While it is a bit of a mouthful, “Allocation of Safety Functions to Protection Layers” describes reasonably well the objective of this task – which is to work out how much risk reduction is to be delivered by the various protection layers.
The SISSafety Instrumented System is just one of the protection layers identified. This task is often referred to as “SIL Determination” – while it is true that the SILSafety Integrity Level of any SIFSafety Instrumented Function ’s is found through this process, this label is not used by IEC 61511 and it doesn’t reflect how important the other protection layers (like relief valves) can be in delivering the required risk reduction to achieve tolerable risks.
As with H&RA, IEC 61511 doesn’t provide detailed guidance on which technique should be used for Allocation of Safety Functions to Protection Layers – since many different techniques are available and some are more suited to particular applications and industries than others. But it does require that this activity is subject to the full force of Functional Safety Management.
Support for these activities are provided by =Method Process Safety Ltd.
LOPA of oil storage site (based on typicals approach)Industry: Water + Waste
LOPA of continuous annealing process in steel industryIndustry: Mining / Metal / Cement
Human Factors Risk Assessment of alarm based independent protection layer to confirm (human) reliability figuresIndustry: Oil and Gas Onshore
Review of earlier LOPA and PHR studiesIndustry: Mining / Metal / Cement
Review of earlier LOPA in preparation for HSE intervention visitIndustry: Oil and Gas Onshore
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