On November 20, the U.S. Chemical Safety and Hazard Investigation Board (CSB) released an update on its investigation into an October 10 fatal release of hydrogen sulfide gas at the PEMEX Deer Park Refinery in Texas that killed 2 workers and injured 13 others.

During maintenance activities at the refinery, approximately 27,000 pounds of toxic hydrogen sulfide gas was released. In addition to the 2 fatalities and 13 serious injuries at the facility, officials in the nearby cities of Deer Park and Pasadena, Texas, issued shelter-in-place orders lasting several hours, and a portion of Texas State Highway 225 was temporarily closed.

According to the board’s update, on the day of the incident, two contract workers at the refinery partially opened a flanged connection on piping containing hydrogen sulfide gas, which caused the release. One of the workers was fatally injured. Work was supposed to be done on a different, isolated piping segment about 5 feet (ft) from the flange the workers opened. Two other contract workers from a separate company who were working on equipment less than 250 ft away and downwind from the release were also affected, one being fatally injured from hydrogen sulfide exposure.

The CSB’s investigation is focused on several key areas that include the following:

• Permit-to-work practices;
• Energy-isolation procedures;
• Contractor management systems;
• Emergency preparedness, communication, and response systems;
• Hazard analyses and risk assessments;
• Maintenance procedures;
• Training programs;
• Respiratory protection; and
• Remote isolation capability.

Board investigators will provide complete findings, analyses, and recommendations when it issues its final investigation report.

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

CSB deploys team to investigate fatal explosion in Louisville

The CSB announced on November 18 it sent a team of investigators to Louisville, Kentucky, to examine a fatal explosion that occurred November 12 at the Givaudan Sense Colour facility. Two employees were killed in the explosion, and 11 others were injured.

The company reported that in addition to the fatalities, serious injuries, and damage to the facility itself, a section of the pressure vessel was ejected beyond the fence line and damaged a residential unit.

“The CSB began an initial inquiry into this terrible incident last week when it happened and collected information from local officials, the ATF, and the company itself,” Owens said in another statement. “We are now deploying an investigative team to the scene to conduct formal interviews, document the incident site, and gather important evidence to help ensure that a tragedy like this does not happen again.”

The CSB is a nonenforcement agency that investigates chemical incidents to determine a cause or probable cause. It issues no citations or penalties but examines incidents and hazards resulting from the production, processing, and handling of chemical substances that can result in death, serious injury, or environmental or property damage.

In its investigation reports, the CSB issues recommendations for companies, industry groups, standards-setting organizations, and other federal agencies, including the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). The board has 12 open recommendations for OSHA.