Safety board begins full Texas City investigation
An internal explosion is among possible explanations for why a 500-pound, bolted-down metal lid flew off a water filtration vessel last month at BP's Texas City refinery in an accident that killed a veteran employee, investigators said Thursday.
A team from the U.S. Chemical Safety and Hazard Investigation Board is examining that as well as other scenarios, having launched a full probe into the Jan. 14 death of William Joseph Gracia, 56, who had worked at the refinery 34 years.
William Wark, one of the board members, said the board considered the "serious history" of accidents at the plant and other factors in moving its initial probe into a full inquiry.
"Over the past 32 years, a total of 41 people have died in workplace accidents at this site," Wark said.
Those include 15 contractors who died in a March 2005 explosion there, which prompted the longest investigation in the board's 10-year history. Gracia's death is the third at the plant since that blast.
And a plant executive testified in a civil trial last year that shortly before the 2005 blast, he studied BP's safety record and found 23 deaths in the previous three decades.
"The goal of the investigation is to determine as precisely as possible what happened to cause this unfortunate event and to make recommendations to BP and others to prevent similar accidents in the future," Wark said. "Conducting this investigation will take a number of months."
Don Holmstrom, who headed the CSB's investigation into the 2005 disaster, also is leading the probe into Gracia's death.
Asked repeatedly Thursday if he and the board were disappointed to be investigating a death at Texas City less than three years after the 2005 carnage, Holmstrom diplomatically said it's too soon to relate Gracia's death to problems that led to earlier accidents.
Will share findings
BP and the Occupational Safety and Health Administration also are investigating the latest one. The company declined comment Thursday on the CSB's findings so far but said BP is cooperating and will share its findings with employees and others in the industry when its investigation is done.
Holmstrom said the water filtration vessel normally operates under moderate pressure. It would have taken significantly higher pressure to blow the lid off with such force to shear off most of the 24 bolts, break the cross pins that held them into place, and strip threads from some, he said.
The lid blew straight into the air and came to rest near the vessel, he said. Black, 100- to 110-degree process water also spewed out.
Holmstrom stood next to a poster-size photograph showing the water filtration vessel, with the dome-shaped lid nearby, after the accident.
A second, close-up photo showed the vessel's rim and the few bolts that remain. The bolts are 9 inches long and nearly 1 inch around.
The water vessel is in the plant's ultracracker unit, which uses highly flammable, high-pressure hydrogen gas to break apart petroleum molecules.
Before hydrogen can be used in the ultracracker, it's cleaned with water in a tower that removes impurities such as hydrocarbons and hydrogen sulfide. That "process water" from the tower is then filtered in the round vessels to remove solid impurities.
Process water's contents
Holmstrom said that workers have told investigators that process water sometimes contained hydrogen, flammable hydrocarbons and hydrogen sulfide, a flammable and toxic gas.
"These substances are a possible fuel for an explosion, in the presence of oxygen and an ignition source," Holmstrom said.
But Holmstrom said it's too early to say whether any of those chemicals should be in process water during normal operations.
Tony Buzbee, an attorney for Gracia's wife and two children, all of whom attended the investigation board's news conference in League City, said they believed from the start that chemicals were involved in the accident.
"Chemicals are not supposed to escape, and lids are not supposed to blow off," Buzbee said.
When the accident happened, the filter was being restarted after maintenance and had been refilled with process water.
Holmstrom said tests will show what was in the water and help determine whether an explosion occurred. The probe will also examine the integrity of the bolts and corrosion.
He said other scenarios haven't been ruled out, including a sudden and unexplained pressure increase.
February 7, 2008