ST. LOUIS (AP) — A giant steam-filled tank weighing nearly 2,000 pounds (900 kilograms) that exploded at a St. Louis box plant, flew a quarter-mile into the air and smashed into a neighboring building, was being used despite needing emergency repairs, federal investigators said Thursday.
The U.S. Chemical Safety and Hazard Investigation Board released findings of its investigation into the horrifying April 3 explosion at Loy-Lange Box Co. that left four people dead. The blast propelled the tank through Loy-Lange's roof and into the offices of Faultless Healthcare Linen.
The steam condensation tank, used in the process of making corrugated packaging products, first sprung a leak in November 2012. The federal report said a contractor made emergency repairs and less than a month later recommended the replacement of lower portions of the tank.
The tank parts were never replaced, investigators said. They also found no evidence that the city ever inspected the tank.
Engineers again noticed a leak on March 31 this year, a Friday, the report said. The steam generation system was shut down and a repair technician was scheduled to arrive the following Monday afternoon, April 3.
"On Monday, despite the leak and the pending technician visit, Loy-Lange started up the steam generation system," the agency's report said. " ... it appears that the catastrophic failure occurred near the end of the startup process."
The failure was caused by corrosion of a 6-inch (15-centimeter) ring that was part of the tank, investigators said.
"The entire ring failed suddenly," the report said. "The tank circle blew away in one piece from the (tank), creating the conditions for the steam explosion."
The result was a massive blast "equivalent to about 350 pounds (160 kilograms) of TNT" that "launched the storage tank like a rocket through the roof."
The nearly 2,000-pound, 17 1/2-foot-long (900-kilogram, 5-meter-long) tank rose to about 425 feet (130 meters) above street level and was airborne for more than 10 seconds before crashing through the roof at Faultless.
Loy-Lange engineer Kenneth Trentham, 59, died. At Faultless, Tonya Gonzalez-Suarez, 46, and her husband, Christopher Watkins, 43, were filling out paperwork for new jobs when they were killed. Clifford Lee, 53, also was fatally injured while filling out papers to begin work at Faultless.
The Loy-Lange Box Co. did not immediately respond to a call seeking comment Thursday.
Safety of things such as boilers and industrial water tanks are regulated almost uniformly in Missouri, with standards that generally include periodic inspections. But St. Louis is exempt from the Missouri law requiring regular inspections by either a state inspector or insurance company.
The city instead requires a company to have a licensed stationary engineer on site. Loy-Lange employed three stationary engineers assigned to the company's two tanks.
"The city provided no evidence of inspection," the federal report said. St. Louis city officials did not respond to a call for comment early Thursday.
The city has insisted its system is safe, saying that because it mandates licensed engineers to operate the tanks, they are under constant inspection, rather than just once per year.
The Chemical Safety and Hazard Investigation Board's role is to investigate industrial chemical accidents. It is not authorized to issue citations or fines, but it can make safety recommendations. The U.S. Occupational Safety and Health Administration also is investigating the accident.