DNV

DNVGL provided independent certification services for the submerged Slip Joint technology applied at the Borssele Wind Farm Site V (Borssele V) offshore wind innovation project in the Netherlands. The Slip Joint is an alternative monopile-to-transition-piece connection method based on two conical sections that slide together, eliminating conventional grouted or bolted connections and enabling a fully submerged interface. According to the project disclosures, DNVGL certified the design and manufacturing of the Slip Joint in the autumn of 2019, supporting its subsequent offshore deployment and demonstrating the technology at full commercial scale. This verification activity formed part of the project’s wider innovation programme, which also included durability and corrosion-protection measures such as thermally sprayed aluminium (TSA) coating and cathodic protection optimisation. The certification work underpinned the project’s goal of reducing installation time and long-term maintenance requirements, while providing additional assurance for a first-of-its-kind foundation connection used on a full-sized offshore wind turbine. The Slip Joint was later installed offshore as part of the 19 MW, two-turbine Borssele V site within the Borssele wind energy zone, with grid connection via TenneT’s offshore infrastructure.