Welding galvanized pipe is possible but includes safety concerns due to the toxic fumes released as the zinc coating burns. Sanding away the coating is necessary to reduce the safety hazards and produce a higher-quality joint.
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Can You Weld Galvanized Metal?
You can weld galvanized metal using the same process used for welding ungalvanized materials. The main issue is the coating.
Galvanizing is a process used to apply a protective coating to iron or steel. It’s made from zinc and helps prevent rust. Galvanized pipe is a common choice for situations where metal is exposed to moisture, such as:
- Car assemblies
- Bicycle frames
- Chain link fences
- Garden staples
- Balconies and ladders
- Nuts, bolts, and nails
The zinc coating protects the underlying metal from exposure to acid rain and moisture. It’s typically added using a hot-dipping process. The metal is dipped in molten zinc at a temperature of about 842 degrees Fahrenheit.
The zinc coating limits the weldability of the material. It also increases the risk of exposure to zinc and lead oxide fumes.
Types of Welding Suitable for Galvanized Metal
After removing the zinc coating, you can use a wide range of welding methods to weld galvanized steel. Potential options include:
- Metal inert gas (MIG) welding
- Tungsten inert gas (TIG) welding
- Shielded metal arc welding (SMAW)
Arc welding is preferred due to its higher temperature and shielding gases. The shielding gases help create a barrier between the galvanized metal and the surrounding atmosphere.
An oxy-acetylene torch produces a maximum temperature of 6,300 degrees Fahrenheit at the hottest point in the flame. Arc welders can reach temperatures of 10,000 degrees Fahrenheit.
Common arc welding methods include MIG, TIG, and stick welding. MIG welding involves the use of a filler wire that doubles as the electrode. The wire is continuously fed through the welding gun.
MIG welding is the preferred welding method when working on large pieces of galvanized steel or when you don’t need to worry about making precise, clean lines.
TIG welding is used when you require greater precision or need to fuse thin sheets of galvanized metal. The electrode doesn’t melt. You hold a filler rod, similar to using an oxy-acetylene torch to weld.
Stick welding is preferred when you need to weld overhead or outdoors, as you don’t need to use a separate shielding gas. Shielded metal arc welding (SMAW) involves using a filler rod containing flux.
The flux is intended to improve the accuracy and quality of your welds. It shields the work materials from the outside atmosphere.
How to Weld Galvanized Pipe
The method used for welding galvanized pipe depends on whether you use arc welding or torch welding. Welding galvanized pipe with an arc welding machine typically requires the following steps:
- Prepare the metal
- Select the right filler/electrode
- Clamp your workpieces
- Choose the welding machine settings
- Turn on the shielding gases
- Turn on the welding machine
- Initiate the electrical arc
The first step is to prepare the metal. You need to remove the zinc coating before welding.
You may also need to cut one or more pieces of metal pipe to ensure a good fit, especially when dealing with plumbing.
Pipe cutters provide the cleanest cut. You can also use a hacksaw but may need to file the end with a metal file to smooth out the rough areas.
You’ll also need the right filler/electrode. Companies don’t make electrodes specifically for galvanized materials. The typical recommendation is to use an electrode intended for welding steel.
You need to secure the galvanized pipe before welding. A clamp is the easiest option when welding a new pipe to existing piping.
You’ll also need to attach the ground clamp to your workpieces to ground the metal when using arc welding. The ground clamp completes the circuit for the electrical arc.
Choose the right settings on your welding machine. You need to choose the amperage when using an arc welding machine. MIG welding also requires you to set the wire feed speed.
MIG welding and TIG welding require the use of shielding gases. The shielding gases are turned on before starting the electrical arc. After turning on the welding machine, you can touch the electrode to the pipe and start welding.
Create a small joint on two sides of the pipe to secure it before working your way around the entire circumference of the outside of the pipe.
Torch welding involves separate steps. You use a filler rod that you hold in one hand and a torch in the other. The flame should be a neutral flame, as an oxidizing flame makes the weld more porous and brittle.
