Working together for a Safer World


LOPA provides a method for evaluating the risk of hazard scenarios and comparing it with risk tolerance criteria to decide if existing safeguards are adequate, and whether additional safeguards are needed. It is a method for evaluating the effectiveness of independent protection layers in reducing the frequency and/or consequence severity of hazardous events. LOPA is used to determine:

·        Safety Integrity Level (SIL) required for a Safety Instrumented Function

·        Need for further risk reduction by adding further layers of protection to reduce the risk to meet risk acceptance criteria.

Sigma-HSE uses a PHA study report for identification of Hazardous Event, causes of the hazardous event or the Initiating Events and consequences of the hazardous event. During LOPA study, our team then assesses.

·        Frequency of all initiating events and probability of enabling conditions.

·        Probability of failure on demand (PFD) for all conditional modifiers and of independent protection layers (IPL) providing risk reduction for each initiating event.

·        Calculate the mitigated event frequency and compare this to the acceptance frequency to determine if further risk reduction is required.

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