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Staying power

Half of all the installations on the NCS will soon have reached their original design life, but their owners want to continue using many of them for a long time to come. The bottom line is that safety must not be compromised.

Materials degrade and weaken with age, and such weaknesses can be highly visible – or well hidden. Any failure is likely to have serious consequences for safety. That makes it essential to monitor degradation, test equipment, pursue maintenance and replace any components as required.

Age-related deterioration is not an exact science, being affected by local conditions, methods of use, materials involved and other factors. Physical working life can be shorter or longer than expected when an installation was new. On behalf of the PSA, the Sintef research foundation has taken a closer look at issues related to aging and production life extension.

Completed in late 2008, its report notes in part that standards applied for such extensions are unclear, uncoordinated and unsystematic.

These findings confirmed the PSA’s impression, and the agency accordingly asked the OLF to develop new standards for safely extending production life.

Some of this work had already been completed by the beginning of 2009, and the aim is have all the standards in place during the coming year.

The PSA consents to an extension on the basis of an application from the installation’s owners, who must document in detail that its condition is good and continued operation acceptable.

Data about the design, materials, technical facilities, operating mode and history are important when considering such requests. A detailed plan for future operation must also be submitted.

“Extensive maintenance may be needed to keep elderly installations in good condition,” notes principal engineer Gerhard Ersdal at the PSA.

“Many considerations and assessments must be taken into account when seeking to sustain an acceptable level of safety on such units.

“Companies have to develop the knowledge, expertise and models which ensure that production life can be safely extended. The challenges include understanding how different equipment and materials are affected by various degradation mechanisms.”

The PSA has frequently requested supplementary information before approving applications to extend production life, Mr Ersdal reports.

“We’re always concerned that somebody’s trying to push the limits. Audits and investigations have unfortunately shown that this happens.

“That’s not necessarily conscious. It could be that people are not sufficiently aware of the consequences of stretching things too far.

“But we’ve naturally seen several cases of managements who put safety and the working environment ahead of financial considerations, schedules and production targets.” Applications for extending production life assume a basic trust between company and regulator. Accompanying documentation is expected to be credible and quality-assured.

“The operator has an overarching responsibility for knowing an installation’s quality at any given time – including plans for necessary maintenance,” says Mr Ersdal.

“We work at the overall level, and don’t verify conditions covered by the application in detail beyond making spot checks where necessary and appropriate.”

By Per Lars Tonstad