The CSB examines two (2) high-consequence incidents in 2025 that were caused by workers mistakenly disassembling the wrong equipment.
In the first incident, on February 1, 2025, contract workers at a Refinery in Martinez, California inadvertently opened a pipe flange on an active system during turnaround maintenance preparation, releasing and igniting flammable hydrocarbons. The refinery estimated that the resulting explosion and fire caused approximately $924 million in property damage.
In the second incident, on May 20, 2025, a maintenance worker disassembled a rupture disc holder in an active chlorine system, releasing approximately 8,000 pounds of toxic chlorine gas. The incident caused one serious injury and resulted in $23 million in property damage. The incident also triggered a shelter-in-place order for the nearby community. The operations team had mistakenly isolated, cleared, and tagged a different but nearly identical piping system and did not isolate, clear, or tag the piping associated with the rupture disc that the maintenance worker disassembled.
These incidents are part of a concerning trend of serious chemical industry accidents linked to ineffective safety management systems governing equipment opening. They are similar to the October 10, 2024, incident at a refinery in Deer Park, Texas, being investigated by the CSB, where workers mistakenly opened the wrong piping flange, releasing toxic hydrogen sulfide gas that resulted in two (2) fatalities and 13 injuries.