Research on automatic welding system for oil and gas pipeline based on laser tracking technology

Abstract With the growing energy demand both domestically and internationally, significant progress has been made in the construction of long-distance oil and gas pipelines and the maintenance of in-service pipelines, which has simultaneously raised higher requirements for automatic welding equipment, process methods, and efficiency. In recent years, automatic welding equipment used for oil and gas pipeline welding has predominantly employed arc-tracking technology, which meets the requirements for fully automatic fill and cap welding in standard groove configurations with stable welding quality. However, in hot-work welding processes for in-service pipeline maintenance and emergency repairs, manual alignment and cutting result in irregular weld seams, leading to poor performance of automatic welding equipment and, consequently, reliance on manual welding, which is inefficient. To address this, a specialized automatic welding machine with a laser vision weld seam tracking system was designed for welding irregular weld seams in long-distance oil and gas pipelines. Research was conducted on its mechanical system, control system, welding system, and tracking process. The specialized machine primarily consists of a power supply box, control box, industrial computer, laser sensing system, and welding carriage. During welding, the laser sensor measures three-dimensional information such as the seam size and center offset in real time along the direction of the welding carriage movement and feeds it back to the controller through the communication system of the machine. The main control system receives the information and adjusts the welding torch’s movement and welding process parameters through internal tracking control algorithms. Welding experiments were conducted on X80 steel V-groove welds of long-distance oil and gas pipelines. The results show that the welding machine can accurately identify the weld seam width, center offset, and height offset, and adjust the welding torch actions and parameters accordingly, achieving fully automated adaptive tracking welding. The precision of single torch oscillation tracking during welding can reach 0.5 mm, and the welding quality is good, meeting the requirements for single-layer single-pass fill welding, and multi-pass welding of irregular pipeline weld seams.