01 September

Clamp Replacement

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Scope Of Work

Charter of DSV ‘Siem N-Sea’ for the provision of vessel based nitrox diving services and WROV.

N-Sea was contracted by BG Group to carry out the North Everest and Lomond Firewater Caisson Clamp installation and survey scope at the North Everest and Lomond Platforms.

There was a requirement to install a new guide/clamp arrangement on the Lomond C2 Firewater caisson at -18m and a new guide/clamp arrangement on the North Everest C1 firewater caisson at -18m. This required preparation of the VDM to take the friction clamp including removal of an anode and doubler plates, the grinding of weld beads and grit blasting.

The clamp installation will utilise the static rigging from topsides as installed for the original scope.
The existing C1 Caisson was removed in August 2014 and therefore new guide needed to be positioned using the existing guides.


  • Late award of contract

  • Challenged to improve upon delivery in terms of efficiency and cost againts previous years campaigns

  • The aim of an incident free operation

  • Project delivery in the agreed timescales

  • Offshore was weather dependent

  • Communications with both platforms


  • Assembled dedicated offshore project teams who had past experience of similar projects
  • Detailed onshore planning and project documentation was delivered to client in a timely manner
  • Realising the rising costs faced by operators in the North Sea we had to ensure that our tender submission reflected these needs without compromising on safety.


The exemplary delivery of services by the N-Sea teams both onshore and offshore allowed the works to be completed in a time frame which surpassed expectations. The constant commitment to safety and excellent communications between all work parties ensured that the work was undertaken without accident or incident. This efficiency and safe delivery allowed the Lomond and Everest operations to continue un-hindered with minimal interruption.

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