SURFACE TREATMENT METHODS
Thermally sprayed metallic coatings: Spray metallisation should be performed in accordance with ISO 2063-1 and ISO 2063-2. The metallising material should be either 100% Zinc or Zinc/Aluminium 85/15% alloy in accordance with ISO 14919. The applicator must provide product data sheets, certificates, and manufacturing data for the metallising materials.
Paint application: For each coat of paint, a stripe coat should be applied by brush to manual welds, corners, edges of brackets, and areas not fully reachable by spray to ensure specified coverage and thickness. Roller application is not acceptable except for topcoat repairs. The application process must follow the specified overcoat and recoat intervals.
PAINT SYSTEMS
Layer thickness: The layer thickness must be measured and comply with ISO 12944-5. Dry film thickness (DFT) and total dry film thickness (TDFT) must be measured according to ISO 12944-5, with the measuring method and calibration following ISO 2808. The arithmetic mean of all DFTs should be equal to or higher than the specified nominal DFT (NDFT), and individual DFTs should be equal to or above 80% of the NDFT. Measurements between 80% and NDFT should not exceed 20% of the total number of individual measurements taken.
Coating intervals and rules: The 90-10 rule is required for offshore applications, while the 80-20 rule is required for onshore applications. The maximum system layer thickness is three times the NDFT, and for each layer, a maximum of two times the nominal layer thickness is allowed.
Edge protection and flange holes: Care must be taken to avoid damaging edges after surface treatment. Flange holes are cleaned for visible objects, coated with a visual cover of Zinc Stripe coat, and protected.
OVERCOATING
Coating intervals for metal surfaces: Blasted and spray metallised surfaces that require further treatment should be protected against contamination, corrosion, and oxidation. Overcoat intervals can be extended by controlling ambient air humidity or applying a sealer (mist coat). Mist coats do not count as a paint layer in the specified system.
Stripe coating and repair application: Stripe coating is applied by brush in areas difficult to access, and repair work may also be applied by brush, except for primer coats and areas hard to reach. Roller application is allowed only for cosmetic repairs.
Curing and handling: The system must be fully cured before handling and transportation. The paint shop should ensure sufficient curing to prevent damage. Curing conditions should follow the product datasheet.
Datasheets and approvals: Technical Data Sheets, Safety Data Sheets, and approval certificates must be obtained from the paint supplier for all handling products.
These standards and requirements ensure the proper surface treatment, coating application, and maintenance of wind turbine components to achieve the desired level of corrosion protection, aligning with industry best practices and quality control measures.