Failures of Storage Tanks as Reported by the Environmental Protection Agency

Catastrophic Failures of Storage Tanks as Reported by the Environmental Protection Agency 

In 1997, the U.S. Environmental Protection Agency started publishing a bulletin entitled Chemical Safety Alert. The intent of these bulletins is to increase awareness of possible hazards. One of the earlier published Alerts that was entitled Catastrophic Failure of Storage Tanks, issued in May 1997. [5] This Alert including the concepts of tank failures of shell to bottom seam or side seam will be reviewed in detail in Chapter 8. However, to highlight recent problems created by maintenance efforts, two paragraphs were quoted from that document and repeated here. 

In a 1992 incident, while workers were welding the outside of a tank empty of liquid, the residual vapor in the tank exploded and propelled the tank upward and into an adjacent river. Three workers were killed and one was injured.. . .  

In a 1994 incident, during a grinding operation on a tank holding petroleum-based sludge, the tank was propelled upward, injuring 17 workers and spilling its contents over a containment berm into a nearby river. 

Generation of combustible vapors is a hazard not only for the storage of pure flammable liquids but also for the storage of any sludge or mixture where a combustible component is present or can be produced by reaction. Sludge (slop tanks) and mixture (e.g., oil/water) tanks may be particularly vulnerable because they are sometimes open to the air explosive atmospheres may form inside and outside the tank. Facilities may not always recognize the hazard. In addition, even tanks appearing to be empty may pose a hazard if they still contain combustible vapors. 

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