Chevron closed parts of its Richmond oil refinery after an explosion in August. Federal investigators said refinery workers were trying to stem a leak from an 8-inch line at one of the refinery units before the fire started.
The company, in an update on its response, said about 20 percent of the affected unit was damaged. It was working to replace damaged structures and processing equipment.
Chevron had said it discovered that the type of metal in the pipe may have contributed to the failure. It added that it was replacing piping in the fire-damaged area with a chrome alloy pipe that was resistant to corrosion.
"The steps we are taking will upgrade certain components of the crude unit, enhance our inspection processes and reduce potential sources for emissions," the company said in a statement.
At peak capacity, the refinery processed around 245,000 barrels of oil per day. Chevron said the facility is operating at around 60 percent of capacity. Full service is expected next year.