HOT DIP GALVANIZING

Hot-dip galvanizing is a special immersion plating technique in which zinc forms a durable and impermeable coating. We do wet galvanizing in a hot-dip bath size 2000 x 800 x 1200 mm (l x w x h) heated by natural gas with automatic temperature regulation of the galvanizing bath. As one of the last, we zinc manually by means of pliers or by means of various hand fixtures, which allows us to galvanize even shape-complicated parts. We provide this service in accordance with ČSN EN 1461 standard and issue a certificate of conformity according to ISO/IEC Guideline 22 for the work. These services are used in construction, telecommunications, transport, agriculture, etc.

Hot-dip galvanizing is one of the most durable ways of protecting metal products against corrosion. Submerging the product into a zinc bath will result in a metallurgical reaction of zinc with iron. The surface thus formed has the same thickness in the area, corners and edges. They can be used especially in construction, engineering, but also in places where a durable surface treatment is required. The lifetime of hot-dip zinc in the exterior is several decades.

Hot-dip galvanizing has been used as corrosion protection for steel for 150 years.
The temperature range of 440°-460°C is usually used for hot-dip galvanizing.
After pre-treatment (degreasing, pickling, fluxing), the hot-dip galvanized part is immersed in molten zinc, where the zinc-iron metallurgical reaction occurs. After pre-treatment (degreasing, pickling, fluxing), the hot-dip galvanized part is immersed in molten zinc, where the zinc-iron metallurgical reaction occurs.
The zinc layer on the steel is even: on the outer surface, on the inner surface, on the edges and corners.
Hot-dip galvanized steel is used as a steel structure in the construction industry, for bridges, road barriers, signage, electricity pylons, fencing, railings, stops, concrete reinforcement, where it forms the same strong band with concrete as untreated steel, etc.
During the construction of the Brooklyn Bridge, 23.330 km of hot-dip galvanized wire was used to manufacture its four main carrier cables. When the bridge was completely renovated after more than 100 years, the hot-dip galvanized wires were in perfect condition.
Hot-dip galvanized steel lasts much longer today than 20 years ago. This is due to much stricter laws, the atmosphere is much cleaner and is contaminated with less sulphur dioxide, which is one of the main corrosive factors.
After some time, reddish-brown stains containing exclusively intermetallic phases may appear on the surface of galvanized steel products. However, it is not a corrosion of steel, but only a very small amount of iron in the iron-zinc alloy layer oxidizes and creates these spots. These stains have no adverse effect on the corrosion resistance of the hot-dip zinc coating.
Corrosion causes 3% of GDP per year in the EU. It is estimated that indirect costs can reach up to 6% of GDP.

1. Competitive acquisition costs

The cost of hot-dip galvanizing, especially for small parts with a simple surface finish, is lower than most alternative coatings. In addition, hot-dip galvanizing becomes cheaper compared to paints. The cause is simple: alternatives, especially paints, are very labour-intensive compared to hot-dip galvanizing, whose technology is highly mechanized.

2. Lowest lifetime cost

Low purchase costs and long service life make hot-dip galvanizing the most versatile and economical way of long-term steel protection. For hot-dip galvanizing, the maintenance of galvanized parts is sufficient at very long intervals, which is advantageous for buildings in difficult to reach locations, on difficult terrain, in building complexes or if the buildings are subject to risk, e.g., masts for power lines.

3. Lifetime

Well documented years of hot-dip galvanizing experience have shown its benefits. Of course, the service life is at least 20 – 40 years in an aggressive seaside and industrial atmosphere and 50 – 100 years in less aggressive atmospheres.

4. Methods of protection

Zinc coatings protect steel in 3 ways. The corrosion rate of the zinc coating is very slow and even compared to steel, so its life in a given atmosphere can be estimated very well. In particular, the coatings provide cathodic protection. Surface areas damaged by drilling, cutting and scratching are still protected against corrosion by zinc corrosion products.

5. Application speed

The time to produce a corrosion-resistant coating, including surface pre-treatment, maybe less than a day.

6. Ease of acceptance

The essence of the hot-dip galvanizing process is that if the coating appears regular and impeccable, so it is. The thickness (or weight per unit area) is specified by EN ISO 1461 and is easily estimated and subsequently determined for a given product type and material. It can be easily controlled by magnetic or other simple non-destructive methods.

7. Reliability

Hot-dip galvanizing is a relatively simple process, directly and accurately controlled. The hot-dip zinc coating is one of the coatings defined in detail by standards (e.g., EN ISO 1461, NS 1978, SFS 2765 or SS3583).

8. Faster construction

Hot-dip galvanized steel is ready for use. No further surface treatment and preparation (coatings, retouching) is required. Once the structure is galvanized, its assembly can begin immediately, speeding up the construction.

9. Strength of coating

Hot-dip galvanizing is unique in that it results in a coating associated with the parent metal (steel) by a metallurgical bond. This can´t be achieved by any other method of coating preparation. The hot-dip zinc coating has by far the highest resistance to mechanical damage during handling, storage, transport and use. This makes the hot-dip zinc coating an ideal solution when the surface is subject to abrasion.

10. Complete coverage

The hot-dip zinc coating is formed when all parts are immersed in a bath of molten zinc and therefore the surface is completely covered by the coating. The coating also covers the inner surface, unpleasant corners and hard-to-reach interior spaces that couldn´t be covered by the coating in any other way.