What is hot-dip galvanizing?
Protection of the metal surface from corrosion is an important part of any industrial, construction process. There are many ways to protect the steel product and extend the service life. The most popular technology is hot-dip galvanizing – what is it?
Galvanizing metal-the process of holding the structure in a heated zinc solution. The technology involves a strict adherence to the recommendations of the state standard until the compliance of the room temperature.
The process begins with the preparatory stage. The item is treated for better adhesion of the chemical solution and the metal structure. The first step is degreasing. With details remove oil, synthetic compounds. Depending on the nature of contamination should choose a reagent for cleaning – acid, alkali.
The second step is etching. Hydrochloric acid concentration of 120-210 g / l perfectly removes rust residues, scale. It should be remembered: acid corrodes the surface of the metal. After etching is over, the product should be thoroughly washed – the reagent should be completely washed off to avoid damage to the metal structure.
Fluxing-applying a solution of flux on the part. The solution performs two important functions: additionally cleans the steel, removing iron oxides, and forms a film. Thanks to the film, the subsequent adhesion of the zinc solution and the metal structure is easier and more reliable. The solution of flux is used in a very concentrated form (400-600 g/l) at a temperature of 60 degrees.
It is strictly forbidden to place the item in the zinc mixture immediately after fluxing. On the surface of the steel remain drops of liquids evaporating during galvanizing. Evaporation produces microexplosions that result in bare, uncoated zinc sites. The protective mixture lies unevenly, poorly. Important after glosowanie dry thoroughly detail with the use of special equipment.
With technically correct carrying out of the preparatory stage, the product should be immersed in a bath filled with 98% zinc melt. The dive is performed inside the spinning drum. To survive optimally 3-10 minutes. Requires special attention to the process of lifting the drum. The thickness of the zinc layer depends on the rate of extraction of the part. While the details of the zinc formed on the surface of the slag. By removing the slag, you can use the finished part.
Having understood what it is – hot dip galvanizing, and what the process looks like, you should learn about all the advantages of the operation:
- the service life of the product is increased up to 50 years;
- a high rate of thermal conductivity and electrical conductivity is maintained;
- the surface of the structure is self-repairing with minor damage-zinc eventually penetrates deeper into the metal structure;
- the item does not require further repair and maintenance.