Hot dip galvanisation
Protection against corrosion by means of hot dip galvanization obtained by the following cycle:
- Degreasing; process carried out by dipping of the material into bathes containing watery surface-active solutions. The aim of this phase is to eliminate from the surface traces of grease/oil left from the previous mechanic works.
- Pickling; process carried out by dipping of the material into bathes containing watery surface-active solutions, hydrochloric acid and corrosion inhibitor. The Aim of this phase is to eliminate from the surface of the different pieces traces of oil/grease left from the previous works and iron oxide generated by the production process of the steel work.
- process carried out by dipping of the material into bathes containing water. The Aim of this phase is to eliminate from the surface rest of the solution of grease and pickling in order to reduce the dragging of iron chloride, produced by the dissolution of the iron oxide during the fluxing phase
- Fluxing;. Process carried out by dipping of the material into bathes containing watery solution enriched with chloride zinc salt and chloride ammonium. Aim of this phase is to cover the surface of material with a protective salt film which protects the material waiting to be galvanised, from possible oxidation which may prevent the galvanisation
- Pre heating ; storage of the fluxed pieces into a ventilated room where the material is heated before to be galvanised at temperature of 90 ° C. The aim of this phase is to dry the material from liquid coming by the previous phases and reduce the difference in temperature with the e approximate temperature of the metal is 450°C. Dipping of the material produces a surface zinc coat which cover it completely and grants its protection from corrosion thanks to an electrochemical process which provides for the corrosion of the zinc in respect to the underlying iron which remains protected even if the protective coat will be damaged.
The obtained coat will be according to UNI EN ISO 1461 with minimum zinc thickness of 55 microns and average thickness 70 microns.