Home > Companies > Wedge Group Galvanizing Ltd > Hot Dip Galvanizing

Hot dip galvanizing process consists of three distinct phases:

  • Pre-treatment.
  • Galvanizing.
  • Inspection.


Pre-treatment for galvanizing consists of four separate stages:

  • Inspection: Items are inspected to ensure they are safe and suitable to galvanize. This involves 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.


Material is immersed in molten zinc at a temperature of around 450°C 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. These alloy layers protect steel from corrosion in excess of 30–40 years.

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.


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.

Related literature

The following content references this product:

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-35-30/360 Hot-dip galvanizing

Product specification

An important note about specifying



Wedge Group Galvanizing Ltd


+44 (0)1902 630311

Product reference

Hot Dip Galvanizing

Coating thickness (minimum):

[ ______ ]

Manufacturer details

Stafford Street,
West Midlands, WV13 1RZ
Tel +44 (0)1902 630311
Fax +44 (0)1902 366353
NBS Plus
NBS National BIM Library