Bundles and towed installation

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Bundles and towed installation

Rockwater (now Subsea 7) installed two pipe bundles, 3.8 km (2.4 mile) in length with 1117.6 mm (44 in) carrier pipe, for Statoil’s Åsgard development, during 1997. The preferred launch method at their Wick site is to mount the bundle on rail bogies, which are released by passing into a dip just below water level. Lateral rails are required to support the skids fitted to the wider tow and trail heads.

BUNDLEFABRICATIONSUMMARY

BUNDLE FABRICATION – SUMMARY

ƒ Two methods ƒ Assemble whole carrier first from shop ƒ Install flowlines from welding shop ƒ All welding completed in controlled environment ƒ Sets of rollers and support plinths ƒ Assemble flowlines first

ƒ Sleeve on 200 m (650 ft) sections of carrier with field welding ƒ Assembly on rail track for ease of launch ƒ Needs long site with access to sheltered bay

ƒ Assembly shop – industrial unit ƒ Pipe storage and pulling winches Any questions?

The two methods used for fabricating a bundle are outlined above. Once fabricated, the towheads are attached and then the bundle is hydrotested, pre-commissioned and launched. We describe these subsequent activities in more detail in the following slides. The field welds are protected from weather by temporary shelters called howdahs.