A modelling approach to assess the effectiveness of BLEVE prevention measures on LPG tanks

Experimental tests were carried out on 3 m3 tanks engulfed by a diesel pool fire, indicating that the coupled installation of a heat resistant coating and of a pressure relief valve resulted the more reliable and convenient solution for BLEVE prevention. The experimental results evidenced that an important increase in the “time to BLEVE” could be achieved by thermal shielding. Nevertheless, the size of the test tank was small if compared to the real scale road tankers or tank wagons used for liquefied gas transportation. A thermal and mechanical model was thus developed and validated on the basis of the experimental results, in order to assess the behaviour of real geometry thermally insulated tanks in a simulated fire engulfment scenario. The model was based on a finite element approach, which allowed to consider both thermal and mechanical loads. The effect of the fluid behaviour and of flame impingement were implemented obtaining the temperature distributions on the tank. These results were used as thermal loads, coupled with the ordinary pressure and weigh loads, in the mechanical simulations aimed to the calculation of stress distributions. A specific analysis of the coating properties was carried out, identifying the critical scenarios leading to tank failure.