SOFUS v2.0 – Follow-Up of SIL in Operation


Safety instrumented systems (SIS) are employed to manage risk for loss of values, such as life and health, economy, environment and reputation. It is crucial that the safety systems meet their performance requirements throughout the whole lifetime.

The standards IEC 61508/61511 lay the foundation for the design, implementation and follow-up in operation of the safety instrumented systems. The industry has long experience with design and implementation of safety instrumented systems, however, the follow-up of the systems in operations can be challenging or even absent. The Norwegian Petroleum Safety Authority claims that «The status of active safety functions shall be available in the central control room» (ref. Facility Regulation, § 8), and thus, that achieved performance needs to be followed up in operation.

Safetec has developed the tool SOFUS («SIL in Operations Follow-Up System») for following up the performance of the safety instrumented systems in operation. SOFUS combines safety requirement specifications and initial data from the design phase with notifications from operation logged in maintenance systems. This information is used to calculate the status of the performance for the safety instrumented systems.

SOFUS is currently implemented at several operators. Several years of experience have revealed the need and potential for streamlining and optimising the collection of information from the maintenance system etc. Safetec is currently working on a comprehensive update of SOFUS; v2.0. SOFUS v2.0 will have an improved interface towards other systems employed by the end user, aiming for a streamlined system for follow-up of safety instrumented systems in operations.

This summer, Safetec has initiated the development process for a prototype of the new version of SOFUS, which will be tailored to each end user. SOFUS v2.0 will provide an immediate visualisation of KPI’s for the safety instrumented functions through an interactive dashboard. This will provide input and support for identification of problem areas and maintenance management, in addition to be a formal basis for decision making regarding potential measures and actions necessary for increasing the safety level – or increased test interval and other cost reducing measures, provided that acceptable safety level is maintained.

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