Oct 5, 2005
CSB Determines Fatal 2003 Incident at Hayes Lemmerz Plant in Indiana Most Likely Caused by Explosion in Dust Collection System; Company Did Not Identify or Control Hazards of Aluminum Dust
Huntington, Indiana, Oct. 5, 2005 - The fatal explosion and fire at the Hayes Lemmerz International, Inc., aluminum wheel plant was caused by the ignition of fine powdered aluminum in a dust collection system in which hazards were neither identified nor adequately addressed, the U.S. Chemical Safety and Hazard Investigation Board (CSB) said today in issuing its final report on the incident.
The explosion, which occurred around 8:30 p.m. Oct. 29, 2003, caused fatal burns to a mechanic working near an aluminum melt furnace, severely injured a second mechanic nearby, and caused lesser burns to a third worker. Four other workers suffered minor injuries.
CSB investigators determined that the dust that exploded originated in a scrap system at the facility. A high concentration of aluminum dust, when suspended in air, is highly combustible. The CSB determined the dust was a byproduct of the process in which aluminum chips and scraps -- which are created as the wheel castings are machined -- are dried prior to being sent to a furnace for re-melting. Dust from the scraps is conveyed into a dust collector outside the building. The CSB determined that an explosion in the collector sent a pressure wave through the system ductwork and back into the building. A fireball then erupted inside the building, which lofted and ignited further aluminum dust that had accumulated on rafters and equipment.
The Board found the company did not address why the chip drying system was releasing excess dust, and did not identify or address the dangers of aluminum dust ignition, despite having a history of small dust fires inside the factory. The CSB also determined that Hayes Lemmerz did not ensure the dust collector system it ordered was designed in accordance with guidance in a prominent fire code published by the National Fire Protection Association.
CSB Chairman Carolyn Merritt said, "This accident followed a classic syndrome we call 'normalization of deviation,' in which organizations come to accept as 'normal' fires, leaks or so-called small explosions. The company failed to investigate the smaller fires as abnormal situations needing correction or as warnings of potentially larger more destructive events. The CSB almost always finds that this behavior precedes a tragedy."
Chairman Merritt noted that aluminum dust collection systems are at particular risk. "The report indicates that aluminum dust is among the most explosive of all metal dusts and the conditions in dust collectors that are not properly designed, installed or maintained present the ideal environment for an explosion and fire," she said.
The report refers to the National Fire Protection Association's NFPA 484 code as an important prevention document for companies to use to reduce the risk of such an explosion. "In this circumstance, NFPA 484 provisions were not being followed and the risk of such an explosion at this facility was extremely high," Chairman Merritt said.
Chairman Merritt cited chemical dust as a particularly insidious danger needing careful hazard analysis and treatment. Noting the CSB is conducting a separate, comprehensive study of the hazards of dust in the workplace following the Hayes Lemmerz incident and two other dust explosions the CSB investigated in Kentucky and North Carolina, Ms. Merritt said, "As has happened in other plants, combustible dust can accumulate on rafters, above false ceilings, on top of equipment, in ventilation ducts and dust collectors just waiting for the right conditions of suspension and ignition. Processes where such dust is created are at risk and must take special care to eliminate the combustible dust hazard."
Because of the destruction, the CSB was not able to identify the exact ignition source that started the explosion chain. Investigator John Vorderbrueggen said, "Any number of sources can set off an explosion, including hot surfaces, electrostatic discharges, or burning embers. What's important to note is that when that much dust accumulates, and becomes suspended in air, it takes very little energy to set off an explosion."
The CSB listed among 22 key findings the company's "inadequate housekeeping" in the foundry area and "insufficient maintenance" of the chip processing equipment, leading to the dust accumulation that fueled the secondary explosion. In particular the findings noted the dust collector filters were infrequently cleaned, some ducts leaked dust because they were eroded, maintenance workers were not wearing flame-retarding clothing at the time of the accident, and the company did not have formal written maintenance procedures or employee training in place for the dust collector system.
The Board further noted that fire inspectors in Indiana have not been trained on recognizing or preventing combustible dust hazards.
The Board issued formal recommendations to the company, urging among other things that it develop and implement a means of handling and processing aluminum chips that minimizes the risk of dust explosions, and implement regular training on such hazards. The CSB recommended the Indiana Occupational Safety and Health Administration develop and distribute an educational bulletin on metal dust explosion prevention, and urged the Indiana Department of Fire and Building Services provide training for fire inspectors on recognition and prevention of combustible metal dust hazards.
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. Please visit our website, www.CSB.gov. For more information, contact Sandy Gilmour 202-261-7614, cell 202-251-5496, or Lindsey Heyl, 202-261-3614, cell 202-725-2204.