White Papers

How to Conduct a Dust Hazards Analysis

The 2016 Edition of NFPA 652 (NFPA, 2016) requires a dust hazards analysis (DHA) of existing processes by September 7, 2018. (DHAs are also needed for material modifications that exceed 25% of the original cost.) A dust hazards analysis is defined by NFPA as “A systematic review to identify and evaluate the potential fire, flash fire, or explosion hazards…” where combustible particulate solids are processed or handled. Read more

InterScience Reactivity Screening Made Easy

During the past decade, large efforts were made by the US chemical and petrochemical industries to implement and maintain effective process safety management (PSM) and responsible care programs. Despite these large investments, incidents continue to occur at an alarming frequency. Many executives of leading companies are trying to understand why. Read more

Key Safety Issues for Combustible Dust Handling

As part of a Combustible Dust National Emphasis Program (NEP), OSHA conducted focused inspections of facilities that generate or handle combustible dusts. Some of these facilities were not even aware that they were handling combustible dusts and may not have been familiar with the necessary safeguards to safely handle these materials. Read more

Laminar Flame Speeds Data Collection

Regarding vessels and tubes containing combustible gases or dusts, it is important to acquire knowledge on the conditions under which a fuel and oxidizer could undergo explosive reactions. These conditions are strongly dependent on the pressure and temperature. Given a premixed fuel-oxidizer system at room temperature and ambient pressure, the mixture is essentially unreactive. However, if an ignition source is applied locally and the composition of the mixture is within certain limits (the so-called flammability limits), a region of explosive reaction can propagate through the gaseous mixture due to mainly two phenomena: (1) Temperature rises substantially, (2) High concentration of radicals to form. Characterizing potential explosive reactions is one of the main objectives of hazard assessment. Safeguards to be implemented in process equipment, best process conditions, appropriate prevention and/or mitigation measures, are some of the key purposes to be clarified when handling flammable mixtures. This characterization requires knowledge of several parameters that directly influence on the explosive reaction behavior. One of these parameters is the Laminar Flame Speed, which is one of the key factors that define the kinetics of the reaction. The present paper addresses how to characterize fuel-oxidizer explosive reactions, and highlights the importance of the laminar flame speed concept. The main purpose of this study is to provide reliable data regarding laminar flame speeds with the aim to ensure accurate calculations for hazard assessment purposes. Read more

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. Read more

No Nonsense Approach to Addressing the Combustible Dust Hazard

February 7, 2008, was the pivotal point where recognizing the severity of dust hazards was pushed to the forefront of industry concerns. This was the date that a huge explosion occurred at the Imperial Sugar refinery in Savannah, Georgia. There were 14 deaths and 38 injuries, including an additional 14 serious burns. Read more