Train derailment accidents and ensuing news coverage of fire-engulfed railcars have brought renewed attention to reactive chemical hazards during transportation and storage. One type of dangerous event which can happen in such unfortunate situations (even in the absence of chemical reactivity) is a BLEVE, which is an explosion caused by the rupture of a vessel containing pressurized liquid at a temperature above its normal boiling point. Vessel failure, often in the context of a fire emergency, leads to rapid (potentially explosive) vaporization of “superheated” liquid that can severely damage the surroundings, and if the material is flammable it can form an explosive vapor cloud; toxic material makes matters worse.
There are many places to get information on this important topic, and the Chemical Safety Board is an excellent resource. Past Fauske & Associates publications have discussed BLEVEs and shared innovative ideas on how to passively prevent them. The late Dr. Hans K. Fauske described the benefit of combined vapor and liquid venting using a conventional vapor venting device to control pressure and a bottom vent or “dip-tube” to remove inventory (FAI Process Safety News, Fall/Winter 1999, and Chemical Engineering Progress, Feb. 2000). Dr. Fauske and Dr. Robert E. Henry described the possibility of using an expanded metal network or “mesh” to prevent BLEVEs by increasing the number of available nucleation sites (minimizing superheat), preventing waterhammer, and minimizing thermal stress (FAI Process Safety News, Fall 2000 and Winter 2001). I encourage you to read these very interesting and still relevant technical articles, and don’t hesitate to contact us if you need support with a specific process safety application.
