How much does hot dip galvanizing cost?
The cost of hot dip galvanizing is determined by a number of factors. These are:

1. The cost of zinc.
2. The type of item being galvanized  - light, medium, heavy, 1, 2, or 3-dimensional, hollow or solid section.
3. The size of the item.
4. The current cost of labour, chemicals, power and gas.
5. Shareholder requirements – profit

The cost of zinc has the greatest impact and can make up 40% of the total processing cost. The zinc price is volatile and from 2004 to 2006 it increased 300%.

The fixed costs of a structural galvanizing plant are high. The furnace must operate on a 24-7 basis and for this reason, large tonnages of structural steel can be processed at a much lower cost than smaller, 3-D items such as trailers.

For this reason, the cost of hot dip galvanizing steel can range from $700/tonne for large tonnages of structural steel, to well over $2000/tonne for small cash-sale items.

It is long-standing industry practice to charge hot dip galvanized coatings on the basis of ‘white weight’.

This is based on the weight of the steel after it has been galvanized. This weight is recorded by the galvanizer using certified weighbridge scales and the customer will be charged at a rate per kg or rate per tonne, based on that weight.

In some cases, a unit rate may be negotiated where repetitious manufactured products such as fence panels, star pickets or building products are processed on a regular basis.

The tonnage of steel that can be processed through the galvanizing bath in a given time will have a big impact on how it is costed. All the fixed overhead costs of the galvanizing business are allocated to the galvanizing bath. Steel fabrications that can be processed at 6 tonnes per hour will incur a lower bath cost component than those than can only be processed at 2 tonnes per hour.

For this reason, attention to detail design can significantly reduce galvanizing costs. A fabrication that can be assembled from 2-dimensional sections will be less costly to process than if it was a 3-dimensional fabrication, as more fabricated sections can be loaded onto the galvanizing jigs in 2-d form. Fabrications that have dimensions within those of the galvanizing bath will avoid the additional cost associated with double-end dipping that is required with items that are longer or deeper than the bath dimensions.

While the costs of galvanizing lighter steel sections appears to be significantly higher than heavier sections, there is a significant cost saving when compared on a surface area basis. Hot dip galvanized coatings are the most cost effective heavy-duty coatings when compared on this basis.

For example, medium structural steel (12mm section thickness) could be galvanized for say, $800/tonne. Steel of this thickness has a surface area of about 20 m2/tonne, so the cost of galvanizing per square metre is $40/tonne. Light steelwork, commonly associated with box trailers or light hollow section that averages 3 mm in thickness may cost $1500/tonne to galvanize. Its surface area is 85 m2/tonne so the cost of hot dip galvanizing is then less than $18/m2.

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