The U.S. Chemical Safety and Hazard Investigation Board (CSB) released its final report on the December 8, 2020, fatal incident at toll manufacturer Optima Belle LLC in Belle, West Virginia. The incident occurred during Optima Belle’s production of a sanitizing compound for Clearon Corp. A dryer at the Optima Belle facility that was removing water from the compound exploded, resulting in an employee's death and significant property damage and a shelter-in-place order for the neighboring community.
CSB Chairperson Steve Owens said in a press release, “Our report identifies a number of factors that led to this needless tragedy. In addition to issues with the production process, OSHA’s and EPA’s regulations do not adequately protect against hazards presented by reactive chemicals. Stronger regulations addressing reactive hazards will help keep similar incidents from occurring in the future, prevent deaths and help protect workers at these facilities and the families who live nearby.”
As part of the agreement, Optima Belle was dehydrating CDB-56 (sodium dichloroisocyanurate (NaDCC) dihydrate, an isocyanurate compound) to make anhydrous NaDCC. While dehydrating CBD-56 inside a pressure-rated rotary double cone dryer, the isocyanurate compound underwent a decomposition reaction, releasing gases that increased the dryer’s internal pressure to above its design pressure. At approximately 10 p.m. on December 8, 2020, the dryer exploded, releasing toxic chlorine gas.
The CSB’s report identifies several key safety issues:
Process Knowledge Management: Clearon lacked effective process knowledge management systems, and as a result, it did not deliver Optima Belle critical safety information as part of the tolling arrangement – Optima Belle was therefore unaware of the circumstances and temperatures that could lead to the hazardous decomposition of the compound they were working with.
Thermal Hazards Assessment: None of the parties involved in the operation effectively assessed the hazards of the chemical being worked with and the circumstances that could possibly lead to a runaway chemical reaction.
Equipment Selection and Design: Optima Belle did the work using equipment that was not designed or sized for the CDB-56 dehydration operation involved in the tolling agreement. It did not verify the adequacy of the dryer’s cooling or pressure relief systems during a decomposition reaction. Laboratory or pilot scale studies were also not conducted for the tolling operation.
Tolling of Hazardous Materials: Companies often augment in-house production by outsourcing chemical processes and other operations. These agreements are called tolling contracts. Clearon established a tolling contract with RCI, who in turn contracted with Optima Belle. The Center for Chemical Process Safety (CCPS) provides industry guidance for safe and effective tolling arrangements. The dryer explosion might have been prevented had Clearon and Optima Belle applied the suggested industry guidance.
Regulatory Coverage of Reactive Hazards: The facility was working with an isocyanurate compound that can undergo self-accelerating decomposition when heated. The reaction may lead to an explosion, fire and toxic emission with severe impacts to people, property and the environment. Yet, many such reactive chemicals are not regulated under OSHA’s Process Safety Management (PSM) standard or the EPA’s Risk Management Program (RMP) rule. Had NaDCC dihydrate been covered under the PSM standard or RMP rule, Optima Belle would have been required to implement risk mitigation and management systems that could have prevented this incident.
Investigator-in-Charge Vincent Vonzella said, “Our investigation found considerable safety management gaps at Optima Belle and Clearon. These gaps are not unique to this specific site. Across industry, there needs to be a better understanding of the safety management system elements that must be in place to prevent incidents from reactive hazards.”