Reader Comment – 01-05-10 – Water Sprays III

Fred Millar, a frequent commentor over the life of this blog, posted a response to an earlier blog extending the conversation about water sprays and hydrogen fluoride releases from refineries. While the earlier part of the discussion was about the CSB emergency order issued in the investigation of the July Citgo refinery incident in Corpus Christi, TX, Fred points at an older accidental release of hydrogen fluoride at the Marathon refinery in Texas City, TX in October 1987. Fred’s comment and the NY Times article he references bring up some of the community (and facility employee) safety issues that are involved in the debate about the continued use of hydrogen fluoride as a catalyst at many refineries around the United States. Anyone following that debate should look at both Fred’s comment and the referenced article. Interestingly, Fred wasn’t sure if the Marathon system was protected by a water spray mitigation system or if one had been used in the emergency response to the October incident. I did find an on-line abstract of an article in Process Safety Progress (vol 17, issue 3, pgs 213-18) that provides an analysis of that accident. According to that abstract a water spray mitigation system was in place, but it discharged late in the incident, well after the peak flow rate of the release had passed. Fortunately, the accident broke a pipe that released HF gas up into the atmosphere; by the time the vapor cloud reached the ground it had dispersed significantly. There were no deaths in that incident and only apparently transitory medical problems for those exposed. Once again, the point that I like to keep making about these spray systems is that they can provide a significant HF (or chlorine, or anhydrous ammonia) scrubbing effect in the event of a release, accidental or otherwise. They should be included as part of the safety and security mitigation system for any facility that houses significant quantities of poison inhalation hazard (PIH) chemicals. They will almost certainly not provide absolute protection for employees and facility neighbors, but they will help to reduce the risk. Additional systems that alert employees and neighbors of releases along with systems to track vapor clouds and predict hazard zones will still be needed to give potentially affected individuals the maximum chance to survive the toxic affects of the release.