal issues, MSDS issues and raw material storage issues. For those of you working in the batch process industry, the UK Chemical Reaction Hazards Forum is a good place to get information on batch incidents. Share these incidents with your operating personnel and check whether it could happen in your organization. For further details go to this link.

Runaway Reactions - Run away if you do not have data!

A runaway reaction is an uncontrolled reaction that does not stop. It can cause catastrophic consequences like rupture of reactors and release of toxic gases. The understanding of reactive chemistry plays a big role in avoiding runaway reactions. Avoid the mistake of scaling up from R & D to plant production without understanding all the details of the reactions and its side reactions. The effect of change in operating parameters and batch recipe or quantity must also be understood. Recently a speaker at a seminar mentioned that many batch processes in India are being operated without complete knowledge of the reaction chemistry. I have also investigated number of incidents involving runaway reactions where operators were operating the batch without proper information on reaction kinetics.There are various scientific tools available to determine these data. Accelerating rate calorimeters, differential scanning calorimetry etc are some of them. Just because you have not experienced a runaway reaction incident, do not be complacent. The only hope of survival in a runaway reaction incident is to run away!
Watch this excellent CSB safety video on the hazards of reactions.