The metallurgical analysis details the same kind of sulfidation corrosion at the Silver Eagle refinery that we found in the Chevron accident. Sulfur compounds in the process stream corroded a steel piping segment, causing the pipe walls to become severely thin. —Dan Tillema, Chemical Safety Board
WOODS CROSS — A segment of a 10-inch pipeline at Silver Eagle Refining that suffered a catastrophic rupture did so because of corrosion and was never inspected in its lifetime, a new report concludes.
The 2009 failure led to a massive explosion and fire at the refinery, 2355 S. 1100 West, blowing four workers off their feet and damaging 100 homes, including one that was knocked from its foundation.
Findings in the report commissioned by the U.S. Chemical Safety Board point to extreme corrosion of the line similar to conditions that led to deaths in other states.
"This is the same syndrome we found in the Bay Area Chevron refinery fire of 2012 and the Tesoro refinery explosion and fire that killed seven in Anacortes, Wash., in 2010," said Rafael Moure-Eraso, board chairman.
"Fortunately, there were no fatalities resulting from the explosion, and it was only by chance no one was in the immediate area. But many lives were disrupted as residents in Woods Cross had to move out of homes pending repairs," Moure-Eraso said.
The investigation showed eerie similarities between the Woods Cross and Bay Area incidents when it came to the extent of corrosion.
“The metallurgical analysis details the same kind of sulfidation corrosion at the Silver Eagle refinery that we found in the Chevron accident. Sulfur compounds in the process stream corroded a steel piping segment, causing the pipe walls to become severely thin," said Dan Tillema, lead investigator from the Chemical Safety Board. "This incident is also similar to Chevron in that, while sulfidation is a well-known damage mechanism at refineries that requires regular inspection and monitoring, the segment that failed has no record of ever being inspected.”
The board noted the problem at Silver Eagle in 2009 is emblematic of a larger, systemic problem in refineries across the country, with companies that rely more on inspections to catch problems rather than assuring safe design at the outset.
An investigation conducted by Exponent — a Texas-based engineering company — showed the pipe segment that failed was put into service in 1993 in the bottom of a reactor in the distillate dewaxing unit. The rupture sent a tremendous blast across the refinery into a nearby subdivision, but did not result in any serious injuries.
Four workers near the process unit at the time of the explosion were knocked to the ground, and one worker was taking readings next to the pipe just minutes before it failed.
The report said the analysis shows that "years of thinning" had taken place in that segment of the pipeline, and refinery records detailed "serious widespread mechanical integrity deficiencies and gaps across the refinery" at the time of the incident.
Earlier that same year, two refinery operators and two contractors suffered serious burns resulting from a flash fire that happened when a flammable vapor cloud released from a storage tank.
The refinery was fined more than $1 million by Utah regulators for equipment and safety violations.
Jerry Lockie, general manager over the refinery, said the facility is on a comprehensive inspection program and all pipelines are maintained.
"I have not personally reviewed the report, but I can say to the best of our knowledge, we have addressed everything that has been noted from the (Chemical Safety Board)," he said.
Moure-Eraso noted that, ironically, the investigation into what happened at Silver Eagle was delayed because of a "pressing" series of accidents in the oil production and refining sector.
The Chemical Safety Board is an independent federal agency charged with investigating industrial chemical accidents. It does not issue citations or fines but makes safety recommendations to industry, labor and regulatory agencies.
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