Making Sense of Combustible Dust PHAs

Process hazard analyses (PHAs) have been conducted for decades in many industries. First conceived at ICI in the 1960s (Kletz, 2009), they have been refined and adapted for various applications, now finding their way into combustible dust hazard management. No matter the industry, the premise is the same, identify hazards, understand their causes and consequences, implement safeguards, and risks will be managed. The CCPS Guidelines for Hazard Evaluation Procedures, Third Edition, states: “A hazard evaluation is an organized effort to identify and analyze the significance of hazardous situations associated with a process or activity.” (Center for Chemical Process Safety, 2008). Keeping these in mind, a simple inclusive approach can be developed and applied.

Several NFPA standards on combustible dust contain provisions for conducting process hazard analyses. The newest standard, NFPA 652, Standard on the Fundamentals of Combustible Dust, 2016 Edition, (NFPA, 2016) became effective on September 7, 2015. It requires that dust hazards analyses (DHAs) be completed on existing facilities and large modifications. The legacy standard, NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids, 2013 Edition, (NFPA, 2013) contains requirements for process hazard analysis that includes hazard assessments. If the facility falls under an industry- or commodity-specific (dust specific) NFPA standard (e.g., metals, agricultural and food, wood processing and woodworking, and sulfur) different hazard analysis requirements may apply. All of these competing recommendations and requirements can make it difficult to know where to start and what approach to use.

This article will summarize the specific requirements in the standards and present some guidance to meet them. The result is a basic, easy to apply approach that will guide implementation of this critical technique.