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A Summary of the Reissued OSHA Combustible Dust NEP

On October 18, 2007, OSHA published a directive for inspection of workplaces that create or handle combustible dusts. On March 3, 2008, OSHA reissued this directive “to increase its enforcement activities and to focus on specific industry groups that have experienced either frequent combustible dust incidents or combustible dust incidents with catastrophic consequences.” The new directive increases activities in outreach, training, the creation and dissemination of guidance and educational materials and cooperative ventures, as well as enhancing its enforcement activities. Read more

Analysis of PRV Stability In Relief Systems Part IV

An independent and accurate estimation of the speed of sound can provide an important quality check for a multitude of single and multi-phase flow applications. More recently, proposed screening methods for the calculation of PRV stability require an accurate estimate of the speed of sound for the fluid/piping system. This paper outlines proper methods for the calculation of thermodynamic properties and speed of sound for single and multi-phase systems. Comparisons with actual measurements indicate that credible values can be obtained for single and multi-phase systems. Read more

Changes to the 2013 Edition of NFPA 654

After much anticipation, the new 2013 Edition of NFPA 6541, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids, has finally been issued. This is one of the key standards utilized for safe handling of combustible solids. Several important updates and additions were incorporated into this edition of the standard, including: Updated definition of a combustible dust, added determination method for a dust flash fire or explosion hazard area, added housekeeping frequency specification and cleaning methods, updated recommendations for separation, segregation, or detachment, updated usage specifics for flexible and rigid intermediate bulk containers, strengthening of included safety management systems (SMSs), and added contractor and subcontractor management system. Read more

Chemical Interaction Matrices

Despite the promulgation of the “PSM Standard” by OSHA in 1992, chemical accidents continue to occur at an alarming rate. As part of the process safety information element of the standard, OSHA requires reactivity data on the chemicals in the process. Part of this reactivity data is a chemical interaction matrix. Several software programs provide simple approaches to generating these interaction charts for common materials using assigned reactive groups. If your process involves materials not included, you are left to determine the reactivity and incompatibilities on your own. This presentation will explain a process for assigning reactive groups using chemical classification and structural analysis. This process can be used for less commonly understood materials such as additives, lubricants, etc. that may come into contact with process chemicals. Read more

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. A recent survey conducted by the US Chemical and Safety Hazard Investigation Board (CSB) concluded that reactive chemicals present a significant safety problem for the chemical process industries. Key root causes identified by the CSB survey included technical and management systems failures. This underscores the importance of the need to understand and manage chemical reaction hazards more effectively. We also believe that the “quality” of implementation, change management, and auditing of corporate PSM programs is the culprit. We focus in this short paper on incidents caused by runaway reactions and provide guidance on how to improve the “Quality” of managing chemical reactions hazards through a combination of screening and experimental tools. Read more