‘Incredibly destructive’: Safety board publishes report on fatal dust explosion

Washington — Hazards related to combustible dust “must be controlled beyond the existing regulatory requirements,” says the Chemical Safety Board, which has renewed its call on OSHA to begin rulemaking on a general industry standard.

CSB recently released a final report on a fatal May 2017 explosion and fire at the Didion Milling dry corn mill in Cambria, WI. Five workers were killed and 14 were injured.

CSB investigators found that the company neglected to develop and implement a written program on combustible grain dust, and failed to install venting or suppression on a dust filter collector to prevent an explosion. However, the agency notes that Didion Milling wasn’t required to enact various safety management systems because OSHA lacks an overarching general industry standard for combustible dust.

CSB recommends that an OSHA standard address hazard recognition, dust hazard analysis, incident investigation, engineering controls, operating procedures, process safety information and training.

Other recommendations:

• Employers should ensure pneumatic transport and dust collection ductwork is designed to maintain a minimum transport velocity.
• Engineering controls such as detection, suppression, isolation, venting and pressure containment should be used during the design of dust safety systems.
• Employers should review fire and building codes to determine the type of construction and evaluate additional requirements based on the materials being handled.
• Employers should ensure the standards applied are applicable and appropriate to hazards inside the facility.
• Employers should consider abnormal and upset conditions when assessing personal protective equipment.

“Combustible dust explosions and fires can be deadly and incredibly destructive,” CSB Chair Steve Owens said in a press release. “The terrible tragedy at Didion was made even worse due to the lack of important safeguards in the design of the mill equipment and the lack of engineering controls at the facility that could have reduced the potential for serious fires and explosions.”