A four-member investigative team from the U.S. Chemical Safety Board (CSB) is deploying to the site of a release of propane and hydrogen fluoride at the ExxonMobil refinery in Joliet, Illinois, according to an agency press release.

At approximately 12:30 p.m. on Thursday, there was a sudden release of propane and hydrogen fluoride (HF) from the vicinity of a pump in the refinery’s alkylation unit, which uses HF as a catalyst. The leak did not ignite, but one operator was transported to the hospital suffering from what were described as serious, HF-related chemical burns; he was initially reported in critical condition. A second operator was examined at the hospital and released. The unit’s water deluge system, which is designed to contain airborne HF releases, was activated and the alkylation unit was shut down. Refinery personnel were instructed to shelter in place.

Chairman John Bresland stated: “We are concerned about the three apparent releases of hydrogen fluoride from refinery alkylation units in Pennsylvania, Texas, and now Illinois that have been reported since March 2009. Because of its high toxicity, any loss of primary containment for hydrogen fluoride is a serious matter.” Recent reported releases include those at the CITGO refinery in Corpus Christi, Texas, on July 19, 2009, and at the Sunoco refinery in Philadelphia, Pennsylvania, on March 11, 2009. The CSB has an investigative team currently at the CITGO Corpus Christi refinery examining that incident.

The CSB investigative team will be headed by Investigation Supervisor Robert Hall, PE.