LOUISVILLE, Ky. (AP) — A federal agency investigating a deadly chemical plant explosion in Kentucky said that crucial maintenance was deferred on a furnace that blew up, and that similar but smaller incidents had been ignored at the Carbide Industries plant.
The independent U.S. Chemical Safety Board released its draft report Thursday on the blast and fire on March 21, 2011, in an industrial section of Louisville known as Rubbertown. Two workers died from burns and two others were injured.
"This accident is literally a case study into the tragic, predictable consequences of running equipment to failure even when repeated safety incidents over many years warn of impending failure," said the agency's chairman, Rafael Moure-Eraso.
The explosion was likely caused when the large electric arc furnace became over-pressured after water leaked into it, the agency said.
The furnace, capable of heating its contents to about 3,800-degrees Fahrenheit, spewed molten calcium carbide, powdered debris and hot gases that blew through the double-pane reinforced glass window of the control room, the report said.
"When control room windows blew out during previous furnace incidents, the company merely reinforced them, rather than taking the safe course and moving the control room farther from the furnace and investigating why the smaller furnace over-pressure events were happening in the first place," Moure-Eraso said in a statement.
He called it an example in which "abnormal events become acceptable in everyday operations."
The plant produces calcium carbide, used in metal fabrication and construction.
Carbide Industries General Manager John Gant said in a statement that the company has supported the board's inquiry and has addressed the recommendations made as a result of the investigation.
"Additional safeguards and policies have been implemented that will further strengthen the safety and environmental performance at Carbide Industries," Gant said Thursday.
The chemical safety board's lead investigator, Johnnie Banks, said 26 work orders were issued by the company to repair water leaks on the furnace cover in the five months leading up to the explosion. The company continued to operate the furnace despite the hazard from those leaks, he said.
"We also found that the company could have prevented this incident had it voluntarily applied elements of a process safety management program, such has hazard analysis, incident investigation and mechanical integrity," he said.
Carbide had planned to replace the furnace cover in May 2011, two months after the explosion, the agency said.
The draft report includes recommendations aimed at preventing a repeat of such explosions.
Investigators found that National Fire Protection Association industry codes governing the safe operation of such furnaces do not include specific requirements regarding safety devices, interlocks and safe distances between the furnaces and occupied work areas.
The draft report recommends that the NFPA develop national standards requiring companies to provide adequate safety controls to prevent explosions, as well as inspection programs and other steps to ensure that control rooms are protected.
"In my view, a national standard adopted by industry and incorporated into state and federal requirements would go a long way to prevent the kind of tragedy that befell the workers at Carbide Industries," Moure-Eraso said.
"While that is important, it's clear that Carbide displayed a chronic lack of commitment to figuring out what was going wrong, ignoring all the warning signs, even as its workers were exposed to a potential massive explosion just a few feet away from their control room."
The agency urged Carbide Industries to modify the design and procedures for the furnace and related areas, including the control room.
The agency, which investigates industrial chemical accidents, does not issue citations or fines but makes safety recommendations to plants, industry and labor groups and regulatory agencies such as the Occupational Safety and Health Administration.