Case Study
Caisson and Conductor Stabilisation: AquaShim®
Significant lateral forces from repeated wave action create unique challenges for caissons and conductors; movement within the guide frame over time leads to impact damage, potential fracture and eventual loss.
This was the concern our client had with four conductors on their platform. AquaTerra Group designed, manufactured and installed pre-cast AquaShim® to stabilise the conductors within the guide frame at -14m elevation.
- Reviewed existing guide arrangement and proposed a suitable stabilisation solution to prevent further fretting and deterioration.
- Provided a full concept and detail design of AquaShim® including independent engineering verification of solution.
- Provision of Workpack including execution statement.
- AquaShim® designed in sections to fit through gratings for lowering down to divers.
- Topside rigged and subsea installation completed by divers.
The existing shims on the conductors at -14m elevation had failed. This was concerning to the client as excessive movement within the guide frame was causing localised fretting, longer-term fatigue and potential fracture.
An excessive annular gap between the conductor and guide frame, and lack of centralisation within the guide frame was a further concern.
The client required the existing guide arrangement reviewed and a suitable stabilisation solution proposed to prevent any further fretting or deterioration of conductors and guide.
AquaTerra designed, manufactured and installed pre-cast AquaShim® to stabilise the four conductors within the guide frame at -14m elevation. We provided a full concept and detailed design of AquaShim® to the client including independent engineering verification of the solution.
The product was cast into sections which were guided into position by the diver team who centralised conductors within the guide frame.
AquaShim® is a polyurethane-based alternative to traditionally engineered mechanical shims, which is quick and simple to install and requires zero lifetime maintenance. Our pre-cast option is just one of our range of solutions to ensure long term reliable stabilisation in the splashzone and in turn, maximise asset lifespan.
The installation of the AquaShim® resolved the fretting and movement issues for the client, prevented any further deterioration and most importantly, maximised the lifespan of the asset.
The solution resulted in several significant cost reductions, with an estimated 80% cost saving over an engineered clamp solution, whilst adding less than 10% of the weight of an engineered clamp. The installation time of one day was also significantly less than alternative solutions.