Hydrogen Blast Leads To Refinery Shutdown

In the wake of a hydrogen fire and explosion, a Utah refinery agreed Nov. 13 to shut down its plant in compliance with a first-ever, stand-down request by the Chemical Safety & Hazard Investigation Board (CSB).

The accident occurred Nov. 4 at the Silver Eagle Refinery in Woods Cross, Utah. CSB stepped in to investigate the fire and explosion that sent flames several hundred feet into the air and created a blast wave that damaged some 100 homes, knocking one off its foundation. No one was seriously injured.

The accident follows another recent one at the Silver Eagle plant, which is located a few miles outside Salt Lake City. On Jan. 12, four workers were burned in a flash fire when light naphtha vapors exiting a large storage tank were ignited. That accident is also being investigated by CSB.

The board's preliminary investigation of the most recent accident found "serious concerns" over piping and equipment integrity at locations throughout the plant, said CSB in a statement. After a discussion among refinery executives and officials with CSB and state and federal industrial safety agencies, the company agreed to stand down as "quickly and safely as possible."

The refinery is now in the process of closing its refining operations, says Cindy Gubler, a Silver Eagle spokesperson. "We just don't flip a switch. We are still determining what will be shut down and for how long," she tells C&EN. "This is, of course, not a normal turnaround. It is unclear what we will need to do for investigations and repairs."

Louis Silva, director of the Utah Occupational Safety & Health Division, applauds the company's decision. "I am glad to see the company voluntarily shut down because that makes it a lot safer for my people to do their work," he tells C&EN. He would not comment on Utah's investigation, saying only that it is an "open case."

The specific explosion was caused by a rupture of a 10-inch pipe carrying hydrogen at 600 psi in the diesel hydrotreater unit, according to CSB.

Although the exact cause of the failure has not been determined, CSB Chairman John Bresland notes, the pipe showed signs of significant thinning that had not been detected by the refinery's mechanical integrity program. Bresland urges that the refinery units remain closed until the integrity and fitness for service of all equipment has been documented and verified.

"Over the coming weeks, the refinery will review and assess the situation and continue to report to all concerned. We take our operating responsibility very seriously," said Dave McSwain, Silver Eagle Refinery president, in a statement.