At what stage of the welding process is gas purging typically required?

Gas purging is typically required during the tacking and throughout the welding of the joint to ensure that the weld area is protected from contamination, which can occur due to atmospheric gases. In the gas tungsten arc welding (GTAW) process, shielding gas, usually argon, is used to create an inert atmosphere around the weld pool. This environment prevents oxidation and contamination of the molten metal, which is crucial for achieving high-quality welds.

By using gas purging during both tacking and the actual welding process, welders can maintain the integrity of the weld metal. This ensures proper fusion and minimizes the risk of defects such as porosity, which can compromise the strength and performance of the weld. Implementing gas purging effectively from the start of the welding operations enhances overall weld quality, making it a critical step in the welding process.