Galvanized metal is a widely used material that gains significant benefits from the galvanization process. By adding a protective zinc coating, the metal gains extended durability, combining the strength and flexibility of steel with effective corrosion resistance. This results in a long-lasting, high-quality product that is both strong and resistant to rust.
Common Applications of Galvanized Steel
In everyday life, you can see galvanized steel almost everywhere, such as in roads, railways, energy plants, oil and gas facilities, agriculture, and sports and leisure areas. It is essential in buildings, bridges, the automotive industry, gates, balconies, and even sculptures.
Why is Zinc Used for Galvanization?
Zinc is commonly used for galvanization because of its excellent corrosion resistance. It acts as a sacrificial layer, preventing the underlying steel from rusting by reacting with oxygen and moisture before the steel can be affected. Zinc’s durability and natural ability to form a protective barrier make it ideal for extending the lifespan of steel products.
There are several methods for galvanizing steel, including:
Hot-Dip Galvanizing
Advantages: The method involves dipping steel into molten zinc to create a thick, corrosion-resistant layer. The coating can be as thick as 1.4 to 3.9 mils, providing excellent protection and lasting 20-50 years in typical environments. This makes it ideal for outdoor and harsh conditions.
Disadvantages: The thick coating is not suitable for smaller or precision parts due to its rough surface and bulkiness.
Electro-Galvanizing
Advantages: This method uses an electrical current to apply a thin layer of zinc. The coating is thin and smooth, making it ideal for products with high appearance requirements. It is also suitable for complex shapes or smaller parts and is more energy-efficient compared to Hot-Dip Galvanizing.
Disadvantages: The thin coating provides weaker corrosion resistance, making it better for indoor or dry environments. It also tends to be less uniform, especially on edges and corners.
Source:https://at-machining.com/galvanization-metal/
Cold Galvanizing / Zinc Rich Paint:
In this method, a zinc-rich paint is applied to the steel surface. It offers a convenient way to provide some protection but generally doesn’t last as long as other methods.
Welding Galvanized Steel
How to Prepare Galvanized Steel for Welding
Zinc is not harmful in its normal state, but during welding, the zinc coating melts and produces toxic fumes. For Hot-Dip Galvanized steel, the coating thickness ranges from 1.4 to 3.9 mils. This thicker coating can affect the quality of the weld, making penetration more challenging. So, it is important to remove the zinc coating before welding. You can remove the coating by grinding it off, but keep in mind that this creates zinc dust, which can also be harmful. Make sure to take proper safety measures.
After removing the coating, it is also important to clean the work area because any leftover dust or particles can react at high temperatures.
Source:https://weldguru.com/how-to-weld-galvanized-steel/
Hazards of Welding Galvanized Steel
Welding galvanized steel is a hazardous task, so you need to pay close attention to any changes in your body. If you experience a metallic taste in your mouth or symptoms like fever, shaking, chills, fatigue, muscle and joint aches, or headache (which may feel like the flu), you need immediate treatment and rest. These symptoms may indicate that you are suffering from metal fume fever.
Source:https://www.redsteelmh.com/
Safety Measures for Welding Galvanized Steel
To avoid health risks, after pre-treating the material, you also need to take further safety precautions. First, ensure you are working in a well-ventilated environment. Second, arm yourself with welding gloves, clothing, shoes, and eye protection to minimize skin contact. The UV and infrared rays from welding, as well as potential splatter of molten zinc and weld metal, can be harmful. Additionally, use proper respiratory protection and a fume extractor to reduce exposure to toxic fumes.
Source:https://blog.blackwoods.com.au/71-series-cored-wires
Welding Methods for Galvanized Steel
Now that you have completed the preparation, it’s time to weld. You can choose between MIG, TIG, or Stick welding. MIG welding is generally recommended for galvanized steel. Make sure to remove the zinc coating completely in the welding area. If the coating is not fully removed, it will produce a lot of spatter during welding, which can adhere to the metal surface and create an unsightly appearance, making further work difficult. Using argon-CO2 shielding gas is recommended, as it provides a stable arc, reduces spatter, and ensures better weld quality.
TIG welding is relatively complex because it can lead to contamination of the tungsten electrode, affecting weld quality. If any galvanization is left that wasn’t fully removed, it can cause popping at the tungsten.
To get the most out of MIG welding, using a high-performance welding torch can make a significant difference. The CNAWELD Tweco 350A MIG Welding Torch, available on our website, is an excellent choice for welding galvanized steel. Engineered with both durability and user comfort in mind, this torch ensures consistent performance for professional-grade results. Key benefits include:
- Robust Durability: Built with premium materials to handle the challenges of welding galvanized steel, even in heavy-duty applications.
- Ergonomic Design: The handle is designed for maximum comfort, reducing strain during prolonged use and improving precision.
- Stable Arc Performance: Optimized for use with argon-CO2 shielding gas, the torch minimizes spatter and ensures cleaner welds.
To explore more from the Tweco series and our wide range of other high-performance products, please visit our website. Discover the tools you need to take your welding projects to the next level.
Can You Re-Galvanize Steel? / Re-Galvanizing Considerations
After welding is completed, first clean the work area. Since the zinc coating was removed during preparation, the exposed metal has lost its rust resistance and durability. Therefore, it is important to re-galvanize the exposed metal.
Among the methods mentioned earlier, Hot-Dip Galvanizing is most suitable for large metal parts. The thick coating makes it less practical for smaller or precision components. For smaller commercial projects and individual use, Zinc Rich Paint or Electro-Galvanizing is more cost-effective and still maintains a long lifespan for the metal.
Conclusions
Welding galvanized steel requires careful preparation and a series of steps to ensure safety and quality. Here is a quick overview of the key steps:
Preparation: Remove the zinc coating from the welding area to prevent toxic fumes and spatter.
Safety Measures: Ensure good ventilation, wear protective gear, and use proper respiratory protection to minimize health risks.
Welding Method: Choose the appropriate welding method. MIG welding is generally recommended due to its simplicity and better results with galvanized steel.
Post-Welding: Clean the work area thoroughly and re-galvanize the exposed metal to restore corrosion resistance.
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