The Galvanising Process
- Material Inspection
Check for material condition, welding and drilling, if necessary and if appropriately done
- Degreasing(Caustic Cleaning)
An alkaline solution removes dirt, oil, grease, shop oil, and soluble markings.
Diluted hydrochloric acid is used to remove surface rust and mill scale to provide a chemically clean metallic surface.
Steel is immersed in liquid flux (zinc ammonium chloride solution) to remove oxides and to prevent oxidation prior to dipping into the molten zinc bath.
The article is immersed in a bath of molten zinc at around 450°C. During galvanising, 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After the steel is withdrawn from the galvanizing bath, excess zinc is removed by draining or vibrating. The galvanised item is then air-cooled or quenched in liquid and sent for inspection and testing.