What is Hot-Dip Galvanizing?
Hot-dip galvanizing, is the process of dipping fabricated steel into a kettle of molten zinc. While the steel is in the kettle, the iron metallurgically reacts with the molten zinc to form a tightly-bonded alloy coating that provides superior corrosion protection to the steel. Hot-dip Galvanizing can easily provides up to 150 years of rust-protection in areas where there are few harsh and corroding elements. In areas where high aggressive corrosion elements exists, galvanized steel may last from 50 and up to 100 years with little or no maintenance. Hot-Dip Galvanizing's low life-cycle and initial application costs means that it is the smartest and preferred choice of corrosion protection for fabricated steel.
There are four steps of Hot-Dip Galvanizing. At LRP Glvanizing, we call this the "Simply Four" process. The "Simply Four" process consists of Preparation, Cleaning, Dipping, and Inspection.
Step 1: Preparation
When your products arrive at our facility, they are inspected for drainage, venting, as well as other designs requirements to ensure that they meet our requirement standards. After the requirement inspection, the product is then ready for the cleaning process.
Step 2: Cleaning/Surface Preparation
There are three 'Cleaning' stages to prepare the material for Hot-Dip Galvanizing:
- Degreasing: In Degreasing, the material is completely submerged into a hot alkali solution to remove any organic compounds such as dirt, paint, oil, etc from the product. The product is then rinsed with water to prepare it for the next cleaning stage.
- Pickling: In this step, the material is completely immersed in the acid tank filled with hydrochloric acid to remove oxides and scale. Once all oxidation has been removed from the material, it is dipped in a water tank and rinsed and sent to the final stage of the cleaning process.
- Fluxing: The purpose of the fluxing is to clean the steel of all oxidation that was developed at the pickling stage. Fluxing also creates a protective coating to prevent the steel from oxidizing before taking a zinc bath.
Step 3: Hot Dip Galvanizing
Now that the material is completely free of contaminants and oxides that might interfere with iron and liquid zinc bonding, it is ready for Hot-Dip Galvanizing. In this step, the product is dipped into the galvanizing kettle and remain in the kettle until it reached the bath temperature (approx. 450° Celsius) to form a proper coating. The Hot-Dip Galvanizing process usually takes less than ten minutes depending on the thickness of the steel.
Step 4: Quality Inspection
To ensure satisfaction, all final products must go through a thorough Quality Inspection before they are sent back to the clients. There are three stages of Quality Inspection at LRP Galvanizing:
- Visibility Inspection: To ensure the appearance of the final product meet our standards. The final product should appear shiny, smooth, and clean from dirt-like elements such as dross and black nodes. Removal of zinc drips or icicles is also done at this stage by carefully grinding them off.
- Layer Thickness Inspection: In this stage, coating thickness is measured to make sure that it meets the minimum coating requirements for each individual product.
- Layer Firmness Inspection: Coating quality is tested by carefully knocking certain suspected areas with small hammer to ensure that the coating is strong and does not peel easily.
What can we offer you:
- 24-hour turnaround service on request
- ISO 9001 quality approved
- Technical & Design Advice
- Collection & delivery Service*
- Double Dip: up to 29m
- Vertical Dip: up to 3.2m
*Collection and delivery service fuel surcharge is applicable. Please contact us for more details.
Designing for Galvanizing
Galvanizing process should be considered at the design stage. Some parts may need additional venting or drainage points and post-galvanizing procedure is neccessary for products with internal tread. We offer free advice and guidance to ensure you receive the best quality galvanizing.