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Installation of the first pipeline to reach the Arctic Circle, the world’s deepest 36-inch system connects gas reserves in the Aasta Hansteen field in the Norwegian Sea and the Nyhamna gas processing facility in western Norway.
Company: Statoil (Equinor)
Location: Norwegian North Sea
1260 m
Max. water depth
Scope of work
- Fabrication of pipeline heads (AFBV, Heusden)
- Installation of 482 km, 36-inch concrete-coated pipeline (incl. 5x in-line tee structures, laydown with pipeline collar connector at Aasta Hansteen platform)
- Installation of a 2-km-long vent line at Aasta Hansteen for commissioning the pipeline
- Pull-in operations at the live Nyhamna gas plant (5 m from existing Langeled gas export pipeline)
- Installation of 27x crossings at existing pipelines & cables
482 km
concrete-coated pipeline
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Specials & challenges
- Deepest pipeline on the Norwegian continental shelf & the first to reach the Arctic Circle
- Water depth record for concrete-coated 36-inch pipe (1260 m)
- Route selection required optimisation of pipeline wall thickness and design of the buckle arrestor (10 combinations of wall thickness / anti-corrosion coating / concrete-weight coating thickness)
- Provision on standby of wet buckle contingency spread comprising 36-inch isolation plug, a 1000-t pipeline recovery tool and a nitrogen dewatering spread with coiled tubing
- Pipeline passes through rough and uneven terrains consisting of ancient icebergs, which necessitate the use of long free spans with rock support
- Lay corridor of only +/- 1 m at locations with preinstalled rock berms and in coral beds
- Pipeline collar connector for final laydown with an axial tolerance of +/- 1.5 m
- More than 40,000 steel pipes weighing a total of 325,000 t
325,000 t
40,000 steel pipes weighing
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