Manual Keyhole Plasma Arc Welding with Application

Making complete-joint-penetration welds on pipes in the 5G fixed position requires the highest skills and concentration from welders. This paper introduces a sensing and control enhanced plasma arc welding (PAW) process as a proposed method to lower the requirements for welder skills and concentration, and to better ensure pipe weld quality. It uses the measurements of arc voltage in innovative ways to detect the weld penetration. As a result, variations in welder operation are compensated such that welders with little training may produce acceptable complete-joint-penetration pipe welds in the 5G fixed position. Welds made by novice welders on SS 316 have successfully passed all nondestructive and mechanical exams. The feasibility and effectiveness of the proposed method are thus verified.