Gas-Press Welding

a welding process in which the metal is heated with gas flames and the hot parts are then upset (pressed together). The heating is done with multiple-flame welding torches consisting of a large number (up to 100 or more) of small flames uniformly distributed over the heated surface which, after a minute or two, becomes partially molten. Next the parts are pressed together and united. Usually acetylene-oxygen flames are employed for heating, and a hydraulic clamping mechanism, which firmly holds the parts to be joined, upsets them. Gas-press welding is used to produce, for instance, butt joints in pipes as well as railway rails. Resistance electric-arc welding is often used in its place.