HDG Process


Degreasing/Caustic Cleaning 
Hot alkaline solution removes dirt, oil, grease, shop oil, and soluble markings.


Dilute solutions of either hydrochloric or sulfuric acid removes surface rust and mill scale to provide a chemically clean metallic surface.


To remove acid and iron salt.


Steel is immersed in liquid flux (usually a zinc ammonium chloride solution) to remove oxides and to prevent oxidation prior to dipping into the bath of molten zinc. In the dry galvanizing process, the item is separately dipped in a liquid flux bath, removed, allowed to dry, and then galvanized. In the wet galvanizing process, the flux floats atop the molten zinc and the item passes through the flux immediately prior to galvanizing.


The article is immersed in a bath of molten zinc around 450°C. During galvanizing, the zinc metallurgically bonds to the steel, creating a series of highly abrasion-resistant zinc-iron alloy layers, commonly topped by a layer of impact-resistant pure zinc.


After the steel is withdrawn from the galvanizing bath, excess zinc is removed by draining. The galvanized item is then air-cooled or quenched in liquid.

Coating-thickness and surface-condition inspections complete the process. Galvanizing is used throughout various markets to provide steel with unmatched protection from the ravages of corrosion.