Tesoro: Anacortes refinery closed through September

Tesoro Corp.'s Anacortes refinery, where an April explosion and fire killed seven people, will remain closed at least through September — three months longer than once expected — a company spokesman said Thursday.

Meanwhile, Robert Hall, who is leading the accident investigation for the U.S. Chemical Safety and Hazard Investigation Board, confirmed that the blast occurred when a heat exchanger ruptured on the unit that processes naphtha, a highly flammable chemical used to make finished petroleum products.

Hydrocarbons released by the rupture then found an ignition source, he said.

Tesoro has said the April 2 explosion and fireball at the refinery happened when the unit, called a hydrotreater, was being returned to service after routine maintenance. Experts say the startup process is especially dangerous because the liquid is being heated to high temperatures at great pressure.

Federal investigators say all seven victims were within 50 feet of the unit and had no chance of escaping.

A heat exchanger raises the temperature of material coming into a processing unit while cooling the product going out. Hall said it's not yet known why the device ruptured, and metallurgical tests will begin Friday at a laboratory in Cleveland.

Sandy Gilmour, a spokesman for the investigative board, said it hopes to have preliminary findings on why the exchanger failed before October. Hector Castro, spokesman for Washington's Department of Labor & Industries, said the state's investigation also should be completed by then.

Investigators had to wait until mid-May to begin examining and removing the exchanger because asbestos scattered by the blast had to be cleaned up.

Tesoro had earlier said the refinery would be closed through June, and that employees would keep their jobs and benefits during the shutdown. But Lynn Westfall, a senior vice president with the San Antonio-based petroleum company, said it still has to finish cleaning the burned area, make repairs and install new equipment, which will take months.

Other parts of the refinery can still function, he said, but the plant can't make finished and marketable products without the naphtha unit.

Kim Nibarger, a health-and-safety specialist with the United Steelworkers union, told a Senate hearing in Washington, D.C., on Thursday that "the high number of fatalities at Tesoro was the result of too many people being where they didn't need to be."

Nibarger, a former worker at what is now a Shell Oil Co. refinery at Anacortes, said he was visiting his parents at the time and felt the Tesoro explosion.

Westfall said Tesoro would not speculate on a cause of the accident until a full investigation has been completed.

"We know there were a lot of people there, but can't speculate on why they were there and whether it was justified," he said.

The Senate hearing was called by Sen. Patty Murray, D-Wash., to look into petroleum-industry accidents, including the Gulf of Mexico oil spill. She said she found it "outrageous" that representatives of BP were invited to testify but declined.