The explosion of flammable hydrocarbon-air mixtures in two or more interconnected compartments is commonly defined as “pressure piling”. Pressure higher than the thermodynamic values are likely to be generated in compartmented or linked geometry, yielding the phenomenon of major interest in industrial safety. The knowledge of the geometrical and thermo-dynamical parameters affecting the intensity of the explosion is then essential for the reduction of the hazard in adjacent buildings, mines, reactors and tanks. In the present paper, a CFD model was developed and applied, aiming at understanding the major factors affecting the pressure piling phenomenon in two cylindrical interconnected vessels, by varying the dimensions of the interconnected vessel. A combustion model able to describe the flame propagation in any of the arising combustion and fluid-dynamic regimes (laminar, flamelet regime, distributed reaction zone regime) has been developed and implemented in the code. The comparison between simulations and computed results shows a satisfactory agreement. The results also allow to show that the pressure peak intensity is mainly affected by the pre-compression of the mixture in the secondary vessel and by the turbulent Bradley number, Brt i.e. by the reaction time to the venting time ratio.