METHOD OF WELDING

摘要

PURPOSE: A method is provided to execute the root pass welding on the opening root shape of the adjacent workpieces(12), and to weld by using a gas tungsten arc welding between the intermediation for the workpieces thick wall and the parts. CONSTITUTION: A process for buttwelding metal workpieces (12) having beveled joint preparations using an automatic GTAW welder (20) using filler wire (32) includes preparing the beveled workpieces (12) with beveled joint areas having minimal land thickness at the root extremities; placing the prepared workpiece joint sections together with an open gap between their adjacent root extremities, the gap having a minimum dimension that avoids harmful compression stress between the workpieces due to weld shrinkage and a maximum dimension that avoids filler wire penetration of the gap; fusion welding the open root area of the adjacent workpieces (12) with a root pass weld using an automatic GTAW welder (20) supplied with filler wire (32) and a shield gas including 1 to 10 % hydrogen and the balance inert gas; and then promptly overlaying the root pass weld with at least one additional filler weld pass using an automatic GTAW welder (20) supplied with filler wire (32) and hydrogen free shield gas