Escalation thresholds in the assessment of domino accidental events

Domino effect is responsible of several catastrophic accidents that took place in the chemical and process industry. Although the destructive potential of these accidental scenarios is widely recognized, scarce attention was paid to this subject in the scientific and technical literature. Thus, well-assessed procedures for the quantitative evaluation of risk caused by domino effect are still lacking. Moreover, a wide uncertainty is present with respect to escalation criteria, and even in the identification of the escalation sequences that should be taken into account in the analysis of domino scenarios, either in the framework of quantitative risk analysis or of land-use planning. The present study focused on the revision and on the improvement of criteria for escalation credibility, based on recent advances in the modelling of fire and explosion damage to process equipment due to different escalation vectors (heat radiation, overpressure and fragment projection). Revised threshold values were proposed, and specific escalation criteria were obtained for the primary scenarios more frequently considered in the risk assessment of industrial sites.