When a SIS is commissioned the SIS and SIFs will be fully validated against the Safety Requirements Specification (SRS) and the SIFs will be tested end to end for correct functionality. When the process is Operational the Safety Instrumented Functions are required to be tested on a periodic basis (set by the SIL verification exercise). The exercise of testing the SIFs is called Proof Testing. It is important that the Proof Test is designed correctly as the purpose of the Proof Test is to detect any unrevealed failures that have not been detected by diagnostics.

​

When developing a Proof Test procedure it is important to include any steps from the instruments Safety Manual as this will also detail the Proof Test Coverage that can be claimed. The sections of the proof test will include:

​

• Pre Job Tasks (Permit to work)

• References (P&ID,C&E,SRS etc)

• Visual Inspection

• Function Test Equipment

• Record Inspection/Test Results

• Maintenance Closeout