A new investigation report recommends that refineries find safer alternatives to replace the hydrofluoric acid (HF) alkylation process that led to the 2019 Philadelphia Energy Solutions explosion and fire.
The U.S. Chemical Safety and Hazard Investigation Board (CSB) wants the Environmental Protection Agency (EPA) to require refineries to use safer alternatives to HF alkylation when possible.
The report states that the industry needs to require improved safeguards against accidental releases of HF, a highly toxic chemical and one of the eight most hazardous chemicals regulated by EPA’s Risk Management Program (RMP).
‘Should be a wake-up call’
In June 2019, a massive explosion and fire occurred at the Philadelphia Energy Solutions Refinery in Philadelphia, Pennsylvania, when a corroded pipe elbow ruptured, releasing process fluid into the refinery’s HF alkylation unit.
During the incident, over 5,000 pounds of HF were released, five employees were injured and a 38,000-pound vessel fragment launched off-site and landed on the other side of the Schuylkill River. This resulted in a property damage of $750 million and endangered the 117,000 residents who live within a mile of the refinery.
“This is one of the largest refinery disasters worldwide in decades in terms of cost,” CSB Interim Executive Authority Steve Owens said. “The local community in Philadelphia fortunately was not seriously harmed, but given the refinery’s location, it could have been much worse. This incident should be a wake-up call to industry to prevent a similar event from occurring in the future.”
Safer alternatives available
Of the 155 U.S. petroleum refineries in operation, 46 operate HF alkylation units, although alternative alkylation technologies have been developed, including solid acid catalyst and new ionic liquid acid catalyst technology. Replacing highly toxic chemicals with less hazardous chemicals is an inherently safer design approach, the CSB states in the investigation report.
Further, some refinery alkylation units already use sulfuric acid as a catalyst instead of HF. While sulfuric acid is highly corrosive, it remains a liquid upon release and doesn’t present the same risk as HF to surrounding communities as HF vaporizes upon release and could potentially travel offsite.
EPA should require periodic evaluations
There is currently no federal regulatory requirement for refineries to analyze inherently safer design strategies to reduce the risk of serious accidental releases, according to the CSB report. However, since there are safer alternatives, the CSB states that refineries should periodically evaluate the new technologies to see if they would be a viable replacement for HF.
The CSB recommends the EPA:
- require refineries to conduct a safer technology and alternatives analysis as part of their process hazard analysis under the EPA RMP rule and evaluate the practicability of any inherently safer technology, and
- initiate prioritization under the Toxic Substances Control Act (TSCA) to evaluate whether hydrofluoric acid is a high priority substance for risk evaluation, and if it is, conduct a TSCA risk evaluation of HF and implement any identified risk mitigation requirements.
“The CSB wants to make sure that regulators are requiring companies to explore, determine and utilize the safest technology available,” CSB member Sylvia Johnson said. “Understanding and mitigating the risk of using highly toxic chemicals such as HF is good for communities, workers, and industry.”
