OVERDICK announced that the BorWin beta topsides has been successfully installed in the German sector of the North Sea, about 53nm NNW of the island of Borkum.
The step marks the completion of the most critical phase in the offshore campaign.
The BorWin beta platform accommodates the Siemens electrical plant for transmitting 800 MW of energy generated by the wind park Global Tech 1 into the electric power grid.
OVERDICK conducted the overall design, structural design as well as transport and installation engineering on behalf of the general contractor Siemens, who continue to strengthen their position as industry leader in offshore power transmission.
The BorWin beta topsides is designed with a watertight hull allowing it to be fabricated at a shipyard and wet towed to field by tugs without a transport barge. The 2700tonne jacket substructure with the cable tower attached had been installed in 40m of water in an earlier campaign in 2013. Once at site, the topsides was positioned over the substructure and the platform legs were lowered to make contact with the subsea pile heads. With all six platform legs resting secure on the piles, the topsides was jacked up to its target elevation of 20m above sea level by means of the temporary hydraulic jacking system.
With its topsides weight of 13400 tonnes during the installation, the BorWin beta platform sets a new record for self-installing HVDC platforms, exceeding its sister platform HelWin alpha which was installed last year. The capacity of the jacking systems for the platforms were scaled according to the topsides weight and thus allowed for installation of the complete topsides in one operation, eliminating the need for multiple expensive offshore lifts. Siemens` electrical engineers benefitted from this approach as they were able to test and commission the entire electrical plant already at the yard, thus minimizing requirements for offshore work. OVERDICK´s MOAB (Mobile Offshore Application Barge) concept of self-installing platforms allows for lifting operations which are beyond the capacity of offshore cranes available, thus providing greater flexibility in terms of design and fabrication as well as adapting to a growing topsides weight as a project evolves.
BorWin beta is the second of three large HVDC platforms designed by OVERDICK for Siemens. The SylWin alpha platform will follow soon while HelWin alpha was installed in 2013.
OVERDICK’s concept for self-installing HVDC platforms continues to demonstrate that it is the ideal solution for ever growing demands in topsides weight. SylWin alpha and DolWin gamma platforms are already destined to set new records in this category.
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