SAN FRANCISCO (AP) — A corroded pipe that failed and triggered a leak and massive fire at one of California's largest refineries had walls as thin as a penny in some areas, federal investigators said.
U.S. Chemical Safety Board officials said late Tuesday that a key part of their probe into the fire at the plant in Richmond is why Chevron Corp. didn't replace the pipe during a routine inspection a year ago.
The board previously found that Chevron had inspected and replaced a larger, corroded 12-inch pipe connected to the smaller one that failed Aug. 6.
"We have obtained internal Chevron policies that recommend that every segment of pipe in this service should have been included in the pipe inspection program," said Don Holmstrom, lead investigator for the board. "There is no indication that this segment of pipe was inspected for thickness during the most recent" inspections.
Chevron did not respond to a request for comment.
The blaze at the San Francisco Bay area facility knocked an important refinery unit offline, reducing production. Gas prices on the West Coast have surpassed $4 a gallon since the fire.
In addition, smoke from the blaze sent thousands of residents to hospitals with health complaints. Local officials have moved to create more thorough air monitoring around refineries in the area along with better emergency response systems.
The destroyed unit remains offline, and the company has provided no timetable for when it might be rebuilt.
Parts of the failed, eight-inch pipe had thinned to 1/16 of an inch from its original thickness of 5/16 of an inch, officials said.
"This represents about an 80 percent wall loss from the original design thickness," Holmstrom said.
The pipe that failed dated back to the 1970s, the board said, and Chevron's own training documents said straight pipes such as the one that leaked were more susceptible to corrosion.
"Understanding the decision-making around the replacement of the eight-inch pipe remains a key focus of the investigation," Holmstrom said.
Engineering experts said the company should have done thorough inspections of connected pipes after it found corrosion and thinning in nearby pipes in the crude unit last year.
"If you find local (pipe) wall loss, you don't just stop there, you extend the inspection further until you find out whether the rest of the pipe is safe to operate," said Ronald Haupt, a mechanical engineer and president of Pressure Piping Engineering Associates Inc.
Jason Dearen can be reached on Twitter at http://www.twitter.com/JHDearen.