Den Helder-based Bluestream has inspected HVDC platforms DolWin alpha, BorWin alpha and DolWin beta in the German section of the North Sea.
Bluestream has used divers, ROVs, multi skilled rope access teams as well as drones to carry out all three inspections.
“One of the reasons why Bluestream was tasked with carrying out this extensive inspection work, was the technical efficiency with which we approached each project,” said commercial manager Anton Janssens.
The first asset to be inspected was the DolWin alpha, the largest offshore conversion platform for wind farm energy in the German section of the North Sea. The platform was installed on a jacket consisting of six legs, and comprises five decks that rise 80 meters above the water surface.
Project engineer Michael van Putten said: “All accessible areas in the platform were inspected by camera, and for the inspection of the outside and underside of the platform, we deployed a rope access team. As well as checking the overall condition of the platform, the central focus of the inspection was on the coating.”
The jacket on which the DolWin alpha is mounted also had to be inspected. The inspection not only covered the section of the jacket protruding above the water, but also the six legs below water level.
As an alternative for an ROV scope, Bluestream deployed the Cathodic Protection (CP) Drop Cell method for this task.
After the completion of the first inspection Bluestream was awarded an order to inspect all accessible areas on the HVDC platform BorWin alpha as well. The total height of the BorWin Alpha is 84 meters, of which 62 meters consists of the support jacket.
The CP Drop Cell method was again used for this project.
Furthermore, Bluestream also received an order to inspect the DolWin beta. This submersible floating platform is moored just 30 meters from the DolWin alpha.
Bluestream was asked to carry out a general visual inspection using a drone operated by business partner Skeye, based in Alphen aan den Rijn.
A small part of the inspection work still had to be carried out by one of Bluestream’s rope access teams, the company noted.
The company has also secured fourth order for inspection services at the BorWin alpha. The task included extensive inspection of all components of the platform, both above the water and subsea.