American Welding Society Forum
Can any one tell me what is difference between Trailing,Backing and Shielding gas durinng welding process?
Hello nauman1489, I believe that "trailing" is generally given to the term where a trailing shield is used when using the GTAW process and most likely used for the welding of titanium, the trailing shield contains the shielding gas over the completed weld bead for a longer period of time than it would otherwise be shielded by the torch cup and allows the weld bead to cool below it's critical temperature before subjecting it to atmospheric exposure. "Backing" gas is the term to describe the application of a shielding gas to protect the other side of a welded joint while welding is taking place on the front side of the same joint, generally used when welding open-root pipe joints, but not always, and applied to a variety of materials, titanium, monel, inconel, stainless steels, chrome-moly, and a host of others, once again relative to the GTAW process and possibly a few others. "Shielding" gas would describe the application to a variety of processes where the function of the gas is to protect the weld pool from atmospheric contamination during the welding process and in many instances to aid in the heat transfer, more so or less, and weld penetration characteristics and profile of the applied weld. These definitions could certainly be expanded upon considerably, but I believe you have the general idea here. Best regards, aevald
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