Successful corrosion protection of offshore wind farms

Positive features from the first windfarms with more than 15 years of service are described in this article, and the importance of quality management is explained.

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Introduction

Constructions such as offshore wind turbine farms are subject to aggressive environments. They are exposed to humidity with high salinity and to intensive UV-radiation. The UV-radiation occurs directly on the constructions as well as light reflections from the sea.

Additionally, an area of concern is the tidal zone (splash-zone), where the wind turbine construction is stressed both from mechanical impacts – service boat collisions and waves – and from corrosion strains created by shifting saline seawater with a high oxygen level. The seawater stress levels can be extensive in waters with high tidal activity, such as the Irish Sea or the English Channel.

Thus, in particular, the protection of the wind turbine foundation, the transition piece (TP), is imperative. Long-term resistant coating systems with no need for future refurbishment – combined with flawless application operation activities – are essential, as offshore repair is costly.

Summary

Offshore wind farms are today protected with paint systems, which are corrosion resistant after more than 15 years of service. With high probability, the protection will remain effective during the designed 25 – 30 years’ lifetime of the farm. A three-coat epoxy-polyurethane system with a DFT of 660 µm is the system used on the most vulnerable area: the TP. 

Such good protection will only be possible with proper quality control, carried out by well-educated painting inspectors, e.g. FROSIO- or ICorr-certified inspectors, and with proper documentation of the whole painting operation processes from the bare steel to the finished construction.