Allied’s steel profiles comes from an inline hot-dip galvanizing process called Flo-Coat. This one-of-a-kind technique runs welded tubing through molten zinc while still on-line.
The Flo-Coat tube process is the superior method of galvanizing steel tubing. It begins with flat strip steel, which is then cold-formed and electric-resistance or induction welded. After welding, the tube receives a triple layer of protection-zinc, conversion coating, and a clear polymer topcoat all applied in-line to assure a uniform coating. The result is a smooth, shiny end product appearance that is unmatched in terms of strength and durability.
In-line galvanized tubing exhibits greater corrosion resistance because of the synergism created between the coatings; the conversion coating passivates the zinc to slow down the white rust growth process, and the clear top-coat then “seals in” the protection.
The triple coat corrosion provided by Allied’s in-line galvanizing process has never been equaled. This triple layer protection (zinc, conversion coating, and clear organic polymer) provides a smooth, shiny product appearance that is unmatched in terms of strength and durability.
Flo-Coat Galvanizing Technology
The Allied Flo-Coat Galvanizing Process Inherent Advantages
- The cold-forming and quenching process creates greater yield and tensile strength than competitive product alternatives.
- The tube is welded prior to the application of coating; thus the weld area is as protected from corrosion as the rest of the tube body.
- Flo-Coat tubing exhibits greater corrosion resistance because of the synergism created between the coatings; the conversion coating passivates the zinc to slow down the white rust growth process, and the clear top-coat then “seals in” the protection.
- The clear third coating also acts as a primer for painting or powder coating. Extensive pre-cleaning is unnecessary, and excellent adhesion is achieved, even at high baking temperatures.
- Powder coating over Allied´s galvanized substrate provides substantial corrosion resistance superiority over powder coating a raw/uncoated substrate. Powder coating over a galvanized surface provides corrosion protection 5-6 times longer than the same over raw or bare surface.
- Welding Flo-Coat is easily done in the exact same manner as welding bare steel. Allied´s zinc coating contains the lowest lead content achievable (99.9% pure zinc, average 13 ppm), so lead oxide fumes generated during welding are kept to an absolute minimum. Hot-dip galvanized products usually contain up to .5% lead (5000 ppm).
- Allied’s galvanized products can be easily fabricated…bent, swaged, wall-to-wall flattened…without deformation of the triple layer of protection. Competitive products tend to flake and chip during fabrication.
Coating Information for Allied Galvanized Steel Products
Exterior Coatings Classifications
Unless otherwise specified by a customer, almost all of our galvanized tube and pipe is triple-coated externally by using the following sequential processes:
- Galvanizing (zinc coating)
- Conversion coating (for passivation film)
- Clear organic polymer application
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.
Clear Organic Polymer Coating
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.
Zinc-Rich Paint Interior Coating
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.