Safety Systems That Fail Safely? The Hidden Risks in SIS Performance and Lifecycle Management

Safety Instrumented Systems (SIS) are designed to reduce the likelihood and consequences of hazardous events, yet many organisations assume that once a system has been installed and commissioned, its safety performance is assured. In reality, the effectiveness of a Safety Instrumented Function (SIF) depends on continuous management throughout the safety lifecycle. Poor proof testing, alarm overload, bypass management failures, inadequate maintenance, and undocumented changes can significantly degrade safety performance over time without being immediately visible to operators or management.

While Safety Integrity Levels (SIL) and risk reduction targets are often established during project design, maintaining those performance requirements throughout operation presents a different set of engineering challenges. Understanding how operational practices, reliability data, human factors, and asset management decisions affect SIS performance is critical for ensuring that safety systems continue to provide the protection assumed during risk assessments.

This session examines the practical realities of Safety Instrumented System lifecycle management and explores the factors that commonly erode safety performance after commissioning. Participants will gain insight into proof testing, SIL verification, alarm management, performance monitoring, reliability considerations, and the operational practices required to sustain functional safety outcomes throughout the life of an asset.

Key Topics Discussed:

• Functional safety lifecycle under IEC 61511
• Safety Instrumented Systems and Safety Instrumented Functions
• SIL targets versus actual operational performance
• Proof testing and proof test interval optimisation
• Dangerous undetected failures and performance degradation
• Alarm management and operator effectiveness
• Bypass management and impairment control
• Reliability engineering and SIS performance
• Safety Requirements Specifications (SRS)
• Functional Safety Assessments (FSA)
• Performance monitoring and leading indicators
• Lessons learned from operational safety system failures
• Maintaining safety integrity throughout the asset lifecycle