CSB Investigators Focus on Pipe at Chevron Refinery
The agency said seven of its investigators deployed to the Richmond, Calif. site last week.
The U.S. Chemical Safety Board officials said many workers at Chevron's oil refinery in Richmond, Calif., were engulfed by a large vapor cloud prior to the fire that heavily damaged the facility on Aug. 6. The cloud formed when combustible hydrocarbon liquid called "gas-oil" leaked from an 8-inch pipe connected to a crude oil distillation tower in the refinery's crude unit, and the workers were fortunate to survive, they said, adding that workers had noticed the leak and were attempting repairs on piping connected to the tower, which was still operating, when the leak suddenly intensified.
Material in the tower was hotter than 600 degrees Fahrenheit, so the leaking gas-oil immediately formed a large, flammable vapor cloud, according to the agency. "Witness testimony collected by CSB investigators indicates that a large number of workers were engulfed in the vapor cloud," said CSB Team Lead Dan Tillema, P.E. "These workers might have been killed or severely injured, had they not escaped the cloud as the release rate escalated and the cloud ignited shortly thereafter."
"Monday's fire was a near-disaster for refinery personnel," said the board's chair, Dr. Rafael Moure-Eraso. "The circumstances warrant a full and independent federal investigation to determine the root causes. Although fortunately no workers were killed, the overall impact of the incident ranks it as among the most serious U.S. refinery incidents in recent years."
The fire resulted in shelter-in-place orders and caused hundreds of local residents to visit emergency rooms complaining of respiratory distress and/or anxiety. The refinery is located northeast of San Francisco.
Tillema said important issues in the investigation include understanding why the pipe that failed was kept in service during a late 2011 maintenance turnaround and what procedures and industry practices exist for responding to a leak of combustible material from a running unit.