Process for welding
AssigneeTri Tool Inc.
InventorDale A. Flood
Life of this patent
Estimating the term…
Abstract
A welding process for non-stainless steel workpieces using GTAW equipment and hydrogen containing shield gas on a first root pass is improved by using a shield gas delivery system comprising hoses or conduits made of elastomeric material having a moisture permeability coefficient of less that 275, preferably less than 100, and using a tungsten electrode composition comprising at least tungsten and lanthanum oxide, and preferably tungsten, lanthanum oxide, yttrium oxide and zirconium oxide. Preventing moisture permeation through the elastomeric hoses delivering hydrogen containing shield gas eliminates expulsion of fused weld metal during second pass filler welding over the root pass weld. Electrode life is enhanced using the tungsten compounds.
Claims16
In a process of buttwelding non-stainless steel metal workpieces having bevel joint preparations using GTAW welder using filler wire including:
- preparing the beveled workpieces with bevel joint areas having minimal land thicknesses at their root extremities;
- placing the prepared workpiece joint sections together with an open gap defining an open root area 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 with a root pass weld using a GTAW welder supplied with filler wire and a shield gas including 1 to 10% hydrogen and the balance inert gas;
- and then
- overlaying the root pass weld with at least one additional filler weld pass using a GTAW welder supplied with filler wire and hydrogen-free shield gas, the improvement wherein
- said open root pass is carried out in the substantial absence of moisture in the area undergoing welding using a shield gas delivery elastomer hose having a moisture permeability coefficient of 0 to 275.
In a process of buttwelding non-stainless steel workpieces having bevel joint preparations using a GTAW welder using filler wire including:
- preparing the beveled workpieces with bevel joint areas having minimal land thicknesses at their 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 with a root pass weld using a GTAW welder supplied with filler wire and a shield gas including 1 to 10% hydrogen and the balance inert gas;
- and then
- overlaying the root pass weld with at least one additional filler weld pass using a GTAW welder supplied with filler wire and hydrogen-free shield gas, the improvement comprising:
- using as a welding electrode a composition comprising by weight:
- Tungsten
- 98.5%
- La2O3
- 1.3 +/− 0.1%
- Y2O3
- 0.1%
- ZrO2
- 0.1%.
In a process of buttwelding non-stainless steel metal workpieces having bevel joint preparations using a GTAW welder using filler wire including:
- preparing the beveled workpieces with bevel joint areas having minimal land thicknesses at their 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 with a root pass weld using a GTAW welder supplied with filler wire and a shield gas including 1 to 10% hydrogen and the balance inert gas;
- and then
- overlaying the root pass weld with at least one additional filler weld pass using a GTAW welder supplied with filler wire and hydrogen-free shield gas,
- the improvement comprising:
- using as a welding electrode a composition comprising 98.5% tungsten and 1.5% lanthanum oxide.
Dependencies are inferred from the claim text.