Performance-based standards: safety instrumented functions and safety integrity levels

Area of Science:

• Engineering
• Safety Systems
• Risk Management

Background:

• Companies increasingly rely on electrical, electronic, and programmable electronic systems for critical safety functions.
• International standards such as ANSI/ISA S84.01 and IEC 61508 provide frameworks for ensuring the safety performance of these systems.
• Performance-based regulations also guide safety system implementation, often overlapping with established standards.

Purpose of the Study:

• To discuss the requirements imposed by ANSI/ISA S84.01 and IEC 61508 on companies using safety instrumented systems.
• To identify common safety elements between these international standards and performance-based regulations.
• To explore various risk analysis techniques applicable for compliance with these safety mandates.

Main Methods:

• Comparative analysis of ANSI/ISA S84.01 and IEC 61508 standards.
• Identification of overlapping safety principles in standards and regulations.
• Discussion and illustration of risk analysis techniques for safety system compliance.

Main Results:

• Key requirements for safety functions performed by electrical, electronic, and programmable electronic systems are outlined.
• Common safety elements between the discussed standards and performance-based regulations are identified.
• Several risk analysis techniques are presented with an illustrative example, detailing their use, advantages, and disadvantages.

Conclusions:

• Compliance with performance-based safety standards like ANSI/ISA S84.01 and IEC 61508 necessitates robust risk analysis.
• Understanding common safety elements across standards and regulations aids in streamlined implementation.
• The selection and application of appropriate risk analysis techniques are crucial for ensuring the safety integrity of automated systems.