What is the purpose of the time during which gas flows to clear air from the nozzle or surrounding the weld zone?

The purpose of the time during which gas flows to clear air from the nozzle or the surrounding weld zone is known as preflow. This stage is crucial in Gas Tungsten Arc Welding (GTAW) because it ensures that the area where the welding will occur is shielded from atmospheric contamination. By allowing inert shielding gas, such as argon, to flow before the arc is initiated, preflow helps to eliminate any air that may be present in the weld area. This is essential for protecting the molten weld pool from oxidation and other reactions that could compromise the integrity of the weld.

Preflow significantly enhances the quality of the weld by creating a stable environment prior to beginning the welding process. This protective gas layer minimizes the introduction of harmful elements, ensuring that the weld achieves the desired characteristics of strength and appearance. The proper use of preflow time is fundamental to successful GTAW operations.