Assessment of the Severity Level of Accident Scenario Consequences when Performing Layer of Protection Analysis (LOPA)

Semi-quantitative risk assessment method “Layer of Protection Analysis” (LOPA) provides calculation and assessment of acceptability (permissibility) of accident risk scenarios identified during qualitative hazard analysis of a workflow. Risk acceptability level for a separate scenario is determined by comparing a design risk value with established criteria. The results obtained are used as a basis to choose measures (engineering, organizational) to improve the safety of a workflow and substantiate the prioritization of their implementation. For each scenario, the criteria of risk acceptability are established based on the severity of associated consequences. A rapid assessment method for the assessment of the severity of combustible substance accidental discharge consequences using elaborated reference tables has been proposed. These tables establish the compliance of the discharge mass (for overheated fluids) or pool area (for stable fluids) with a certain level of severity of consequences.