ELECTRO GAS WELDING
This process is an extension of MIG I MAG welding, designed for single pass vertical welding of steel plates in the thickness range of 10 to 38 mm. The two plates are held vertically with a gap of 12 mm regardless of plate thickness. The wire electrode is introduced downwards into the cavity formed by two plates to be joined and two movable water-cooled copper chill blocks. The cavity is kept free of air by the shielding gas usually a mixture of argon and CO2. Wire diameter may vary from 1.6 mm to 2.4 mm. The welding head is suspended from elevator mechanism, which provides automatic control of vertical travel speed during welding. The welding head is automatically raised as the molten metal is building up. The welding is completely automatic. This technique is used in shipyards and in fabrication of storage tanks and large diameter pipes. Two such indigenous machine have been developed in WRI and they are used in BHEL, Bhopal & Haridwar for fabrication of structure by welding in the vertical direction.