CO2 welding is one of the variations of t he GMAW (Gas Met al Arc Welding) process which is now used for welding most structural and alloy steels. The operating principle & the equipment required are same as for GMAW. The CO2 welding system is basically very simple. A filler wire is continuously fed by a motor driven rolls to a welding gun where current is fed into it from a power source. The welding arc is struck between the workpiece and the tip of the wire which melts into the weld pool. The arc and weld pool are both shielded by CO2 gas flowing from the gun. The process is very versatile in that, by selection of the proper wire diameter and composition it can be used for welding of thin sheet as well as thick plates.EQUIPMENTThe CO2 welding unit consists of a power source, a wire feed unit, a torch assembly and control system.