The present study introduces an innovative approach to the detailed simulation of the pressure build-up in equipment containing saturated liquids when exposed to fire. The approach is based on the adoption of a fully three-dimensional (3D) computational fluid dynamics (CFD) model of the inner fluid, Experimental data gathered from literature studies were used to validate the model considering vessels of several scales and geometries exposed to a full engulfing pool fire. The comparison between the results of the 3D CFD model developed and those of two-dimensional (2D) literature models was also carried out. This enabled deriving precise indications on the selection of the most suitable approach based on the type of accidental scenario to reproduce, confirming 2D models as sound and reliable tools to model the fluid behaviour when homogeneous heat exposure conditions are present. On the other side, limitations of 2D approaches in capturing edge effects on i) temperature profiles, ii) recirculation patterns, and iii) energy accumulation in the vessel lading during fire exposure were identified and discussed. The results obtained represent a valuable source of information to support risk management and emergency response planning.