Some of the tips for maintaining and ca ring for hot-dip galvanized products are.
- Do not expose your galvanized steel product to environments where pH is below 6 and above 12 for long hours. Outside pH 6-12 range, the galvanized coating is open to quick corrosion.
- Do not roughly clean your galvanized product and try avoiding rough washing of your galvanized product altogether. Galvanizing protects the steel from corrosion by developing a thin barrier film of insoluble zinc corrosion products (known as patina) on outer surface of galvanized steel through exposure to atmosphere. Frictional cleaning removes protective patina and galvanized articles have to build this barrier protection again which leads to consuming more zinc. Constant irritational cleaning will consume zinc more quickly and reduce the life of the product.
- Galvanizing should be cleaned by using alkaline-based cleaners with pH of 12 or lower, water-based emulsifiers or organic solvents. The area should be rinsed with fresh water and wiped clean with a soft cloth.
- Avoid direct contact of galvanized steel products with dissimilar metals, like copper and brass, in corrosive environments. In case of dissimilar metals being used together make sure that there is an insulator between dissimilar metal and galvanized products.
- If a galvanizing product is situated in a highly corrosive environment like heavy, coastal, industrial, etc the product should be rinsed with potable water regularly under sheltered conditions.
- Do not store a galvanized product for a long time in a damp and poorly ventilated condition. The storage location should be dry with effective ventilation.
- In case of physical damage to the galvanized coating of the product, the damaged area should be repaired in accordance with AS/NZS 4680.
Cleaning Galvanized Steel
While building or renovation, cement and mortar can be dropped on galvanized steel which is very difficult to remove once hardened. Remove large parts of deposit as close to surface as practicable, after that oxalic acid can be used to remove all the remnants from galvanized steel which should be followed with rinsing. Other acids are effective on mortar or cement, but they are very aggressive on zinc and are not recommended.
Paints, like graffiti, should be removed by thinners. If scraping is required, you can use plastic or wooden scrapers. In case the paint is wet or fresh, normal thinners can be used. Once the paint gets hardened, a non-alkaline stripper can be used. Rinsing is important to remove residues that cause discoloration later or encourage corrosion.
Mild stains can be removed by using common household ammonia cleaners and being sure to rinse the galvanized article with fresh water afterward.
Water draining of other adjacent steelwork which is rusting can flow on galvanized steel and cause brown stain. It can be treated by using commercial oxalic acid or proprietary solution which is generally used for descaling pots and pans. Rinsing with water is important to remove corrosive residues of cleaner.
In order to generally clean bulk contaminants like dirt and dust ordinary laundry soaps can be used. For stubborn or large areas, the use of low-pressure wash in collaboration with cleaning materials like car or truck wash or pure water are effective. Truck and car cleaners minimize corrosion on vehicles metallic parts and are suitable for use on galvanized steel. It is important that the steel is washed down with fresh water after cleaning.