Preliminary Findings Indicate Combustible Dust, Likely Ignited by a Malfunctioning Oven, Caused Fatal CTA Explosion
(Corbin, KY, July 8, 2003) The explosion and fire at the CTA Acoustics plant in Corbin, KY, earlier this year was caused when combustible dust in the plant ignited, according to preliminary findings of investigators of the U.S. Chemical Safety and Hazard Investigation Board (CSB).
The Feb. 20, 2003 accident took seven lives and caused over thirty injuries. The investigators will present their initial findings at a community meeting at the Corbin Civic Center at 7 p.m. tonight. Board Members Dr. Gerald Poje, who will chair the meeting, and John Bresland will hear from members of the public who wish to speak.
The investigation, which is not complete, so far has found the initial explosion and fire occurred on a production line that was partially shut down and being cleaned at the time of the incident. During the cleaning, a thick cloud of dust dispersed around the line. The dust was likely ignited by a fire that spread from the production line's oven, which was still operating, investigators said.
"The plant's four production lines had a history of small fires erupting in the ovens," said lead investigator Bill Hoyle. "Plant operators routinely put out these fires. However, during the cleaning operation, no one was present in the immediate area of the oven who could have detected a fire."
Dr. Gerald Poje, a CSB Board Member who will preside at the meeting, said, "Dust explosions are a significant hazard in manufacturing operations. This accident happened only a few weeks after the terrible tragedy in Kinston, North Carolina, which was also caused by the ignition of dust in the plant and which claimed six lives. As the investigation proceeds and we begin to consider safety recommendations, we will be looking closely at the fact that OSHA has safety standards to prevent dust explosions in grain elevators, but not in other types of manufacturing facilities."
The CSB preliminary report to the community found that one or more oven doors on the production line where the incident began had been left open to cool down the oven because temperature controls had been malfunctioning for several days. Flames likely escaped from the oven door and ignited the dust cloud.
"The fire quickly spread over a wide area of the plant," according to Investigator Hoyle. "Dust that had accumulated on flat surfaces throughout the plant was disturbed and became airborne, providing more fuel for the fire. The initial explosion stirred up more dust and led to secondary explosions," Mr. Hoyle said.
The dust was composed primarily of phenolic resin, a raw material used in the production process. The resin is similar in consistency to talcum powder.
Mr. Hoyle said the next steps of the ongoing investigation will include reviewing hazard information provided by the resin supplier to the company, completing a review of company documents and programs, and reviewing the adequacy of existing regulations and guidance on dust explosion prevention.
The presentation to the community is scheduled to include videotape of a laboratory-scale dust explosion performed using resin recovered from the CTA plant, as well as a computer simulation showing the initial dust explosion and the probable path of the flash fire and secondary dust explosions in the plant.
The CSB is an independent federal agency charged with investigating industrial chemical accidents. CSB investigations look into all aspects of such events, including physical causes such as equipment failure as well as inadequacies in safety management systems. Typically, the investigations involve extensive witness interviews, examination of physical evidence and chemical and forensic testing.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups and regulatory agencies such as OSHA and EPA. Further information about the CSB is available from www.csb.gov.