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Hot dip galvanizing is a coating for steel made from an alloy of zinc and iron.

Galvanizing is a once-only process – no substrate preparation and multiple coating is required. It offers total coverage – all exposed steelwork is coated both internally and externally. Galvanized coatings protect steel even at its most vulnerable areas. It is thicker at corners and edges of steelwork, an important advantage over organic coatings which can thin out in these critical areas to expose the steel to corrosion. This saves time, money and ensures the integrity of the finished result.

Galvanizing protects steel from corrosion in three major ways. Firstly, it provides an metallurgically-bonded impermeable barrier around the steelwork preventing the access of the moisture and air that cause corrosion. Secondly, it forms an insoluble protective patina when exposed to the atmosphere which reduces the effect of corrosion on even the zinc-iron alloy layer. Thirdly, the galvanized coating provides electrochemical cathodic protection. This means if the steelwork is damaged by impact, drilling or cutting then the coating sacrificially protects the exposed steel. Besides corrosion protection, galvanizing also protects steel mechanically from impacts and abrasion because the zinc-iron alloys layers are more than 50% harder than the base steel. Normal organic coatings are removed in these situations, leaving the steelwork exposed to underfilm corrosion.

Galvanizing is said to be an environmentally friendly and sustainable way to protect steel. Zinc is unique in that it can be recycled indefinitely and still retain its positive characteristics. Over 30% of the zinc currently used is recycled. This will increase as items galvanized over 60 -70 years ago are brought back for refurbishment. Zinc is a natural element that is indispensible for humans, animals and plants and is commonly added to food as a health supplement.

Acknowledgement: Galvanizers Association of Australia

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