Abstract
The use of Plasma welding technique (PAW process) together with a tailored equipment facing the process new demands proves that structural welds on thick-walled pipes is possible, by joining two or more sections of centrispun tube
materials.
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Front side of Keyhole Bead |
Front side of Powder Finishing Bead |
Plasma Arc Welding technique, in keyhole mode, assures a complete root penetration in the first
pass (convex root surface) with high quality from both the production demand and the control of structural characteristics of the joint.
The groove finishing by Powder Plasma Arc Welding (PPAW), performed in single pass after the first in keyhole mode (melt-throu), represents the most innovative and attractive aspect of this
technique, gaining a perfect near-net shape bead at face of weld, thus leaving the two joint beads (face and root of weld ) in the as-welded state.
The paper briefly describes the PAW and PPAW technique, the main characteristics of the welding equipment, the operative variable control and optimization and their influence on the welded joint shape ratio
Keywords
Plasma arc welding; keyhole; butt joint; groove; joint penetration; complete joint penetration; backing; root opening ; shape ratio; stringer bead; weave bead; heat-affected zone
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