BLEVE Research - Images

BLEVE Research

BLEVE Testing


PRV Field Trials


Thermal Protection Detection Trials 2004

Tank-Car Insulation Defects
Thermal Modelling
Graduate Students

A.M. Birk, P.Eng

Two-Step Slow BLEVE

In this case there is a significant time between when the original fissure opens and when the tank fails catastrophically. First a small hole forms in the vapour space wall and this leads to a pressure drop which then causes a liquid boiling response that causes pressure recovery in the tank. This pressure recovery drives the crack along the length of the tank to cause the total loss of containment and BLEVE. In this case the crack velocity may be as low as 1 m/s.

Single-Step Rapid BLEVE

The figures show the BLEVE of a 400 litre propane tank (non- ASME code) exposed to torch fire impingement from above. In this case the tank has a 3 mm wall rather than the 6 mm needed to be an ASME code tank. This tank failed so rapidly that the liquid flashing had little or no role in the tank failure. In other words, the vapour energy was sufficient to drive the failure crack the full length of the tank. In this case the crack velocity was of the order of 150 m/s.

Transient Jet Release

If the tank has not been weakened sufficiently then a BLEVE does not take place after thermal rupture is initiated. In this case the fissure does not run the entire tank length but is arrested in strong material. In this case the tank contents vent as a two-phase transient jet. If the hole is large (i.e., the hole length is of the order of the tank diameter) then the release looks very much like a BLEVE (i.e., all contents vent in a fraction of a second, large fireball, tank may rocket).

Fireballs from BLEVEs

The shape and liftoff of BLEVE fireballs vary significantly and depend on the detailed thermodynamic state of the liquid, and the details of the tank failure. If the tank fails rapidly then classical spherical fireballs result. If the failure is slow then the initial jet release sends the fireball high in to the air. If the liquid is relatively cool then a large ground fire is possible. These differences can change the hazards to nearby objects (such as emergency responders) significantly.