Re-evaluate the allocation of safety functions to protection layers

2 Re-evaluate the allocation of safety functions to protection layers 

Where it appears that a risk reduction equivalent to SIL 4 SIF is required, it is first recommended that additional analysis be performed to ensure that the risk has been properly assessed. As shown in Table J.1, quantitative risk assessment should be considered to verify the hazardous event frequency, and consequence models should be considered to verify the consequence severity. If the risk has been properly assessed, consider inherently safer principles to redesign the process to reduce the risk. 

No reproduction or networking permitted without license from IHS 

1 Consequence and its severity Is the consequence and its severity for this scenario correctly understood Consider dispersion and consequence modeling to verify the severity estimate 

2 Initiating event frequency Is the estimate for the initiating event frequency correct Can the initiating event frequency be reduced by redesign of the process Consider quantitative risk assessment to verify the initiating event frequency 

---