Wedge Galvanizing Group Ltd - Galvanization Process

The Galvanizing Process

The process consists of 3 distinct phases:

• Pre-Treatment

• Galvanizing

• Inspection

Pre-Treatment - consists of 4 separate stages:

• Inspection - Items are inspected to ensure they are safe and suitable to galvanize. This may involve checking whether they are adequately vented. Surfaces are checked for signs of contamination with paint, grease, etc. as these will not be removed in the process and would cause the process to fail.

• Degreasing - Steel is immersed in a degreasing solution which removes light oil contamination.

• Pickling - Acid strips the steel surface back to clean base steel.

• Fluxing - A flux solution is applied to the steel to assist with the galvanizing reaction.

Galvanizing
Material is loaded onto jigs, before being immersed in molten zinc at a temperature of around 450 degrees until the temperature of the work is the same as the zinc. During this process the molten zinc reacts with the surface of the steel to form a series of zinc/iron alloys. As work is removed from the zinc, the zinc on its surface will begin to solidify, as this happens excess zinc is removed to ensure a smooth finish. Work is then usually transferred to a quench tank where it is cooled to allow handling.

Inspection
The galvanized steel is first visually inspected for its appearance and conformity to standard. Batches may then be non-destructively tested for coating thickness and uniformity.

Centrifuge/Spin Galvanizing
This follows the same process as general galvanizing, except that the work is placed in baskets to be galvanized and rapidly removed from the bath before the zinc on the work solidifies, the basket is then placed in a centrifuge and spun for several seconds. Click for a real life case study from Wedge Group Galvanizing.

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