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Report on flexible pipelines and risers - failure modes, inspection, testing and monitoring

The Petroleum Safety Authority Norway (PSA) has commissioned a study that was performed by Seaflex, with the main purpose of summing up the status on failure modes, inspection, testing and monitoring of flexible pipelines and risers.


During 2006 and 2007 and in parallel with the Seaflex study, the PSA has conducted a review of the industry’s knowledge concerning flexible risers and pipelines. The review focused on operation, inspection and maintenance programs, and how such programs are documented and monitored in order to provide the best understanding of the true condition of the flexible pipe.

In December 2007, the PSA hosted an industry seminar in Stavanger where the intention was to increase the general knowledge about flexible pipelines and risers and to exchange experience within the industry.

As part of our industry review, Seaflex was contracted to compile a report providing state of the art knowledge of failure modes from manufacturing, transportation, installation and operation of flexible pipelines and risers. The following items are covered in the report:

• Historical review of design (Presumptions, design criteria, applicable standards)
• Overview and description of failure modes and mechanisms
• Inspection methods and integrity monitoring

The report is based on world-wide experience. As most flexible pipes in operation in the Norwegian offshore sector are unbonded pipes, this is the main focus, but a brief summary on bonded pipes has been included to broaden the report.

The Facilities Regulations Section 9 on Plants, systems and equipment, specifies that ‘Plants, systems and equipment shall have a design which is robust and as simple as possible’.
Further the Management Regulations Section 22 on Improvement states that ‘Provision shall be made for using knowledge gained through experience from own activities as well as the activities of others in the improvement efforts.’

These requirements are of great importance for flexible pipelines and risers to ensure safe operation during the design phase and operating life. By establishing clear objectives for design, installation and operation, sharing experiences and lessons learnt in the industry and by increasing the general knowledge about flexibles, we aim to further reduce the number of incidents.

Contact in the Petroleum Safety Authority Norway
Trond Sundby

Media inquiries:
Kristin Hoffmann
Telephone: 51 87 62 19