Troll Phase 1, large-diameter pipeline pull-in and curve lay-away
- A/S Norske Shell, Bergen (Norway)
- European Marine Contractors Ltd., London (United Kingdom)
During 1995 two 36-in. and one 16-in. pipeline were pulled into the gravity base structure (GBS) of the Troll Phase 1 platform offshore Noway at a waterdepth of 303 m. Pull-in and subsequent riser tie-in welding were on the critical path for completion of the overall project construction program. The prevailing waterdepth dictated the use of a diverless solution and this was achieved by a unique combination of special equipment and construction features. Pipeline risers were pre-installed inside a permanently dry riser shaft, one of the four legs of the FBS. At the bottom of this shaft custom-made sealtubes penetrate the concrete structure acting as pipeline pullhead receivers. Pull-in was carried ut by means of a 500-ton linear winch arrangement on the platform topsides. The associated 115 and 70 mm pull-in cables were guided through 8-in. riser shaft pull-tubes connected at the lower end to the sealtubes. Following pull-in, atmospheric tie-in welding of pipeline to riser completed the operation inside the riser shaft. Pipeline curve lay-away from the platform took care of pipeline thermal expansion rather than diver assisted installation and connection of a traditional expansion spool. The article highlights pipeline pull-in and curve lay-away design and engineering background and construction experiences.
- OSTI ID:
- 400900
- Report Number(s):
- CONF-9606279--; ISBN 0-7918-1494-7
- Country of Publication:
- United States
- Language:
- English
Similar Records
Experience from first 100 tie-ins at Troll Oil
Troll Phase I pipelines: Tie-ins to the subsea tunnel