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-
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Thread: Stainless 316 Handrail
04-05-2007, 08:16 AM #1JettIndFab Guest
Stainless 316 Handrail
04-05-2007, 11:33 AM #2Junior Member
- Join Date
- Apr 2007
- Moore Ok
I second this, I'm having the same with the same material same filler. I am welding with a synchro 250. I've clamped it skip welded welded a little at a time and it is still distorted, it's driving me to distraction, can anyone help?
04-05-2007, 03:42 PM #3
hotter and faster, welding slower heats up the piece more, aswell as welding a small bead and letting it cool, then welding another, will create more distortion as each weld bead you put down is doing a little bit of pulling, then the next one is pulling a little bit more....etc
you could also try putting in a reverse bend, ie clamp it with a bow in the opposite direction of the distortion, aswell as keeping the piece clamped untill it finished coolingmm210
04-06-2007, 09:35 PM #4
My experience is that each weld has the ability to pull X amount. So i sequence the welds so that they counteract each other.
Like Phax said weld faster. Where ever you are getting the distortion is most likely where you are welding first, so at that position I would just put a small tack using a little filler as I could. Then go the that positions mirror and do the same the more you lock it down with tacks the better off you'll be.
04-06-2007, 10:19 PM #5
I third the above advice! Hot and Fast. Running lower amps and going slower just loads the metal up with heat and causes more problems.
Also, Stainless Steel tends pull more than mild steel or aluminum, a lot more. Try to sequence your welds so the distortions counteract each other...
04-07-2007, 12:41 AM #6Junior Member
- Join Date
- Apr 2007
- Moore Ok
Thanks for the help guys, I welded faster and tacked it good, it really helped stop the distortion.
04-07-2007, 08:18 AM #7
All the above is good advice. Glad to hear it is helping. Sometimes things will just warp no matter what you do & need to be straightened after it cools, especially stainless. If your doing a lot of the same parts then it pays to fixture it or prebend it to compensate but just for a few pieces it is usually faster straightening it afterwards.MM250
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04-15-2007, 01:15 PM #8
Hot and fast is right. But to prevent the distortion you will have to overbend the top rail in the opposite direction. A strongback will minimize but not prevent. I am in the stainless steel railwork business, mostly boats, and I designed a jig using a large c-clamp and welding plate and angle together. The clamp has a single piece of angle welded to the adjustable threads on the c-clamp which touches the top of the handrail just above the weld.Two other pieces of angle grabbed the rail underneath on each side of the weld. The more you tightened the clamp, the more you would over bend the top rail. After welding and cooling, the clamp was released and the overbent tube would spring back to straight. You could even use this after welding to remove any other bent pieces. I do not have pictures so you will have to use your own inginuity with the info given. Good luck.