Safety Integrity Level (SIL) evaluation of safety instrumented systems considering competing failure modes and subsystem priorities

IF 9.4 1区工程技术 Q1 ENGINEERING, INDUSTRIAL

Reliability Engineering & System Safety Pub Date : 2025-03-19 DOI:10.1016/j.ress.2025.111025

Morteza Cheraghi, Sharareh Taghipour

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引用次数: 0

Abstract

Safety Integrity Level (SIL) is a crucial measure of the safety performance of Safety Instrumented Systems (SISs), reflecting their ability to reduce risk. However, SIL analysis has often overlooked the impact of competing failure modes and subsystem priorities within SISs. This paper introduces a novel probabilistic model for evaluating the SIL of safety functions that incorporates these critical aspects. The model calculates the time-dependent Probability of (dangerous) Failure on Demand (PFD) and Probability of Failing Safely (PFS) at the component, subsystem, and system levels. The average PFD (PFD_avg) and SIL are calculated considering both planned and unplanned proof tests. The proposed model is validated through Monte Carlo simulations and applied to a safety system designed to protect a process vessel from high-pressure hazards. A comparative analysis with existing models demonstrates that competing failure modes and subsystem priorities significantly influence PFD, PFS, PFD_avg, and consequently SIL, especially in systems with longer proof test intervals and higher Safe Failure Fractions (SFFs).

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来源期刊

Reliability Engineering & System Safety 管理科学-工程：工业

CiteScore

15.20

自引率

39.50%

发文量

621

审稿时长

67 days

期刊介绍： Elsevier publishes Reliability Engineering & System Safety in association with the European Safety and Reliability Association and the Safety Engineering and Risk Analysis Division. The international journal is devoted to developing and applying methods to enhance the safety and reliability of complex technological systems, like nuclear power plants, chemical plants, hazardous waste facilities, space systems, offshore and maritime systems, transportation systems, constructed infrastructure, and manufacturing plants. The journal normally publishes only articles that involve the analysis of substantive problems related to the reliability of complex systems or present techniques and/or theoretical results that have a discernable relationship to the solution of such problems. An important aim is to balance academic material and practical applications.