Patent ID: 8610031

Claim:
A method for pulse arc welding a root pass of a butt weld joint, comprising: providing first and second joint members with first and second facing edges tapered to form an included angle; positioning the first and second facing edges to define a channel; moving only a single electrode within the channel; applying current that passes between the single electrode and the first and second facing edges to form a complete root pass between the first and second facing edges from a single side of the first and second joint members, the root pass forming a weld bead along a bottom surface opposite the first and second facing edges, and being formed exclusively by the single electrode and between the first and second facing edges without a weld bead supporting medium; said current having a waveform comprising a constant background current level and fixed frequency current pulses, wherein a stable background current level is about 5 amps to about 40 amps, and the waveform is configured to produce a stable focused arc that penetrates a root pass area of the first and second facing edges.