Requirements to fabrications that are to be hot-dip galvanized:
- Fabrications should be made from low-carbon steel with the content of carbon < 0,24% and silicium < 0,03% (or 0,12 to 0,25%).
- Surface purity should not be lower than the 3rd class
- The possibility of suspension. It is necessary to foresee the openings on fabrications. The openings must be located in such a way that the element could not be deformed under its own weight.
- There should be any closed space on the article. All parts of the article should be accessible for free entrance and exit of the liquid, molten zinc and gases.
- The article should have a form that enables free inlet and outlet of zinc, air and flux. This form should enable zinc to float to all internal and external surfaces.
- Fabrications should have the openings located on the opposite sides for free air inlet and outlet and for free zinc floating.
- The pipes and socket pipes should have any plags in order not to hinder free zinc floating.
- The article surface should be free of rolled-in scale, burrs, excessive lubricant, graphite, paint, swarf and welded dross.
- There should be additional space (1-2 mm) for the screw openings.
- Constructions should be joint-welded or welded with the help of two-sided weld seam.
- Weld seams of surface joints should be closed on the edge.
- Weld seams should be even and continuous along the whole length.
- The pores, cracks , dross, weld seams voltage are intolerable (all weld seams must be dressed)
- Acute angles of fabrications should be rounded (with radius – not less than 0,3 mm).
It is necessary to use materials with similar chemical composition. It is recommended to avoid materials with the silicium content that makes 0,03% – 0,12%, and the materials with the content of carbon and silicon, that taken together makes more than 0,5%.
If you inform the supplier of steel that the steel goods at the final stage will be hot-dip galvanized and if you demand silicium guarantee of the steel goods, you will ensure high-quality hot-dip galvanizing!
It is inadmissible:
- to plan closed spaces,
- to join elements which have various thickness. The maximum and minimum thickness must be in the ratio of 5:1. It can not be higher, because during the immersion at 450°С previously manufactured forms can be deformed .
It is necessary to avoid:
large-dimensioned articles. It is easier and much economically to galvanize the flat elements. When the element is not large-dimensioned, it is much easier to transport it and to use loading area.
Normally we galvanize the elements, which have the following dimensions: 6,3 х 2,4 х 1,5, and the weight- up to 5,5 t.
The elements which have bigger sizes can be galvanized after prior consultation with our specialists.
