Analytical and numerical analyses of fuel storage tanks subjected to internal deflagrations

This study examines the roof activation pressure of Fuel Storage (FS) tanks during internal gas explosions through analytical and numerical analyses. In continuously welded FS tanks, elastic or inelastic buckling induces localized stresses at the weld that joins the roof plate to the top angle, triggering the roof activation. Simplified equations are proposed to estimate this activation pressure, indicating that existing API 650 equations may significantly underestimate actual values if (Formula presented). For FS tanks with stitch welds, the roof’s activation pressure can be determined using a simplified equation based on force equilibrium and a von Mises weld strength criterion. This approach extends to Finite Element (FE) simulations that incorporate large-deflection effects to establish the threshold at which the mid-surface stress of the roof plate reaches a critical value ((Formula presented) ) or by modeling the weld through multiple spot-welds of predefined strength. Static FE simulations in ANSYS are adequate for determining the roof’s activation pressure, while dynamic analyses in LS-DYNA provide insights into the localized damage associated with the following roof detachment process. The proposed equations and methods are validated using blast test data reported by Lu et al. (1996), offering a robust framework for predicting FS tank roof activation under deflagration scenarios.