Common shielding gases used for the GTAW process are:

• A. Argon
• B. Inert gases, such as argon
• C. Oxygen
• D. Nitrogen

Answer: (B)

Shielding gas selection for GTAW is about protecting the weld from the atmosphere with a gas that won’t react with the molten metal. The best answer reflects that GTAW typically uses inert shielding gases, with argon being the most common example. Inert gases like argon (and others such as helium in some cases) provide a stable arc and prevent oxidation and other reactive changes in the weld pool. Gases such as oxygen or nitrogen would react with the molten metal or introduce defects, so they are not standard shielding gases for GTAW. That’s why the option stating inert gases, such as argon, is the most correct choice.