E-RAD saves valuable time at Gemini Offshore Wind Farm
The Gemini Offshore Wind Farm consists of 150 wind turbines being built about 85 km north of the coast of Groningen. When operational in 2017, the park will provide green energy for 1.5 million people in the Netherlands. The turbines are 154 meters above sea level and the rotor diameter is an impressive 130 meters. But how do you quickly and accurately tension 15,600 M72 foundation bolts?
Figure 1: Van Oord’s installation vessel ‘AEOLUS’ installs the turbine foundations
Flange connection of turbine foundation
The wind turbine tower stands on a foundation consisting of two piles connected by a flange. This is held together by 104 bolts of M72. Step by step, this flange connection is tensioned where speed and accuracy must go hand in hand. In the first step, the bolts are preloaded using an E-RAD BLU electric torque wrench with a maximum torque of 8,000 Nm. Hydraulic torque wrenches are used to achieve the final torque of over 20,000 Nm.
Van Oord building the Gemini park
One of the Gemini project partners is Van Oord. This family business operates worldwide as a leading contractor of dredging, marine engineering and offshore energy projects (oil, gas and wind) with innovative solutions to maritime challenges. The company operates in more than 50 countries worldwide.
The customer's word
Project Engineer Tino Kuin of Van Oord says, “The E-RAD BLU from RAD Torque came out of the test as the best for preloading the bolts. The electric drive ensures continuous rotation of the bolt whereas with a hydraulic wrench the bolt rotates about 24 degrees per cycle. That saves a lot of valuable time at sea. In addition, RAD Torque offers a number of accessories that make work ergonomically lighter.”
The result
The last foundation was installed offshore at the end of 2015. E-RAD torque wrenches quickly and accurately set the 15,600 bolts to the desired preload. In 2017, the park will make a significant contribution to the Dutch Energy Agreement with the goal of generating up to 16% of energy needs sustainably by 2023.
