SIL verification

SIL (design) verification

Schematic view of instrumented safeguard (SIS) for SIL verification (HIPPS).
Schematic view of instrumented safeguard (SIS) for SIL verification (HIPPS).

For every single SIL 1/2/3 or 4 safeguard, it should be verified that the safeguard is designed according to the standards IEC 61511 or IEC 61508, this is called SIL verification;

  • Identification of safeguard. It is wise to make a schematic drawing with all the relevant sensors, components and final elements.
  • Verifying the functionality of the safeguard.
  • Determine whether the safeguard is independent (enough) from the control system.
  • Check against the architectural requirements (e.g. is one valve sufficient?).
  • Check to the probabilistic requirements (calculation of probability of failure on demand).
  • Check for systematic faults.

It is highly recommended to make taylor-made test procedures during design phase.

Also for HIPPS systems (High-integrity pressure protection system) it is necessary to perform a SIL verification.