Taking the gas storage tank in a gas?liquid linkage actuator of a gas transmission pipeline as an example, the software Ansys Fluent was used to establish a 3D model with the same proportion, to simulate the change of pressure and temperature with continuous heat input when external fire occur. Aspen Hysys was used to calculate the minimum PSV diameter required for safe discharge under fire conditions. The results show that the temperature and pressure of the tank rise sharply, reaching to the steel tank collapse temperature and design pressure in a very short time, when the external fire occurs. The time to reach the collapse temperature of steel tank is lagged behind the time to reach the design pressure of the gas tank. From a security perspective, the PSV should be set, which can also help to reduce the damage of the accidents even if the tanks collapse. The minimum diameter of the PSV calculated by Aspen Hysys is 0.13 cm2, and the recommended diameter of the PSV is no less than 0.15 cm2.
