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Chapter 24

Pipe-in-pipe and Bundle Systems

24.1 General
The main feature of pipe-in-pipe and pipeline bundle systems is that the pipeline is comprised
of concentric inner and outer pipes. The inner pipe or pipes within sleeve pipes carry the
production fluids and are insulated, whilst the outer pipe or carrier pipe provides mechanical
protection.

The first known pipe-in-pipe system was installed in 1973 by Pertamina Offshore Indonesia.
This pipeline was 8 miles long extending from shore to a single point mooring facility. The
outer and inner diameters of this pipeline were 40 and 36" respectively.

Up till now nearly 36 pipeline bundles have been installed by controlled depth tow method
(CDTM). The first one was installed at the Murchison field in 1980. The longest pipeline
bundle is the one being designed, constructed and installed in Norwegian Sector by
Rockwater. This bundle is 14 lun long with 46" carrier pipe and three production lines.

This Chapter presents the design procedure and strength acceptance criteria for pipe-in-pipe
and pipeline bundle system. The design should ensure that adequate structural integrity is
maintained against all possible failure modes. All relevant failure modes for pipelines
described in Chapter 4 are to be considered in the design of pipe-in-pipe and bundle system.

24.2 Pipe-in-Pipe System

24.2.1 Introduction
Many of the newly emerging generation of high pressure high temperature (HP/HT)
reservoirs in the North Sea are being exploited using pipe bundles and single pipe-in-pipe
configurations as part of subsea tie-backs to existing platforms. Not only are reservoir
conditions more harsh but there is a need to insulate the flowlines to prevent wax and hydrate
formation as the product cools along the length of the pipeline.