About the company Hot-dip galvanizing process Passiveerimine Client information Gallery FAQ Contact
Kuusalu vald 74604
Kiiu Harjumaa
Phone +372 60 35 770

Customer service:
Phone +372 603 5773
GSM +372 53 33 0093

Download contract form

Hot-dip galvanizing process

1. grease and oil removal
2. rust removal with hydrochloric acid
3. dipping into slag
4. pre-heating/drying
5. dipping into molten zinc
6. cooling and cleaning
7. weighing
8. quality assurance
Hot-dip galvanizing is an anti-corrosion treatment in which the products are covered with a thin layer of zinc. The process consists of several stages and can be more or less thorough for different hot-dip galvanizing companies. In addition to large-scale baths, the AS Galv-Est plant also uses a modern technical cycle, which includes all the necessary processes and equipment that can positively influence the quality of the product, the environment, and the safety of the personnel.

Since molten zinc only reacts to a chemically clean metal surface, this has to be assured through pre-treatment. Dirt, oils, grease, and rust are removed during the treatment process in the plant but paint, varnish and other non-washable substances that also do not dissolve in hydrochloric acid have to be removed mechanically beforehand by the customer. If, upon mutual agreement, this additional work is left to be carried out by the company performing the galvanizing, it will also be reflected in the price of the service.

The chemical pre-treatment of steel components starts with washing in a bath with a special solution warmed up to 70°C followed by treatment in two consequent baths.

Further pickling in hydrochloric acid baths ensures that any rust is removed from the surface of the steel.

After rinsing in water the parts are dipped into slag, which prevents the rapid oxidation of the clean steel surface before galvanizing.

Another important step in the process for ensuring quality and safety is the subsequent drying and pre-heating of the parts in a special chamber immediately before galvanizing. This stops the formation of steam in the molten zinc bath.

During galvanization, the dried and pre-heated steel parts are dipped into a bath with molten zinc.

The zinc bath at the AS Galv-Est plant has dimensions of 14 x 3 x 1.6 m, and to provide for more safety in its vicinity it is covered with a specially constructed hood with hatches. At 450°C the zinc and the steel react chemically to each other creating firm and maintenance-free corrosion protection for decades to come.

After galvanizing, the galvanized parts undergo visual inspection, after-treatment, measuring of the thickness of the zinc layer, and weighing. The steel surface, with correct and even Si-content for galvanizing, is usually glossy and of high quality, and the thickness of the zinc layer varies from 60-150 µm.