A significant contribution to the economy of this form of energy is provided by corrosion protection. Service life of 20 to 30 years, as sought by the operators, is only possible with high quality requirements for the coating systems. In the Butendiek offshore wind farm, corrosion protection coating systems with a total coating area of 140,000 m2 were applied. Butendiek is the first park with solvent-free foundation and monopile coating from Sherwin-Williams Protective & Marine to set the tone for sustainability.
Repair challenges
Offshore wind turbines are subject to severe corrosive attack. In addition to wind and weather, they are particularly exposed to underwater, tidal and splash water stresses, the maritime atmosphere, extreme temperature fluctuations, strong UV effects or permanent mechanical influences and abrasion as well as salts and other aggressive substances. Consequently, the repair of possible damage to the corrosion protection system has to be dealt with, repair scenarios must be devised for it and made as simple as possible, and of course their quality must also be made as high as possible in terms of corrosion protection. The idea of sustainability in the coating system should also be transferred to the repair system.
The single-layer repair material
Based on these considerations, Sherwin-Williams has developed a two-component, single-layer and solvent-free repair solution – Repacor SW-1000. This is an abrasion-resistant, innovative 2-component coating for the maintenance and repair of damaged or corroded coating areas in onshore and offshore environments, especially when a simple, high-performance and durable repair coating is required. Repacor SW-1000 can be applied in just one work step and hardens quickly to complete repair during a single visit. The product is delivered in a coaxial cartridge that allows for simple repair (no weighing, no mixing, less waste). This leads to enormous savings in maintenance costs by simplifying and accelerating repair work, especially in hard-to-reach areas, saving a lot of time, loss of material and waste. In this way, a resource-saving repair is possible from an economic and ecological point of view. All corrosion protection requirements for offshore applications are met, including very good colour stability and adhesion to all imaginable substrates.
Experience in repairing damage at the Butendiek Offshore Wind Farm
Repacor SW-1000 in RAL 1023 was used for the repair of mechanically damaged surfaces for the Butendiek offshore wind farm, which has been installed for 4 years now. An annual monitoring of the repair work carried out on the transition pieces in 2016 and 2017 was consistently positive. Despite sometimes difficult initial conditions – critical climatic conditions such as rain on the fresh coating, mechanical damage due to the design (hooks, attachment devices, locking mechanism) or impurities such as grease, dirt and lubricants – no changes from the inspection in 2018 could be detected in 2019. As a result, the coating material Repacor SW-1000 will also be used for future repairs of damage to the corrosion protection coating system.
Proven corrosion protection with the initial coating
The decision in favour of a proven offshore coating system from Sherwin-Williams had already been taken in the construction phase of the individual components for the wind farm, such as monopiles, transition pieces and platform. The project was successfully completed in close co-operation with our long-standing customer, the Krebs Group. The coating work for this wind farm was carried out at four different Krebs sites – Lubmin, Stralsund, 2 × Rostock. The service team of Sherwin-Williams accompanied the comprehensive factory coatings as well as the repair with Repacor SW-1000 with continual and competent support. This enabled all technical questions to be taken up and resolved.
