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Assured Corrosion Protection for Wind Energy Units Laura Saure Dörken Coatings GmbH & Co. KG – Herdecke, Germany coatings@doerken.de
High-performance corrosion protection for screwed fasteners in high-tensile steel enables wind energy units to be largely maintenance free. Zinc flake systems have proven their reliability in the area of rotor blade fastenings for over 30 years.
T
he rotor blades are fundamental, key components of a wind energy unit. They are used to extract energy from flows of air and
move this to the generator. The blade lengths of up to 85 metres and a weight of up to 25 tonnes mean that the fastening of the rotor blades to the rotor hub is particularly significant. This is achieved using fasteners, consisting of so-called double ends, barrel-nuts and hexagonal nuts, typically in the M30 to M36 dimension range.
Diverse stresses and requirements The rotor blades and thereby also their screwed fasteners are subjected to extreme climatic as well as dynamic stress from wind load and the operation of the unit itself. This is joined by static forces from prestressing of the bolts and the mass of the connected elements. As a consequence of the high level of stress for the screwed fasteners, the choice of corrosion protection is especially important. The protective coating needs to meet specified coefficients of friction in order to guarantee problem-free fastening on the construction site, typically with considerable time pressure and under difficult conditions. In addition, the coating must offer highly-effective and long-lasting corrosion protection to ensure the long-term, reliable operation of the unit.
Corrosion protection with multiple benefits The best solution is therefore a coating system like the extremely thin zinc flake coatings from Dörken. They fulfil all of these requirements and consist of a basecoat and an organic or inorganic topcoat tailored to the respective components. The zinc-containing basecoat determines the corrosion properties and is responsible for the cathodic corrosion protection. In addition to adding further protection, the tailored topcoat enables the observance of defined coefficients of friction and therefore safe and fast assembly.
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N.37 - 2021 APRIL - ipcm® Protective Coatings
