Excess Lethal Acid Blamed for Refinery Blast
The explosion and fire that rocked the Mobil Oil Corp. refinery in Torrance last month was caused by an excess of lethal hydrofluoric acid in a refinery unit that produces gasoline, company officials said Friday.
The Nov. 24 explosion injured four people, shattered windows in nearby homes and businesses and sparked a spectacular fire that took two days to extinguish.
Earlier this week, before the cause of the fire was known, Torrance city officials expressed concern about the use of hydrofluoric acid at the refinery after an environmental group said it could cause a major disaster. The Torrance City Council launched a study to determine whether the 730-acre refinery in the heart of the city is being operated safely.
On Friday, Mobil said the blast originated in a propane treater at one of the refinery’s alkylation units. The 30-foot-tall unit removes water and impurities as it produces gasoline, propane and butane, while a propane treater removes small amounts of acid from liquid propane.
The blast apparently occurred when an excess amount of hydrofluoric acid reached the treater “due to malfunctioning instrumentation,” the company said.
“The resulting reaction caused abnormal pressure in the propane treater vessel, causing the vessel to rupture,” Mobil spokesman James A. Carbonetti said in a statement.
Pieces of the exploding vessel then severed pipelines carrying fuel, which fed the fire.
“Studies are under way to identify appropriate additional safeguards for preventing a recurrence of this incident,” Carbonetti said.
The Environmental Policy Institute, a nonprofit environmental group based in Washington, said Dec. 4 that 58 U.S. oil refineries, including Mobil and two others in the Los Angeles area, use hydrofluoric acid. The group warned that release of the chemical could cause a disaster similar to the accident at a Union Carbide plant in Bhopal, India, which claimed more than 2,000 lives in December, 1984.
Mobil refinery manager Wyman D. Robb said the environmental group “largely overstated” the risk and said the acid has been used safely “for over 40 years” at the Torrance refinery to boost the octane in gasoline.
