Scotland-based FoundOcean has received five inspection, repair and maintenance (IRM) contracts for platforms located in the North Sea which will be complete by the end of 2012.
Four of these projects are for grouted repair clamps to restore structural integrity, while the fifth project is to rectify movements in a platform by addressing seabed scour.
Special air-driven batch mixing equipment will be used to comply with Hazardous Zone 2 regulations as the repairs take place in live platform environments.
In the first contract, a platform’s firewater corroded caisson will be repaired by fitting two grouted clamps connected by four new structural members around the caisson, and for structural integrity an ordinary Portland cement and seawater mix will be injected into the annulus.
The second contract calls for repairs to a platform’s corroded caisson located off the north-east coast of the Shetland Islands. It will be repaired by fitting it with a grouted clamp over the damaged areas and filling the rest of the clamp / caisson annulus.
Clamp’s bolt-together sections and are equipped with primary and secondary grout inlets, which will be attached by a stressed mechanical clamp to an adjacent brace member to restrict lateral movement.
In the third contract, the company will insert a bladder into the caisson and once inflated a grout plug will be set at the bottom of the clamp and a stinger will be injected into the annulus between the clamp and the caisson.
FoundOcean grouted sleeves one, three and four in 2007, leaving sleeve two which could not be completed before the end of the planned maintenance period.
FoundOcean’s fourth platform’s jacket will be fitted with two stressed clamp configurations, an X-Node clamp assembly and the second a K-Node clamp assembly, which have bolt-together sections with primary and secondary grout connections.
The company will use CEM I Type 52.5 Ferrocrete cement to achieve a specific gravity of 1.98. The fifth platform work invloves restricting movement by rectifying the scour and strengthening the leg-to-pile connection.
Image: A jacket member fitted with a grouted repair clamp. Photo courtesy of FoundOcean.