Growth through Research, development & demonstration in Offshore Wind

World’s first full-sized submerged Slip Joint successfully installed

On 25 April, Van Oord installed successfully the first foundation with a Slip Joint at the Borssele Wind Farm Site V. SIF has made the Slip Joint and DNV GL has certified it. This step was made possible due to the innovation realised by the GROW consortium.

Last year, DOT successfully completed the GROW project 'Slip Joint Offshore Research (SJOR)'. In close collaboration with Heerema and the GROW partners Eneco, SIF, Van Oord, TU Delft and TNO, DOT tested this innovation for the first time under offshore conditions. The test was carried out in Eneco's Amalia wind farm on the North Sea.

The Slip Joint is an alternative connection between a monopile and a transition piece. It consists of two conical sections placed on top of each other. The Slip Joint is based on friction, with the weight ensuring firmness and stability. Installation takes place by sliding the wind turbine’s foundation elements over the monopile, without having to use grout or bolts. Unlike standard solutions, the Slip Joint makes a submerged connection possible, allowing for a more balanced weight distribution between monopile and transition piece.

It therefore opens up the possibility of manufacturing larger foundations for the next generation of wind turbines with existing manufacturing facilities and installing them at deep-sea locations using existing vessels. The (conical) sections that make the connection are produced using standard manufacturing methods. The Slip Joint provides a rapid, simple and safe installation solution in combination with reduced maintenance for the duration of the project.

            Installation transition piece Borssele Wind Farm V, Source Van Oord
Installation transition piece Borssele Wind Farm V, Source Van Oord