RICHMOND -- Portions of the 8-inch carbon steel pipe whose failure triggered last month's major fire at the Chevron refinery had thinned to about the thickness of a penny before leaking 600-degree diesel oil, federal investigators told the City Council this week.
The U.S. Chemical Safety Board also revealed that the deteriorating pipe apparently was not inspected by Chevron during a maintenance shutdown last year.
What caused the corrosion and why the pipe had not been replaced during maintenance work on the unit in November are key lines of inquiry, according to Chemical Safety Board officials. "We want to understand Chevron's decisions," said Don Holmstrom, the agency's western regional manager.
Holmstrom said Chevron's internal policies suggested that an inspection of the pipe should have occurred, but the pipe that later failed "doesn't appear to have been inspected." Pipe thickness is typically measured by ultrasound technology, CSB Managing Director Daniel Horowitz said.Holmstrom and Horowitz were joined at the council meeting by CSB Chairman Rafael Moure-Eraso.
The investigators said they and officials from the state Division of Occupational Safety and Health took joint custody of a 5-foot section of pipe from the Aug. 6 fire and turned it over to a metallurgical lab for "failure analysis testing."
Parts of the pipe had thinned to 1/16 of an inch, down from an original thickness of 5/16 of an inch. CSB officials have said
During the November maintenance work, Chevron decided to replace nearby lines within the No. 4 crude unit of the refinery, but did not inspect the section that later failed, safety board officials said.
Chevron spokesman Derek Jansen on Wednesday declined to say whether the pipe was inspected in November.
"We adhere to all applicable laws and regulations and cooperate with all inspections," Jansen wrote in an email. "The investigation is ongoing and it will take time before all the facts are known about the incident."
Officials also broadcast for the first time Tuesday surveillance video showing the formation of a large white vapor cloud shortly before the fire sparked.
The meeting was the first CSB presentation since Chevron released a 30-day report last week revealing there was a "flash fire" extinguished about 10 minutes before the larger fire.
Chevron's report also raised questions about the composition of a white cloud that formed minutes before the large fire. Chevron suggested that the cloud was mostly steam rather than combustible vapors, as previous CSB statements indicated.
Before Tuesday's briefing, Horowitz said safety board investigators and Chevron officials met this week to discuss the composition of the vapor cloud, but that Chevron's report and the CSB's early pronouncements about the cloud are not necessarily at odds.
"It's more complex than that," Horowitz said. "But there is no dispute that there was a large release of hydrocarbons" before the fire.
The question of the vapor cloud looms large in part because more than a dozen refinery workers were in the cloud and evacuated minutes before the fire, narrowly escaping serious injury or death.
"When this vapor cloud erupted, there were at least 18 employees in it," Holmstrom said.
CSB officials also called on the public to share photos and videos of the cloud to help with modeling analysis to better understand its composition.
The Aug. 6 fire sent black smoke across the East Bay, resulted in minor injuries to six refinery workers and sent more than 15,000 people to area hospitals complaining of illness.
Tuesday's briefing was the latest in a series of news conferences and other communications from the CSB, an investigatory agency with no regulatory power. Mayor Gayle McLaughlin asked CSB officials to provide the public briefing Tuesday. Safety board officials vowed to continue to be "transparent" about their findings as the investigation continues.
Greg Karras, senior scientist for Communities for a Better Environment, said the biggest news Tuesday was the revelation that the corroded pipe may have eluded inspection in November.
"The pipe was way beyond the minimum thickness," Karras said. "Not only was it not replaced, but the CSB can't find evidence that it was even checked."
Top Chevron officials were also on hand Tuesday. Refinery General Manager Nigel Hearne addressed the council after the CSB's presentation.
Hearne apologized for the incident and said he was committed to working with investigators, ensuring that Richmond residents get jobs rebuilding the unit and installing air monitoring systems in nearby neighborhoods.
"We are dedicated to learning from this," Hearne said.