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Does structural steel rust?

Does structural steel rust? The simple answer is yes. However, there are many ways that steel fabricators and others can prevent corrosion and ensure long-term durability of their steel.

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While it’s likely been years since you last set foot in a science classroom, today, we’re diving back into the world of science. Why? If you’ve ever pondered whether structural steel rusts, science holds the key to the answer.

To give you a quick insight, the simple answer is yes. While structural steel boasts impressive strength and durability, rust remains a potential downside. 

Whether you’ve recently constructed a home with structural steel or find yourself working in a building built using structural steel, this realisation may not be particularly reassuring. However, fear not! The good news is that rust can be prevented. 

In this blog, we’ll look at why structural steel rusts and delve into the innovative methods employed by steel fabricators and others to combat corrosion and ensure the long-term resilience of structural steel.

Understanding the science of rust

It’s time to put on your lab coat and the thickest glasses you can find. Bunsen burners are optional. 

Rust develops in steel when iron, a primary component of steel, reacts with oxygen and water. This chemical reaction, known as oxidation, causes iron atoms to lose electrons to oxygen atoms in the presence of moisture, leading to the formation of iron oxide or rust. 

In very basic terms, rust is the result of steel “rusting away” due to exposure to air and water. 

In the context of structural steel, primarily composed of iron and carbon, rust formation can occur when the surface of the steel is exposed to environmental factors conducive to corrosion. 

These factors include:

  • Water, which is a primary catalyst for rust formation, as it provides the necessary medium for the oxidation reaction to occur. Rain, humidity and condensation can all contribute to the accumulation of moisture on steel surfaces, accelerating the corrosion process.
  • The presence of oxygen is essential for the oxidation of iron, as it facilitates the transfer of electrons from iron atoms to oxygen molecules. Atmospheric oxygen readily reacts with exposed steel surfaces, leading to the formation of iron oxide.
  • Certain substances, such as salt and pollutants, can act as electrolytes and accelerate the corrosion of steel. Saltwater, in particular, is notorious for its corrosive effects on metal surfaces, making coastal environments especially prone to rust formation.

Rust never sleeps. Neither does the effort to prevent it

Rust Never Sleeps was a popular album by Canadian American singer-songwriter Neil Young and American band Crazy Horse. You could argue that the term rings true for steel, given that water and oxygen are everywhere.

However, the effort to prevent rust in steel is wide awake, too!

While structural steel can be susceptible to rust, steel fabricators employ a variety of techniques to mitigate corrosion and ensure the longevity of steel structures.

These techniques include:

  • Galvanisation is one of the most effective methods for preventing rust on structural steel. This process – which has been in use for over 200 years – involves coating steel with a layer of zinc, either through hot-dip galvanising or electroplating. Zinc serves as what is known as a sacrificial anode, corroding preferentially to the underlying steel and providing a protective barrier against moisture and oxygen.
  • You may paint, or oil timber at home to provide protection, and protective coatings can also be applied to structural steel. Applying a high-quality paint or protective coating to steel surfaces can effectively shield against rust formation. Epoxy, polyurethane and powder coatings are commonly used to provide a durable barrier against moisture and corrosion. This also enhances the aesthetic appeal of steel structures.
  • Cathodic protection systems utilise sacrificial anodes or impressed currents to prevent rust formation on steel structures. By introducing a more reactive metal, such as zinc or aluminium, into the system, corrosion is redirected away from the steel, prolonging its lifespan.
  • Regular inspection, cleaning and maintenance can also be used to preserve the integrity of structural steel and prevent rust. Removing dirt, debris and corrosive contaminants from steel surfaces, as well as promptly repairing any damage or coating failures, can help mitigate the risk of corrosion and ensure long-term durability.

Let Kelly Steel look after the science and the protection

If you’re a commercial, industrial or residential client and you need structural steel for your project, should you be concerned about rust affecting the longevity of your structure?

Absolutely not. As we’ve seen above, while structural steel is susceptible to rust under certain environmental conditions, innovative solutions are employed by steel fabricators to effectively prevent corrosion. This helps to prolong the lifespan of steel structures and ensures their integrity for generations to come.

The good news is that no matter your background or how much you know about science or steel fabrication if you need structural steel, you can leave the details to us. As part of the planning and design process, we’ll discuss and analyse your project in detail to determine the most adequate protection required for your steel.


Whether you need a crane lifting platform or beacon platforms for around marine environments, a canopy for a service station or structural steel for a commercial building, Kelly Steel will help ensure your structure stands the test of time.

Will structural steel produced today still be around in 100 years

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