Which welding processes require shielding gas, and what gases are typical?

Which welding processes require shielding gas, and what gases are typical?

• A. MIG (GMAW) and TIG (GTAW) require shielding gas; typical gases: CO2 or Ar/CO2 mixtures for GMAW; pure Ar or Ar-He for GTAW.
• B. Only MIG requires shielding gas; typical gas: pure oxygen.
• C. TIG requires shielding gas; typical gas: nitrogen.
• D. Shielding gas is not used in any welding process.

Answer: (A)