Whether you’re a chemical engineer designing production equipment or one supervising operations and maintenance, you need to be aware of combustible dust risks. Increasing fines and incidents, such as the deadly 2013 explosion at the West Fertilizer Company site near Waco, Texas, are impacting the chemical industry.
This article provides a roadmap for evaluating your dust and process hazards, and suggests steps to plan a suitable mitigation strategy for your unique risk profile.
The Regulatory Landscape
Chemical processors must balance product output with the responsibility to address risks posed by dust-producing materials and processes. How you address such risks impacts production and how your plant fares during inspections from a growing host of regulators. Such “authorities having jurisdiction” (AHJs) include fire marshals, insurance appraisers, code enforcers and U.S. Occupational Safety and Health Administration (OSHA) inspectors. AHJs can prosecute, issue fines, deny permits or even shut down production if they consider the way you address your hazards to be unacceptable.
No one explicit regulation harmonizes all the others, so your method of risk management must satisfy all pertinent standards and codes, potentially including:
• Fire and chemical codes of the International Code Council;
• National Fire Protection Association (NFPA) standards;
• FM Global or other property loss insurance company guidance;
• OSHA’s General Duty Clause safeguarding workers;
• State and municipal codes; and
• Corporate codes and standards.
Some of the more-detailed risk mitigation guidance comes from NFPA standards, which many municipalities adopt as their legally enforced codes. NFPA 654, “Standard for the Prevention of Fire and Dust Explosions…,” and the more recently released NFPA 652, “Standard on the Fundamentals of Combustible Dust,” outline a requirement for all facilities that handle, process or produce combustible dust to complete a dust hazards analysis (DHA). If risks emerge in the DHA, you’ll need to address them with a defensible mitigation strategy.
Steps In A Hazards Analysis
Completing a DHA takes you through key questions about combustible-dust-related risks, including questions on the probability of combustion events and the potential consequences if one occurs. Both the properties of your dusts and the processes present in your facility will impact how you respond to these questions. After a hazards analysis, you’ll have information to help you plan a risk mitigation strategy that can address both fire and explosion risks.
Here are some key questions you’ll want to address in a DHA:
1. Are any dusts combustible or explosible, and what level of combustion risk do those dusts represent?
2. What other risks or hazards do the dusts pose?
3. Where and how are nuisance dusts released in your facility, and how can you reduce such releases?
4. How can you decrease the likelihood of combustible dust events?
5. How can you minimize the consequences should a combustible-dust-related fire or explosion occur?
Let’s walk through these key questions.
1. Determine dust combustibility. Operations at chemical plants often involve producing or handling particulates that are flammable or explosible. A wide variety of raw materials may pose concerns. Also, consider liquids in your production process that represent combustion risks.