The U.S. Chemical Safety and Hazard Investigation Board (CSB) released a final report on a fatal 2022 naphtha release and fire at the BP-Husky Toledo Refinery in Oregon, Ohio, the board announced June 24.

The chemical release and fire led to the deaths of two BP employees, who were brothers. During an emergency at the refinery, liquid naphtha was released from a pressurized vessel, which resulted in a vapor cloud that subsequently ignited, causing a flash fire that fatally injured the two BP employees.

The September 2022 incident resulted in approximately $597 million in property damage at the refinery, including loss of use. Over 23,000 pounds of naphtha was released during the incident, according to the board.

It was the largest fatal incident at a BP-operated petroleum refinery in the United States since the fatal explosions and fires at the BP refinery in Texas City, Texas, in 2005, which resulted in the deaths of 15 workers and injured 180 other people.

The board’s report details a series of cascading and worsening events throughout the day of September 20, 2022, that contributed to the release and fire. Board investigators found there was an “alarm flood,” with more than 3,700 alarms going off in the 12-hour period before the fatal incident that overwhelmed and distracted BP’s board operators, causing delays and errors in responding to critical alarms. Investigators also found the refinery failed to implement a shutdown or hot circulation through the use of stop-work authority or other means in time to prevent the fatal incident.

According to the report, critical safety issues that contributed to a catastrophic outcome included the following:

• Liquid overflow prevention: The refinery's process hazard analyses (PHAs) identified potential risks, including overflow events. However, the safeguards in place, such as safety instrumented systems and emergency pressure-relief valves, didn’t prevent liquid overflow into the fuel gas system.
• Abnormal situation management: Ineffective management of abnormal situations—process disturbances that the basic process control system can’t cope with that can create a stressful environment for the operators and escalate to a more serious incident—led up to the incident. The BP Toledo Refinery experienced several abnormal situations across several units, escalating to the overfilling of multiple vessels. This prompted two BP employees to release the vessel’s contents to the ground, ultimately cascading to the vapor cloud, fire, and fatal injuries.
• Alarm flood: An alarm flood occurs when there are more alarms than what board operators can effectively manage or respond to. Board operators were dealing with an alarm flood for nearly 12 hours before the incident occurred, with 3,712 alarms going off during this period. Excessive alarms contributed to delays and errors in response and mitigation of the overflow of naphtha into the fuel gas system.
• Learning from incidents: Board investigators found that a previous incident at the BP Toledo Refinery occurred in 2019 in which naphtha began to fill the vessel after a refinery-wide process upset. In an internal investigation, the BP Toledo Refinery team identified catastrophic incident warning signs but didn’t develop action items to prevent naphtha from filling the vessel, resulting in a missed opportunity to improve safety and prevent another incident.

CSB investigators also found similarities between the overflow events at the BP Toledo Refinery and the fatal explosions and fires in 2005 at BP’s Texas City refinery.

“Nearly everything that could go wrong did go wrong during this incident,” Steve Owens, the CSB’s chairperson, said in a board statement. “The tragic loss of life resulting from this fire underscores the importance of putting in place the tools that employees need to perform tasks safely, such as stop work authority, and having adequate policies, procedures, and safeguards in place to effectively manage highly stressful abnormal situations, including alarm floods.”