Safety board investigation of 2020 explosion yields three lessons

Washington — Facilities that handle flammable gases and other hazardous materials should ensure their workers and supervisors undergo process safety management and emergency response training, the Chemical Safety Board says.

CSB outlines its concerns in a recently released final report on a deadly January 2020 chemical release and explosion at the Watson Grinding facility in Houston. Two workers and a nearby resident died when an incidental release of the flammable gas propylene formed inside the building and exploded.  

The agency found that a degraded rubber welding hose that disconnected from its fitting inside a coating booth caused the release. Also contributing to the event: failure to close the manual shutoff valve at the propylene storage tank the previous workday and an inoperative automated gas detection alarm, exhaust fan startup and gas shutoff system.

In a press release, CSB Chair Steve Owens faults the organization for lacking emergency response training as well as “an effective program … to assess potential hazards in its propylene process.”

The report identifies three safety lessons:

• Employers have a duty of care to ensure the safety of their workers who handle flammable gases or other hazardous materials, as well as protect surrounding communities and the environment. This is true regardless of whether the chemical(s) onsite meets the threshold quantity under OSHA’s standard on process safety management of highly hazardous chemicals (1910.119) or the Environmental Protection Agency’s Risk Management Program rule.
• Gas detection, alarm, exhaust and shutdown systems at facilities that handle flammable gases or other hazardous materials must be adequately designed, maintained, inspected and tested to ensure reliability.
• Facilities should ensure a comprehensive written emergency response plan, which addresses all actions to be taken in the event of a chemical release, is in place. Workers must be trained on the plan, and periodic drills should be conducted to check the plan’s implementation.