CSB sounds alarm over critical gaps in OSHA regulations
A combustible dust explosion, asphyxiating gas release, and flammable vapor explosion are the subjects of three investigation reports issued in the waning days of 2023. Packed with recommendations, the reports from the Chemical Safety Board (CSB) urge OSHA to issue two new regulations. At the same time, all three investigations put a spotlight on a lack of emergency preparedness.
Combustible dust explosion
One night in May 2017, workers at a Wisconsin dry corn milling facility smelled smoke in the mill. While investigating the smoke, several heard an explosion and saw fire coming from piping on mill equipment. The workers scrambled to evacuate as the fire spread through the equipment and interconnected dust collection systems. Dust collection equipment exploded, and secondary explosions subsequently occurred throughout the facility.
The CSB determined the cause of the dust explosions was the ignition of combustible corn dust inside process equipment. This transitioned to multiple explosions. The board’s report determined that OSHA regulations for combustible dust operations are insufficient. Therefore, the report recommends that the agency publish a comprehensive regulation on combustible dust with the following elements:
- Hazard recognition,
- Dust hazard analysis,
- Management of change,
- Incident investigation,
- Engineering controls,
- Building design,
- Fugitive dust management,
- Operating procedures,
- Process safety information,
- Investigation report,
- External audit management,
- Worker training,
- Emergency response, and
- Personal protective equipment (PPE).
The report also highlights that emergency plans need to instruct workers when and how to trigger evacuations. The workers spent at least 30 minutes trying to locate the source of smoke, but no one attempted to shut down the mill or evacuate until they observed fire.
Asphyxiating gas release
In January 2021, liquid nitrogen overflowed from a freezer located inside a food plant in Georgia. The release happened while maintenance workers were troubleshooting issues with the freezer. Once released, the liquid nitrogen vaporized filling the room and killing the two workers. An hour later another worker spotted a five-foot vapor cloud filling the room and notified management. During an evacuation, other workers investigated the room or attempted rescue. Unfortunately, four more workers were killed, and three others were injured by asphyxiation.
The CSB’s report concluded that a tube was bent during maintenance in the freezer room. The board also said that the severity of the incident was worsened by the company’s inadequate emergency preparedness. The final CSB report emphasizes five safety issues:
- Single point of failure,
- Atmospheric monitoring and alarm systems,
- Emergency preparedness and response,
- Process safety management, and
- Product stewardship.
However, the report also suggests that OSHA issue a new regulation on cryogenic asphyxiants that covers:
- Design, construction, and installation of equipment;
- Atmospheric monitoring for indoor equipment;
- Emergency shutdown;
- Worker training;
- Emergency planning;
- Process hazard analysis;
- Management of change; and
- Other process safety elements.
Flammable vapor explosion
In April 2021, a mixture of flammable naphtha solvent vapors and resin liquid escaped through the seal of a closed manway of an operating kettle. This created a flammable vapor cloud that spread throughout the Ohio facility. Within minutes the vapor cloud found an ignition source, causing a huge explosion and a fire that burned for roughly 11 hours. The explosion shook nearby homes and caused an estimated $90 million in damage to the site. One employee was killed and eight others transported to area hospitals with third-degree burns and crushed or broken bones.
The latest CSB report highlights three safety issues:
- Mechanical integrity of low-pressure vessels,
- A hierarchy of controls, and
- Emergency preparedness training.
On the night of the incident, evacuation alarms and worker training specific to the hazards of the chemicals present in the resin manufacturing area could have prevented casualties. These precautions were missing in the incident, the board explains.
The CSB report warns that effective emergency preparedness is crucial in the event of a flammable vapor cloud release. This should, among other things, include:
- Prompt notification via gas detection and alarms,
- Effective training to ensure workers know how to safely respond in an emergency, and
- Ensuring that workers wear sufficient PPE if a timely evacuation from the area is not possible.
Two more CSB reports anticipated
CSB says it’s working to complete two more final investigation reports (with more recommendations) by the end of 2023 for:
- A 2019 fire and explosion at a Texas chemical manufacturing facility that caused one fatality and multiple injuries; and
- A 2020 gas well explosion in Texas that fatally injured three contractors.
With 973 recommendations made so far by CSB since 1998, the agency is closing in on the 1,000 milestone!
Key to remember
Packed with safety recommendations, three chemical incident investigation reports from the CSB urge OSHA to issue two new regulations.