Design of Overlay System in 2g Condition using Tig Welding Process for Pipes and Elbow

Abstract

In the manufacturing of pressure vessel, pipes and elbows, welding is primary process by which different parts are joined to each other. Mostly carbon steel material is used for manufacturing pipes and elbows. Pipes and elbows constantly comes in contact with water or other fluid or gases. Carbon steel is corrosive material so that it cannot be directly used. On the other hand stainless steel is non-corrosive material, so it is used for manufacturing. Stainless steel is more costly as compared to carbon steel. To overcome this situation overlay welding technique is developed. In overlay welding pipes or elbows made from carbon steel and thin layer of the stainless steel material is welded inside surface of the pipes and elbows. Weld productivity and quality directly depends on welding fixture. Present work discusses design of welding fixture for overlay welding. In overlay welding stainless steel or any non-corrosive material which is in the form of strip or wire is welded inside surface of the pipes or elbows. For overlay welding submerged arc welding or tungsten arc welding can be used. In the current work, it is required to design a new setup in order to easy set-up and increase productivity for overlay welding using TIG technique. Overlay welding setup is designed for pipe diameter ranging from 75 mm to 1270 mm and pipe length up to 1500 mm including run in/out. In the first stage of design various proposed solutions or conceptual design are discussed considering different parameters like rotation of work piece or rotation of welding torch, space utilization, welding facility. From different proposed design, one which gives better performance is selected for overlay welding and the same is designed. The designed machine have six degree of freedom from which ve is motorised and one is manual. Because of the rotation of the torch assembly it can overlay conical pipe also. Y-2 axis has 1000 mm stroke so it can overlay conical pipe up to 1000 mm height. Workpiece can be rotated by rotating table and it has capacity of ten tonne.