Glossary · Verification and validation
SIL validation
Also known as: SIS safety validation
German: SIL-Validierung
In functional safety under IEC 61511, SIL validation (SIS safety validation) is the activity of demonstrating, by inspection and testing of the installed and commissioned system, that the safety instrumented system and its functions meet the safety requirements specification.
- Verification
- Functional safety
In one sentence
SIL validation shows by inspection and testing that the installed safety instrumented system meets its safety requirements specification.
Example
Before startup, the team forces each process condition at the field sensors, confirms that the correct valves close within the specified time and signs off each SIF in the validation report.
How it applies
- Commissioning: Validation takes place after installation and commissioning and before the hazards are present. It covers the complete functions from sensor to final element, including diagnostics, bypasses, resets and manual shutdown.
- Planning: A Validation plan defines the tests, acceptance criteria, responsible persons and required documentation in advance.
- Deviations: Failed tests lead to corrections and repeated tests. The validation report records the result of each function and any open items.
- Documentation: Validation records are key Safety evidence. The documentation team should make sure each test result traces back to an SRS requirement and that the installed software version and configuration are recorded.
SIL validation vs. SIL verification
SIL verification checks that the outputs of each lifecycle phase meet its inputs, for example that the calculated failure measure meets the required SIL. SIL validation checks the finished, installed system against the SRS. Passing a calculation does not replace validation, and a successful test does not prove the failure probability.