Which method is commonly used to initiate the arc in GTAW?

• A. Touching the energized electrode to the work and quickly withdrawing it to desired length, which contaminates both electrode and work
• B. High frequency spark between the electrode and the work eliminates the need to touch the electrode to the work
• C. Use of a non-transferred pilot arc similar to that used in plasma arc cutting
• D. Striking the arc by applying a magnetic field to the electrode

Answer: (B)

In GTAW, starting the arc cleanly and quickly is achieved with a high-frequency electrical spark between the tungsten electrode and the workpiece. This high-frequency start ionizes the shielding gas and creates a conductive path so the arc can form without the electrode touching the metal. It protects the tungsten tip and the work from contamination, which is crucial for maintaining weld quality in GTAW where a clean, inert environment is essential. Touching the electrode to the work can introduce oxides and alloying elements into the tip and work, degrading weld quality. A non-transferred pilot arc is more typical in plasma cutting and isn’t the standard GTAW start, and using a magnetic field to strike the arc isn’t a valid method.