Release of hazardous substances in flood events: Damage model for horizontal cylindrical vessels

•a model for the failure of horizontal vessels caused by floods was developed.•the model was validated with available literature data.•simplified correlations were obtained to allow the straightforward calculation of vessel failure probability.•the model is suitable the assessment of NaTech scenarios triggered by floods.•the assessment of a case-study evidenced that high failure frequencies may be obtained if flood-prone areas.

Severe accidents may be triggered by the impact of floods on process and storage equipment containing hazardous substances. The present study analyses the possible damage of horizontal cylindrical equipment, either operating at atmospheric or at higher pressures. A mechanical damage model was developed and validated by available literature data on past accidents. Simplified correlations were then obtained to calculate the critical flooding conditions leading to vessel failure. A fragility model was proposed for the straightforward assessment of equipment damage probability in the framework of the quantitative risk assessment of NaTech scenarios triggered by floods. A case-study was discussed to test the potentialities of the method.