By Hussain, technical estimator and trainee design engineer at Steelo.

As a technical estimator and trainee design engineer working at Steelo, I frequently come across questions regarding the durability of galvanised steel. One of the most recurring concerns is whether galvanized steel is susceptible to rust. This article aims to provide a detailed answer to this query, exploring the factors that influence galvanized steel’s rust resistance and the role of steel finishes in enhancing its longevity.

Galvanised steel is a popular choice for construction projects, mainly due to its resistance to rust and corrosion. The steel fabrication process involves adding a protective layer of zinc to the structural steel, creating a barrier against environmental elements that cause rust. This protective layer is known as ‘galvanizing’, and it plays a vital role in prolonging the service life of steel products.

Does Galvanised Steel Rust?

Generally speaking, galvanised steel exhibits strong resistance to rust and corrosion, thanks to the protective zinc layer. However, it is important to emphasize that galvanized steel is not entirely immune to rust. Several factors can contribute to the corrosion of galvanised steel, including:

Exposure to harsh environments

Although the zinc layer on galvanised steel offers considerable protection, it may not be sufficient to prevent rust in highly corrosive environments like coastal regions with high salt concentrations.

Compromised coating

The galvanised steel layer can be weakened if scratched, chipped, or otherwise damaged. In such instances, the exposed steel might start to rust over time.

Ageing and wear

As with any material, galvanized steel is subject to wear and tear over time. As the zinc layer becomes thinner, the underlying steel becomes more prone to rust.

Inadequate coating

The quality of the galvanising process can also impact the steel’s resistance to rust. Poorly applied or thin layers can result in accelerated corrosion.

Steel Finishes for Improved Durability

There are several steel finishes available that can offer extra protection to galvanised steel, further improving its resistance to rust and corrosion.

Some of the most common steel finishes include:

• Powder coating: This finish entails applying a robust, weather-resistant powder to the surface of the galvanised steel. It provides an additional layer of protection and is available in an extensive range of colours and textures.
• Epoxy coatings: Epoxy coatings are applied to the steel surface to create a thick, long-lasting barrier that safeguards against rust and corrosion. These coatings are highly resistant to chemicals, abrasion, and UV radiation.
• Paint coatings: High-quality paint can also be applied to galvanised steel to enhance its visual appeal and protect against rust.

In conclusion, while galvanised steel is highly resistant to rust and corrosion, it is not entirely rust-proof. By understanding the factors contributing to rust and considering additional steel finishes, you can prolong the life of your structural steel and ensure its durability under various conditions. As a technical estimator and trainee design engineer at Steelo, I strongly recommend consulting with a trusted structural steel fabrication firm to discuss the most suitable options for your project.