Chemical Safety Board Investigation Finds CTA Acoustics Explosion Caused by Dust Hazard That Was Known to Management, Phenolic Resin Supplier

February 15, 2005

UPDATED: London, KY, February 15, 2005, 9 p.m. EST - By a vote of 3-0, the U.S. Chemical Safety and Hazard Investigation Board (CSB) tonight approved the final report on the phenolic resin dust explosion at CTA Acoustics. In approving the staff report, the Board added a root cause related to Borden Chemical's product stewardship program (Borden Chemical supplied phenolic resin powder to CTA). The report identified four other root causes related to CTA's safety systems and the design of the CTA facility by former owner CertainTeed. The full report, as amended, will be available soon from, along with a transcript and videotape of the public meeting.

London, KY, February 15, 2005 - The U.S. Chemical Safety and Hazard Investigation Board (CSB) today released its final report on the investigation of the 2003 accident at CTA Acoustics Inc. in Corbin, KY, determining that the fatal dust explosion and fire could have been prevented because the hazards of the material involved were known to several parties, including CTA management and raw material supplier Borden Chemical. The February 20, 2003, accident killed seven workers and injured 37 others.

The report is set to be considered today by the full Board at a public meeting at the London Community Center, 529 South Main Street, at 7 p.m. Investigators will present their findings and recommendations followed by public comment and a vote on whether to accept the report.

The CSB found the accident occurred when a cloud of phenolic resin dust, generated during the cleaning of a production line, was ignited by a fire in a malfunctioning oven. Phenolic resin powder was one of the raw materials CTA used to produce acoustic fiberglass insulation for automobiles.

At the time of the accident, workers were cleaning a production line known as Line 405. The CSB found that dust removal activities -- involving the use of compressed air, electric fans, and brooms -- formed a dust cloud near the Line 405 oven. The oven had a malfunctioning temperature controller, which caused it to run hot. The door was left open to help control the temperature. Investigators concluded that a fire developed inside the 405 oven and ignited the dust cloud. The first dust explosion and fire set off subsequent explosions through several production lines. The explosions destroyed much of the production area.

The CSB found that ovens at the plant had a history of small fires caused by the accumulation of combustible material. These fires were routinely put out by plant personnel using extinguishers and hoses, but on the morning of the incident workers were occupied by the cleaning activity and none were in the vicinity of the oven.

Investigators found that CTA had been aware that combustible dust in the plant could explode, but did not communicate this hazard to workers or modify operating procedures or the design of the plant. CTA company memoranda and safety committee meeting minutes from 1992 through 1995 showed a concern about creating explosive dust hazards when cleaning the production line. Further concerns were raised in 1997 documents.

Investigators said that Borden Chemical's material safety data sheets (MSDSs) for the resin it supplied to CTA did note that resin dust was combustible, but did not explicitly warn of the dustÂ?s explosive properties. In addition, Borden did not tell its customers of the explosion hazard following a catastrophic explosion and fire involving a similar Borden phenolic resin used at the Jahn Foundry in Springfield, MA, in 1999, an accident that killed three people.

The CSB also found that CTA plant ovens had a history of small fires due to the accumulation of combustible material inside.

Other key findings of the report include:

- The Kentucky Office of Occupational Safety and Health conducted several comprehensive inspections of CTA, but did not cite the combustible dust hazard.

- Numerous inspections by insurance companies failed to identify phenolic resin dust as an explosion hazard in an eight-year period prior to the accident.

- The Kentucky fire marshal's office, which has the responsibility to enforce fire safety standards, does not routinely inspect industrial facilities, and had never inspected the CTA facility, which was built in 1972.

CSB Chairman Carolyn Merritt said, "What this report reveals are many missed opportunities to prevent this explosion. The company, the supplier, state regulators, and private insurers all overlooked the deadly hazard posed by combustible dust that was allowed to accumulate and which was handled unsafely during manufacturing and maintenance operations."

"Following the Jahn Foundry explosion in 1999, Borden drafted a letter to its phenolic resin customers to alert them to the danger but never sent it," Ms. Merritt said, adding that many of the CSB's recommendations are aimed at making certain that adequate warnings of combustible dust hazards be communicated effectively in the future.

The report also points out that neither the federal Occupational Safety and Health Administration (OSHA) nor the Kentucky Office of Occupational Safety and Health has a comprehensive standard that addresses combustible dust safety for industrial facilities.

"In order to gain a greater understanding of the hazards of combustible dust in industrial settings, we are now conducting a nationwide study of such accidents," said Bill Hoyle, lead investigator. "Preliminary information indicates more than 150 serious industrial dust explosions have occurred in the U.S. over the last 20 years. We will be looking at the adequacy of federal and state regulations covering these industrial hazards, as well as building and fire codes," Mr. Hoyle added.

The accident occurred only a few weeks after a polyethylene dust explosion and fire killed six workers at a rubber manufacturing plant in Kinston, NC, which the CSB investigated (the report is available at The agency also is investigating a dust explosion at the Hayes Lemmerz plant in Huntington, IN, which occurred October. 29, 2003.

In its report, the CSB recommended CTA develop a program using the good practice guidelines of the National Fire Protection Association (NFPA) including:

- Minimizing surfaces where combustible dust could accumulate.

- Ensuring its facility is designed to prevent the spread of fires or explosions involving combustible dust by using firewalls and blast resistant construction.

- Cleaning process areas frequently, using appropriate dust cleaning methods, to prevent accumulation of dust.

- Ensuring that workers know the dangers of combustible dust and are appropriately trained.

CSB investigators listed several root and contributing causes:

- CTA management did not implement effective measures to prevent combustible dust explosions, such as those contained in NFPA Standard 654, and did not communicate the hazards to its workers. - The CTA cleaning and maintenance procedures for production lines did not prevent the accumulation of unsafe levels of combustible dust.

- The facility design by the original owner, CertainTeed Corporation, and subsequent building modifications by CTA, did not adequately address the fire and explosion hazards associated with combustible dusts. - The Borden Chemical product stewardship program did not adequately convey to CTA the explosive hazards of phenolic resin.

- The design and installation of the Line 405 oven did not include adequate fire protection equipment.

- The CTA incident investigation program was inadequate.

- CTA did not have effective procedures for evaluating the hazards associated with non-routine operating conditions on line 405.

Other CSB recommendations included one urging that Borden Chemical strengthen warnings in its phenolic resin MSDSs and distribute additional educational material about the dust explosion hazard. The report also recommends that the Kentucky OSH office distribute an educational bulletin on preventing combustible dust explosions. The Kentucky Office of Housing, Buildings, and Construction, which oversees the office of the state fire marshal, was urged to identify sites that handle combustible dusts in order for them to be inspected.

The CSB is an independent federal agency charged with investigating industrial chemical accidents. The agency's board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in safety management systems.

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

For more information, contact Daniel Horowitz, 202-441-6074 (cell), Sandy Gilmour, 202-251-5496 (cell) or Kara Wenzel, 202-577-8448 (cell).

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