Galvanizing – process and costs in comparison

What galvanizing processes are there?

Hot-dip galvanizing

During hot-dip galvanizing the... steel construction or the components in one Bath of liquid zinc submerged. The temperature of the zinc is around 450°C. The Zinc layer thicknesses are between 50 and 150 micrometers. In continuous strip galvanizing systems, such as those used for galvanizing steel sheets or pipes, significantly smaller zinc layer thicknesses are produced.

Large components are suspended individually and dipped into the zinc bath. Small components are centrifugally galvanized. The components are immersed in the zinc bath in baskets and the excess zinc is then separated off in a centrifuge.

You can see how hot-dip galvanizing works in the accompanying explanatory video about hot-dip galvanizing Institute for hot-dip galvanizing.

What should be taken into account when hot-dip galvanizing?

For hot-dip galvanizing, the components must be prepared professionally. It must be ensured that the liquid zinc gets to all parts of the component and can also flow away again. Become this Inlet and ventilation openings drilled. The components must also be clean before galvanizing. Varnish, oil and other residues must be completely removed. Cleaning can also be carried out at the galvanizing plant.

The warming can cause deformations come. This is particularly problematic with welded components, as well as with thin-walled and large-area sheets. Tight tolerances must therefore be reworked. Threads must be recut after galvanizing.

During hot-dip galvanizing, the parts are immersed in a bath of liquid zinc. It is completely normal that the Zinc layer thickness is not the same everywhere. The surface cannot be compared to a painted surface. Defects may occur due to the process and must be tolerated in accordance with the EN ISO 1461 standard. Sharp edges and depressions are particularly problematic.

Hot-dip galvanized components can then also be powder-coated or painted. In order to get good surface quality, they must be prepared after galvanizing. Defects can be eliminated by fine plastering and the surface straightened. In order for the paint to stick to the zinc layer, the surface must be chemically treated.

Where can you find suppliers of hot-dip galvanizing?

You can find some on the Stahlbau-lieferant.de directory Providers of hot-dip galvanizing from Austria and Eastern Europe. You can find a list of hot-dip galvanizing plants in Germany at Hot-dip galvanizing industry association. In order to keep the transport costs for galvanizing low, it is recommended to choose a galvanizing plant close to the supplier or close to the customer.

Galvanizing

When galvanizing, the components are not immersed in a zinc melt, but rather in a Electrolyte bath. The steel structure or the components are used for galvanizing as a cathode. One serves as an anode Pure zinc electrode. By applying voltage, a layer of zinc is deposited on the steel structure.

The thickness of this zinc layer can be controlled by the duration of the process. However, it will Zinc layer not uniformly thick everywhere. As a rule, this is how you achieve it Layer thicknesses between 5 and 40 micrometers, significantly less than with hot-dip galvanizing.

The Corrosion Protection Galvanizing is therefore fundamental worse than hot-dip galvanizing, but the process also offers many advantages.

What are the differences between electrogalvanizing and hot-dip galvanizing?

• Due to the small thickness of the zinc layer Dimensional accuracy the components are better with galvanizing than with hot-dip galvanizing. 
• Threads do not need to be reworked when galvanizing.
• Galvanizing can also be used for temperature-sensitive workpieces be applied. During hot-dip galvanizing, these would warp due to the heat.
• To further improve corrosion protection, the components can be chromated or powder-coated.

Hot-dip galvanizing offers significantly better corrosion protection than galvanizing. When it comes to the corrosion resistance of simple components, hot-dip galvanizing is the best choice. If the components need to be precise or have a surface that is as uniform as possible, galvanizing is more suitable. Galvanizing is also advantageous for components that have a strong tendency to warp.

Spray galvanizing

During spray galvanizing, zinc wire is melted and, like painting, applied to the workpiece using compressed air. The layer thicknesses are similar to those of hot-dip galvanizing and are between 80 and 150 microns. The main disadvantages are that it... not in cavities can be applied and that the workload is comparatively high. For that can Spray galvanizing can also be used on components that are not suitable for hot-dip galvanizing can also directly on construction sites be performed. Spray galvanizing does not require any drying time because the zinc solidifies immediately.

When hot-dip galvanizing, the size of the components depends on the dimensions of the zinc bath. Many galvanizing plants can only galvanize components up to 8m in length, some even up to 15m. Spray galvanizing can also be used to coat components that are too large for hot-dip galvanizing.

The layer thickness can be individually adjusted during spray galvanizing. A component can have a higher layer thickness in important places.

How much does galvanizing cost in 2023?

The costs for galvanizing depend on the respective process. Basically, in the industrial environment, components made of profiles or pipes cost 0,25 – 0,6€ per kg of finished steel structure to be expected. Galvanizing smaller components is significantly more expensive. Private users with small quantities also have to expect significantly higher prices.

For thin-walled components such as sheet metal, the price also depends on the geometry. You can find a more precise estimate of the costs under the respective procedures.

There are also transport costs and costs for the preparation and follow-up of the components.

Compared to alternative materials and processes, galvanizing is very attractive in the long term. Galvanized components cost less than stainless steel components and the corrosion protection provided by galvanizing is higher than with painted components. Galvanizing is often the cheapest alternative in the long term, especially for outdoor applications. In this article you will also find examples of this Price per kg of steel structure for different components.

Hot-dip galvanizing costs

The cost of hot-dip galvanizing depends on the order volume and the size and complexity of the components. In addition, the prices for galvanizing depend heavily on energy costs and the price of zinc. The price of zinc is currently very high, which is why many galvanizing plants had to increase prices in 2022.

The Prices for hot-dip galvanizing from very heavy steel structures start at approx. 0,40 € / kg. For light steel construction in an industrial environment, one kilogram of hot-dip galvanizing costs around €0,60. Centrifugal galvanizing for smaller components under 3kg costs around €1,30/kg for industrial customers.

For small quantities for private customers you have to expect prices of more than 1€/kg.

Additional costs of 0,20 – 0,30 €/kg can be expected for fine plastering.

Costs for spray galvanizing

The costs for spray galvanizing are: approx. 10-12€/m². There are also costs for the previous sandblasting. These depend very much on the nature of the surface and the component geometry. Furthermore, the components must be further coated or painted after spray galvanizing. The amount of work involved in spray galvanizing is very high, which is why labor costs are a decisive factor in spray galvanizing.

Costs for galvanizing

The Costs for galvanizing depend primarily on the layer thickness and start at around 0,25 € / kg. In many applications, galvanizing is cheaper than hot-dip galvanizing. However, for the same layer thickness, galvanizing is much more expensive than hot-dip galvanizing.