Natech Risk Induced by Lightning. Case Study of a Floating Roof Atmospheric Fuel Storage Tank

The main international databases highlight that lightning strikes are the most frequent initiating events for NaTech incidents (Natural Hazard Triggering Technological Disasters) in industrial establishments with major accident hazards. This is because lightning can interact with industrial equipment both directly and indirectly, for example, through control systems and electrical circuits. An incident is more likely when the materials released post-lightning are flammable, with fire being the most common outcome. The worst damage mechanisms are due to the direct action of lightning, which heats the affected areas, causes breaks and/or perforations in tanks and/or connecting pipelines, and, for example, ignites vapors found on floating roofs of atmospheric tanks containing liquid fuels, typically resulting in the entire tank catching fire. The article aims to introduce a simplified index-based method to provide an initial assessment of NaTech risk from lightning, RNatech,F, for each equipment capable of causing a major accident, based on three main factors: Ng = ground lightning density; V = vulnerability of the equipment; E = exposure, understood as the extent and severity of damage to receptors potentially affected by the consequences of lightning-initiated accidents (workers, population, environment, assets, infrastructure). After evaluating the RNatech,F for all the equipment installed in the industrial establishment studied, appropriate proposals for the prevention and mitigation of the risk are described. A case study of an atmospheric fuel storage tank with a floating roof is illustrated as an application example. Furthermore, authors describe the main effects on the health of workers and citizens living near industrial plants, caused by lightning-induced accidents that lead to fires, explosions, and the release of toxic substances.