December 7, 2023

CSB Determines Cause of Fatal Explosion and Fire at a Resin Plant

Last week, the U.S. Chemical Safety and Hazard Investigation Board (CSB) issued its final report (PDF) on an explosion and fire that occurred at a resin plant in Columbus, Ohio, on April 8, 2021. According to CSB, the incident at the Yenkin-Majestic facility occurred after naphtha solvent vapors and resin liquid leaked through the seal of a closed manway of an operating kettle. The escaped vapor formed a flammable cloud that spread through the facility and ignited, causing an explosion heard and felt throughout Columbus. The resulting fire burned for about 11 hours. One employee was fatally injured, and eight others received serious injuries, with one requiring a leg amputation. Yenkin-Majestic also reported more than $90 million in property damage.

CSB’s report explains that the manway through which the flammable vapor escaped “was not designed, constructed, or pressure tested to a design pressure appropriate for the process.” Yenkin-Majestic had installed the new manway three months before the incident on a kettle known to build pressure up to 15 pounds per square inch gauge (psig). The company performed a leak check up to 4 psig. On the day of the explosion and fire, the manway withstood up to 9 psig before leaking hot resin and solvent vapor into the facility.

Pressure built up in the kettle after an operator added liquid solvent to the resin while the kettle agitator was turned off, contrary to established procedures. The activation of the agitator caused the solvent to vaporize. CSB determined that Yenkin-Majestic had not installed engineering controls to prevent operators from adding solvent while the agitator was inactive but had relied on computer panel indicators to communicate agitator status to operators.

The company lacked audible alarms to notify workers of a hazardous gas release and the need to evacuate, CSB found. Workers were also not trained to identify flammable gas hazards or required to wear flame-resistant personal protective equipment.

CSB’s report includes recommendations made to Yenkin-Majestic to address the identified safety issues. The board also recommends that the American Petroleum Institute and the American Society of Mechanical Engineers develop guidance concerning low-pressure vessels used in hazardous chemical processes.

More information can be found in CSB’s press release.