After safeguards are realized, they have to be validated correctly. It has to be demonstrated that safeguard are implemented according to the principles and requirements. The physical testing will be performed by qualified personnel according to taylor-made test procedures. The test results must be recorded.
During the SIF validation, the SIF’s should be visually inspected. Temporarily applied overrides are not (any longer) allowed. Manual valves must be in the correct position (preferably locked open or locked close). Junction boxes must be closed. The logic solver should function properly.
The functions in the safety PLC shall be validated as well.
All the preceding steps (from hazard identification) may have no effect if the last step is not performed.