Page 16 - Occupational Health & Safety, May 2018

COMBUSTIBLE DUST
Handling Combustible Dusts
The biggest mistake food manufacturers make is assuming that because their plants have been in operation for years without accidents and without being cited, they are in compliance.
BY DAVID KENNEDY Many in the manufacturing industry are not knowledgeable about combustible dusts and the potential impact of those dusts on their business. Accidents such as the massive explosion at the Imperial Sugar fac- tory in 2008 and increasingly stringent regulation and enforcement of standards for managing combus- tible dusts have raised awareness in the field. Under a Combustible Dust National Emphasis Program (NEP) reissued in 2008 following the disaster at the Imperial factory, OSHA is increasing its vigilance and enforcement of worker safety regulations in plants that handle combustible dusts, which include almost
every food manufacturing plant.
Lessons Learned from Imperial Sugar
The four-story Imperial Sugar refinery on the bank of the Savannah River was built in 1916. The facility was about 872,000 square feet, and it refined 14.51 million hundredweight of sugar in the last full fis- cal year before the disaster. The explosion occurred at around 7 p.m. on Feb. 7, 2008, and the cause was determined to be sugar dust. Fourteen people were killed and 42 injured.
Imperial Sugar was a poster child for a problem that is highly prevalent in the industry—older facili- ties using antiquated equipment without awareness of the danger of combustible dusts. Newer plants are designed with that danger in mind, but decision mak- ers at older plants may erroneously assume that their older equipment and facilities are grandfathered in, or that dusts are not a problem. The truth is that in any situation where any kind of powder is being handled, precautions must be taken to control combustible dusts in line with regulations.
About Combustible Dusts
Almost every organic product is combustible. That includes sugar, cocoa, flour, spices, and starch. Any plant that handles grain products like wheat flour or corn flour is dealing with combustible dust. Other ex- amples include whey powder, nonfat dried milk, egg white powder, and gluten. Artificial sweeteners are particularly dangerous, as they are highly explosive.
Flour milling, sugar drying, spray drying of liq- uids, and handling of grains are processes that com- monly generate combustible dust. Milling and grind-
Explosions commonly begin inside a piece of equipment, such as a dust collector or dryer, so a thorough inspection will include the insides of all equipment.
ing are also risky operations. Once a cloud of dust is created, an ignition source can quickly lead to an explosion. Catastrophic explosions occur when an initial primary explosion is followed by a secondary explosion of dust released by the first explosion.
A 2006 study by the U.S. Chemical Safety Board found that there were at least 281 dust explosions in the United States between 1980 and 2005, killing 119 workers and injuring 718. Statistics on combustible dust explosions are thought to be under-reported. If an incident occurs and no one is injured, it may be quietly corrected.
Under OSHA’s NEP, it is inspecting facilities that generate or handle combustible dusts that pose a haz- ard. A plant may comply with local fire department regulations but still run afoul of OSHA. In spite of OSHA’s stepped-up vigilance, the Chemical Safety Board documented a further 35 explosions, with 26 dead and 128 injured, since the beginning of 2008.
The National Fire Protection Association issues consensus standards related to combustible dusts, in- cluding guidelines for testing dusts for the potential to cause a fire or explosion.
Preventing Dust Explosions
The biggest mistake food manufacturers make is as- suming that because their plants have been in opera- tion for years without accidents and without being cited, they are in compliance. It is the manufacturer’s responsibility to know the regulations and bring all facilities up to date. Measures for mitigating risk from combustible dusts include those that prevent dust ex- plosions and those that protect human life when those explosions occur.
Because retrofitting is costly, many plant managers attempt to economize by meeting the bare minimum that regulations require. Unfortunately, that strategy can leave gaps in safety coverage.
The first step in assessment of combustible dust hazards is a Process Hazards Analysis (PHA), in
16 Occupational Health & Safety | MAY 2018
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