How is steel treated to prevent corrosion?

In today’s market, steel products range from domestic roofing and fencing through to high-speed engines and pressure piping. To prevent corrosion, different types of coatings are used for different products.

In today’s market, steel products range from domestic roofing and fencing through to high-speed engines and pressure piping. For different products, different types of coatings are used.

The main types of steel coatings for the prevention of corrosion include:

• Powder coatings and bonded colour steel
• Emulsions
• Galvanisation
• Water based coatings
• Solvent based coatings

Powder coatings and bonded colour steel

"Pre-painted" steel – marketed in Australia as Colorbond steel products by BlueScope – is steel with a painted finish. It’s created by bonding a coloured powder coating to the steel.

Powder coatings are applied during the steel manufacturing process and require some form of heat or pressure treatment for the chemical bonding to occur.

Colour-bonded steel panels are very popular for use in roofing and walling, external fencing, water tank construction and cool room panelling.

For extreme weather conditions, there are also specific colour and metallic coatings available, which are designed specially for coastal or industrial settings.

The typical corrosion resistant warranty for these products is 25+ years.

Emulsions

Organic and inorganic emulsions are primarily used in industrial settings.  They are often available as solvent style cleaner/coatings.

These oil- or water-based emulsions are effective in preventing rust in industrial scenarios.

They require regular reapplication and are mainly used on equipment with moving parts; including those exposed to high temperatures.

Galvanisation

Since the late 1970s, modern metallic-coated roofing has been using an aluminium/zinc alloy as the predominant metal material.

This is marketed and sold in Australia as ZincAlume, a BlueScope Steel product.  Galvabond is a galvanised product from the same manufacturer.

Traditional galvanized steel roofs are still manufactured today and are among the most common metal roof panel in Australia, especially in industrial and commercial settings.

Water based

Water-based acrylic coatings are excellent for restoring metal roofs.

Water-based roof coatings commonly consist of an acrylic primer together with an acrylic roof coating.

While these coatings require reapplication to maintain the roof’s corrosion protection, they will usually several years.

Solvent based

Solvent based roof coatings are preferred on locations with high humidity or around air-conditioning equipment.

Typical solvent-based roof coatings include butyal coating, (which is a solvent-based, vapour barrier roof coating), and silicone coating with an epoxy primer.

These coatings require maintenance every 5-10 years.

If you want to find exactly the right steel product for your needs, talk to your steel supplier or manufacturer about the types of coatings available. Don’t forget to ask about the ongoing maintenance associated with each type of coating.

Reference:
Yellow Pages. (2015, April). How Is Steel Treated to Prevent Corrosion? Yellowpages.com.au. https://www.yellowpages.com.au/articles/steel-supplies-and-merchants/how-is-steel-treated-to-prevent-corrosion