Bundles and towed installation

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Bundles and towed installation

The main advantage with bundle systems is that they can be fabricated and pre-commissioned onshore, prior to installation. The controlled onshore environment enables a greater assurance in the quality of the fabrication at lower costs than in comparison with offshore commissioned systems. Bundles are fabricated with several pipelines contained within a single carrier pipe. The compact design has advantages in that multiple pipelines can be installed at once using minimal space on the seabed. There are five installation methods; on and off-bottom towing, controlled-depth tow, surface tow and controlled-depth surface towing. Bundles can also incorporate integral active heating systems to maintain product temperatures during production. Depending on the integrity of the bundle at the end of the field life, it may be possible to re- use the bundle on other field developments. Standard bundle designs are usually not sufficiently strong to be used for deep-water applications. However, ‘special’ bundles have been developed for deep-water usage. They may utilise internal pressurisation or flooding of the carrier pipe to enable it to withstand the hydrostatic pressures associated with deep water.