Dutch mechanical and structural engineering expert Tillen B.V. recently successfully tested a light and heavy version of their new sling adapters for installation vessels in a unique test setup for their client.
As the number of offshore wind energy projects grows so does the weight of the individual components being used. Early offshore projects, 25 years ago, involved 1.5MW to 2MW turbines, weighing 56t placed on monopile foundations up to 50m long, with a diameter of 4m and weighing 200t. Today there are plans for wind farms with a 15MW turbine nacelle weighing 1,300t on foundations weighing 4,000t in deeper water than was ever envisaged at the beginning of this century. Obviously, the industry can no longer depend on installation methods and tools from that era.
New floating offshore installation vessels are being built with cranes up to 5,000t and lifting devices are being built and tested to work under the hook of these cranes, allowing for efficient connecting and manoeuvring of the component being lifted.
The design of one such lifting device has been designed and now fabricated by Tillen b.v., the Dutch mechanical and structural engineering experts based in the Utrecht suburb of De Meern. The two versions, one light and one heavy, versions of their sling adapters have now been built and tested.
To earn the approval of their client, a major offshore wind installation contractor, and the contractor’s classification organisation, Tillen needed to test their devices to the limits ordered by their client.
Unique test setup
A few weeks after testing the light version to 3,000t, and with representatives present from the client and the classification organisation, the testing of the heavier version was carried out on a test rig that had been built in the fabrication yard of Gouda Constructie b.v. Tillen developed, designed and built a compact and innovative testing setup with a knuckle mechanism, which enabled them to conduct the tests themself. As far as they know this is a unique setup never shown before in the market.
The testing involved increasing the pressure to a hydraulic cylinder which would force apart the arms of the sling adapter. The movement from the hydraulic cylinder during the test would be no more than a few centimetres, replicating a force of 6,000t. The whole testing procedure had been monitored with strategically placed cameras and sensors for measuring any movement or changes in status.
Increasing the hydraulic pressure in steps of 50 bar to 75 bar up to the peak of 620 bar forced the hydraulic cylinder head a distance of 10cm, to replicate the 6,000t requirement, before returning zero over a period of 45 minutes.
The test had proved successful.
Tillen’s ability to complete this project in the time available was certainly an important factor for their client to select them. Shortly after the successful tests the tools were shipped to the vessel, just in time for installation on deck.
This article was written by the editor of our sister title HeavyLiftNews. All images: Tillen
Read also the interview with Tillen which appeared in the spring 2023-edition of Windpowernl magazine.