SIL Assessment

SIS Management: SIL Assessment Workflow

This workflow describes the process of performing a Safety Integrity Level (SIL) assessment by defining the instrumented functions and the target SIL for each instrumented function.

In the following workflow diagram, the blue text in a shape indicates that a corresponding description has been provided in the sections that follow the diagram. For more information, refer to the topic Interpreting the Workflow Diagrams.

Create SIL AnalysisDefine Logic Solver RequirementsSafety Instrumented Function?Create Instrumented FunctionProtective Instrumented Function?Define Standard Control System Alarm/InterlockQualitatively Assess SILSelect SIL Assessment MethodSIL VerificationLOPAHAZOP AnalysisPromote to ASMAsset Strategy ManagementCreate Risk Assessment Recommendation

Create SIL Analysis

Persona: Analyst

Create an SIL Analysis record to store the details of the SIL Analysis that you want to conduct.

Define Logic Solver Requirements

Persona: Analyst

Identify the logic solver that you want to use in the SIL Analysis. Create a Logic Solver to store the details of the logic solver.

Safety Instrumented Function?

Persona: Analyst

Determine if the instrumented function is critical to operational, health, and environmental aspects of safety, and assemble all the background information. You must assess the Safety Integrity level (SIL) and the logic solver requirements that you need to maintain for the instrumented function to keep the process safe.

Protective Instrumented Function?

Persona: Analyst

Determine if the instrumented function is not critical to safety, but is required to minimize the economic impact in the event of a failure.

Define Standard Control System Alarm/Interlock

Persona: Analyst

If the instrumented function is not critical to safety or is not protective, then you must install a standard control system interlock to warn an operator in case of a failure. However, you need not perform SIL assessment for the control system.

Create Instrumented Function

Persona: Analyst

Create an Instrumented Function to record the details of the instrumented function such as the initiating event, safe state, and response time.

HAZOP Analysis

Persona: Analyst

Go to the HAZOP Analysis workflow.

SIL Thresholds

Persona: Analyst

If you will perform SIL assessment using a Risk Matrix, you must refer to the SIL threshold values defined in a SIL Threshold record. The risk rank that you specify in the Risk Matrix will be compared with these SIL threshold values to calculate the target SIL value.

Asset Strategy Management

Persona: Analyst

Go to the Asset Strategy Management workflow.

Qualitatively Assess SIL

Persona: Analyst

If you will perform SIL assessment using a Hazards Analysis, and then link the Hazards Analysis to the Instrumented Function. If you will perform SIL assessment using a Risk Matrix, specify the risk rank for the various aspects of the Risk Matrix (e.g., Safety, Operational, Environment). You can also perform an external SIL assessment.

Select SIL Assessment Method

Persona: Analyst

After performing various types of SIL assessment (i.e., LOPA, Risk Matrix, PHA, External), you must associate one of them with the Instrumented Function. The SIL calculations related to the selected record will be associated with the Instrumented Function. These calculations are used to compare the achieved SIL values (from SIL Verification).

Create Risk Assessment Recommendation

Persona: Analyst

Create a Risk Assessment Recommendation to provide suggestions on how to achieve the target SIL.

Promote to ASM

Persona: Analyst

Promote the Recommendation to Asset Strategy Management (ASM), where the associated action can be implemented as an Inspection Task of the task type Proof Test.

LOPA

Persona: Analyst

Go to the LOPA workflow.