Which of the following is NOT a method to start the arc in GTAW?

In Gas Tungsten Arc Welding (GTAW), there are several established methods for starting the arc, including scratch start, lift start, and high frequency start. Each of these methods is designed to initiate the welding process using the non-consumable tungsten electrode.

Scratch start involves physically scratching the tungsten electrode against the workpiece to create the arc. Lift start entails lifting the electrode slightly off the surface to create a separation that initiates the arc when the electrode is lowered back down. High frequency start uses high-frequency electrical signals to establish the arc without needing to make physical contact with the metal, which is particularly useful for preventing contamination of the electrode and ensuring a stable start.

Direct pulse start, on the other hand, is not a recognized method within GTAW for initiating an arc. While pulse technologies may be used during the welding process itself to control heat input and enhance bead characteristics, they are not a standalone method for starting the arc. Therefore, this choice does not pertain to standard practices for initiating the welding arc in GTAW.