(Reuters) bp's Toledo, Ohio, oil refinery experienced multiple problems and a naphtha spill before a fire that killed two workers last year, according to a report by the U.S. Chemical Safety and Hazard Investigation Board (CSB).
The two refinery workers died from their burns following an explosion in September 2022 at the 150,800 barrel-per-day Toledo oil refinery.
The report said that at 3:20 a.m. on Sept. 20, an emergency pressure-relief valve on the feed to the naphtha hydrotreater (NHT) opened. The same valve opened at 8 a.m. as well, while another relief valve upstream on the NHT feed opened around the same time and began vibrating.
The refinery's emergency response team isolated a 63,625-pound naphtha leak that occurred due to the piping vibration. The Crude 1 Unit and all other units except the NHT and the saturated gas plant continued to operate, while the coker gas plant (CGP) was bypassed as a repair plan was being evaluated, the report said.
"At approximately 6:09 p.m., flammable liquid naphtha began to fill a Fuel Gas Mix Drum. ... Starting at approximately 6:32 p.m., naphtha from the Mix Drum was also drained directly to the ground creating a vapor cloud," the report said.
"At approximately 6:46 p.m., the vapor cloud of flammable naphtha that had formed on the ground reached an ignition source, which generated a large fire."
bp said in a statement that it had been cooperating with CSB as it investigates the incident further.
A report published by U.S. investigators in March showed the company violated process safety rules and did not properly train workers at the Toledo refinery.
