What Does Zinc Spray Galvanizing Mean?
Zinc spray galvanizing is process where a coating is applied to a steel surface by spraying it with atomized particles of molten zinc. This is done by projecting the particles onto the abrasive surface using a handgun applicator or a special flame. The zinc coating provides excellent corrosion resistance for steel and iron objects and structures used in various environments such as marine, industrial and other unfavorable atmospheric conditions.
This process is suitable for structural components which cannot be dipped into a galvanizing bath due to large size and for objects that would become distorted during hot-dip galvanizing. The method is also used on sections of objects that cannot be accessed by dip galvanizing.
Corrosionpedia Explains Zinc Spray Galvanizing
The zinc spray galvanizing process starts with the preparation of the structure’s surface by removing rust, unwanted surface coatings, oil and other contaminants. The cleaning is done using high-pressure abrasive blasting, which also roughens the surface. This increases the surface area and ensures a successful adherence of the zinc coating.
The atomized metal particles are then sprayed onto the roughened surface where they attach to the surface and solidify. Several layers are applied so as to build up the coating thickness, with typical values ranging between 80 microns and 300 microns, but thicknesses of 50 to 500 microns are also possible.
Zinc coatings widely used for the protection of finished objects are made from mild, low-alloy and high-carbon steels. The excellent corrosion protection is effective in most atmospheric conditions and also when the product comes into contact with either natural or synthetic corrosive substances. Protection against aggressive environments such as salt spray conditions can be enhanced by applying one or two epoxy paint coats onto the zinc coating.
Zinc spray galvanizing is commonly used on structural steelwork for:
- Windmill towers
- Chemical, cement and fertilizer industries
- Power plants
- Bridges and other marine applications
- Transformer tanks
Other advantages of using zinc spray galvanizing include:
- Cold process
- Suitable for all sizes
- Surface is ideal for painting
- No hydrogen embrittlement
- Suitable for alkaline conditions
- Jobs can be done on-site
- Long-term protection
- Variable coating thickness