RICHMOND -- More than a dozen workers were nearly killed when the vapor cloud that sparked Monday's massive Chevron refinery fire engulfed them as they worked on a leaky, four-decades-old pipe that the oil giant had not replaced during a round of maintenance last year, federal investigators said Saturday.
The team of U.S. Chemical Safety Board investigators painted a frightening picture of the seconds after the pipe released a 600-degree "gas-oil" liquid that created a highly flammable vapor cloud that quickly engulfed Chevron employees who were examining the pipe. In revealing these new details, they called it one of the worst refinery accidents in recent years and noted that it was rare for so many employees to be in harm's way.
"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," said team leader Dan Tillema.
Five Chevron workers had minor injuries.
"Monday's fire was a near-disaster for refinery personnel," said Dr. Rafael Moure-Eraso, the chemical board's chairperson. "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."
A 12-inch pipe adjacent to the leaky pipe, which dates to the 1970s and is original to the No. 4 crude processing unit, was reportedly replaced during maintenance last year after it was found to be corroded, but not the 8-inch one that failed just before the fire, said Dr. Daniel Horowitz, chemical board spokesman. Investigators have asked for that inspection report from last year.
"One of the key issues for us will be to understand what condition the 8-inch pipe was in during the inspection," Horowitz said.
To have left the pipe in place would mean Chevron employees believed it could last another five years before the next mandatory inspection, he said.
On Monday, workers found the old pipe leaking at 20 drips a minute and took two hours before deciding to remove the pipe's fiberglass insulation while the unit was still processing crude, causing the leak to accelerate and quickly ignite. The large fire sent black smoke billowing across the East Bay, leading to more than 5,700 residents seeking medical treatment for symptoms ranging from anxiety to respiratory distress, according to the Contra Costa health department.
Federal investigators plan to evaluate what procedures and industry practices exist when responding to a combustible material leak at a running unit. Critics have questioned why Chevron did not shut down the crude processing unit while investigating the leak. The oil company's officials have said shutting down the plant can cause other dangers and is not always the best course.
"We agree that this is a serious incident that warrants thorough investigation," Chevron spokesman Justin Higgs wrote in an e-mail Saturday. "We are cooperating with all regulatory agencies and are committed to better understanding the root cause of this incident."
Chevron employees are safe, Higgs wrote, "because of the professionalism of emergency responders and their strict adherence to emergency procedures in evacuating the area when it became clear that the situation was escalating."
Asked how old the pipe in question was, why it hadn't been replaced and what standards the refinery uses for maintaining its pipes and infrastructure, Higgs said the company is not publicly disclosing that information and that investigators have yet to see the leaky pipe's testing records. Given its age and the condition of the pipes around it, corrosion remained a possible cause for its failure, he said.
"As soon as the investigation concludes, we fully intend to make that information public," Higgs said.
The Chemical Safety Board investigators have already conducted witness interviews and reviewed documents, and plan to let their structural and industrial safety experts visit the fire site Monday once the area has been deemed safe.
They will do independent testing of the leaking section of the pipe to determine how it failed, as well as review the county's emergency notification system, which has been criticized for spotty siren sounding and tardy phone notifications.
Pipes from the 1970s and earlier remain throughout the No. 4 crude unit and the rest of the 110-year-old facility, the oldest refinery on the West Coast which began processing crude oil before Richmond became a city, said Randy Sawyer, Contra Costa Hazardous Materials Program director.
"If there was no source of corrosion, they could be there for a very long time," he said of the network of pipes.
Even if the refinery had followed a strict inspection plan in search of corrosion, pipes could still fail, said Richard Kuprewicz, a pipeline safety consultant.
"Just because a pipe is old doesn't mean you have to replace it," he said, adding that technology and equipment on units that process crude oil have not changed much since the 1970s.
Most refineries pipes are made of carbon steel, wrapped in fiberglass insulation and an aluminum shield and are inspected for thinning or fatigue though human inspection, ultrasounds, X-rays and dye testing.
Performing maintenance on a running unit is dangerous, as evidenced by the 1999 Tosco refinery accident in Avon, north of Concord. Workers attempted a risky operation to replace a leaky pipe around a crude-processing unit while it was still operating. Employees cut out part of the pipe, and hot petroleum spewed out and ignited, killing four workers and severely burning a fifth. Two company mergers later, Tesoro now operates the Avon refinery.
"When do you make the decision to shut down and go in when the unit is cold and you've removed the hazardous materials?" Horowitz asked rhetorically. "Or when is it OK to go into it with a running unit?"
Industry experts say leaks are common at refineries, but national regulators warn of the inherent risks.
"That's not an acceptable posture saying there will be leaks at refineries," Horowitz said. "That wouldn't be tolerated at a nuclear plant."
And local leaders are concerned as well.
Contra Costa Supervisor John Gioia, of Richmond, wants to know why Chevron did not replace the pipe in November when the unit was shut down and every pipe inspected.
"In order to prevent these type of accidents in the future we need to know why that pipe was not replaced at the last turnaround," he said. "This is what you classify as a near miss."