Troll Phase 1, installation of large spools before pipelay
- Rockwater AS, Stavanger (Norway)
- A/S Norske Shell, Bergen (Norway)
Development of the Troll Phase 1 project required landfall--towards a gas conditioning plant on the Norwegian west coast--of both 36-in. wet gas fed (or import) pipelines and 40-inch dry gas export pipelines. The very uneven seabed necessitated both the driving of a 3.5 km long subsea tunnel system and extensive route preparations. The lateral separation of 142 to 163 m between subsea tunnel pipeline risers and offshore pipeline laydown was bridged by fabricating four large--147 to 186 tons--spools. These spools were installed gas-filled in unique single lifts using special sea fastening and guidance systems. The odd-shaped 3-D spool configurations were fabricated to match an extensively prepared seabed. The spools were installed after tunnel pipeline riser completion but before pipeline laydown to minimize the duration of underwater activities late in the season. Special support structures were fabricated to support hyperbaric welding and pipeline laydown operations. Accurate pipeline laydown facilitated simple and quick lift, shift and alignment operations, and all (seven) automated hyperbaric welds with the Pipeline Repair Systems (PRS) were completed on schedule without the use of pup-pieces. Diver support during these activities constituted a significant operation in itself.
- OSTI ID:
- 400903
- Report Number(s):
- CONF-9606279-; ISBN 0-7918-1494-7; TRN: IM9650%%309
- Resource Relation:
- Conference: 14. international conference on offshore mechanics arctic engineering (OMAE), Florence (Italy), 16-20 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of OMAE 1996 -- Proceedings of the 15. international conference on offshore mechanics and arctic engineering. Volume 5: Pipeline technology; Murray, A. [ed.] [Nova Gas Transmission, Calgary, Alberta (Canada)]; Bruschi, R. [ed.] [Snamprogetti, S.p.A., Fano (Italy)]; PB: 612 p.
- Country of Publication:
- United States
- Language:
- English
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