SIS Availability vs Proof Testing
Use risk-based proof test intervals, partial stroke testing, and online diagnostics to maintain required SIL integrity without unnecessary production impairment.
CyberTRIZ analysis · Seveso contradiction FS002 · one of 8,235 worked contradictions published by CyberTRIZ.AI
Regulations
Business Context
Safety Instrumented Systems require periodic proof testing to verify
that safety functions remain capable of operating when demanded. These
tests frequently require temporary bypasses, equipment isolation, or
production interruptions.
The Contradiction
More frequent proof testing increases confidence in SIS performance.
More testing reduces system availability and increases maintenance
effort.
Why It Exists
Proof testing temporarily removes protective functions from normal
operation while engineers verify sensors, logic solvers, and final
elements.
Direction
Optimize proof test intervals using SIL verification, diagnostics,
partial stroke testing, and condition monitoring while minimizing
impairment of protective functions.