Stainless 316 Railing

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We are Fabricating a SS316 handrail using 1-1/2" sch 40 pipe with a #4 finish.we seem to be having a major problem with distortion, that we only slightly had with the aluminum and steel railing that we have done (this is the first time doing SS railing).  We have a plywood "teepee" shaped bench setup for guys to weld on both sides of the table.  we are using angle screwed to the table to act as our jig, then clamping the pipe to the angle.  there are approx. 2 clamps per post, intermediate rail, and top rail between posts.  we are seeing distortion of the intermediate rail and top rail between the posts, as well as a curve to the entire piece (10'-20' long).  we are all scratching our heads and trying different things such as, doubling the amount of clamps, lowering amperage to lower heat input, skipping around the welds instead of a left to right sequence, with no success.  Our next trial is to weld one side with a lower amperage then the other side, and/or weld both sides with one amperage then flip it again and run over the welds again to try and draw it back. ANY suggestions anybody may have is greatly appreciated.We are Tig welding the joints using 98 amps (90 & 98 for the above trial), 1/16" Tungsten-2% ceriated, and 1/16" Radnor 308L Filler metal, DC negative current, 100% Argon flowing at 15cubicft/hr, and laying down an 1/8" weld joint.  Using welders: Miller Syncrowave 250, and Lincoln Squarewave 255.PLEASE HELP   -THANK YOU-
Reply:Stainless is very susceptible to distortion. I like to tack the work piece every few inches (or less depending on the size), one tack on one side then another tack on the other, then let it cool, then start running the beads. When SS gets hot, it starts bending like the golden arches!Last edited by MicroZone; 04-05-2007 at 10:29 AM.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:When clamping you really need to make sure it is clamped well.... as Micro says SS has a mind of its own. You may want to try doing as much tacking as you can from one side, flip the rail and weld it. When I say tack I mean several tacks that will hold. You could try to pre-bend the rail to compensate for the distortion as well._________________Chris
Reply:I think you are running a little to hot.bring it down to 80-85 amps and tacks lots and back step your welds.
Reply:After an almost mind numbing day I think we might have a plan of attack. #1, this alloy seems to have it's own set of rules it refuses to follow!! #2, after some experimentation, we have found that to overcome 'most' of the distortion we give each joint a good 'swat' with a dead-blow hammer while the joint is still hot. #3, after turning the rail around we started welding on the 'peak' of the joint at all connections. Then coming back to finish the sides. So far it seems promising! I'll try backing the amperage down to 80 to 85 in the morning and give it a try. I know at 90 amps. we are getting good fusion and a good finish to the welds. I'll keep you posted. Dave
Reply:Sorry folks, I forgot to introduce myself. My name is Dave and I am the lead welder in the shop that is doing the handrail project. I appreciate all your help and ideas! I started learning this 38 years ago and I keep learning each and every day!!
Reply:Originally Posted by deacon3j I started learning this 38 years ago and I keep learning each and every day!!
Reply:Thanks Chris
Reply:Originally Posted by deacon3jAfter an almost mind numbing day I think we might have a plan of attack. #1, this alloy seems to have it's own set of rules it refuses to follow!! #2, after some experimentation, we have found that to overcome 'most' of the distortion we give each joint a good 'swat' with a dead-blow hammer while the joint is still hot. #3, after turning the rail around we started welding on the 'peak' of the joint at all connections. Then coming back to finish the sides. So far it seems promising! I'll try backing the amperage down to 80 to 85 in the morning and give it a try. I know at 90 amps. we are getting good fusion and a good finish to the welds. I'll keep you posted. Dave
Reply:I am working on a bridge project with 10" 316 stainless pipe with 1/2" flanges welded at one end . I tried everything to try and stop the flanges from curling towards the large 3/8" bead I am laying down with the mig in spray arc mode.  The only thing I have come up with the stop the seemingly unstoppable shrinkage of the stainless was using it against itself by bolting two flanges together and making two progressive welds on both flanges so they pull against each other and thus cancelling each other out. Otherwise like you guys said beating the pieces silly will work two.  I have done a few stainless railings also . I think I remember heat forming the opposite side of the tubing to recreate the amount of heat you put at the fishmouth - or whatever type of joint your using. You would just take the tig and run a rapid heat line opposite of the weld . But then , you have to buff out the mar you just added to most likely the top of the handrail.   Goodluck
Reply:Here's what we tried and it seemed to help with the railing. All joints are fishmouthed to 15/32 depth. After making our 'normal' weld on one side of the rail, stess relieving with the hammer and getting it turned and reclamped, we started welding at the 'crown' of the joint. Did that for the whole length of the rail, then came back and finished the sides. After cooling, we unclamped the piece and it only moved about 1/4". My last dilemma is the free ends and controling them but, we are experimenting with them. Johnny Weld, are you welding inside and outside of the pipes? If you are, try doing the inside weld first, then bolt a standard IPS flange to it to act as a heat sink. Make your outside weld and leave til cool. Another trick we tried was to take a spray gun filled with very cold water, pattern adjusted to a tight cone, air and fluid wide open and shoot it til the part is cold.  No guarantee but it might be worth a try. Good luck to you too.
Reply:This thread is useless without pics.. Post pics of the problem and then we'll see......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I've done a couple of stainless railings but in 1.25"x0.065" and another in 5/8" solid bar. I would stress relieve the joints after with an oxy/acet torch and in extreme cases heat it red and bend it straight. Heat marks can be a bitch to buff out though. On mitered joints I did some test pieces and found the majic amount to compensate so the joint would cool to the desired angle. Sorry, no real majic tricks to share.Man invented metal, he can do whatever he wants with it.KMAC
Reply:Yes ,deacon3j, I am welding both sides . Only the inside is a 1/8 " tig . It doesn't affect the 3/8 weld at all. But  It all worked out great . thanks
Reply:An update folks. I tried to post a couple of pictures with no success. Sorry.  This has been a real challenge! I learned long ago that stainless has it's own set of rules that it doesn't bother to follow!! I've read all your responses here and in other forums that this has been posted to with great interest. I've taken all your suggestions to heart and tried to apply them to the project with limited success. What may work on 1 piece of railing may not work on the next.Here's what we have done.Cut our weld sizes down as far as we dare and still have good welds. !/8 being the norm.Clamped, clamped and clamped some more.Staggered the weld patterns.Stress relieved the joints with a dead blow hammer immediately after welding.Adjusted weld settings both up and down, changed filler wire diameter.Taken some old blacksmithing ideas and applied them, heat, quench and draw, PRAY.All with moderate success, some better than others! 308l filler wire was what our supplier recommended to us. I went to them with questions before we cut the first piece of pipe. They said the same as everyone else, good luck Dave. lol!! We ARE slowly winning the battle. Thanks everyone for your advice, Dave Jones