Precautions for Welding Galvanized Steel
Galvanization is a cost effective way to add to steel parts corrosion resistant properties. Galvanization of steel material involves a similar process to plating where the product is coated with zinc. Because galvanizing creates a coating on the metal, instead of actually bonding molecularly with the steel, this coating can be worn or burned off the metal with intense heat.
Welding Galvanized Steel
Welding of course involves a process of applying intense heat to metal, then adding to and bond together steel or other metal materials. In the case of galvanized steel the welding process also affects the galvanization of the material where the weld occurs. The zinc coating that covers the steel reacts to the heat and vaporizes, emitting fumes. These fumes can be toxic if prolonged and high levels of exposure exist. The condition created by the fumes is known as metal fume fever.
Limitations on Welding Galvanized Steel
Due to the health concerns related to fumes created when welding galvanized steel, metal part manufacturers prefer to limit weldments on galvanized materials. On parts that require welding and galvanizing a fabricator may choose to use raw steel (CRS or HRS) for manufacturing the part and perform a hot dip galvanize finishing process. This method of producing the part is significantly more expensive, but it eliminates the potential hazards of welding on a pre-galvanized part. Smaller weldments (under 4 inches) may be performed on a galvanized part in well ventilated areas.
Galvanized Steel and Welding Video -
For more information on welding galvanized material we suggest checking out our video on the subject in our Metal Manufacturing Video Series - Spot Welding / Resistance Welding and Arc Welding