With the increasing use of flexible pipe technology - driven by the move to deeper, more marginal and more challenging conditions - the need for systematic management of the flexible pipes is becoming more apparent. In particular, the full implementation of Riser Integrity Management (RIM) plays a vital role to ensure an efficient and safe operation.

This paper will discuss issues regarding Riser Integrity Management raised by operators and addressed to NKT Flexibles (NKTF) as the supplier. The discussion will include measurements and tests of flexible pipes, assessment and repair of possible damages, as well as assessment of change of regime e.g. change of location/ bore contents/ pressure/ temperature/ souring.

Riser condition monitoring and inspection form an important part of integrity management together with processing and analyses of the monitored data. The present paper identifies and discusses available and emerging options for condition monitoring and for engineering assessments and remedial actions, and discusses the recently developed technology of embedded optical fiber monitoring for quantifying the integrity of the flexible risers during their service life.

Early Flexible Pipe Development

The development and use of flexible riser and pipeline technology for offshore oil and gas production is relatively young, however, flexible pipelines were applied for other purposes, before the introduction to the offshore industry.

The concept of a flexible armored marine pipeline was first introduced and applied at a significant scale in the World War II project codenamed PLUTO (PipeLine Under The Ocean) for transporting fuel under the British Channel from the United Kingdom to Normandy, France. The design was based on high voltage marine power cable technology.

The first commercial marine pipeline was installed between two Danish islands in 1964, also based on marine power cable technology.

The step on to high pressure pipelines, reinforced against collapse, for the offshore industry was taken in 1972, applying technologies developed by IFP, France.

Early Experiences

Initially, flexible pipelines have been considered maintenance free and not in need for regular inspection.

Since their first introduction, a vast number of improvements have been introduced to the design and manufacturing of the pipes, end-terminations and accessories.

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