UK: New Installation Technique Used at Dogger Bank Offshore Wind Zone

The Dogger Bank offshore wind zone is proving to be a site for innovation as a new and safer installation technique has been used to lift Forewind’s initial meteorological mast tower on top of the innovative suction-installed bucket foundation.

The use of the Bucket Foundation was also a UK industry first when placed on site in February.

Fred. Olsen United implemented the concept of moving the riggers, who previously had to be near the lattice towers during installation, and instead introducing guide cones, therefore eliminating the risk of a swinging or falling load causing an accident. The use of guide cones enables the crew to stay on deck away from the lifting hazards.

Forewind General Manager Lee Clarke said the innovative installation technique was another example of industry cooperation and the potential safety and efficiency gains to be made through developers and contractors working closely together.

Developed jointly between Forewind, Fred. Olsen United and its partners in the project, the “human-free” installation employs strong plastic guide cones that are strapped to the tower flanges before any lifting activity. SeaRoc Ltd, the contractor for the project’s topsides, drew the detailed design and provided the final solution for the 93 metre high tower.

The lightweight plastic cones have a number of benefits as they enable easier handling, do not affect coating on the flanges, and also act as weak-links to avoid structural damage to the mast.

Fred. Olsen United HSEQ Manager Jan Fredrik Platou said that it was was both safer than traditional methods, but also much faster as the cones helped to quickly stabilise the load in the final stage of the lifting.

“This project is a significant achievement for Fred. Olsen United as it demonstrates the combined capabilities of the Fred. Olsen related companies and of our unique suction bucket technology, designed by Universal Foundation,” he said. “This is a project of many firsts and we are very proud to be at the forefront.”

The installation of the 44 tonne galvanized steel tower for Dogger Bank Met Mast East was carried out by Fred. Olsen Windcarrier’s 132m jack-up vessel Brave Tern.

The Forewind project has been supported by the Carbon Trust’s Offshore Wind Accelerator programme, which takes the best concepts for offshore wind turbine foundations from design to deployment, and The Crown Estate through its co-investment in the development of the zone.

Head of Offshore Wind at The Crown Estate, Huub den Rooijen said that the installation of the first met mast on the Dogger Bank is a tremendous step forward for the UK offshore wind industry.

“Not only do we now have a structure that can measure wind speeds within our largest offshore wind zone; Forewind and its contractors have also successfully demonstrated a range of new innovations, from suction bucket foundations to new and innovative lifting techniques, that have the potential to reduce costs and improve health and safety performance as our industry develops.”

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Press release, March 27, 2013; Image: forewind