Dillinger heavy plate for the
DolWin6 offshore grid connection

Dillinger steel for the sustainable energy supply of the future

The DolWin6 offshore grid connection makes a key contribution to the energy turnaround in Germany by bringing clean, renewable wind energy from offshore wind farms in the North Sea to the inland. DolWin6 is a high-voltage direct current (HVDC) transmission system which operates at a voltage of 320 kV and can transmit power of up to 900 megawatts. The heart of DolWin6, the associated converter platform DolWin kappa, is located offshore around 45 kilometers off the coast of Lower Saxony. The platform itself is a technical masterpiece executed by Siemens Energy and its consortium partner, Dragados Offshore. It is able to convert the alternating current generated by the offshore wind farms into direct current and thus efficiently conduct the energy over long distances. In this case it is about 90 km before it is fed into the German power grid. In this way, it contributes to the supply of more than a million households.

DolWin kappa: Innovative design and installation in record time

The DolWin kappa converter platform is designed to withstand extreme weather conditions and remain stable at sea. The installation of DolWin kappa was an impressive technical and logistical challenge, requiring state-of-the-art engineering and careful planning executed by Dragados Offshore in consortium with Siemens Energy, for the German TSO, TenneT. The platform and the jacket were built in Cádiz, all components were included there, shipped to Rotterdam and taken over from the Pioneering Spirit for its final destination in the North Sea. The Pioneering Spirit, the world’s largest working vessel at 382 meters in length, took only twelve days for the complete installation of DolWin kappa. From Rotterdam, it transported the offshore platform and the jacket to their destination. The foundation structure (jacket), which is around 44 meters high and weighs over 5,000 tons, was set down first. Ten piles were then driven up to 68 meters deep into the seabed and connected to the foundation structure. The topside structure, weighing around 11,000 tons, was then placed on top of the foundation structure. With a total height of around 82 meters, the imposing DolWin kappa platform protrudes around 53 meters above the surface of the North Sea. The entire installation of DolWin kappa is a prime example of modern offshore infrastructure projects and a decisive step towards a sustainable energy future.

For the realization of the DolWin6 kappa platform platform, Dillinger supplied its client, Dragados Offshore, with approx. 16,000 tons of heavy plate in various structural steel and offshore grades (S355J/K2, S420ML, S420NL, S355G9/10+M, S420G1/2+M, S420MLO, S460G2+M) in thicknesses of up to 120 mm and widths over 4.6 meters.