Operational parameter fields in hyperbaric plasma keyhole welding of mild steel line pipe
- Univ. der Bundeswehr, Hamburg (Germany)
- Norsk Hydro A/S, Porsgrunn (Norway)
Based on recent work on orbital plasma keyhole welding of Duplex Stainless Steels and Low Carbon Martensitic 12--13% Cr-Steels, the capability of the plasma keyhole process for hyperbaric positional welding is explored. Based on respective nozzle geometry development, constant position welding of 100 mm OD 5 mm wall thickness St 35 pipe test pieces is carried out at constant welding speeds of 3mm/s at various constant currents and plasma Argon gas flow rates. As a result, the operational parameter fields are basically limited by lack of penetration (LOP) at too low gas flows and cutting (CT) together with dropping at too high gas flow rates. Based on present hyperbaric specifications for fabrication, limiting conditions for minimum root weld widths of 3mm and maximum root reinforcements of 2mm are established, for 11 and 41 bar as well as for the 3h, 6h and 12 h position. As common operating parameter sets for all positions, 135 A and 1.5 l/min plasma gas flow and 120 A and 1.8 l/min plasma gas flow are identified for 11 bar and 41 bar respectively.
- OSTI ID:
- 403605
- Report Number(s):
- CONF-9606279--; ISBN 0-7918-1492-0
- Country of Publication:
- United States
- Language:
- English
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