Coating Systems Available for the Corrosion Protection of Structural Steel
It goes without saying that steel is one of the most robust materials available on the construction market today. But corrosion is a major threat to the longevity of unprotected steel. That's why the makers of construction-grade steel have invested in a number of surface protection systems to prevent corrosion of steel substrate, and thus significantly increase the lifespan of their products.
Discussed below are two of the most popular corrosion-protection systems available for construction-grade or structural steel products.
Protective Paint Coating Systems
Paint application is the most common method used to protect the surface of many construction materials from the elements. Its use in the corrosion-protection of structural steel, therefore, comes as no big surprise. There is an extensive range of paint products that can be used to protect structural steelwork from corrosion, and they can be applied to steel substrates using different methods. But every protective paint system must comprise three types of coats: the prime coat, the intermediate coat and the top coat.
The prime coat is the first layer of paint that is applied directly onto the surface of the steel substrate. Its primary purpose is to ensure that subsequent coats of paint adhere well. The intermediate coat (or coats) is simply applied to make the initial/prime coat thicker. As its name implies, the top coat is the final coat of paint applied onto the steel surface. It is also known as the finish coat. Apart from being the first line of defence against corrosive elements, it may also serve to make the steel products look aesthetically pleasing.
Protective Metallic Coating Systems
Basically, this involves the application of a metallic coating onto the surface of the steel. The metal material chosen to be used as coating for the steel substrate should offer superior corrosion-resistance than steel itself. The logic here is to coat steel with another metal, which is more effective at resisting corrosion. This process is referred to as galvanic protection and it can be applied in a number of ways, including hot-dip galvanising, sprayed metal coating, zinc electroplating and sherardising.
In many applications, structural steel is hot-dip galvanised using zinc as the coating material. This is because zinc coatings provide corrosion protection that can last for the entire lifespan of the steel structure.
As long as surface preparation has been done properly, a suitable product used and the application process performed correctly, both types of coating systems are effective at protecting structural steel from corrosion.