Abstract:

After HAZOP analysis and SIL assessment, it is necessary to confirm whether the SIF loop satisfies the SIL requirements. If a specified SIL is achieved, the corresponding requirements for the probability of dangerous failure on demand (PFD) in low demand mode or the frequency of dangerous failure per hour (PFH) in high demand mode, the structural constraints and the system capabilities should be met, respectively. This article provides the calculation methods and SIL assessment criteria for the above indicators, and discusses in detail the SIL verification according to regulatory requirements.

Key words: SIL verification, PFD, PFH, structural constraints, system capabilities