Why is purge gas important during aluminum GTAW welding, and what purge method is recommended?

• A. Purging speeds up welding.
• B. Purging removes oxygen from behind the weld to prevent oxide formation; use cup purge or long purge lines, maintain adequate gas flow, and pre-purge/post-purge as required by joint geometry.
• C. Purging adds extra filler metal.
• D. Purging changes shielding gas color.

Answer: (B)