Prediction of the collapse time of an outdoor storage tank under rainfall due to internal steam condensation

Thin-walled storage tanks are prone to vacuum collapse due to the development of a net external pressure. Condensation of steam inside the vessel can cause a rapid development of this mode of failure. External atmospheric conditions also affect the process; specifically, the enhanced heat transfer associated with rainfall on the vessel external surface accelerates the collapse process. Short but intense rain storms are becoming more common. An expression to predict the time taken for a storage vessel to collapse while subject to external rainfall is developed. Good agreement was found between the predictions of the modelling techniques and the experimentally obtained results. It is shown that the thermal energy stored in the vessel wall is very significant in determining the collapse time especially for outdoor vessels exposed to rain.