Can Galvanization be Removed from Steel?

The galvanization of steel is a procedure where a film of zinc coating is applied to a metal’s surface to prevent corrosion or oxidation. Once the individual items have been galvanized, they may last for decades with minimal maintenance in comparison to other rust prevention methods.

The finished product is durable and long-lasting and, for best results, should be left unscathed. However, there are occasions where galvanized products need to be joined together through a heat-inducing process like welding or brazing, for example. But can galvanization be removed and is it safe to do so?

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Importance of Removing Galvanization before welding

As with all projects involving steel, the metal needs to be prepared before welding. With galvanized materials, the surface area to be welded needs to be brought back to the base metal. This means that the galvanizing zinc film needs to be removed. There are various methods for achieving this, however, it is important to note that the galvanization must be removed and there are two fundamental reasons why this must be done:

  1. Heating metals to melting point to join them together may produce chemical reactions within the metallic items. Welding zinc metal raises its core temperature allowing it to vaporise which produces toxic chemical fumes. These fumes may cause a condition called “Metal Fume Fever“ (MFF) which produces flu-like symptoms and may result in eye, nasal or lung damage.
  2. Zinc coatings may produce electrical currents which might interfere with the welding process and prevent a natural welding arc from forming. Additionally, once cooled within a welding joint, it may cause premature corrosion.


4 Ways to Remove Galvanization from Base Metal Steel

There are various ways to remove galvanizing film from base metals. The most cost-effective way is to soak the item in vinegar and then remove the film with a wire brush; however, this process is laborious and time-consuming. Here are four, more efficient ways to remove galvanizing from steel.

*Always wear appropriate personal protective equipment (PPE) while working*

  1. Hammer and Chisel: For smaller, domestic-type projects, these tools may be used to rid the metal of the zinc covering. Use the chisel to score the steel at the welding point, then, use the hammer to tap along the weld line. Finish off with the chisel to peel the film from the surface area.
  2. Angle Grinder: This method is one of the quickest and may be used for large or small welding surfaces. A thick zinc covering may require a mild grinding disk due to the film’s ability to clog disc flaps; however, a 40-grit flap disc should be sufficient to clear thinner films. Begin at a slow speed with medium pressure, increasing in both as you notice zinc flakes peeling off.
  3. Sandblasting: Another popular, but sometimes messy solution is to make use of abrasive blasting to clean the metal. Using high-speed abrasive particles through a nozzle attached to an air compressor is very effective, especially in tight working spaces. Modern advances in blasting have replaced sand with more effective aluminium oxide, crushed glass or garnet.
  4. Muriatic Acid: Is inexpensive and widely available, but extremely caustic. It is, however, very effective when used to remove galvanizing. Clean the surfaces with soap and water and bathe the pieces in the acidic solution in a well-ventilated area (preferably outside). When the liquid stops bubbling, the galvanizing has been removed. Neutralize the acid by bathing the items in a solution of baking soda, borax and water. The acid is extremely toxic and exposure or inhalation of it could lead to conditions similar to MFF.

Industry leader in galvanization, Armco Superlite, bare the SATAS mark for Hot Dipped Galvanized Steel. All our galvanized products are according to SANS 121/ISO 1461 specifications. We also hold the SATAS mark for the manufacture of W-Beam guardrail and all our guardrail is manufactured in accordance with SANS 1350. For a full inventory of Armco Superlite’s products and services, consult with us and arm yourself with Armco.

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