February 8, 2024

Employer “Did Not Properly Limit” Emergency Response Role of Operations Staff in Fatal Accident, CSB Finds

The U.S. Chemical Safety and Hazard Investigation Board has released its report (PDF) on the April 2, 2019, explosion and fire that caused the death of one worker and serious injury of two others at the KMCO LLC facility in Crosby, Texas. The incident occurred after isobutylene leaked through fractured piping to form a flammable vapor cloud, which ignited. CSB found that KMCO’s reliance on operations staff, instead of emergency response personnel, to take action after the isobutylene release contributed to the incident’s severity.

On the morning of the incident, KMCO operations staff were completing a batch of sulfurized isobutylene, a lubrication additive product. Isobutylene is “a highly flammable, colorless gas with a sweet gasoline odor,” the CSB report explains. The leak began when a piece of cast iron broke away from a filtration device in the isobutylene system piping. CSB states that cast iron is a brittle material “that existing industry standards and good practice guidance documents either prohibit or warn against using in hazardous applications, such as KMCO’s isobutylene system.”

A field operator and contract worker heard the piping break and saw isobutylene vapor pouring into the surrounding area. While the contractor evacuated, the field operator—a trainee who had been at the facility for six months—called a board operator for help assessing the situation.

The report calls attention to the role of KMCO operations staff, rather than the company’s emergency response team, in responding to the release. After the board operator identified the releasing vapor as isobutylene, he radioed KMCO personnel to evacuate the area around the sulfurized isobutylene unit. He then donned a self-contained breathing apparatus and returned to the isobutylene unit, where he was joined by a second board operator, also wearing an SCBA. The two board operators manually closed valves to stop the isobutylene leak and activated firewater monitors and water deluge systems to control the released vapor. Meanwhile, the trainee field operator helped a senior field operator instruct workers to shut down equipment, evacuate, and close gates to prevent vehicles from entering the area.

The call for all personnel to evacuate the facility was made via radio by a shift supervisor, who reported seeing a “river” of vapor flowing down the road. The shift supervisor assisted in activating firewater monitors and then attempted to leave the area.

This failure to “properly limit the role of [KMCO’s] operators” put them in unnecessary danger, CSB found. Because they were tasked with responding to the leak, the two board operators were still inside the vapor cloud when it ignited, and the shift supervisor was nearby. The first board operator and shift supervisor received medical treatment for severe burn injuries. The second board operator was reported missing after the explosion and found deceased by emergency responders. KMCO’s emergency response team did not begin to don personal protective equipment and approach the isobutylene unit until about three minutes after the explosion.

“Because KMCO relied on its unit operators to take quick actions to stop chemical releases, workers who were in a safe location moved toward the flammable isobutylene vapor cloud, which put them in harm’s way,” the report states. “KMCO could have reduced the severity of the event by establishing clear policies and training its workforce to respond to a chemical release without putting themselves in harm’s way.”

CSB’s report also notes that KMCO’s plant alarm system was never activated to alert the more than 200 employees, contractors, and visitors at the facility of the need to evacuate. Most KMCO employees carried a radio and therefore received the calls issued by the first board operator and the shift supervisor, but not all contracted workers heard these communications. One group was not aware of the release until they saw the river of vapor. After the explosion, these workers evacuated by escaping under a locked gate.

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