April's deadly boiler explosion at the Loy-Lange Box Company in the Soulard neighborhood occurred because steel at the bottom of the tank had deteriorated, the U.S. Chemical Safety Board said in a report released Thursday.
The board noted that investigators found the metal in the area of the tank that ruptured was less than one-third of its original thickness.
The immediate cause of the April 4 explosion was “sudden mechanical integrity failure” of the ring at the bottom of the tank, investigators said. The board’s report noted that the bottom of the tank had undergone an “emergency repair” in 2012 that included a custom-made center section.
The blast killed four employees of the Faultless Linen Company when a piece of the boiler traveled more than 500 feet and crashed through its roof. The explosion released energy equivalent to 350 pounds of TNT, investigators said.
According to the Occupational Safety and Health Administration, the Loy-Lange Box Company had paid fines for violating workplace regulations three times in the past three years. The organization also opened a case on the company this April. An OSHA representative said they could not comment on any ongoing investigations.
The chemical safety board said it had not received a notice of an inspection by the city of St. Louis, which is required by ordinance to inspect the tank.
Loy-Lange Box officials declined to comment Thursday.
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