Galvanising: our process.
At Medway Galvanising, each step of the galvanising process is meticulously controlled by experienced and highly skilled supervisors and operatives.

Preparation
Our first step is to prepare the materials to be galvanised. Since the process involves subjecting materials to extremely high temperatures, it is critical that our clients’ materials are fabricated with no sealed tubes, blind corners or any other potentially explosive areas. Customers should ensure that materials are free from all welding slag, heavy grease and paint from the products, as these will not be dislodged by pre-treatment chemicals.

Treatment
With initial preparation complete, fabricated products are then wired on to beams at an approximate 30° angle to facilitate draining, before being immersed in an acid degreasing agent to remove any light grease and cutting oils, since any remaining excessively heavy grease would require further pre-treatment and add to costs.

The materials are then immersed in hydrochloric acid at ambient temperature in order to scour the steel surface and eradicate all mill scale and rust. The hydrochloric acid contains an inhibitor to avoid over-pickling, so ensuring a perfect surface for the galvanised coating.
Finally, the materials are rinsed to remove acid residues before being immersed in flux to ensure the efficient flow of zinc over the products’ internal and external surfaces.

Hot-dip galvanising
The materials are immersed in molten zinc at a temperature of 450ºC until they reach the same high temperature as the zinc. The products are then gradually withdrawn to allow excess zinc to drain off. The coated products are then quenched or air-cooled depending on client requirements.

For details on the resultant galvanised coatings click here.