While mixing chemicals led to an explosion that killed four workers, a federal investigation says deeper operational problems at the plant were the real cause.
A U.S. Chemical Safety and Hazard Investigation Board (CSB) final report says the cause of a massive explosion and fire at the AB Specialty Silicones LLC manufacturing facility in Waukegan, IL, on May 2, 2019 that killed four employees was “deficiencies in … operations, policies, and practices … and the lack of a safety management system addressing process safety.
Same drum, different chemical
Here are the specifics of what happened on the day of the explosion, according to the CSB:
- Employees were performing a batch operation that involved manually mixing chemicals in a tank
- An employee pumped an incorrect chemical into the tank
- The incorrect, incompatible chemical was stored in a drum almost identical to one with the correct chemicals, with only a small label differentiating them
- A chemical reaction occurred inside the tank, causing the contents to foam and overflow
- Hydrogen gas was produced, which released inside the facility’s production building
- Soon after the hydrogen gas release, it ignited, causing a massive explosion and fire, and
- The explosion fatally injured four employees, destroyed the production building, and forced the company to cease some and relocate other operations until rebuilding occurred.
More than a mix-up
But the CSB says there was more to what led to the explosion than just a mix-up in chemicals.
Beyond mixing incompatible materials, the CSB investigation noted problems in these safety areas:
- Hazard analysis: AB Specialty’s “technical service request” process didn’t assess the hazards of performing a process operation or establish safeguards to reduce risk
- Emergency preparedness: Workers didn’t recognize the immediate hydrogen hazard created by the chemical mix-up. Without gas detectors and alarms, or effective training, the workers didn’t realize they needed to evacuate
- Process safety culture: “In the years leading up to the incident, AB Specialty exhibited characteristics of a weak process safety culture,” according to the CSB. This included lack of engineering controls, heavy reliance on procedural controls as primary safeguards, allowing incompatible chemicals to be visibly undifferentiated and not performing a thorough hazard analysis
- Safety Management System: AB Specialty didn’t have a safety management system that addressed process safety at the time of the incident.
Key: Correcting just the chemical mix-up could leave the company open to other process safety mistakes down the road. More comprehensive corrections, including establishment of a safety management system that addresses process safety at the facility, will have a much broader positive effect on safety.