Failure of a horizontal pressure vessel containing a high temperature liquid: the velocity of end-cap and rocket missiles

Many process plant installations include cylindrical vessels which contain high temperature liquids with the remaining space above occupied by vapour or a vapour/gas mixture. If such a pressure vessel were to be ruptured, missiles (i.e. fragments) may be generated and equipment in the vicinity put at risk. There is a particular threat from large missiles. Theoretical models have been developed to describe the peak velocity achieved by end-caps and `rocket' missiles generated by the circumferential failure of a vessel. The end-cap missile model assumes that the action of the escaping vapour/liquid on the end-cap is analogous to a missile driven by a gas jet from a constant pressure source. The `rocket' missile velocities are derived via a simple approximation to the impulse applied to the internal face of the closed end of the `rocket'. Experiments have confirmed the validity of these approaches and upper limit values to end-cap and `rocket' velocities have been defined.