<![CDATA[Stainless steel pipe joining in piping infrastructure demands strict mechanical integrity, where selecting Shielded Metal Arc Welding (SMAW) or Gas Tungsten Arc Welding (GTAW) directly dictates joint reliability. General Background Pipe joints serve critical functions in industrial transport systems, making welding method selection vital for structural stability. Specific Background SMAW offers practical adaptability for field operations, whereas GTAW provides refined control for clean root pass deposition on NPS 4 Inch Sch 80 pipes. Knowledge Gap Comparative evaluations assessing mechanical strength, surface defect formation, and heat-affected zone behavior across varied current levels remain underreported for thick-walled pipe configurations. Aims This study evaluates the tensile strength, bending performance, microhardness distribution, and structural morphology of pipe joints welded via SMAW and GTAW across current ranges of 90 to 150 Amperes. Results Tensile testing demonstrated that both methods satisfy ASME II A standards at 90 A reaching 581 N/mm², whereas SMAW displayed higher tensile resistance at 130 A. However, bending assessments revealed larger open surface defects in SMAW specimens at higher currents, accompanied by elevated hardness in the heat-affected zone due to higher heat input. Novelty This research delivers a dual-method empirical comparative baseline establishing current thresholds that balance tensile capability with defect suppression in pipe fabrication. Implications Selecting GTAW for root passes and controlling current levels reduces defect propensity, aiding welding engineers in optimizing process specifications for high-pressure fluid pipelines. Key Findings Highlights Both SMAW and GTAW joints fulfill ASME II A tensile standards at 90 A, reaching average strength values of 581 N/mm². Increasing welding current up to 150 A accelerates surface defect sizes in SMAW bending tests up to 11.24 mm. Higher heat input in SMAW produces elevated hardness across the heat-affected zone compared to GTAW joints. Keywords : SMAW, GTAW, Stainless Steel Pipe, Tensile Strength, Bending Test]]>
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