GB649888A - Improvements in or relating to electric arc welding - Google Patents

Abstract

649,888. Uniting by fusion. BABCOCK & WILCOX, Ltd. Oct. 14, 1948, No. 26722. Convention date, Oct. 17, 1947. [Class 83 (iv)] In a method of electric arc welding, a stream of inert gas of relatively low arc voltage characteristics, i.e. one requiring a relatively low voltage to start and maintain an arc, is directed about the arc and a stream of gas of relatively high arc voltage characteristics is directed around the first gas stream. A tube blank 10 of stainless steel normally filled with hydrogen is moved relatively to a welding head having a tungsten electrode 11 mounted in a vertically adjustable holder 13 and a nozzle 15 which terminates in a tip 20 provided with a discharge annular port 21 slightly above the level of the arcing end of the electrode 11. Inert gas, e.g. helium, supplied to a conduit 27 flows through passages 24 in a barrel 23 and, when this is adjusted to abut the washer 29, through slots 26. It is discharged from the port 26 about the arc. A manifold 31 is adjustably mounted about the nozzle 15 and has an annular discharge port 30 through which flows a gas of relatively high are voltage characteristics, e.g. hydrogen, supplied through a conduit 40 to embrace the first gas stream. Liquid cooling means 45 are provided about the welding head. The inner and outer gas streams may be helium or argon and hydrogen or argon and helium.