The presentated paper will briefly explain safety instrumented functions and their classification within the safety integrity levels. During the pipeline design phase various safety review studies - e.g. Hazards and Operability Analysis (HAZOP), Quantitative Risk Analysis (QRA), Project Health, Safety, Environmental Review (PHSER) - are required and the determination of the SIL is ranked as one element within the safety aspects design workflow. The approach how to determine the proper integrity level is demonstrated in detail on risk graphs. The risk graph approach is not only limited to safety aspects as it is more and more common to use these also for environmental and commercial aspects. This requires a proper calibration of the risk graphs which big oil & gas operators define within their company standards.

The paper provides examples for a SIL review assessment including its reporting and flag the required input data. It refers to the relevant norms and standards and explain how pipeline operators are calibrating the risk graphs for the environmental and commercial aspects within their company standards.