My friend is having trouble with 2205 stainless pipe welds

admin

The guy is a pretty good pipe welder but this is his first time with 2205...He is having problems with the (ROOT PASS) very inside edges not burning in.....any advice on weld gas, purge gas, and technique?   Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:knife edge land.  1/8" root opening.  1/8" TIG filler rod.  Clean every thing with a flapper on a straight grinder, then with acetone..  Seal the joint with aluminum purge tape.  purge until the volume inside the purge area has been flushed at least 7 times over.  (If purge volume is 1 cubic foot, then purge at 20 CFH for about 20 minutes to dilute and remove as much oxygen as possible)  If a purge O2 meter is available then purge to less than 100ppm of O2 inside the dam.  Use amperage between what you'd normally used for Mild steel and stainless steel.  (if you'd put the root in on stainless with 80 amps, and mild steel at 90 amps, then try the duplex at around 85 amps)  Your exact settings will depend on the material thickness and personal preference.Weld gas is 100% argon for TIG.  If the WPS permits the back purge can contain 1% - 2% Nitrogen with the balance being Argon.  The nitrogen helps with keeping the right microstructure and it also makes the puddle wet in a little easier.  But, this must be approved in the weld procedure qualification and welder qualification ahead of time.  No last minute substitutions to try and make it work...Last edited by A_DAB_will_do; 05-23-2014 at 01:05 PM.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Really can't walk the wire and pressure feed 2205. Try keyhole and dipping the rootSent from my SGH-M919 using TapatalkLong after the price is forgotten, the quality will remain.Both of my Poppy's 1954 Short Hoods -Third generation to weld with it and teaching a fourthSA 2## - Bought and sold more than I can remember or care to list, 8 in the shop right now
Reply:Get the weld procedure (from the 'office' or engineers) and follow it.To the "T".Clean.  Backpurge.  Weld.The specified purge gas(es) may or may not contain (or even be 100%, at least on the backpurge) nitrogen.  Follow the WPS.Purge gas may be spec'd as 100% N2.  Shield gas may be spec'd as 98-2 Ar-N2 for GTAW.  Watch the interpass temp (usual is keep it below 250C/482F MAX for 2205, generally cool to 150C/300F before next pass).  Heat input in the range of 0.5-2.5 kJ/mm.Follow the WPS.  The best laid schemes ... Gang oft agley ...