Technological process of hot-dip galvanizing
MAIN PHASES OF THE TECHNOLOGOCAL PROCESS
Degreasing process is intended to remove grease and fat stains, oils and other synthetic impurities from the ferrous metal structures, which aggravate and inhibit the process of pickling.
Rinsing after degreasing is carried out to remove droplets of fat from metal structures and to prevent their falling into the pickling baths.
Pickling is carried out to prepare metal surface for galvanizing. Process of pickling is intended to remove rust and scale. Steel surface is activated without being damaged.
Rinsing is required after the process of pickling to remove iron chloride residual from the surface of metal structures and prevent transfer of hydrochloric acid solution into flux bath.
It is a process of the protective coating application on the surface of metal structures. The flux eliminates formation of oxides. It provides high degree adhesion of zinc melt to the metal surface.
Metal structures are exposed to heating up to 100 - 120°С. Moisture is removed from the surface of the materials, and they are prepared for dip-galvanizing by heating.
4. Hot-dip galvanizing
Galvanizing is a main technological process of hot-dip galvanizing. It is carried out in zinc melt at 450°С.
Final appearance of zinc coating on metal structures is formed during the process of cooling.
6. Quality control of zinc coating
Quality control of zinc coating is carried out by visual and instrumental method in compliance with the standards GOST 9.307-89, STB ISO 1461-2009
7. Metal structures are unloaded and transferred to the open storage.