The aim of a SIF Analysis is to design the Subsystems such that the Achieved PFD is equal or higher than the Target PFD. The Target PFDs are typically established during the LOPA study. In some cases, a SIF Analysis can be started independent from a LOPA, e.g., when you have an emergency button. In this case a static Target SIL must be specified during the SIF Analysis.
If the SIF is connected to a LOPA
After a SIF Barrier has been added to the LOPA, the calculated risk gap shown as the Overall PFD in the Assessment Summary is transferred to the SIF Analysis as the Target PFD for the SIF design verification calculations in the SIF Analysis.
- The Target PFD will always be the Overall PFD shown when the SIF Barrier's PFD L and H is set to "1.00E+00".
- You can play around with the SIF PFD values to see how the Overall PFD is influence, but this will not affect the Target PFD.
- Even if more than one SIF Analysis is connected to the LOPA, all of them will still have the Overall PFD (with all SIF Barriers having a PFD = 1) as Target PFD.
The Overall PFD is transferred to SIF Analysis as the Target PFD. The SIF name is a hyperlink that will navigate you to the SIF Analysis.
The LOPA and SIF Analysis are linked. Note: When the Target PFD of the SIF is changed from the LOPA, the SIF Analysis (if Approved) will fall back to Draft.
If connected to multiple LOPAs
It is possible to have multi scenario LOPAs for a SIF Analysis. All LOPAs will show on the SIF Analysis. The worst Overall PFD will be used as the Target PFD for the SIF design verification calculations in the SIF Analysis.
A SIF Analysis connected to multiple LOPAs.
If the SIF is not connected to a LOPA
If not connected to a LOPA, you can set the Target PFD during the SIF Analysis.