Installation of the largest offshore wind power monopile foundations ever with support from Schaaf Technology
With the new installation vessel “Orion” and the most powerful Liebherr crane HLC295000 in terms of its lifting capacity, the Deme-Group is erecting offshore wind turbine monopile foundations at the Arcadis Ost1 wind farm. The Arcadis Ost1 wind farm with a total capacity of 257MW is located in the Baltic Sea near the island of Ruegen and will contribute to the electricity supply from 2023. To generate renewable energy from wind, the wind farm will be equipped with Vestas V174-9.5MW wind turbines.
These huge dimensions of a monopile show that it is necessary to think in new dimensions during erection. Thus, the Liebherr HLC295000 with a lifting capacity of 5000 tonnes and a jib length of 155 metres is an essential part in the erection chain. For bolting together the three main components of the crane tower, Liebherr used connecting components from Schaaf, the leading company in the field of joining technology. The crane column’s total of 660 bolting points of size M120, divided over 3 levels, are equipped with Schaaf threaded bolts and Schaaf TTG nuts and ensure a secure, maintenance-free connection. With the TTG thread developed and patented by Schaaf, the setting force losses are reduced, which means that higher residual pretensioning forces can be achieved. The generation of the pretensioning force was applied by means of Schaaf special pretensioning tools. The weight of the threaded bolts of up to 100kg per bolt and the weight of the TTG nuts of 23kg per nut posed particular handling challenges. The documentation provided by Schaaf is remarkable. The elongation of the threaded bolts was measured in real time via an integrated elongation measurement during the tightening process and recorded in a Mobile Mounting Documentation System (MMDS) as a pretensioning force. This process makes the tightening process transparent and a significant logging of the tightening process is possible. In addition to the integrated length measurement during the tightening process, a ΔL check for maintenance purposes is possible. This is feasible due to the special feature of the threaded bolts. These have a so-called tensionless rod, through which a change in length between the untensioned state and the tensioned state is reflected. This measurement can be repeated for maintenance purposes and thus draw conclusions about any settling force losses during operation. Therefore, Schaaf as a system supplier is significantly involved in the connection components, the tools, the assembly as well as in the documentation of the bolting cases of the HLC295000.
The monopiles constructed by Orion serve as foundations for the Vestas V174-9.5MW wind turbines. Schaaf fasteners are also used in the drive train of these turbines. For electricity to be generated from wind, the rotary motion of the blades must be transmitted to the generator. Flexible carbon fibre composite couplings are used in the drive train of the V174 wind turbine to protect the gearbox from vibrations and pulsating loads. Schaaf uses ExpaTen QL to connect the coupling halves to the rotor and gearbox shafts. The term ExpaTen is made up of the components Expa for Expansion, Ten for Tension and QL for Quick Locking. The expansion creates a 100% positive lock in the flange bore, whereas the tension ensures a frictional lock in the parting line. The innovative design of the ExpaTen QL makes it possible to transmit the extreme torque of the blade rotation in a very small installation space. 40 pieces of ExpaTen QL each ensure an efficient, precise and backlash-free connection of the components. In addition to the complete documentation during coupling assembly, the ExpaTen QL is also convincing during offshore maintenance work on the gearbox and rotor shaft due to its reusability, simple and quick mounting and demounting. With the Schaaf technology, energy can be obtained from wind efficiently and in a resource-saving manner!