CSB Safety Video: Outsourcing Responsibility - Explosion at Optima Belle

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has released a new safety video on its investigation into the fatal December 8, 2020, explosion at the Optima Belle chemical facility in Belle, West Virginia.

The CSB's new safety video, called “Outsourcing Responsibility: Explosion at Optima Belle,” includes an animation of the events leading to the incident, and commentary from CSB Board Member Sylvia Johnson, Investigator-In-Charge Vonzella Vincent, and Investigator Drew Sahli.

Optima Belle is a toll manufacturer – a company that provides chemical processing services under contract to other companies, typically using its own equipment. On the day of the incident, Optima Belle was working on behalf of Clearon Corporation (Clearon). As part of its agreement with Clearon, Optima Belle was to dehydrate a chemical product called CDB-56, a reactive compound, in batches using a piece of equipment called a rotary double cone dryer. Because Clearon had never before used this type of pressurized dryer to dehydrate CBD-56 and Optima Belle had never before dehydrated CSB-56, Optima Belle, in conjunction with Clearon, developed a new procedure to use the rotary double cone dryer for the dehydration operation.

The CSB’s investigation found that Clearon did not give Optima Belle sufficient information about CDB-56’s chemical properties to use when developing the new procedure for the rotary double cone dryer. In addition, neither Clearon nor Optima Belle performed an extensive thermal hazard assessment or located adequate publicly available information on the chemical hazards of the compound. Consequently, Optima Belle did not realize that heating CDB-56 inside the dryer could cause the compound to unexpectedly decompose at temperatures below the dryer’s maximum internal temperature of approximately 130 degrees Celsius. The decomposition reaction produced gas that sharply increased the pressure inside the dryer to above the dryer’s design limit.

At approximately 10:00 pm on December 8, 2020, the dryer exploded, and toxic chlorine gas released to the atmosphere. Metal debris and dryer fragments propelled off-site and within the facility, striking a methanol pipe that then caught fire, leading to an estimated $33.1 million in property damage. One Optima Belle employee was fatally injured, two others were evaluated for respiratory irritation, and one member of the public reported an injury related to the explosion. The explosion prompted local authorities to issue a shelter-in-place order for the region within two miles of the Optima Belle site for over four hours. Debris from the explosion was found almost a half mile from the site.

The CSB released its final investigation report on the Optima Belle incident in July 2023. The new safety video covers the five key safety issues identified in the CSB’s report that contributed to the incident:

• 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.

The video also highlights safety recommendations made by the CSB in the report to Optima Belle, Clearon, the Occupational Safety and Health Administration (OSHA), and the Environmental Protection Agency (EPA). One recommendation being that OSHA amend the PSM standard to achieve more comprehensive control of reactive hazards that could have catastrophic consequences, and also that the EPA amend the RMP rule to explicitly cover catastrophic reactive hazards that have the potential to seriously impact the public.

In the video, Board Member Johnson states, “Our report identifies several factors that led to this tragedy. In particular, we have found that gaps in the existing regulations do not adequately protect against hazards presented by reactive chemicals. This longstanding safety gap must be addressed."

Board Member Johnson added: “The CSB believes OSHA and the EPA must strengthen their regulations on reactive chemicals. Regulations addressing reactive hazards will help keep similar incidents from occurring, prevent injuries, deaths, and protect those who live in nearby communities. The time is now for those agencies to act.”

About the CSB

The CSB is an independent, non-regulatory federal agency whose mission is to drive chemical safety change through independent investigations to protect people and the environment. The agency’s board members are appointed by the President and confirmed by the Senate. CSB investigations look into all aspects of chemical incidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems. The CSB does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. For more information, please visit www.csb.gov.