A generalized equipment vulnerability model for the quantitative risk assessment of horizontal vessels involved in Natech scenarios triggered by floods

Severe NaTech scenarios may be triggered by the impact of floods on chemical and process installations. The currently available equipment vulnerability models addressing the potential failure of equipment caused by floods suitable for use in a quantitative risk assessment framework are mostly limited to the specific case of storage tanks, not addressing other types of process equipment. The present study aims at filling this gap, proposing a generalized vulnerability model applicable also to other types of horizontal cylindrical vessels widely used in the chemical and process industry and in oil and gas installations (e.g., shell and tube heat exchangers, separators, etc.). The generalized vulnerability model developed allows a simplified assessment of the possible structural damage due to floating or displacement caused by floodwater, based on floodwater height and velocity, and on detailed geometrical data of the vessel. Shortcut correlations were also developed to provide a preliminary screening, allowing the identification of the more vulnerable equipment. The models were applied to the analysis of an extended case study, in order to assess their suitability and the interest of the results provided in the framework of quantitative risk assessment of NaTech events triggered by floods.