Burst pipe probed in Utah refinery blast as questions asked over safety
Sunday, November 8, 2009
Federal investigators with the Chemical Safety Board (CSB) of the United States have declared that a recent explosion that damaged homes alongside a Woods Cross, Utah refinery was triggered when a pipe burst. The revelation comes as locals begin questioning the decision to build houses near the facility.
The explosion at the Silver Eagle refinery on Wednesday morning was the second next year, and blasted a fireball into the neighbourhood. Ten houses suffered damage including cracked foundations, roofs lifted off, doors and windows blown out and debris hurled into rooms. One resident, Linda Wood, has been told to leave her house, which lies condemned after it was knocked clear of its foundations and damaged structurally.
Two local emergency dispatch centers were clogged up as calls came through to the 911 emergency number. Firefighters arrived quickly and tackled the resulting blaze at the refinery after establishing that there were no injuries. The 1950s refinery was not evacuated and is expected to continue operating despite the damage. It employs 80 people.
Silver Eagle’s own firefighting crews were already in control when they were joined by the emergency services, and together they put the flames out in around thirty minutes. Woods Cross mayor Kent Perry said that over the last six months there have been a lot of improvements in local firefighting and praised the reaction of emergency services. Later, 120 residents were visited by structural engineers to assess damage. There were also power outages in the area, with two other refineries amongst those affected.
Silver Eagle had also sent employees on a firefighting course following another explosion in January. In that accident, a large cloud of flammable vapour developed over a tank of naptha before igniting, causing a flash fire that injured several employees. The firm has said they will pay for all the damages caused by the latest incident, and Perry advised affected people to keep track of expenses incurred.
As well as the CSB, Utah’s Occupational Safety and Health Administration and Silver Eagle themselves are investigating the accident. The CSB released preliminary findings yesterday that indicated a burst pipe was to blame, although the reasons for its failure are unknown.
A pipe ten inches in diameter burst along a horizontal section near a point where it changed direction from vertical. The pipe normally carried hydrogen and diesel and was linked to a reactor that took waxes out of diesel fuel, but due to maintenance by Silver Eagle the pipe was only transporting pressurised hydrogen. When it failed at 9:15 630 pounds of hydrogen spilled out and were ignited by a nearby furnace. The resulting 800 degrees Fahrenheit fireball leapt 100 feet into the air and sent a string of pressure waves to buffet the housing, as the pipe pointed east towards the homes.
The CSB’s Donald Holmstrom commented that “The unit was immediately engulfed in flames… We’re extremely fortunate that no one got hurt. Five workers were in this process unit just a few minutes before.” The revelations come as local residents expressed concern about the fact that houses were built so close to the refinery in the first place.
It has been discovered that there were no houses near the refinery until six years ago, when an application was denied after an engineer commissioned by the council reported that the risks were too high. However, the developer convinced officials to change their minds with a report by a company he had hired himself. The CSB is due to look into these studies as well as one by the refinery. An opinion piece by the Salt Lake Tribune also criticised the company’s safety record, with the refinery also experiencing explosions in 2005 and 2007. However, the refinery had recently passed a safety inspection when the accident occurred. The CSB will examine whether the refinery was properly inspecting the pipe.