Effect of Welding Voltages on Weldment Zones in Oil and Gas Transportation Steel Pipelines

Pipeline failure in weldment zones is a major concern in the oil and gas sectors, as it can have disastrous effects on the economy and surrounding environment. The intention of this study was to evaluate the mechanical properties of the weldment zone, with welding voltage as the key factor for joining pipes. The steel pipeline was collected at the Petroleum Product Marketing Company (PPMC) Center in Mosimi Sagamu and welded at weld voltages of 130 volts, 140 volts, 150 volts, 160 volts, and 170 volts using gauge 10 low hydrogen electrodes. The steel pipe sample, which was 5 mm thick, with external and internal diameters of 168 and 158 mm was sectioned and prepared as a single V-butt joint with an angle of 60°. The weldment zones were subjected to tensile and hardness tests, and microstructural analysis of the grains was performed using a metallographic microscope. The outcomes indicated that the elongation of the joints was significantly affected by welding voltage. Higher voltages result in higher ductility, strength, and fracture resistance, indicating greater strength and resistance to abrasion and wear. Microstructural analysis of the grain structures at different voltages revealed an increase in ferrite structures with increasing voltage. An increase in the welding voltage resulted in higher fracture point values, suggesting greater ductility and strength.