How might air be drawn into the shielding gas between the nozzle and the weld?

• A. The air can be drawn in under the nozzle if the torch is held at too sharp an angle to the metal.
• B. Air is drawn in if shielding gas flow is too high.
• C. Air is drawn in if the nozzle is worn.
• D. Air is drawn in when using a smaller nozzle.

Answer: (A)

The shielding gas must form a tight curtain around the weld to keep out ambient air. If the torch is held at too sharp an angle to the metal, the gas jet is deflected away from the weld and can stir and entrain air from below, drawing it under the nozzle into the shielding region. That intrusion of air contaminates the weld pool and increases porosity and oxidation.

While other issues like excessively high gas flow, a worn nozzle, or using a smaller nozzle can degrade shielding and visibility, they don’t create the direct, downward path for ambient air under the nozzle in the same way that an improper angle does.