ASSESSMENT OF THE FEASIBILITY OF REPLACING GTAW WITH GMAW IN GAS PIPELINE WELDING

The welding procedures employed in the natural gas industry are predominantly based on arc welding processes, which often involve manual operations. In pursuit of higher productivity, this study proposed the qualification of a semi-automatic welding procedure characterized by high travel speeds and elevated deposition rates: Gas Metal Arc Welding (GMAW). Gas pipelines welded using a well-established process, Gas Tungsten Arc Welding (GTAW), were compared with pipelines welded using the proposed process, GMAW with inert shielding gas, in terms of execution time, deposition rate, and mechanical properties.The study sought to reproduce the welding procedure qualification tests on specimens extracted from the welded pipelines in order to develop a valid Welding Procedure Specification (WPS) and compare the results with both applicable code requirements and the performance of an already qualified GTAW procedure. The results demonstrated that the GMAW satisfactory mechanical performance, outperforming GTAW even in the destructive testing results. However, full validation of the welding procedure could not be achieved due to limitations associated with the qualification process, including welder qualification requirements, an insufficient number of approved test specimens relative to code requirements, and the execution of the tests in a laboratory lacking formal accreditation.