Background & Challenges
An operator responsible for safety-critical gas infrastructure engaged Equinox Automation after identifying that, while individual functional safety activities were being performed across its assets, there was no single functional safety management system defining when, why, and how functional safety decisions were made and maintained across the asset lifecycle. The scope related specifically to Safety Instrumented Systems (SIS) operating within the intent of IEC 61511 for the process industry sector.
The challenge was not IEC 61511 alignment itself, but governance and standardised lifecycle management across projects and operations. Functional safety activities were undertaken without a single functional safety management system, and safety documentation was not consistently managed across the lifecycle.
Equinox was engaged to define and establish the functional safety management system and supporting processes aligned with IEC 61511, and to validate their application through a controlled pilot on existing Safety Instrumented Functions (SIFs).
Solution
Drawing on operational experience, Equinox defined a functional safety management system covering the full lifecycle, from analysis through implementation and operation. The work clarified when Layer of Protection Analysis (LOPA) risk assessment and SIL determination are required, how risk criteria inform SIL targets, and what level of evidence is expected at each stage of the lifecycle.
Common procedures were established for LOPA risk assessment, SIL verification, and Safety Requirement Specifications (SRS) development, providing a consistent basis for use across projects and existing assets. A pilot program spanning a representative set of existing SIFs was used to test the system against operating assets, following a defined sequence and acceptance basis to maintain traceability from hazard identification through to verified SIF performance.
Results
The outcome was an IEC 61511-aligned functional safety lifecycle management system approved for internal use. Functional safety decisions are now repeatable, auditable, and transferable across assets and projects. The client has since applied the system to existing assets, with Equinox providing lifecycle implementation support where required.
For enquiries about applying this approach to your assets, or for broader functional safety support, contact our team.
Figure 1: Example process facility where IEC 61511 functional safety is typically implemented
