About Safety Integrity Level (SIL) Assessment Using a Risk Matrix

You can assess the Safety Integrity Level (SIL) of an instrumented function using the standard GE Digital APM Risk Matrix interface to select the risk rank values for specific categories of risk.

To determine the SIL value using a Risk Matrix, you must:

Specify the SIL Threshold values. An SIL Threshold record stores the upper and lower boundary values for each SIL.
Select the risk assessment that you want to use to assess the SIL value. You can use the baseline Risk Matrix or a custom Risk Matrix.
Select the unmitigated risk rank values for each category in the Risk Matrix. GE Digital APM then calculates the overall unmitigated risk rank by adding the unmitigated risk rank values for each category. This value is stored in the Unmitigated Risk Rank box above the Risk Matrix on the Risk Assessment Interface.

The category that has been assigned with the highest risk rank in the Risk Matrix is called the Driving Risk, and the corresponding risk rank is called the Driving Risk Rank. Depending on the range in which the driving risk rank value falls, the system determines the SIL, and then populates the Selected SIL Level field with this value.

Note: If the driving risk rank value falls on the boundary value of two SIL thresholds, GE Digital APM populates the Selected SIL Level field with the higher SIL value. For example, suppose that the SIL Threshold contains SIL value 1 for the risk range 0 through 10, and SIL value 2 for the risk range 10 through 100. If the driving risk in the risk assessment is 10, the Selected SIL Level field is populated with the SIL value 2.