On 25 April, the Slip Joint foundation was successfully installed at the Borssele Wind Farm Site V. It is the first time anywhere that a submerged Slip Joint was used on a full-sized offshore wind turbine on a fully commercial basis. After years of developing the system in cooperation with its technology partners, Van Oord deployed offshore installation vessel Aeolus to install the Slip Joint foundation this week. The design and production of the Slip Joint was certified by DNVGL in the autumn of 2019, with MottMcDonald assessing it on bankability aspects. The Borssele Site V project consists of two 9.5 MW wind turbines and Van Oord has been awarded the Balance of Plant scope for this project.
Slip Joint foundation
The Slip Joint is an alternative connection between foundation elements, 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.