Fragility curves of storage tanks impacted by strong winds

Industrial infrastructures may be subjected to severe damage by strong winds, storms, tornadoes, and hurricanes. For instance, the two hurricanes Katrina and Rita in 2005, in the Gulf of Mexico (United States) resulted in multiple damages to approximately 611 industrial equipment such as offshore platforms, oil pipelines, and storage tanks. This type of events is defined as NaTech (Natural accidents triggered by Natural Events). Due to their structural characteristics, atmospheric storage tanks are particularly vulnerable to NaTech. Indeed, the interaction of strong winds may result in a structural damage and the following release of hazardous substances in the environment. In this work, a computational tool was developed in order to obtain fragility curves for storage tank, designed on the basis of API-650, and subjected to strong winds. This tool includes the reduction of uncertainty by Monte Carlo simulations, and it analyzes individual tanks and the entire tanks area. The model includes different damage modes such as the buckling of the wall due to external pressure and the damage to the tank shell due to the impact of the projectiles transported by the wind, in addition to the loss of containment calculation once the equipment has failed. Finally, the tool takes into account the mechanical characteristics of the tank together with its operating conditions for the fragility analysis, the results of which will be the input information to include events of natural origin within the classical risk analysis. Copyright © 2019, AIDIC Servizi S.r.l