Monopile Refurbishment At Scroby Sands Offshore Wind Farm

Project Information

Scroby Sands wind farm is an offshore wind farm located 2.5km off the coast of Great Yarmouth on the Scroby Sands sandbank in the North Sea. The wind farm itself consists of 30 wind turbine generators each rated at 2MW, mounted on monopile foundations. Scroby Sands, owned and managed by E.ON, has been operational since 2004 and is one of the UK’s first commercial wind farms. Offshore wind turbines are subject to severe problems with corrosion due to the extreme environment they operate in and the longer corrosion is left untreated the greater the problem becomes. Regular preservation programs should be operated and managed to allow the turbines to function at their peak level.

Having extensive experience in dealing with corrosion and specialist coatings, Abfad Ltd were brought in to refurbish the monopiles steelwork, from grating elevation to sea level, using rope access techniques and their unique magnetic positioning system.

Magnetic Positioning Aid

The magnetic positioning system was developed and patented by Abfad to allow their rope access blaster/sprayers to safely and securely hold their position whilst suspended from the ropes. This technique ensures blaster/sprayers can perform the required work to the highest standard and with precision due to being held securely in position by the magnetic clamps and not having to attempt to “tie in” on difficult to access structures, a key factor on this particular project.

Abfad’s magnetic positioning system has proven invaluable in areas that can only be accessed by rope but need a reliable method of moving the rope technician closer to the working surface and anchoring them securely to enable them to carry out any required work.

Use of this Magnet System provides the user with a productivity advantage, increasing the speed of work, such as, blasting, mechanical surface preparation, welding, drilling, NDT inspections etc. by securing the rope technician to the ferrous substrate and enabling a greater precision of work.

Phases of Work

The work itself was carried out in two phases to enable the complete refurbishment of the monopile. Phase 1 consisted of structural steelwork below the walkway gratings being refurbished, as far as the monopile collar section. Phase 2 was to refurbish all steelwork below the collar section to sea elevation. Walkway gratings and davit arms were removed in stages to enable each phase to be successfully completed before moving onto the next. Once the first phase was completed the gratings and davit arms were reinstated and the remaining half removed in preparation for the second phase to get under way.

Once on the monopile structure the extent of the corrosion could be clearly seen and was quite severe in places. Blasting work to SA2.5 standard was carried out to remove all sections of corrosion and the existing coating was profiled and feathered back in preparation for the new protective coating to be applied. The chosen coating, from the International Paints line, was then applied using an airless spray unit and applied to the nominated thickness.

The work by Abfad was a complete success, with all corrosion removed and the new coating applied, ensuring the monopile was left with optimum protection against the elements and looking as good as the day it was constructed.