Identifying the influence of orbital pipe welding parameters on mechanical properties using SS316L pipe

Abstract

Pipeline systems play a pivotal role across various industries, serving as the lifelines for transporting materials like oil, water, and gas. Among the welding techniques, orbital pipe welding, particularly Gas Tungsten Arc Welding (GTAW) without filler metal, is the fitting method for joining these critical piping systems. This study examined orbital pipe welding on SS316L pipes with a 114-mm outer diameter and 3-mm thickness. The main goal was to evaluate the weld's tensile strength and microhardness carefully. Constant current and three welding speeds – 1.3, 1.4, and 1.5 mm/s – achieved this goal. In addition, welding experiments covered 0°, 90°, 180°, and 270° pipe positions. First, the necessary tools and test objects were prepared, and then the test materials were welded. The final phase was testing tensile strength and microhardness. This investigation used a 5G-specific prototype orbital pipe welding equipment. The 5G method requires horizontal welding with the vertical pipe axis. The study used ASTM E-8M-compliant standardized test material for precise and repeatable tensile strength measurements. This standardization ensured outcomes reliability. One of the significant findings was that 1.4 mm/s welding at the 270° pipe position with 110A current produced the maximum tensile strength. This shows that these conditions are best for welding SS316L-type stainless steel pipes with an outside diameter of 114 mm and a thickness of 3 mm. Strangely, microhardness testing showed that horizontal distribution welding quality decreased at 1.4 mm/s. This implies that further experimentation may be needed to fine-tune the welding parameters to optimize the process and achieve superior microhardness values.