Preparing Galvanized Metal for Welding
Removing the zinc coating is important when preparing galvanized metal for welding. You can use sandpaper, an angle grinder, or a chemical bath to remove the zinc coating.
Using an angle grinder offers the fastest results. Before using the angle grinder, you’ll need to secure the workpiece in a clamp or vice.
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Wear a respirator before grinding away the zinc coating. You want to avoid inhaling any of the zinc residues.
Use sandpaper after the angle grinder to help remove smaller areas of zinc coating that remain around corners and edges. You may also need to use a wire brush to get around the nooks and crannies.
Soaking galvanized metal in vinegar is another method for removing the zinc coating. This works best on smaller materials, such as galvanized nails and bolts.
Soak the materials in vinegar for at least an hour. You should notice that bubbles and lumps of zinc coating start appearing on the surface of the liquid.
Remove the pieces from the vinegar. Rinse the pieces under cool water while scraping the surface with a wire brush. The remaining zinc coating should break away easily enough.
Whether you use an angle grinder, sandpaper, or vinegar, rinse the material in alcohol afterwards to remove any remaining debris.
Safety Hazards When Welding Galvanized Metal
Here are some of the potential safety hazards when welding galvanized metal:
- Inhalation of toxic fumes
- Electrical shock
- Eye damage
Exposure to zinc oxide fumes can result in an illness called metal fume fever. Symptoms of this illness include:
- Muscle aches
The symptoms may pass after 6 to 24 hours. High levels of exposure can leave a metallic taste in your mouth. However, the symptoms should pass without long-term effects.
The greater threat is exposure to lead fumes. Zinc coatings contain varying amounts of lead. Lead exposure can cause irreversible harm, including weakness and permanent kidney or brain damage.
Shielding gases help protect against the inhalation of zinc and lead fumes when welding galvanized metal. A respirator designed specifically for welding can also help protect your lungs from harmful fumes. Yet, good air ventilation is also required to prevent gases from building up.
Working outdoors may not be an option in all situations. If possible, work in an area with good ventilation, such as a garage with the door open.
Arc welding also adds the risk of electrical shock, eye damage, and burns. These hazards can be minimized by wearing proper personal protective equipment (PPE).
Welding galvanized steel requires a welding machine. You may also need the following equipment, depending on the type of welding that you plan to use:
- Shielding gases
- Angle grinder
- Wire brush
- Personal protective equipment
- Fume extractor/fans
A filler metal or consumable electrode is needed for arc welding and torch welding. The filler metal typically melts at a lower temperature compared to the base materials.
You’ll also need shielding gases when using MIG welding. You can use a filler rod covered in flux or a flux-cored filler rod for other welding methods. The flux can replace the need for shielding gas.
Sandpaper, an angle grinder, and a wire brush are used to remove the zinc coating. Alcohol is used to rinse the metal and remove any remaining impurities.
Use welding clamps to secure your pieces. Don’t use plastic clamps. The high temperatures used to melt metal can melt plastic faster and release more toxic fumes.
Personal protective equipment is required to shield against burns, cuts, eye damage, and toxic fumes. You’ll need a welding mask, apron, gloves, and respirator.
A fume extractor is recommended when welding galvanized materials or working in an enclosed area. The extractor is essentially a heavy-duty fan that sucks up the fumes from the welding process. Use several fans or weld outdoors if a fume extractor isn’t available.
Welding galvanized metal requires the removal of the galvanized coating. Galvanized metal contains a coating of zinc, which can produce toxic fumes when burnt.
Zinc oxide fumes can cause fever-like symptoms. However, galvanized coatings can also release lead oxide fumes, which pose a greater threat.
Using personal protective equipment, such as a respirator and a fume extractor or fans, can help minimize the presence of harmful fumes.
Try to remove as much of the coating as possible before welding. Start with an angle grinder before switching to sandpaper. You can also soak smaller items, such as nuts and bolts, in vinegar.