How to Weld Galvanized Steel

Step-by-Step Guide

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   Step 1: Understand the metal you are working with.

   Galvanized steel has a zinc coating or plating to protect it from corrosion.
   
   There are two basic types of galvanizing, and for welding purposes, some minor, but significant differences.
   
   These are:
   Electroplated galvanize has a (generally) thinner zinc coating, which will allow for a cleaner weld with less burn off and splatter.
   
   Hot dipped galvanized steel has a thicker plating, since the steel has actually been submerged in molten zinc.
   
   This coating will burn away during welding, but will leave a dirtier weld and weld area, and require slightly more amperage for sufficient penetration.
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   Step 2: Set up your welding machine.

   For most purposes, a 150 amp AC SMAW or arc welder will weld galvanized steel.
   
   You will need to set up the amperage according to the thickness of the metal and the diameter of your rods.
   
   A 1⁄8 inch (0.3 cm) 6011 rod will run about 90-110 amps, smaller rods, slightly lower amperages, larger rods, higher. , Assuming you are joining two pieces, fit the parts to be welded so there is a minimum gap.
   
   Grind a weld prep, or bevel on edges of metal over 1⁄4 inch (0.6 cm) thick to recieve the filler metal during the weld and to insure full penetration. , This is helpful in striking and maintaining a steady arc, but isn't critical if you are dealing with a thin galvanized coating and using appropriate rods.
   
   Still, since the galvanized coating will be burnt away during the weld anyway, there is no real harm in removing it prior to welding if it is practical. , For coated metal like galvanized steel, a 6011 rod will give good results without having to clean the weld joint.
   
   For high strength rods like E7018, you will find cleaning down to the steel very helpful, since these rods must either be used at high amperage or you will need to endure a lot of sticking as the combined slag and burnt zinc will cause this. , Using a fan or welding outdoors where there is a slight breeze will drift the combustion fumes away from you is a good idea.
   
   If you are welding in a confined space (never recommended in any circumstance), you may need a respirator capable of filtering out the particulates produced during welding. , Since galvanized steel behaves slightly differently from regular mild steel, it may take a little practice to get used to the larger, more plentiful sparks you will create while welding, and the slightly slower welding speed required to allow the zinc to burn out of your way. , Strike your arc, hold it in position to maintain a good arc flame, and move along the weld path sweeping the electrode slightly side to side to create a neat weld.  Make subsequent passes if you cannot fill the whole weld prep in a single pass, rather than overheating the metal trying to finish in a single pass. ,, This won't equal the corrosion resistance of the original galvanized coating, but it will help.
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   Step 3: Prepare the metal to be welded.

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   Step 4: Grind away the zinc coating at the site of the weld.

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   Step 5: Choose an appropriate rod.

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   Step 6: Make sure you have plenty of fresh air while welding.

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   Step 7: Trial weld a small piece of the same metal you are welding together to practice.

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   Step 8: Go ahead and weld your metal.

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   Step 9: Clean the slag and zinc oxide (a light grey to white powder residue along the weld) between each pass and after your are finished

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    Step 10: then grind the weld smooth

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    Step 11: if required.

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    Step 12: Coat the weld with a zinc rich primer after the metal has cooled and been cleaned.

Detailed Guide

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