The U.S. Chemical Safety and Hazard Investigation Board (CSB) called for stricter environmental and occupational safety regulations to help prevent reactive chemical accidents, like an explosion and fire at AB Specialty Silicones’ Waukegan, Illinois, facility. CSB reiterated an earlier recommendation for the EPA to revise its risk management plan (RMP) regulations and for the Occupational Safety and Health Administration (OSHA) to revise its process safety management (PSM) of highly hazardous chemicals standard.
The board urged OSHA to broaden the scope of the PSM standard to cover reactive hazards resulting from process-specific conditions and combinations of chemicals and hazards from self-reactive chemicals. CSB also recommended that OSHA require employers to consult multiple sources of information to adequately understand and control potential reactive hazards when compiling process safety information. The board also suggested that process hazard analysis (PHA) needed to include consideration of several relevant factors in evaluating reactive hazards, such as:
- Rate and quantity of heat or gas generated by a process;
- Maximum operating temperature to avoid decomposition;
- Thermal stability of reactants, reaction mixtures, byproducts, wastestreams, and products;
- Effect of variables such as charging rates, catalyst addition, and possible contaminants; and
- An understanding of the consequences of runaway reactions or toxic gas evolution.
On May 2, 2019, operators at the AB Specialty Silicones, LLC, facility in Waukegan were performing a batch operation that involved manually adding and mixing chemicals in a tank inside the production building, according to CSB investigators, when an operator pumped an incorrect chemical into the tank, which was incompatible with another chemical added to the tank. Investigators determined that the incorrect, incompatible chemical was stored in a drum identical to one of the correct chemicals.
After the chemicals were mixed, the tank contents underwent a chemical reaction, causing the tank contents to foam and overflow from the tank’s top opening and form a fog.
The reaction produced hydrogen gas, releasing it inside the manufacturing facility’s production building. The hydrogen gas ignited, causing a massive explosion and fire and fatally injuring four employees.
The explosion and fire destroyed the facility’s production building, forcing the company to cease some operations and relocate others.
CSB recommended that AB Specialty Silicones ensure hydrogen gas detection and alarm systems are properly installed, maintained, and configured. The board also recommended that the company establish a safety management system that addresses process safety at the facility, incorporating elements of industry guidance, like the Center for Chemical Process Safety’s (CCPS) Guidelines for Risk Based Process Safety and Guidelines for Implementing Process Safety Management.
Fatal chemical fire
CSB also released its finding in an investigation into a fire at the Evergreen Packaging Mill in Canton, North Carolina, that resulted in two contractors’ deaths. The board reiterated an earlier recommendation for OSHA to publish a Safety and Health Information Bulletin on hazards and controls when using flammable materials in a confined space. CSB had a new recommendation for OSHA, urging the agency to issue a safety information product, such as a letter of interpretation, addressing the identification and control of hazards that are not preexisting but that result from work activities in confined spaces.
CSB’s investigation of the fire at Evergreen Packaging determined that while employees from two contractors’ firms were performing maintenance work inside two connected process vessels, a heat gun fell into a 5-gallon bucket containing flammable resin, igniting a fire in one of the vessels. Smoke and flames spread to the connected vessel, fatally injuring two contractor employees.