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October 16, 2013
Combustible dust standard is CSB's first 'most wanted safety improvement'

In 2006, in the wake of a series of deadly major explosions and fires caused by combustible dusts, the U.S. Chemical Safety Board (CSB) issued a set of recommendations for controlling these hazards.

Just 2 years later, a combustible sugar dust explosion at the Imperial Sugar Company in Port Wentworth, Georgia, killed 14 workers, and the CSB renewed its call for federal OSHA to “proceed expeditiously” on its dust standard rulemaking. But the rule remained uncompleted.

In 2011, three iron dust-related flash fires at the Hoeganaes Corporation facility in Gallatin, Tennessee, killed five workers. The CSB added metal dusts to its recommendations and urged OSHA to issue a proposed rule within 1 year.

As of now, no federal combustible dust rule has been released, and the CSB is taking steps to increase pressure on OSHA to issue one.

CSB’s most wanted

The CSB is not a regulatory agency. It is an independent federal agency that conducts root cause investigations of chemical accidents at fixed industrial facilities. Based on its findings, the CSB makes recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and the Environmental Protection Agency (EPA).

To better advocate for the adoption of its recommendations, the CSB created a program in 2012 to identify its “most wanted” changes list. The CSB’s “Most Wanted Safety Improvement” program is modeled on a similar one used by the National Transportation Safety Board (NTSB) another independent agency that makes recommendations to industries and regulatory agencies.

The program is intended to highlight safety issues identified by accident investigations and increase industry, congressional, and public awareness about these priority issues and recommended safety solutions.

In July 2013, the CSB named its first Most Wanted Safety Improvement: a general industry combustible dust standard. The CSB will strongly advocate for such a program to be implemented within the next 3 years.

OSHA published an advance notice of proposed rulemaking (ANPR)—a request for information to be used in creating a standard—relating to combustible dust, on October 29, 2011. Progress has since stalled; OSHA did not list this proposed rulemaking on its most recent regulatory agenda.

In California, however, a standard regulating combustible dust already exists. The state’s General Industry Safety Orders (GISO) Section 5174 requires employers to:

Control sources of ignition. Whenever a dust explosion is possible, all sources of ignition must be eliminated. If combustible material is process in grinding, shredding, or pulverizing equipment, pneumatic or magnetic separators must be provided to remove metal or foreign matter that could spark or ignite the combustible material.

Static electricity is a source of ignition that requires special attention because it can form during the production of combustible dusts. To prevent a buildup of static electricity:

  • All machines, conveyors, housings, and conductive surfaces in locations where combustible dusts are generated or present must be electrically bonded.
  • Hoses and nozzles used in collecting or blowing dusts must have electrical continuity maintained along the entire length from coupling to nozzle, and must be bonded to ground.
  • Static electricity must be removed from belts from grounded metal combs or other static elimination devices.

Practice good housekeeping. Do not allow dust to accumulate on floors, ledges, beams, equipment, machines, or anywhere it may cause a fire or explosion hazard. All enclosed areas where combustible dusts are generated or are present (except for closed or covered containers) must be cleaned as often as necessary to prevent dust accumulation. Employer must provide a safe means of access for cleaning all surfaces.

Collect and segregate dusts at the point of generation. When deflagration explosions occur, the accompanying pressure wave can burst or rupture the enclosure.

To prevent this, machines and equipment that pose a dust explosion hazard must be located, constructed, enclosed, or vented so the force of an explosion in the machine or equipment will be dissipated without endangering employees in the regular performance of their duties.

Dust collectors for combustible dusts that present an explosion hazard must be located outdoors or in detached rooms of fire-resistant construction (except for liquid-spray types). They must be provided with adequate explosion vents.

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