Many organizations could be vulnerable to catastrophic events, but they have not taken sufficient and proper steps to identify and truly understand their potential chemical reactivity hazards. If chemical reaction hazards are not identified during development or scale up of a process early on, they cannot be properly managed later on.
Read this article to explore key lessons on chemical reactivity from a 2020 runaway reaction at a West Virginia toll manufacturer, along with common testing methods for evaluating desired and undesired chemical reactions. The test data can be used to develop kinetic models for profiling thermal stability and for pressure relief and vent containment design, as well as for process optimization.
On December 8, 2020, a fatal explosion occurred at a toll manufacturer in Belle, West Virginia. On the day of the incident, the facility was dehydrating a chemical product in batches using a rotary double cone dryer. The dryer exploded, and toxic chlorine gas released to the atmosphere. The incident led to one fatality and two injuries, as well as a shelter-in-place for community members within a 2-mile radius of the facility. [1]
The U.S. Chemical Safety and Hazard Investigation Board investigation identified 5 key safety issues that led to the fatal thermal runaway reaction, explosion, and chlorine gas release:
Process Knowledge Management: The client failed to pass critical process safety information (PSI) a technology package regarding the decomposition characteristics and safe operational temperature limits of the chemical (sodium dichloroisocyanurate dihydrate / CDB-56®) to the toll manufacturer.
Thermal Hazard Assessment: None of the entities involved conducted proper testing or evaluations — such as Differential Scanning Calorimetry (DSC) or Accelerating Rate Calorimetry (ARC) to analyze the thermal sensitivity and reaction kinetics of the compound during dehydration.
Equipment Selection and Process Design: The toll manufacturer selected a double-cone rotary dryer that was not designed or properly sized for CDB-56® dehydration.
Tolling of Hazardous Materials: Flaws in contract/tolling management led to critical gaps in oversight. Clear roles, responsibilities, hazard communication, and technical reviews between the client, the broker, and the toll manufacturer were not established or followed according to industry tolling safety guidelines (i.e., CCPS publication “Guidelines for Process Safety in Outsourced Manufacturing”).
Regulatory Coverage of Reactive Hazards: Chlorinated isocyanurate compounds like NaDCC dihydrate can undergo self-accelerating decomposition, yet they are not explicitly listed on OSHA or EPA highly hazardous chemical list.
Chemical reactivity and thermal stability data cannot be inferred from generic Safety Data Sheets (SDSs) or legacy product sheets; they must be empirically measured for the specific process conditions, equipment geometry, and operating parameters used.
There are numerous existing, proven, and efficient tools and a systematic process that can be used to identify and manage chemical reaction hazards. It cannot be assumed there are no reactivity hazards if none have been previously identified in current literature or previous process descriptions. Often reactivity screening has simply never been completed. The reactivity screening methods chosen play an important role in cost-effective reactivity management systems.
Expert interpretation of test data can be extremely useful in determining if the measured data is reliable or not. Not every measured data set is a good data set. Critical tests should be repeated. ISO certified testing laboratories should be used if testing is to be contracted to third-party testing laboratories.
Ultimately, the main requirement is for a coherent and consistent approach using the best means available. All instruments and methodologies have inherent strengths and weaknesses. Diversity of approach stimulates active interpretation and understanding and avoids common mode errors.
[1] U.S. Chemical Safety and Hazard Investigation Board. (2023, July 6). Fatal Chemical Decomposition Reaction and Explosion at Optima Belle LLC. https://www.csb.gov/assets/1/6/optima_report_for_publication.pdf
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