Hello, I am Ismael Rodriguez, an industrial hygienist with the Department of Labor & Industries, Division of Occupational Safety and Health. In July, 2012, I investigated an incident where a worker was fatally burned when a large amount hot water mixed with boric acid engulfed him.
The workplace was a chemical processing facility that contained over 4000 gallons of a hot water/boric acid slurry mixture in this large vessel and other equipment inside the building on the right. The mixture was kept at a temperature of 180 to 223 degrees Fahrenheit to keep it from solidifying. A recirculating pump inside the building needed to be removed for maintenance.
Before removing the recirculation pump, the large vessel was normally drained at the 3 inch valve at the bottom as shown in these photos. Sometimes the valve would plug up and workers would use a metal rod to unclog it. However, there was no way to determine if the system was completely drained.
This photo shows the heat exchanger inside the building that also contained the water/boric acid solution and maintained it at a hot temperature. The recirculation pump that needed replacing is shown by the red arrow.
This photo shows the disconnected recirculation pump, inside the building, that was being replaced. Outside the building, the storage vessel had been drained of it contents and it was assumed that the entire system was empty. This pump is also at the lowest part of the chemical system.
When the workers attempted to remove the pump using mechanical pullers, it suddenly broke free, releasing 300 to 400 gallons of hot water/boric acid mixture engulfing the worker standing at the red X. He was not wearing any protective clothing. Co-workers helped the injured worker to the emergency shower and began washing him off and paramedics were called. He was airlifted to Harborview Hospital Burn Unit in Seattle, but he died 3 days later from his burns. His injuries were primarily from the hot water, since boric acid is a very weak acid.
The employer was cited for lack of a positive lockout device to block hot liquid in the chemical system from spilling, and for not developing a hazard assessment requiring the use of personal protective equipment in case of a uncontrolled spill of hot liquid for this particular operation. The employer has since installed blocking valves, like the one in the photo just above the recirculation pump, that can be closed before the pump is disconnected.
Letís keep Washington Safe and Working by always providing a positive means of locking out chemical process equipment and conducting a hazard assessment to determine if personal protective equipment is needed for workers exposed to potential chemical spills and leaks.