Boiling-liquid-expanding-vapor explosion mechanism

The superheat limit was first proposed in the late 1970s as a possible mechanism for explaining catastrophic vessel failures. Reid (1979), Jones (1985), Martinsen et al. (1986), Davenport (1988), and Dunn (1988) suggest that BLEVEs (Boiling Liquid Expanding Vapor Explosions) are superheat explosions and therefore are easily predicted by assessing the superheat limit for any pressurized liquid material. 

A Latin American chemical plant experienced a catastrophic fire and series of Boiling Liquid Expanding Vapor Explosions (BLEVEs) that resulted in the loss of one life and 5 million in direct damages (1977 dollars). The initial vapor cloud occurred as a maintenance mechanic started to remove a pneumatic actuator from the liquid discharge line below a tank of flashing flammable liquid that had a boiling point of 7° F (—14° C). 

Boiling Liquid Expanding Vapor Explosion (BLEVE) characterizes the failure mechanism of a liquid gas container where the major part of the contents are released by flash vaporization and explode while the remainder forms a pool which bums down. Three conditions need to be met (i) the liquid is supeiheated, (ii) a sudden pressure drop occurs, (iii) pressure and temperature conditions are such that flash vaporization is possible. This type of explosion is caused if a storage tank is exposed to a heat source from outside. A tank stmcture weakened by the high temperatures, a high inner pressure, and tensions in the container wall near the gas / liquid boundary layer eventually results in the catastrophic failure, however, merely causing pressure waves. An intact safety valve could delay, but possibly not prevent the vapor explosion [73]. 

Venart, J. E. S. 1998. Boiling Liquid Expanding Vapor Explosions (BLEVE) Possible Failure Mechanisms , in Very Farge-Scale Fires, ASTM STP 1336, ed. N. R. Keltner, N. J. Alvares, and S. J. Grayson, pp. 112-132. 

Boiling liquid expanding vapor explosions (BLEVEs) are one of the most severe accidents that can occur in the process industry or in the transportation of hazardous materials. Strictly speaking, these explosions do not necessarily imply thermal effects. However, in most cases the substance involved is a fuel that causes a severe fireball after the explosion. Usually BLEVE refers to the combination of these two phenomena, BLEVE and fireball, i.e., to an accident simultaneously involving mechanical and thermal effects. 

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