Bolt Anticorrosion Treatment and Life Extension
- What are the common anti-corrosion treatment methods for bolts?
Common methods include galvanizing, which forms a zinc layer on the bolt surface through electro-galvanizing or hot-dip galvanizing to isolate air and moisture, with a zinc layer thickness of generally 8 - 15μm. Dacromet treatment (zinc-chromium coating) forms a protective film, and its corrosion resistance is 3 - 5 times that of galvanizing, suitable for humid, coastal and other corrosive environments. Applying anti-corrosion paint is simple and easy, and different types of paints can be selected according to the environment, such as epoxy paint and polyurethane paint.
- How to select bolt anti-corrosion treatment methods in different environments?
In dry inland areas, ordinary galvanizing can meet the anti-corrosion requirements with low cost. In humid, rainy or industrially polluted areas, Dacromet treatment is recommended, which has stronger corrosion resistance and can resist the erosion of water vapor and industrial waste gas. In coastal areas with high salt content, hot-dip galvanizing (thick zinc layer) or Dacromet treatment should be selected to prevent chloride ion corrosion.
- What are the causes of damage to the bolt anti-corrosion layer?
Scratches on the anti-corrosion layer caused by tool collision during installation; long-term vibration causes friction between bolts and connectors, wearing the anti-corrosion layer; corrosive media in the environment (such as acid rain, salt spray) penetrate into the damaged part of the anti-corrosion layer, accelerating corrosion; the anti-corrosion layer itself has poor quality, such as uneven galvanized layer and pinholes, which are easy to be penetrated by corrosive media.
- How to check the integrity of the bolt anti-corrosion layer?
Visually inspect whether the bolt surface has scratches, peeling, rust, etc.; use a coating thickness gauge to measure the thickness of the anti-corrosion layer to ensure it meets the regulations (such as galvanized layer ≥8μm); for parts suspected of damage, penetrant testing can be used, after applying penetrant and cleaning, apply developer, and defects will show color marks.
- What maintenance measures can extend the anti-corrosion life of bolts?
Regularly clean the bolt surface to remove dust and dirt to prevent the accumulation of corrosive media; if the anti-corrosion layer is damaged, repair it in time, such as touching up anti-corrosion paint or zinc spray; in highly corrosive environments, increase the thickness of the anti-corrosion layer or adopt composite anti-corrosion measures (such as galvanizing + painting); regularly replace severely rusted bolts to avoid affecting the connection performance.