Surveillance camera video shows a 100-foot fireball ripping through a Utah refinery during a gas explosion that knocked a nearby home off its foundation earlier this month.
The footage captured at the Silver Eagle refinery briefly shows a white cloud, which investigators say is hydrogen escaping from a ruptured pipe that erupts into a massive explosion.
The Nov. 4 blast damaged 100 homes in the Woods Cross area _ though not all of them seriously. Four workers were thrown to the ground in the blast but were not seriously hurt. Another worker had been next to the pipe that exploded just minutes before, federal investigators said.
"I think it's a miracle that this didn't result in much more serious consequences," Don Holmstrom, the U.S. Chemical Safety Board's lead inspector on the blast, said Tuesday. "This accident could have been much, much worse."
Board investigators are focusing on a 10-inch pipe that failed catastrophically and "serious deficiencies" in the plant's program that's supposed make sure its networks of pipes and equipment is safe and working properly.
Company officials last week heeded a recommendation from investigators to shut down the refinery until it's deemed safe to reopen. Board officials say it's the first time they've ever recommended a plant temporarily shut down.
Four of Silver Eagle's five processing units were shut down, with the remaining shutdown expected in days.
Company president Dave McSwain said last week that the move was in the best interest of the safety and health of its employees and the community.
Company officials in a statement Tuesday said they were "truly sorry" for the incident and were grateful that no one got hurt. It also said it has hired a consulting firm to help identify problems and make sure they're fixed before operations resume.
They said Silver Eagle has been following "an established mechanical integrity program and disagrees with any suggestion or assertion to the contrary."
"Silver Eagle has also worked hard in recent years to upgrade the refinery and improve safety," the company said. "However, in light of the November 4 incident and the preliminary findings, it is apparent to the refinery that the program was insufficient and that changes need to be made."
CSB board chairman John Bresland on Tuesday urged the company to conduct a comprehensive review of its operations and make any necessary repairs before starting up. Investigators have raised concerns about the company's previous contractors who were supposed to ensure the plant's pipes remained thick enough to handle operations. Pipes that show excessive thinness are typically targeted for retirement.
Holmstrom said there was no documentation of those inspections for a "significant percentage of pipes" at Silver Eagle. Others were miscalculated, he said.
"There is the potential that multiple pieces of equipment have been operating at below the required thickness for safety _ and creating the potential for other serious accidents," Holmstrom said.
The company brought in a new contractor and had been working to remedy those problems, board officials said.
It was unclear how long the plant, which employs about 60 people, will be shut down. The Woods Cross refinery ranks 130th in production among U.S. refineries at an operable capacity of 10,250 barrels a day, according to the Energy Information Administration.
The explosion came as investigators were still trying to determine the cause of a fire earlier this year. On Jan. 12, four people were seriously burned at Silver Eagle when a 440,000 gallon storage tank caught fire and burned for 11 hours.
Bresland said three of eight refinery investigations under way by his agency are in Utah.
"The current rate of accidents in refineries is not sustainable and is not acceptable," he said.