A series of “gaps” in safety systems, along with violations of ExxonMobil safety standards, led to the February 2015 explosion at the then-ExxonMobil refinery in Torrance that injured four people, according to a report released Wednesday by the U.S. Chemical Safety Board.
The report also confirmed that the explosion nearly resulted in the rupture of a tank storing thousands of pounds of toxic hydroflouric acid. The refinery is now owned by PBF Energy.
“This explosion and near miss should not have happened, and likely would not have happened, had a more robust process safety management system been in place,” said Vanessa Allen Sutherland, chair of the CSB. “The CSB’s report concludes that the unit was operating without proper procedures.”
The CSB does not issue any citations, but the report makes a series of recommendations for improving safety at the facility.
The explosion occurred on Feb. 18, 2015, and led state regulators to issue 19 citations against ExxonMobil.
The CSB report largely confirmed earlier probes into the cause of the blast, concluding that “slide valve” malfunctioned in the refinery’s fluid catalytic cracking unit, or FCC, causing hydrocarbons to leak into the “air side” of the unit, creating an explosive mix.
“The incident occurred when ExxonMobil was attempting to isolate equipment for maintenance while the unit was in an idled mode of operation; preparations for the maintenance activity caused a pressure deviation that allowed hydrocarbons to backflow through the process and ignite in the ESP (electrostatic precipitator),” according to the report.
“The CSB found that this incident occurred due to weaknesses in the ExxonMobile Torrance refinery’s process safety management system,” according to the report. “These weaknesses led to operation of the FCC unit without pre- established safe operating limits and criteria for unit shutdown, reliance on safeguards that ccould not be verified, the degradation of a safety-critical safeguard and the re-use of a previous procedure deviation without a sufficient hazard analysis that confirmed that the assumed process conditions were still valid.”
The report also notes that debris from the blast nearly struck tanks storing hydroflouric acid, “a highly toxic chemical that can seriously injure or cause death at a concentration of 30 parts per million.”
CSB investigators said ExxonMobil officials “resisted” providing safety information regarding the potential for an acid release during the blast, and the company “continues to refuse to provide the CSB with information detailing safeguards to prevent or mitigate a release of (hydroflouric acid).”
CSB officials have issued subpoenas for the information, “and is pursuing enforcement in U.S. federal district court,” according to the report.
— City News Service