Investigators from the U.S. Chemical Safety Board (CSB) have concluded that an explosion and fire at Catalyst Systems Inc. in Gnadenhutten, Ohio, last January most likely occurred when 200 pounds of benzoyl peroxide in a vacuum dryer rapidly decomposed. The runaway chemical reaction produced large volumes of gas under high pressure.
Presenting their findings in the form of a case study to the five-member CSB Board in Washington, DC, today, investigators said they were unable to determine the specific initiating event that led to the thermal decomposition, in which a chemical breakdown produces heat that leads to further breakdown. But the study noted the likely underlying cause of the accident was that management had not put in place a proper hazard identification system.
The force of the explosion propelled the heavy vacuum dryer like a rocket across the room and through a wall, causing extensive damage to the building, but missing workers eating lunch just 35 feet away in the same room.
The operators described thick black smoke with rolling flames and a loud boom. They quickly exited the building. One worker received a puncture wound in his shoulder, most likely from flying debris.
CSB Board Chairman Carolyn Merritt said: "The workers were fortunate they were not standing by the vacuum dryer at the time of the explosion. This is another example of the dangers of not recognizing the inherent hazards of materials being handled, not using properly designed equipment, and not performing hazard identification studies. We noted this in our major report on reactive hazards last year, and I remain determined to continue our work focusing the industry on these hazards. Small businesses also need to know they must follow safe handling practices."
The purpose of the process was to concentrate benzoyl peroxide, or BPO, to 98 percent by drying it. In this form BPO is the consistency of beach sand, and can decompose explosively when overheated. BPO is used to make a number of products, including plastics, silicone rubber, and automobile body putty.
The process, involving highly reactive materials, was not sufficiently evaluated by management, the study said, adding that Catalyst Systems had no program to formally take the hazards, generally well known in the industry, into account in the design of the dryer. The study found the dryer had been purchased second-hand, with no wiring diagram or engineering drawings. No written operating procedures were developed for drying the chemical only verbal instructions were provided operators.
Lead investigator Lisa Long said: "The accident might have been avoided had the company evaluated the potential hazards in their process and used this information to design appropriate safeguards into the drying process."
The case study notes that management systems including explicit, detailed procedures and practices and clear statements of accountability for implementing the procedures and practices -- are vital for preventing catastrophic accidents, particularly where hazardous materials are used. Management systems are developed after considering a range of information, including the hazardous properties of chemicals and equipment design. The case study says, "Catalyst Systems did not have a process safety management program in place, nor were employees trained in the use of these systems."
While not determining the specific initiating event of the explosion, the study listed several probable sources. These included failure of a temperature probe, a hot spot in the dryer, failure of the vacuum pump, and leaving the chemical in the dryer too long.
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.
For more information, contact Daniel Horowitz, 202-261-7613 / 202-441-6074 (cell) or Sandy Gilmour Communications, 202-261-7614 / 202-251-5496 (cell).