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In the wake of the Husky Refinery fire in 2017, the Chemical Safety Board is calling on the federal government to review its existing Hydrofluoric Acid (HF) study to determine the effectiveness of existing regulations as well as the viability of utilizing inherently safer alkylation technologies in petroleum refineries.

“In the last four years, the CSB has investigated two refinery incidents where an explosion elevated the threat of a release of HF,” said CSB Interim Executive Kristen Kulinowski. “Refinery workers and surrounding community residents are rightly concerned about the adequacy of the risk management for the use of hazardous chemicals like HF. The Environmental Protection Agency (EPA) should review its 1993 HF study to ensure the health and safety of communities near petroleum refineries utilizing HF.”

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Kulinowski released a letter she sent to the EPA calling for the new HF study.

HF is a highly toxic chemical that can seriously injure or cause death at a concentration of 30 parts per million (PPM), which is used in about fifty of the U.S.’s approximately 150 refineries, as well as many other industries.

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In a refinery, the chemical is used as a catalyst in the creation of a blending agent for high octane gasoline. In both of its investigations, the CSB conducted a public hearing in which members of the surrounding communities expressed their concerns about the adequacy of the risk management strategies for the use of HF and the effectiveness of community notification procedures in the event of a catastrophic release.

“The EPA is the appropriate agency to assess the adequacy of risk management for the use of chemicals like HF,” Kulinowski said. “Refiners, their workforce and communities that surround the refineries need assurances that the risk plans are adequate to prevent a catastrophic release.”

In one case, Kulinowski cited, on February 18, 2015, an explosion occurred in the ExxonMobil Torrance, California refinery’s Electrostatic Precipitator (ESP), a pollution control device in the fluid catalytic cracking (FCC) unit that removes catalyst particles using charged plates that produce sparks—potential ignition sources—during normal operation. The incident occurred when ExxonMobil was attempting to isolate equipment for maintenance while the unit was in an idled mode of operation; preparations for the maintenance activity caused a pressure deviation that allowed hydrocarbons to backflow through the process and ignite in the ESP.

As a result of this incident, a near miss event occurred in the modified hydrofluoric acid (MHF) alkylation unit when explosion debris nearly hit tanks in close proximity to the ESP, each containing hydrofluoric acid (HF), water, hydrocarbons, and a chemical additive intended to reduce the amount of HF vaporized during a loss of containment event

In the Husky Refinery case, on April 26, 2018, and explosion and subsequent fires at the Husky Superior Refinery in Superior, Wisconsin. The initial explosion occurred in the refinery’s Fluid Catalytic Cracking Unit (FCCU) at 10 a.m. while the refinery was shutting down the FCCU for periodic maintenance and inspection.

One piece of debris from the explosion flew about 200 feet, and struck a large, nearby, aboveground storage tank containing about 50,000 barrels of asphalt. The side of the tank was punctured, resulting in the release of over 15,000 barrels of hot asphalt into the refinery. Two hours after the release, the asphalt ignited, resulting in a large fire. While there was no HF release in this case, it was pointed out the asphalt tanks were further away from the explosion than the refinery’s HF storage tanks.

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