An 8-foot section of the pipe at the Chevron refinery in Richmond, CA, that thinned dangerously before it failed last month and help start a massive blaze is now in a lab undergoing analysis, federal officials said.
The wall of the 5/16th-inch-thick, 8-inch-diameter pipe leading away from the No. 4 Crude Unit had “lost most of its original thickness,” said U.S. Chemical Safety Board investigators. The section will undergo analysis for corrosion or other factors that may have led to its rupture and the Aug. 6 fireball.
The probe will focus on whether Chevron followed industry standards in deciding to leave the pipe in place last year when the refinery was shut down for maintenance, said Don Holmstrom, the Chemical Safety Board’s western regional manager.
Chevron decided to replace a nearby 12-inch-diameter line during that refinery shutdown because of corrosion. The company considered replacing the 8-inch line but in the end kept the pipe in place.
Holmstrom said the federal investigators were still trying to determine how badly thinned the pipe was last year when Chevron made the initial decision to replace it.
One source close to the investigation said the pipe had lost roughly 80 percent of its wall thickness near the spot that ruptured, leaving about 1/16th of an inch of its wall remaining in some locations.
Holmstrom said federal investigators are also looking at whether regulators, notably the state’s Division of Occupational Safety and Health, exercised proper oversight of the refinery operation.
A recent federal audit found Cal/OSHA’s industrial process safety unit was conducting “very few, if any” comprehensive workplace-safety inspections of refineries and chemical plants in the state. A Chronicle review found what inspections the state has performed have not resulted in a single fine against a major oil company.