APPLICATIONS OF CO2 WELDING
CO2 welding is extremely useful for joining thin sheets of thickness range 1.0 to 2.0 mm because it is possible to keep the heat input low to avoid excessive melting and yet ensure adequate fusion. This is achieved by selecting a combination of wire diameter, current and arc voltage which allows the use of a stable short circuiting arc. Butt, lap and fillet joints can be made successfully in all positions. Butt welds can be made with or without backing. For unbaked joints up to 1.2 mm thick, close butted joints are preferred. For thicker sheets from 1.2 to 3.0 mm, a root gap of 0 to 1 mm is preferred depending on position and sheet thickness.The CO2 free flight or open arc welding with a deposition rate of 4 to 7 kg / hr is well suited for welding of steel plates of thickness 6 mm or greater. Horizontal & vertical fillets up to 6 mm leg length can be made in one pass and square butt welds in plate upto 6 mm can be welded with one pass either side. For single or double sided welds of 6 mm thickness and upwards a suitable joint preparation is recommended. CO2 welding is also extensively used for welding of wide range of pipe sizes and applications such as process pipe work and oil / gas pipelines.