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Safety system independence in focus

A study of safety systems on the Norwegian continental shelf has found that official requirements for their independence and robustness are not being adequately fulfilled.

That reflects a trend towards these solutions becoming increasingly interconnected, in part because the same manufacturer delivers both control and safety systems.

Other factors include applying the same software and user interfaces in different systems, shared hardware, increased signal transmission between systems and integrated operation (IO).

The Petroleum Safety Authority Norway (PSA) has witnessed an increasing degree of integration and interconnection between safety and control systems.

But the regulations specify that sufficient separation must be maintained between safety barriers, including an ability to perform their intended function independently from other systems.

Technological developments and the growing use of integrated systems have prompted the PSA to question whether its regulatory requirements are being adequately met.

On that basis, it has implemented a project with support from the Sintef research foundation to assess how safety-critical the specified connections and dependencies actually are.

Another main aim was to identify whether certain typical types of dependencies are unacceptable and therefore need to be specially flagged with the industry.

Based on a survey conducted in 2007, this project involved audits of three operators on the NCS and three suppliers of safety systems.

The main purpose of these checks was to investigate how far the PSA’s requirements for independence were met and to assess safety criticality.

In that context, attention was concentrated on errors and incidents which could lead to hazardous conditions because safety functions failed to work as intended.

The study report lists areas where the industry has an identified improvement potential, and concludes on this basis that companies lack an adequate overview of system independencies.

They also have insufficient understanding about the possible safety consequences of undesirable information and communication technology (ICT) incidents.

Knowledge and awareness of these conditions should be strengthened through increased use of risk and vulnerability analyses.

Better collaboration between such disciplines as ICT, process technology, automation, instrumentation and telecommunications is also needed, along with a general expertise enhancement.

The PSA will follow up the industry to ensure that it gets to grips with the weaknesses identified in the report, which is only available in Norwegian.

Contact persons in the PSA