How to prevent corrosion in steel structures?

Corrosion is a common challenge in steel structures, particularly in industrial environments where exposure to moisture, chemicals, and varying temperatures can accelerate deterioration. For MSMEs that purchase steel online, understanding how to protect steel from corrosion is essential to ensure the longevity and durability of their structures. By carefully selecting materials such as hot-rolled steel, Pre-Painted Galvalume Steel (PPGL), Galvalume Steel (GL), and Galvanised Plain Steel (GP) and applying the right treatments, you can effectively mitigate the risk of corrosion. Here are some tips and techniques for protecting steel structures from corrosion.

1. Choosing the right material

Selecting the appropriate type of steel is the first line of defence against corrosion. Different steel materials offer varying levels of resistance based on their composition and coatings:

• Hot-rolled steel: while hot-rolled steel is known for its strength and malleability, it is also more prone to corrosion if left untreated. Applying protective coatings or galvanising hot-rolled steel can significantly enhance its rust resistance and extend its lifespan, especially in outdoor or humid environments.

• PPGL: pre-painted galvalume steel is coated with zinc and then painted to add an extra layer of protection against corrosion. The zinc coating acts as a sacrificial layer, protecting the steel from rust by corroding in place of the underlying metal. The additional paint layer provides further protection and can be customised to meet aesthetic requirements while enhancing durability.

• Gl: galvalume steel is coated with an alloy of aluminium and zinc, providing excellent resistance to corrosion. The aluminium in the coating enhances its ability to withstand oxidation and rust, making it a great choice for environments with high humidity or salinity, such as coastal areas. Galvalume steel balances corrosion resistance and aesthetic appeal with a smooth, reflective surface.

• GP: galvanised plain steel is coated with a layer of zinc to protect against corrosion. This material is cost-effective and protects environments with moderate exposure to corrosive elements. The zinc coating is a barrier that prevents moisture and oxygen from reaching the steel, reducing the risk of rust.

2. Applying protective coatings

Applying protective coatings to steel surfaces is a proven method for preventing corrosion. Different coatings can provide varying levels of protection based on the specific environmental conditions and the type of steel being used:

• Galvanising: this process involves coating steel with a layer of zinc, which acts as a protective barrier against corrosion. The zinc coating provides physical protection and serves as a sacrificial anode, corroding in place of the steel. Galvanised steel, including galvanised iron (GI) sheets, is widely used in construction due to its enhanced durability and corrosion resistance.

• Paint coatings: using high-quality paints and primers designed for steel can provide a robust barrier against moisture and oxygen. Paint coatings are particularly effective when combined with galvanised or galvalume steel, offering an additional layer of protection while allowing for aesthetic customisation.

• Powder coating: this technique involves applying a dry powder to the steel surface and then curing it under heat to form a hard, protective layer. Powder coating is highly durable and resistant to chipping, scratching, and fading, making it ideal for steel structures exposed to harsh environmental conditions.

3. Regular maintenance and inspection

Regularly maintaining and inspecting steel structures are crucial for early corrosion detection and prompt intervention. Implementing a proactive maintenance programme can help extend the lifespan of steel structures:

• Routine inspections: regularly check for signs of corrosion, such as rust spots, discolouration, or blistering paint. Early detection allows for timely repairs and prevents further deterioration.

• Cleaning and surface preparation: keeping steel surfaces clean and free of dirt, debris, and contaminants can reduce the risk of corrosion. Regularly washing steel structures, particularly in areas prone to salt or chemical exposure, can help prevent corrosive elements from settling on the surface.

• Touch-up coatings: if you notice any areas where the protective coating has worn off or been damaged, apply touch-up coatings promptly to restore protection. This can prevent moisture and corrosive agents from penetrating the steel.

4. Material selection and design considerations

Beyond coatings and treatments, material selection and design play a vital role in preventing corrosion. Consider the following strategies when designing steel structures:

• Use of corrosion-resistant alloys: consider using corrosion-resistant alloys such as stainless steel or weathering steel in highly corrosive environments. These materials have been specially formulated to resist corrosion without additional coatings.

• Drainage design: ensure that the steel structure's design allows for proper water and other liquid drainage. Trapped moisture can accelerate corrosion, so designing with sloped surfaces and adequate drainage systems can help mitigate this risk.

• Avoiding dissimilar metals: galvanic corrosion can occur when different metals are used together. This type of corrosion happens when two dissimilar metals come into contact in an electrolyte, such as water. To prevent this, avoid using dissimilar metals or insulating materials to separate them.

Conclusion

Preventing corrosion in steel structures requires a combination of careful material selection, protective coatings, regular maintenance, and thoughtful design. By choosing materials like hot-rolled steel, PPGL, galvalume, and GP steel and applying the appropriate treatments, MSMEs can significantly reduce the risk of corrosion and ensure the longevity of their structures. Understanding the importance of corrosion prevention and investing in proper protection techniques will help maintain the integrity and performance of steel structures, ultimately leading to cost savings and enhanced durability over time. Regularly monitoring steel prices, including hot-rolled coil, sheet metal, and steel plate prices, can also help MSMEs make informed decisions and optimise their material investments.