10.1 Introduction

Flexible pipes have been used in the oil industry since 1972, when Coflexip was awarded a patent to build a high pressure, flexible steel pipe. The first application was used in drilling as a 15,000 psi Kill and Choke line. Since then, flexible pipe designs have improved to produce the flowlines and risers that are now used in the offshore oil industry.

For deepwater, the flexible pipes are used mainly for dynamic risers from a subsea pipeline end manifold (PLEM) or riser tower to a floating production system such as an FSO, FPSO, and TLPs. The other uses are static risers, static flowlines, subsea jumpers, topside jumpers, and expansion joints. Flexible pipes are used for versatile offshore oil and gas applications including production, gas lift, gas injection, water injection, and various ancillary lines including potable water and liquid chemical lines.

The main advantages of flexible pipelines are:

• Ease and speed of installation

• No large spans because it follows the contours of the seabed

• Almost no maintenance for life of the project

• Good insulation properties are inherent

• Excellent corrosion properties

• No field joints because the pipe is of continuous manufacture

• No need of expansion loops

• Can be made with enhanced flow characteristics

• Sufficient submerged weight for lateral stability

• Accommodates misalignments during installation and tie-in operations

• Diverless installation is possible no metrology necessary

• Load-out and installation is safer, faster, and cheaper than any other pipe application

• Retrievability and...