welding flanges to pipe ends

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Hi guys,I tried to tig weld  a 1/2" flange to 1/16"thick  x 3"diameter  pipe for making an exhaust midpipe using 304 stainless steel.the problem is that i have the flange bended  and distorted from heat about 1/16"here is the setup:I used 100 amps because the flange was hard to get to temperature and melt.I welded at about 1" increments one at the oposite position at a time triyng  to heat  the flange symetricaly. I did not preheat anything. 308l filler rod 1/16 diameter.Can someone please help me?i am not a pro.it is my first tig weld in a situation like that and i do not know how to do it right.I apreciate any help.Thanks
Reply:Belt sander bud, you can set it flat And true the flange back upMiller bobcat 225g  - spoolmatic 1Mm250 - 30a spoolMiller spectrum 375Thermal arc 95 Everlast Ex 250As the boiler turns, these are the days of our lives
Reply:I do not have a belt sander. I have a 12" disk sander and tried to flaten one flange. It seems so difficult and time consuming. I wonder if there is a way to weld these without distort them...I have 3 more to weld and still searching if there is a correct way do do it with minimum distortion or with no distortion at allThanks.
Reply:Get a thicker copper plate (1/8"-1/4") and clamp to the flange, give that a try.Hobart EZ-Tig newbie.
Reply:Originally Posted by chimmikeGet a thicker copper plate (1/8"-1/4") and clamp to the flange, give that a try.
Reply:I keep some pieces of 1/2 inch copper for welding ss. See my build a box post. I used these copper pieces and got no warping at all. I will admit i was using 10 ga ss, not thin stuffMiller diversion 165Miller mig 211Hypertherm pm 30Milwaukee 6230 14 inch chop sawMd 45 mag drill (RIP; fell on its head)New MD 45! Thanks to the esposa!Finally got an O/A setup
Reply:Believe it or not, depending on the shape and type of the flange, the ears warping back can be a good thing. What does your flange look like?Welding/Fab Pics: www.UtahWeld.com
Reply:Yes the ears are slightly bent back!You are wright that this might help.I will try the heat sinking. Can i use aluminium plate instead of coper? What size the plate should be?Thanks for the support!
Reply:It seems odd that you are bending a flange that is half inch thick when the wall thickness on the pipe is only 1/16th.   Are you welding a fillet on the OD of the pipe?  A fillet larger than 1/8th is excessive and might be the reason for your distortion.   If you are having difficulty reaching into the corner consider a gas lense and increasing the stickout of the electode past the cup.
Reply:Weld the pipe to the inside of the flange. You can now wash the thinner tube into the flange. This is common in header building too.www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:i slide the pipe inside the flange hole in a way that the pipe protudes about 1/4" out of the flange so to push fit inside the  flange  of the next exhaust piece. there is only one filet weld at the OD of the tube at the side of the large piece of the tube and to at the end of the 1/4" section that protudes.i assume that if i position the lip of the tube at the center of the 1/2"flange and weld internaly will solve the warping problems since the heat will tend to lengthen the  part and not to bent it.i have already welded pieces that is welded OD only in one side of flange similiar the way i am trying to do  . how the welder did it?as final solution if i will not find a way to do it is to weld internaly at the center of the flange. is that enouth for an exaust aplication? if i add a second fillet at the outside?if only to tack the inside , then bolt a aluminum plate as a sink and complete the OD welding?thanks for your help!
Reply:If you're warping a 1/2" flange welding a 1/16" thick tube to it, you're putting way too much heat into the material.Either drop back on the amps or use the pulser (if available).  Smaller filler (say .045) is also in order.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by AchillesGri slide the pipe inside the flange hole in a way that the pipe protudes about 1/4" out of the flange so to push fit inside the  flange  of the next exhaust piece. there is only one filet weld at the OD of the tube at the side of the large piece of the tube and to at the end of the 1/4" section that protudes.
Reply:Post a picture of the flange of find one on google images. The warpage is probably going to help it seal better.Welding/Fab Pics: www.UtahWeld.com
Reply:you can set it flat And true the flange back up
Reply:If you have a few, make a jig out of heavy steel plate to bolt the flanges to.  If just a couple, you can clamp the flange to a heavy block of metal in as many places as your weld will permit, and then weld it and leave it until it cools...