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Wheatstone J-Tube and Flowline Stabilisation

Client: Technip

Offshore facilities to gather and partially process gas and associated condensate and deliver it onshore for further processing. Key offshore components include:

  • Well infrastructure and subsea installations
  •  Gas processing platform in 73m of water
  • 225km trunkline to transport gas from the platform to the onshore facilities at Ashburton North.

The platform J-Tubes were at risk of sagging fatigue due to the high water velocities at the base of the structure. Technip approached Subcon design a formwork that not only supported the J-Tube but also shielded the it from lateral flow.

Subcon scope

Subcon’s scope was to design and supply a support that protects the J-Tubes from sagging fatigue and with a high shoulder to shield J-Tube from high flow velocities. Heavy density grout designed to remain stable in cyclonic conditions.
The deliverables included:

  • 12 bespoke fabric formworks
  • 3rd party validated grout design
  • Full scale onshore SIT
  • Additional custom grout supports with scour skirts for flowline free spans

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