Welding of stainless/duplex pipe spools

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Hi Question: A stainless steel/duplex pipe spool has been welded in accordance with the procedure.A post weld dimensional check is done and it is found to be slightly out of shape.Common industry practice is to warm on half of some of the butts in the spool which brings it into the correct shape.When stainless/duplex steel is heated to around 450 to 550 degrees C brittle intermetalic compounds are formed such as sigma phase etc.Does anyone know of a method of adjusting the geometry of a welded pipe spool without affecting the mechanical properties of the welds?CheersAlan
Reply:There is no simple, easy solution to your problem.  If you cut and re-weld, or heat and bend, you must solution anneal and quench the piece to restore the balance of austenite and ferrite in the HAZ and weld deposit.  The other problem is that the post weld heat treatment may very well introduce more distortion in the parts than you have already.If the spools are small then re-heat treating them might be an option, but I'd look for an expert in heat treatment, with prior experience to discuss the feasibility of doing this.In the end, it may be simpler to scrap the parts that are out of spec for finished dimensions.  Then create or buy some fixturing that does a better job of holding the pieces in place for welding.  Then make new spools.Either way, you're out of pocket a lot of money...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector