Sea Discovery


Unique Maritime Group Announces Two Key Projects


Image: Seaflex Unique Maritime Group, one of the world’s leading integrated turnkey subsea and offshore solution providers, today announced two key projects, involving buoyancy systems provided by Seaflex Ltd.

World’s Largest Offshore Windfarm
The London Array is an offshore wind farm under construction in the outer Thames Estuary in the United Kingdom. With 1,000-megawatt (MW) capacity, it is expected to become the world's largest offshore wind farm.

Seaflex products played a key role in three critical phases of the wind farm construction

? Assistance with the float out of heavy gauge steel monopiles, on top of which each wind turbine is mounted
? The installation of the export power cable to the onshore power management station in Kent
? The final connection of the power cable to each wind turbine

Seaflex were contacted by Ballast Nedam B.V. with the request to supply bespoke buoyancy modules to be fitted inside mono piles prior to tow out to the site off the Kent coast from Vlissingen in Holland. Each monopile was of tubular steel construction at 4.5m diameter and up to 65m long. With a wall thickness of 75mm – 80mm each monopile weighed in the region of 400t.

Seaflex were contracted to manufacture 6 x 88t Inflatable Buoyancy Units with a diameter of 4.5m and 6m in length to suit a standard pile. Each buoyancy unit was double skinned for added protection against the inner wall of the monopiles. It was decided two sets would be needed to enable one set to be in use while the other was on it's return trip to Vlissingen, keeping the project on schedule. The project was a complete success with all piles installed without incident.

Visser and Smit contacted Seaflex for the remaining two phases, to connect the export power cable from the cable lay vessel Spirit to the power management station ashore, and to patch in each wind turbine to the offshore hubs – or subsea junction boxes in layman’s terms.

The main export power cable has a diameter of 208mm and weighs over 80kg/m in the water. Seaflex supplied over 3km of SeaSerpent cable buoyancy system in 50m and 100m lengths, each section delivered on a steel deployment reel. SeaSerpent was the perfect product for this installation due to the extremely shallow water (0m to 6m over 3km) and because due to tidal variations, the cable route dried out for 8 hours in every 12.

SeaSerpent allows for a high rate of lay meaning the 4 operational hours were used to maximum efficiency. All Visser & Smit deck personnel attended SeaSerpent training at Seaflex premises with Seaflex also supplying two field engineers ensuring the shore pull went smoothly.


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