What shielding gas options are used for GTAW and how do gas flow rate and gas purity influence weld quality?

• A. Argon only; gas purity has no effect.
• B. Argon (and sometimes helium or argon-helium mixtures); typical flow is 5–10 cfh; high purity is not critical.
• C. Argon (and sometimes helium or argon-helium mixtures) with typical flow 15–25 cfh; high purity helps prevent porosity and oxidation; improper flow can cause porosity or arc instability.
• D. Oxygen is the primary shielding gas; purity matters.

Answer: (C)