The US Chemical Safety and Hazard Investigation Board (CSB) issued two significant reports in late July. One praises voluntary actions of Airgas after a deadly incident at a nitrous oxide facility. The second is a factual update to the ongoing investigation of an incident at an Aghorn Operating facility in Texas in which a worker and his wife died from exposure to toxic hydrogen sulfide gas.
The CSB is an independent, nonregulatory federal agency that investigates chemical accidents.
In a Safety Spotlight report, the CSB lauds Airgas, now a subsidiary of Air Liquide, for rapidly developing and implementing a robust process safety management program (PSM) in response to an explosion in 2016 that killed one worker.
CSB stresses that the effort was voluntary, as nitrous oxide handlers are not required by US federal law to develop a PSM program. The incident occurred during the loading of a trailer truck at an Airgas facility in Cantonment, Florida. In the transfer, a pump heated the nitrous oxide above its safe operating limits, causing decomposition and the explosion.
According to the CSB, after the incident, the company began to review its safety programs for its nitrous oxide production facilities, trucking fleet, and cylinder-filling operations. The review resulted in several reforms, such as better audit practices and inherently safer designs.
The CSB issued its investigation report and recommendations in 2017. In the Safety Spotlight, the agency notes that by 2019 Airgas had reengineered its approach to managing process safety in its nitrous oxide business.
“Taking proactive, effective action, similar to what Airgas did following this incident, is the hallmark of driving chemical safety change,” says CSB chairperson Katherine Lemos.
In a statement, Airgas notes that it shut down the Florida facility but uses the PSM program it developed at its nitrous oxide facilities that are currently operating.
“We appreciate the collaboration with the Chemical Safety Board throughout this investigation,” Airgas adds.
The board’s investigation found that explosions had occurred at US nitrous oxide facilities an average of once every 4 years since 2001. Since 1987, such incidents have killed 6 workers and injured 21. Half were caused by an overheated pump, like the explosion at Cantonment.
The Aghorn accident occurred in 2019 at an oil-field station where water used to extract oil and gas is recycled and returned to further enhance oil and gas production. A pump failure caused the release of water containing hydrogen sulfide, the CSB says in its update. An automatic warning system notified an Aghorn employee of a problem, and he drove to the site to investigate.
When he failed to return home 3 hours later, his wife went to the site with their children. Emergency responders later rescued the children from their car and found the parents’ bodies inside the pump house.