Multiple arc welding device and method

Abstract

Apparatus and method for welding girth joints in pipelines and similar structures, of the general type described and claimed in U.S. Pat. No. 3,806,694, is improved by adding to the normal or conventional head, on its frame, a second or supplemental welding head with its own independent wire electrode, electric power and shielding gas supply. The second head is mounted on an adjustable support for accommodating work pieces of different radius or for varying arc positions. Oscillating means for spreading the molten metal across the width of the joint, as normally provided for the single welding head in the patent mentioned, are adapted to operate the second head as well and to vary its amplitude of movement. Separate means are provided for adjusting the spacing between each head and the work and also for lateral adjustment to align the heads with the plane of the joint. By these means, the number of stations required for a multiple pass operation, on thick wall pipe, for example, may be reduced. By operating two welding heads on each of two or more carriages, welding equipment requirements may be cut nearly in half, with beneficial effects on the weld, due to improved thermal effects. Either head may precede the other; cantilever means provide stability for the head mounted most remotely from the frame.