Galvanized steel is a type of steel that’s coated with zinc oxide to make it corrosion resistant. A manufacturer dips the steel into molten zinc and the two materials bond together to form a stronger, more durable steel. This process is known as hot-dip galvanizing. Galvanized steel is often used in modern steel frame buildings and structures commissioned in open environments. But even galvanized steel can become compromised if neglected for long periods. To maximise the lifespan of galvanized steel products, it is imperative that proper cleaning and maintenance be performed. Here is how to care for galvanized steel.
Cleaning galvanized steel
There are several ways to clean galvanized steel, especially when removing surface stains or marks. It is recommended that any cleaning approach towards galvanized steel should be mild at first. If the stains prove difficult to remove, then a steadily aggressive approach may be used. Another thing worth noting is that whenever mechanical abrasion (a.k.a scrubbing) is needed, a plastic-bristled brush should be used as using a steel brush may cause discolouration.
When cleaning contaminants such as dirt and debris, using ordinary laundry detergents will prove just fine. Larger areas covered with dirt can be cleaned with a low-pressure washer like a gurney gun and a cleaning agent such as a car wash shampoo. These types of cleaning agents are designed to minimise corrosion on the metallic parts of vehicles, making them perfect for cleaning galvanized steel.
Mild stains caused by liquids (water stains, beverages, and the like) can be safely removed by using ammonia-based cleaners. Ammonia cleaners leave a streak-free shine can tackle watermarks and stains with ease. Make sure to rinse the galvanized steel with fresh water afterwards.
In instances where rusty water drains from adjacent steelwork, it can leave a conspicuous brown stain on galvanized steel surfaces. To remove such stains, use a commercial oxalic acid mixed with equal parts water. This solution will safely remove brown rust stains on galvanised steel without damaging the alloy. Again, rinsing with fresh water is important to remove any corrosive residues left by the oxalic acid.
Often times galvanized steel can become covered with mortar during building or renovation projects which can be difficult to remove once it hardens. First, remove large-scale deposits as close to the steel surface as possible. The remaining vestiges can then be removed by using oxalic acid followed with a thorough rinsing. While other acids like muriatic acid can dissolve mortar more effectively, they can be very aggressive on galvanised steel and are not recommended for cleaning.
Fresh stains coming from paintwork or graffiti can easily be removed using paint thinner. If the paint has hardened, a stronger solvent such as paint strippers will suffice. If the paint is too thick and some form of scraping is necessary, use a plastic or wooden scraper to avoid damaging the surface. Like with other cleaning agents, rinsing is crucial to ensure no residues are left and discolouration is unlikely to occur afterwards.
Maintaining galvanized steel
While hot-dipped galvanized steel is stronger and more durable than its non-dipped counterpart, it’s not fully corrosion-proof. Fortunately, maintaining galvanized steel is relatively easy. Follow these practical tips for proper maintenance of galvanized steel.
- – Make sure the galvanized steel is set in an environment where the pH levels are below 6 and above 12. Outside this range, the galvanized is at greater risk of corrosion than normal.
- Do not let galvanized steel get in direct contact with dissimilar metals like copper and brass, especially in corrosive environments. If dissimilar metals need to be used along with galvanized steel, use an insulator between the two materials to limit corrosion.
- – Do not use abrasive methods when cleaning galvanized steel. Abrasive cleaning will remove the protective coating that shields the galvanized steel from corrosion.
- – Galvanized steel may be cleaned using water-based emulsifiers and alkaline-based cleaners that do not exceed a pH level of 12. It’s always worth consulting your galvanizer on which cleaning products are best for your galvanized steel products to avoid damaging them.
- – For galvanized steel that’s situated in a highly corrosive environment (i.e. coastal locations and heavy industrial applications), rinsing the product with potable water regularly is ideal. This is especially true if the galvanized steel is frequently exposed to the sun and rain.
- – Avoid storing galvanized steel in damp and poorly ventilated conditions. Make sure the storage area is well-ventilated to limit the risk of corrosion.
- – Any physical damage to the galvanizes steel should be addressed as soon as possible. It is highly recommended that the damaged product be repaired according to the AS/NZ 4680 standards.
Galvanized steel is renowned for its corrosion resistance characteristics. Its coating life and performance are highly reliable, especially when used in outdoor applications. That said, galvanized steel isn’t’ completely invincible to rust and its life expectancy will be significantly reduced if proper cleaning and maintenance aren’t in place. By following these tips, you can expect more out of your galvanized steel products and maintain their structural integrity for years to come.