What is Hop-dip Galvanising?

come evitare la ruggine per sempre
zincatura a caldo dante negro

Hot-dip galvanising is worthwhile: its cost is fully repaid over time! The price of this treatment is zero compared to the risk caused by corrosion. In fact, when rust is noticed, it can be too late and the mechanical and structural resistance of the product can be compromised. So why running the risk to save some money?

ferro con ruggine

Thanks to hot-dip galvanizing, you can solve any rust problem with a 10-year to 30-year warranty. All our products benefit from this treatment. See the gallery of our galvanized products.

But how does a product need to be in order to be galvanised?

The article must be built according to some precautions:

  • the steel must be cleaned on the surface;
  • must be solid and continuous welded;
  • must be suitable and of good quality;
  • all pipes must have a vent and discharge duct to the outside.

How does galvanising work?

The hot-dip galvanising process can be summarised briefly in the following steps:

  • The material is fastened to frames that allow it to be subsequently moved inside the plant by means of iron wire, hooks or chains;
  • The products are degreased with special solutions to remove any traces of machining oils;
  • The pickling phase is carried out in hydrochloric (or sulphuric) acid solutions in order to remove any traces of rust from the pieces and thus obtain surfaces of pure steel;
  • Washing in water to avoid acid entrainment.

A distinction should now be made between ‘dry’ and ‘wet’ galvanising. Let us proceed with the first type.

  • Flushing in aqueous solution of ammonium chloride in order to delay the oxidation of the “bare” metallic surface before galvanizing;
  • Drying and preheating in a heated room with the smoke from the oven (approx. 150° C). This phase is important to eliminate any trace of liquid from the pieces: vapours that develop during galvanizing due to the presence of a stagnation of liquid can cause real explosions, dangerous for man and the artefacts if these have not been made according to the adjustments initially exposed;
  • Galvanizing by immersion in molten zinc at about 450° C for a few minutes depending on the type of material and the desired coating thickness. The immersion time, its rate of descent and ascent, the purity of the bath and the compatibility of the material with zinc are some of the decisive factors for the success of a galvanizing process;
  • Cooling in air or water, material release.

In the case of the “wet” process, there is no flushing phase (phase 1) and after preheating, galvanising takes place in a bath of molten zinc covered with flushing salts:the final quality of the galvanised part is the same for both processes.

tavoli e sedie outdoor

Above: photo of Fiordaliso table with Salli chairs under a metre of snow. Our products do not need to be covered during the winter