Allied uses special high-grade quality zinc for its galvanizing operation. Our zinc is 99.99% pure and contains only a trace amount of lead. Hot-dipped galvanized pipe or pipe made from pre-galvanized steel coils normally use Prime Western grade zinc and other grades which contain a high level of lead, sometimes more than 1% by weight.
The conversion coating over the galvanized surface is formed due to a chemical reaction and this film becomes an integral part of the zinc coating. The film passivates the highly reactive zinc surface and retards the formation of white rust by a substantial margin. Also, the conversion film enhances bonding or adhesion of any additional paints or coatings applied over the galvanized surface.
The clear organic polymer coating is applied as a third coat or final finish on the exterior surface. This final layer acts as a barrier coating and further reduces the atmospheric corrosion of the product. However, there is an interesting phenomenon that occurs as a result of the combination of the second and third coating. Combined performance (corrosion protection of these two coatings) is more than the summation of the individual protection provided.
We have a number of ID (interior diameter) zinc coatings which have been specially formulated to meet specific customer fabrication requirements. We are continuously upgrading our ID coatings to maximize the overall corrosion resistance of the interior of the tube. All our ID coatings are applied after the tube is welded…thereby assuring a uniform coating on the entire interior surface. In addition, none of our ID coatings will contaminate paint or powder coat cleaning systems.
