Have you heard of the Slip Joint connection? This connection between offshore wind farm foundation elements, a monopile and a transition piece is a promising alternative to a grouted or bolted connection. Van Oord and DOT have developed a one-day course for engineers who wish to understand how to design a Slip Joint connection.

The first course will take place on 15 February 2023 at De Oude Bibliotheek in Delft, the Netherlands.

This dedicated course dives deeper into the most important aspects that come into play when designing a Slip Joint for offshore applications and will be taught by the engineers who were involved directly in its development. You will have the opportunity to design a monopile and transition piece Slip Joint interface, both submerged and in air, for front-end engineering design (FEED) study purposes. The course consists of both theory and practice and will be hosted by DOB Academy.

‘With this course, Van Oord is aiming to share the Slip Joint knowledge that it acquired over the past decade and that eventually led to successful installation in Borssele V,’ says Sander Suur, Design Lead Borssele V Slip Joint at Van Oord. ‘This course will allow interested parties in the offshore wind industry to figure out for themselves when the Slip Joint is a feasible solution for their projects. The course will be taught by the engineers who designed the Slip Joints for engineers who want to design Slip Joints.’

Also read: Van Oord installs world’s first submerged slip joint

The Slip Joint

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 production 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 is a rapid, simple and safe installation solution that also requires less maintenance for the duration of the project.

Slip Joint installation
Slip Joint installation (by Van Oord).

Thijs Kamphuis, Project Engineer at DOT: ‘The Slip Joint enables the all-important acceleration of offshore wind deployment. Since 2016, Van Oord and DOT have joined forces in pushing this innovation to market readiness. The next step is to share our combined know-how and lessons learned with the sector. I’m happy that we are continuing our collaboration as a “one-stop shop”, which will help disseminate the knowledge to industry faster and with higher value.’

Also read: Van Oord sells share in Borssele V to Octopus Energy Generation

Borssele V

Van Oord successfully installed the first Slip Joint foundation in a commercial offshore wind farm in 2020. Borssele Wind Farm Site V is a sustainable energy zone some 20 kilometres off the Dutch coast and has been designated as an innovation site. The Two Towers consortium, consisting of Van Oord, Investri Offshore and Green Giraffe, was awarded the project, providing a unique opportunity to test and demonstrate advanced technologies.

Also read: Two Towers consortium wins Borssele V tender