While steel is undoubtedly one of the more popular construction materials, it’s not without its shortcomings. Steel is vulnerable to corroding. Here at Specialty Steel Treating, we’d like to offer some guidance on how to protect steel so it lasts as long as possible and looks its best for as long as possible to make the most of your investment.
Special anti-corrosion coatings are one of the best things you can use on steel to protect and preserve it. Not only are such coatings effective, they’re affordable as well. What makes them work is the coating creates a shield. This shield blocks the transfer of the electrochemical charges that cause corrosion in the first place. Besides paint coatings, there are also dry powder coatings. These adhere to the metal when steel is heated up. Examples of powders used in steel heat treating include urethane, epoxy, nylon and acrylic.
CONTROL THE ENVIRONMENT
Another step you can take to keep your steel from succumbing to corrosion is to keep the environment where you store steel well controlled. While you can always go so far as to control how much oxygen, sulfur and chlorine are in the air with water boilers, you should also protect your steel from saltwater and rain. If you have space, storing your metal inside is a great preventative strategy. If you do decide to use water boilers, it’s best to add softeners to the feed water to properly adjust the oxygen content, sulfur or chloride.
There are unique chemicals that can be applied to steel that inhibit corrosion. They block the chemical reaction that causes corrosion with a protective film. One example of the use of such inhibitors is the blue-green film on the Statue of Liberty. Note that it’s possible to modify such inhibitors so they’re more durable. If you do decide to use a modified inhibitor, make sure it won’t lock in water, dust or other common types of debris.
There are several types of plating, also known as metallic coatings. With mechanical plating, a metal powder is welded to a substrate metal with the help of a fluid solution. There’s also electroplating. This is when a metal film is spread over the steel in an electrolytic bath. This electrolytic bath is made up of metal salts and water. Electroless plating involves glazing steel with a coating metal through a chemical reaction. Finally, there’s hot dipping, which applies a protective sheen to steel through a molten bath.
Cathodic protection is a corrosion-blocking method that shifts the active sites on metal to passive sites. This method creates an opposing current that releases free electrons that block the process of corrosion. The two different processes of cathodic protection are impressed current protection, which is mainly used on ship hulls and buried pipelines, and sacrificial system, which involves the use of magnesium, aluminum, and zinc. Both work to prevent corrosion by blocking the activity of corrosive electrolytes.
Besides the above methods, we recommend you also pay close attention to the overall condition of your steel. Any crevices or cracks in the material are more likely to lead to an increased risk of your steel breaking down. Note that such cracks and crevices can be the result of time, flaws in manufacturing and the overall needs of the construction project. Be sure to thoroughly inspect steel before purchasing it, while you’re completing your project. You might want to conduct a follow-up afterward just to be on the safe side.
DON’T FORGET ABOUT CREVICE CORROSION AND STRESS CORROSION
Crevice corrosion is another common concern. To combat it, address any tight spaces there might be in your steel, such as under washers, screws and barnacles, and between joint hinges. The reason these spaces are so vulnerable to corrosion are they have a wide enough gap for fluids to collect underneath them, but that gap isn’t large enough to allow the fluid to drain once it’s collected. You can prevent corrosion by either improving circulation in the above areas. Another option is to close the gaps entirely.
As far as stress corrosion, load-bearing steel becomes fractured and cracked before it’s even reached its load limit. Corrosive ions might be present, which allow for the spread of small cracks. The best way to combat this particular type of corrosion is to make sure the steel you use has been properly tested for stress. It’s also worth noting that stress corrosion is made worse in higher temperatures and liquids that have dissolved chlorides.
If the steel is going to be exposed to water, it’s best to have it treated with a high-quality marine epoxy paint. Not only are you working to prevent corrosion, you also keep marine life from growing on the steel. You may not know it, but barnacles that latch onto steel can actually exacerbate corrosion.
Hopefully, this article gave you some insight on how to protect steel from corrosion.