Education

Education

Surface Preparation: For high quality hot-dip galvanizing, steel must be properly prepared prior to being immersed in a bath of molten zinc. During the surface preparation stage, material going through degreasing/caustic cleaning, pickling, and fluxing.

Degreasing/Caustic Cleaning: A hot alkali solution, mild acidic bath, or biological cleaning bath removes contaminants from the steel such as dirt, grease and oil.

Descaling: To remove mill scale and iron oxides, the steel goes through a diluted solution of heated sulfuric acid or ambient hydrochloric acid.

Fluxing: Through the final surface preparation step, any remaining oxides are removed in a zinc ammonium chloride solution and a protective layer is deposited on the steel to prevent any further oxides from forming prior to galvanizing. Surface Preparation: For high quality hot-dip galvanizing, steel must be properly prepared prior to being immersed in a bath of molten zinc. During the surface preparation stage, material going through degreasing/caustic cleaning, pickling, and fluxing.

Degreasing/Caustic Cleaning: A hot alkali solution, mild acidic bath, or biological cleaning bath removes contaminants from the steel such as dirt, grease and oil.

Descaling: To remove mill scale and iron oxides, the steel goes through a diluted solution of heated sulfuric acid or ambient hydrochloric acid.

Fluxing: Through the final surface preparation step, any remaining oxides are removed in a zinc ammonium chloride solution and a protective layer is deposited on the steel to prevent any further oxides from forming prior to galvanizing.

Successful hot dip galvanizing of fabricated steelwork is heavily dependent on design of the fabrication. To be satisfactorily galvanized, the fabrication must be completely immersed in a series of pre-treatment baths to prepare the surface for galvanizing, and then be submerged in a bath of molten zinc at about 830ºF (443ºC). If the pre-treatment chemicals and the molten zinc cannot get access to all surfaces, the item will not be effectively coated. Fabrication techniques can also either create or alleviate problems in the galvanizing process. Valmont Coatings sales staff are available to advise on design for galvanizing, and will assist with design detailing prior to fabrication to ensure that a high quality hot-dip galvanized coating is applied to customers’ projects.

Our team is available to advise on design for galvanizing and will assist with design detailing prior to fabrication to ensure high quality results. Download our Hot-Dip Galvanizing Design & Specifiers Guide.

Key Design Factors
There are a number of fundamental considerations when designing for hot-dip galvanizing. The key components include:

The size of the item that can be galvanized will be governed by the size of the galvanizing bath. Long items can be galvanized by double-end dipping but items larger than the galvanizing bath in two dimensions cannot be galvanized.

Venting is Vital! If a hollow section traps 18% of its internal volume as air, it will not sink in the molten zinc.