Chemical Safety Board: Refinery Explosion Was Preventable

The U.S. Chemical Safety Board (CSB) says the 2015 explosion at the ExxonMobil refinery in Torrance, California, could probably have been prevented if a more rigorous process safety management (PSM) system had been in place.

Inspectors at an oil refinery

Photo credit: Chemical Safety Board

According to a CSB report issued May 3, the blast caused extensive property damage and minor injuries but could have had a catastrophic impact. The CSB is a non-regulatory federal agency that reviews chemical incidents and makes recommendations.

The explosion occurred in the refinery’s fluid catalytic cracking (FCC) unit where products including gasoline are produced. A reaction between hydrocarbons and catalyst takes place in the hydrocarbon side of the FCC unit, rather than what’s known as the air side of the unit. According to the CSB, it is critical that hydrocarbons not flow into the air side as this can create an explosive atmosphere. On the day of the incident, a slide valve acting as a barrier failed. That allowed hydrocarbons to flow into the air side of the FCC. There, they ignited a piece of equipment called an electrostatic precipitator (ESP), which caused the explosion.

CSB Chairperson Vanessa Allen Sutherland said the incident should not have happened and likely would not have, had the PSM system been more robust. In its report, the CSB identified multiple gaps in process safety, including reliance on safeguards that could not be verified. CSB also found that ExxonMobil violated corporate safety standards, including lockout/tagout requirements, multiple times before the incident.

In 2016, the refinery was sold to PBF Holding Company, LLC. Since the explosion, the refinery has experienced multiple incidents.

The U.S. Chemical Safety Board does not issue citations or fines, but does make safety recommendations. See more at