Many flammable products are stored in large tanks at atmospheric pressure. Ignition of a hydrocarbonair mixture in such tanks can lead to an explosion and cause lethal casualties or damage the surrounding facilities and buildings. To apprehend this, safety distances for humans, structures, and equipments need to be defined. Several simple methodologies have been set up to estimate safety distances in case of an atmospheric storage tank explosion. This third and last article concerning fixed roof atmospheric storage tank explosions focuses on numerical modeling, including gas explosion and structural response simulations. Three-dimensional gas explosion simulations using the CFD code FLACS have been performed to define a typical pressure load profile to apply on the inner side of the tank shell. Then, the structural response of the tank (deformation and displacement), under the loading conditions previously obtained, has been computed with LSDYNA. Consequently, the findings question some of the assumptions used in analytical methods described previously. The specific input data needed to obtain a reasonably conservative estimation of the safety distances have been identified. (c) 2011 American Institute of Chemical Engineers Process Saf Prog, 2012