Accidental fires represent a serious threat for vessels devoted to the transportation and storage of liquefied gases, such as propane and butane. The present work focuses the impact of full engulfing hydrocarbon pool fires on propane and butane storage tanks. The analysis was carried out using a computational fluid dynamics (CFD) model, previously validated against experimental data. Results are presented in terms of pressurization rates, and temperature distributions showing the difference in the response to fire between propane and butane tanks. The effect of the filling degree is also pointed out. The outcomes of this work provide useful results to evaluate the possible failure conditions, thus supporting the emergency response to accidental fires in the proximity of storage tanks or transport units.