Engineering Perfection in GTAW Welding: Taguchi-Optimized Root Height Reduction for SS316L Pipe Joints

This study presents a systematic optimization of GTAW welding parameters to achieve a pipe-to-pipe butt weld with a root height consistently below 2 mm when joining stainless steel 316L material, employing the Taguchi design of experiments. The input parameters considered include GTAW welding current, voltage, welding speed, and root gap configurations of 1 mm, 1.5 mm, and 2 mm. Welding was performed according to the Taguchi L-09 experimental design. All 9 welded samples were evaluated using liquid penetrant testing to detect surface-breaking defects such as porosity, laps, and cracks; X-ray radiography to identify internal defects; and profile radiography to assess erosion, corrosion, and root height. Among the nine welded plate samples, the optimal root height (less than 2 mm) was selected and further validated through the welding of a one-pipe sample. An additional macro examination was conducted to confirm the root height and assess the overall root weld integrity and quality.