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Allocation of Safety Functions to Protection Layers

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.

Safety Functions

What =Method can do for you

  • Experienced study facilitators for HazID, HazOp, LOPA and FTA studies.
  • Independent verification when studies are delivered by others.
  • Training and mentoring support for aspiring HazOp Study Leaders.
  • HazOp Team Members training – either as a standalone training course or as part of our preparation for delivering a particular study.

Support for these activities are provided by =Method Process Safety Ltd.

Most recent projects for Allocation of Safety Functions

LOPA of oil storage site (based on typicals approach)

Industry: Water + Waste
Topic: Layer of Protection Analysis (LOPA)

LOPA of continuous annealing process in steel industry

Industry: Mining / Metal / Cement
Topic: Layer of Protection Analysis (LOPA)

Human Factors Risk Assessment of alarm based independent protection layer to confirm (human) reliability figures

Industry: Oil and Gas Onshore
Topic: Human Factors Risk Assesment (HFRA)

Review of earlier LOPA and PHR studies

Industry: Mining / Metal / Cement
Topic: Layer of Protection Analysis (LOPA)

Review of earlier LOPA in preparation for HSE intervention visit

Industry: Oil and Gas Onshore
Topic: Layer of Protection Analysis (LOPA)

View all of our recent projects here

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Functional Safety Lifecycle

Assessments at key Lifecycle Stages - Functional Safety Management

Planning throughout the Lifecycle - Functional Safety Management

Verification at every Lifecycle Stage - Functional Safety Management
Hazard & Risk Assessment Allocation of Safety Funct's to Protection Layers Safety Requirements Specification Design & Engineering Installation, Commissioning & Validation Operation & Maintenance Modification Decommission
Functional Safety Management
Functional Safety Audit
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