The single filler wires used most commonly have diameters in the range 3.2–4.8 mm; smaller wires are prone to cause random arc wander, particularly with the relatively long electrical stick-outs that are used, and larger diameter wires are more difficult to feed. welding processes
- Although it is possible to use standard fluxes, special flux formulations with improved slag release characteristics have been devised for narrow-gap SAW.
- The power used is DC electrode positive or AC; AC gives greater resistance to magnetic arc blow and square wave AC power supplies have also been used to improve control of the process.
Increased productivity and improved process control may be achieved by applying the techniques normally applied to conventional submerged arc welding to the narrow-gap process, i.e.:
- extended stick-out;
- twin wire;
- hot wire;
- metal powder addition;
- flux-cored consumables
These techniques are not widely used at present although some development work has been reported.
- The standard NGSAW process has been in use in many commercial applications since the early 1980s.
- Some of these are summarized in Table above; they range from nuclear reactor containment vessels in 600 mm thick Ni/Cr/Mo alloy steels to the welding of 60 mm material for offshore tubular.
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