ORBITAL WELDING OF CORROSION RESISTANT MATERIALS FOR BIOPROCESS PIPING APPLICATIONS
- The use of AL-6XN superaustenitic stainless steel has seen an increase in the pharmaceutical and food industries during the past few years
- In applications requiring superior corrosion resistance to that of 316L stainless steel.
- Molybdenum segregation occurs during the welding of AL-6XN reducing its corrosion resistance unless filler overalloyed in molybdenum is added to the molten weld pool.
- Wire is typically used as filler, but this paper examined the feasibility of using a C-22 insert ring high in molybdenum in conjunction with orbital welding equipment designed for autogenous welding to weld AL-6XN.
- Critical pitting temperatures (CPTs) determined by ASTM G-48 showed that autogenous orbital welds of AL-6XN had higher CPTs, and thus better corrosion resistance, than manual GTA welds without filler
- Autogenous orbital welds done with a C-22 insert ring had higher CPTs than manual GTA welds with filler.
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