Sounding the Alarm on Dust Explosions

By Matthew Harwood

Fire and safety stakeholders continue to neglect the  threat of chemical dust explosions, a government safety official warned.

The cautionary note comes five months after a dust explosion ripped through an Imperial Sugar Company plant in Port Wentworth, Georgia. The blast killed 13 and injured 37.

William E. Wright, member of the U.S. Chemical Safety and Hazard Investigation Board (CSB), gave a detailed presentation of the threat and precautionary measures to perform to stakeholders at the National Fire Protection Association's (NFPA) World Safety Conference this week in Las Vegas.

To help promote awareness of chemical safety the CSB investigates chemical incidents, determines the incident's causes, and makes recommendations.

According to a CSB study of incidents between 1980 and 2005, there have been 281 dust fires and explosions in the United States. The incidents have killed 119 people and injured 718 people injured. More fatal incidents have occured since, says Wright, noting the deadly explosion at Imperial Sugar.

For a dust explosion to occur, Wright explains, five factors must be present: fuel, oxygen, confinement, dispersion, and ignition. Common explosive dusts incude aluminum, coal, flour, plastics, powder coatings, resins, rubber, and sugar. Even light accumulations of dust, when disturbed, can create an explosive dust cloud under the right conditions, he says. The worst explosions are known as the "double whammy." First, a dust explosion occurs within equipment, which disperses external dust into the air, which then ignites due to the primary explosion.

While CSB hazardous communications, NFPA consensus standards, state and local fire codes, voluntary initiatives, and Occupational Safety and Health Administration standards all exist to provide guidance to industry to prevent dust explosions, but some government resources fail to adequately present the risk.

Material Safety Data Sheets (MSDS), says Wright, do not "adequately convey combustible dust hazards," while OSHA's Hazard Communication Standard does not explicitly apply to combustible dusts and does not list them in its list of physical hazards.

This could change soon. The U.S. House of Representatives approved a bill in early May that gives OSHA 90 days to write new safety standards and final safety standards; the bill is now before the Senate. The Bush Administration says it would veto the bill if passed by the Senate because it "has serious concerns with the expedited and one-size-fits-all regulatory approach required by the bill," the Associated Press reports.

Whether or not there are enforceable government standards, Wright argues companies should do their best to weigh the risks of not investing in safety. He is fond of quoting Dr. Trevor Kletz, an adjunct professor of process safety at Texas A&M University, who says, "If you think safety is expensive, try an accident!"

For instance, the CSB discovered that if British Petroleum had invested $25 million in safety at its plant in Texas City, Texas, it could have avoided a liquid hydrocarbon vapor cloud explosion in 2005 that killed 15 workers and injured 180 others. The company has since spent $4 billion in litigation fees, infrastructure improvements, and other associated costs due to the explosion.

The same lesson should apply to companies that experience a dust explosion, says Wright.

According to John M. Cholin, a fire protection engineering consultant, in each example of a dust explosion presented by Wright, the company had not complied with the relevant NFPA standards to prevent dust explosions.

Even after the explosion at its Port Wentworth plant, OSHA had to shut down another Imperial Sugar plant in Gramercy, Louisiana, because, in the words of Edwin G. Foulke, Jr., assistant secretary of labor for OSHA, because "there was a very thick dust level" which presented an "imminent danger situation."

The CSB, however, does not have the power to shut down plants. It's not an enforcement agency, says Wright, and has no authority to assess fines or penalties when its recommendations are not enforced.

The best the board can hope for, according to Wright, is to promote enough awareness through its investigations, reports, and congressional testimonies that firms globally enact the proper measures to prevent chemical accidents, such as dust explosions, from occurring.

Currently, the CSB is educating firms to understand what constitutes a dust hazard, increase worker training and awareness, conduct periodic risk audits, and ensure facilities have adequate detection and suppression systems to snub out a threat before it becomes a tragedy.

CSB also advises companies to take the requisite preventative actions such as minimizing the accumulation of dust, reducing oxygen levels in confined collection systems, and eliminating ignition sources.

CSB was established by Congress in 1990 as part of the Clean Air Act to help ensure a chemical explosion like the Bhopal disaster in India did not occur in the United States.

The 1984 chemical leak at Union Carbide's Bhopal, India plant released methyl isocyanate into the surrounding area exposing approximately 200,000 people to the toxic gas, initially killing anywhere between 2,500 and 3,800 people, while another 14,000 are estimated to have died in the aftermath due to their exposure.


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