International coatings group NOF Metal Coatings Group reports that it has had success with its Geomet 321 corrosion protection coating, which has been used by international electronic and electrical engineering group Siemens Wind Power on fasteners of wind turbine blades, since the end of last year.

For this application, Siemens Wind Power requires that the coating is able to exist in a C5-H environment – in accordance with ISO 12944 – without corrosion of the substrate material even after a 1 440 hours salt spray test. For this reason, Geomet 321 is being applied at a thickness of 15 µm.

At the same time, electrical services and capital company General Electric’s (GE’s) division in charge of the construction of wind power plants, GE Power & Water, has approved the zinc flake systems Geomet and Geoblack in its latest standard – P14A-AL-0218. Specific requirements, such as 1 000 hours salt spray resistance – in accordance with ASTM B117 or ISO 9227 – could be met and mechanical damage tests were convincing.

In addition to these new standards, the systems Geomet 321 + Plus VLh on the one hand and Geomet 500 + Plus XL on the other have been certified by independent advisory institute Germanischer Lloyd regarding the corrosion protection of fasteners in oceanic and offshore atmospheres with high salinity levels – C5-M high, in accordance with ISO 12944. This means a salt spray resistance of 1 440 hours to 2 016 hours without the appearance of red rust.

NOF Metal Coatings Group is the first company to receive certification from two different institutes and, in so doing, confirms the potential of low-thickness corrosion protection for offshore installations.

Aside from the recent certificates by Germanischer Lloyd, the French Corrosion Institute had already certified the technologies Geomet and Dacromet in 2010 and proved their ability to pass the ISO 20340 standard for performance requirements regarding coating systems for the protection of offshore plants and associated facilities, which corresponds to level C5-M, in accordance with ISO 12944.

The tests, in accordance with the ISO 20340 standard, include 25 cycles of one week each, with three days of ultraviolet exposure with condensation, three days of salt spray tests and one day of low temperature exposure at –20 °C.