METHOD TO IMPROVE THE CHARACTERISTICS OF A ROOT PASS PIPE WELD

摘要

A method and a system for forming a root pass weld for a root pipe joint. A substantially periodic electric welding waveform is generated and a series of electric arc pulses are generated between an advancing welding electrode and a root pipe joint in response to the electric welding waveform. The electric welding waveform includes a base cycle having a background current phase providing a background current level, a peak current phase providing a peak current level, a tail-out current phase providing a decreasing tail-out current level, and at least one heat-increasing current pulse during the background current phase providing a heat-increasing current level being above the background current level.