Assessment of the probability of structural damage due to lightning impact on process equipment in the chemical and process industry

A detailed analysis of past accidents evidenced that lightning strikes on storage or process vessels containing flammable materials may cause severe accidents at refineries, storage sites, processing sites and other industrial facilities where hazardous materials are stored or processed. Although the hazard due to lightning is well known and is usually considered in the safety analysis of chemical and process plants, well accepted quantitative procedures to assess the contribution of accidents triggered by lightning to industrial risk are still lacking. In particular, the approaches to the assessment of lightning strike probability, damage caused by lightning strike and intensity of loss of containment (LOC) caused by lightning are mostly based on expert judgment and not on up-to-date models that take into account the relevant progress made in the last years in the analysis of the lightning phenomenon. In the present paper an innovative procedure for the quantitative assessment of the industrial risk due to LOC of hazardous substances triggered by lightning is introduced. The study was focused on the development of models for lightning impact probability and for damage probability. In particular, a Monte Carlo approach was developed to calculate the probability of lightning impact on the basis of the geometry of the structure and of lightning intensity and frequency data.