Chemical Safety Board explores factors leading to fatal gas release

Washington — The Chemical Safety Board is emphasizing the importance of thorough risk assessments and emergency preparedness as it continues to investigate a fatal release of hydrogen sulfide.

The release happened after contract workers opened an incorrect flange. In a recent update, CSB says it’s also examining energy isolation procedures, contractor management systems, hazard analyses, and maintenance and training protocol at a refinery in Deer Park, TX. Two workers died and 13 were injured after an incident involving the release of around 27,000 pounds of hydrogen sulfide – a toxic, colorless gas.

The agency reports that one contract worker suffered fatal injuries during the chemical release and another from a different company died while working on equipment less than 250 feet away.

The work was intended to be performed on a “depressurized, purged and isolated” piping segment about 5 feet from the piping flange opened in error, per CSB.

The update cites a federal chemical database that states a concentration of hydrogen sulfide as low as 100 parts per million is considered immediately dangerous to life and health. Exposure to concentrations above 1,000 ppm can trigger a near-immediate fatality, according to OSHA.

“Hydrogen sulfide is a highly toxic substance that can result in serious injury and death even at low concentrations,” CSB Chair Steve Owens said in a press release. “This dangerous incident resulted in the death of two workers and put other workers and the surrounding communities at very serious risk.”