Metal Galvanizing

Metal galvanizing is a process of applying a special coating to the surface of a product. Such solutions are based on zinc, which is the most suitable raw material. It prevents corrosion and also protects the surface from the effects of aggressive substances. The treated sheet becomes stronger, more resistant to temperature and chemicals, and has a longer service life.

We have industrial hot-dip galvanizing baths that allow processing of large and long elements.

Bath dimensions:

• Length: 6,000 mm (6 meters)

• Width: 1,100 mm (1.1 meters)

• Depth: 2,000 mm (2 meters)

Hot-Dip Galvanizing

Hot-dip galvanizing using a high-temperature plasma jet is a method of applying anti-corrosion coatings performed with mobile installations. These systems provide high productivity, automation, and allow adjustment of coating thickness and adhesion by changing the speed and temperature of the plasma flow.

Before hot-dip galvanizing hollow structures (pipes, boxes), it is mandatory to drill vent and drainage holes. They ensure free flow of zinc and cleaning liquids, guarantee complete coverage, and prevent dangerous pressure (explosions).

Main Rules for Drilling Holes

1. For hollow profiles (pipes, boxes, square and rectangular tubes):

• At both ends: There must be a hole at each end of the profile.

• Corners: Holes should be as close as possible to the ends/corners.

• Size: Hole diameter usually ranges from 8–12 mm for small profiles (up to 50 mm) and up to 25–30 mm for larger pipes.

2. For tanks and closed volumes (reservoirs, boxes):

• Vent hole (highest point): Located at the top point of the element when immersed in zinc.

• Drain hole (lowest point): Located at the lowest point when removing from the bath.

• Diagonal placement: For large flat elements, holes should be placed diagonally (opposite corners) for maximum flow.

3. For reinforcements (ribs and plates):

• Holes in ribs: Drill holes in the ribs themselves to allow free zinc flow between them and the main structure.

Stages of Hot-Dip Galvanizing

1. Cleaning (Degreasing and Pickling): Removes contaminants and rust.

2. Fluxing: A chemical flux is applied to prevent oxidation and ensure adhesion.

3. Immersion: The element is immersed in molten zinc (450°C), forming zinc-iron alloy layers.

4. Cooling and Inspection: The product is cooled and inspected for coating quality.

Cold Galvanizing

Cold galvanizing (zinc-rich coating or primer) is an anti-corrosion protection method that does not involve immersion in molten metal.

What is it?
A zinc-rich coating (over 90% zinc in dry film) is applied using:

1. Spraying – for large uniform surfaces.

2. Brush – for small or hard-to-reach areas.

3. Roller – for large flat surfaces.

Comparison Table Between Hot and Cold Galvanizing

Conclusion

Galvanizing protects metal parts from corrosion, moisture, and aggressive substances. It maintains the aesthetic appearance of the metal and reduces maintenance costs, making it one of the most widely used anti-corrosion protection methods.