IEC 61511-2:2016

Overview

IEC 61511-2:2016 - Functional safety - Safety instrumented systems for the process industry sector - Part 2: Guidelines for the application of IEC 61511-1:2016 - provides practical guidance for applying the requirements of Part 1 to Safety Instrumented Functions (SIFs) and Safety Instrumented Systems (SIS) in the process industry. This 2nd edition (2016) replaces the 2003 edition and is a technical revision that adds real-world guidance across the safety life cycle and updated annexes that address the transition from traditional software to modern application programming.

Key topics and technical requirements

The standard complements IEC 61511-1 by expanding on how to implement its requirements. Major subjects covered include:

• Management of functional safety: roles, responsibilities and lifecycle governance for SIS projects.
• Safety life-cycle guidance: practical steps from concept and design to decommissioning for SIFs and SIS.
• Verification and validation: planning and evidence needed to demonstrate compliance with safety requirements.
• Process hazard and risk assessment (H&RA): inputs for defining SIFs and determining required Safety Integrity Levels (SILs).
• Allocation of safety functions to protection layers: methods to assign risk reduction between SIS and other layers (BPCS, alarms).
• SIS safety requirements specification (SRS): how to write and manage SRS documents for application programming and hardware.
• SIS design, engineering and hardware selection: architecture, diagnostics, hardware fault tolerance and field device considerations.
• Application program development: lifecycle, tools, methodology and verification for SIS logic solvers and safety PLCs.
• Factory Acceptance Testing (FAT), installation, commissioning, validation, operation, maintenance and proof testing.
• Documentation, modification, decommissioning: recordkeeping and change-control practices.
• Annexes and examples: techniques for probability-of-failure calculations, typical architectures, application program examples and transition guidance from non-programmable to programmable equipment.

Practical applications and users

IEC 61511-2 is intended for organizations and professionals involved in the design, implementation and lifecycle management of safety instrumented systems in process industries:

• Functional safety engineers and SIS designers
• Process safety managers and plant operators
• Control system integrators and automation engineers
• Software developers of SIS application programs and safety PLC code
• Maintenance teams, inspectors and auditors
• Regulatory and compliance personnel

Use cases include establishing SRS documents, performing SIL allocation and LOPA, designing SIS architectures, conducting FAT and commissioning, and developing/verifying safety application software.

Related standards

• IEC 61511-1:2016 - Requirements for SIS (primary normative reference)
• IEC 61508 series - generic functional safety for electrical/electronic/programmable systems
• Industry-specific guidance and local regulatory process-safety standards

Keywords: IEC 61511-2, IEC 61511-1, functional safety, safety instrumented systems, SIS, SIF, process industry, SIL, safety lifecycle, safety PLC, application programming, proof testing, FAT, LOPA.