Washington — Chemical facility operators and workers should be aware that low-pressure vessels with “potential to build any pressure above atmospheric may still have safety implications,” Chemical Safety Board investigator Melike Yersiz says.
Yersiz speaks in a new CSB video examining the events that led to a fatal vapor explosion and fire in April 2021 at the Yenkin-Majestic facility in Columbus, OH, where paint and coatings were being manufactured. One worker died and eight others were injured when the manway lid and gasket of a kettle reactor failed, releasing a flammable vapor cloud that permeated the plant. The cloud ignited and caused the explosion and fire.
CSB released a final report on the incident in November 2023. The agency determined that the manway wasn’t designed, constructed or pressure tested to a design pressure appropriate for the process.
In the video, Yersiz says current industry codes and standards exempt vessels not exceeding an internal pressure of 15 pounds per square inch gauge. The Yenkin-Majestic manway, however, didn’t withstand more than 9 psig while performing what Yersiz called “highly hazardous chemical service.”
The video revisits safety lessons featured in the report, including:
- Facilities should use Hierarchy of Controls and Prevention Through Design principles throughout a plant’s entire life cycle to design and maintain fault-tolerant systems, so a single worker action or equipment failure doesn’t result in a catastrophic incident.
- Because flammable dense gases can form ground-level vapor clouds that can cover large distances to reach an ignition source, facilities that handle flammable materials should install lower explosive limit detectors that trigger automatic shutdowns of process equipment, with alarms warning workers to evacuate.
Yersiz added that facilities should ensure equipment can function within safe operating limits documented in process safety guidance.
“There are thousands of facilities across the country that deal with flammable and other hazardous chemicals at low operating pressures,” CSB member Sylvia Johnson says during the video. “For them, safe pressure vessel operation, implementation of the Hierarchy of Controls and proper emergency response training for personnel are imperative.”
