AWS Process to minimize distortion
AWS Process to minimize distortion
(OP)
I was wondering if anyone knows of an AWS (or similar) process specification to minimize distortion when welding stainless steel plate. We are assembling large vacuum chambers and need to control heat distortion that occurs during welding. We don't do the work in house but want to be able to provide as much assistance as possible to our vendors and to accurately specify what is reasonable to expect as an outcome from the assembly process.
Thanks
dsgn2mfg
Thanks
dsgn2mfg





RE: AWS Process to minimize distortion
What is the specific grade of stainless steel and wall thickness?
RE: AWS Process to minimize distortion
Usually we do structural GMAW stitch welds on the exterior and GTAW full length all around on the interior for vacuum seal. We then leak test the chambers with helium to requiring at least 2 x 10-8 atm-cc/sec.
A typical chamber will be a box 66" long, 60" wide and 12" tall. Construction will be to weld materials ground to 1.25" for top plates, 1.13" for end plates, .5" for side and bottom plates. Tops and bottoms will almost always have external carbons steel stiffeners. We almost always do post weld secondary machining on the end plates that requires flatnesses and parallelisms from end to end of .005".
RE: AWS Process to minimize distortion
I was not sure if I completely understood your fabrication sequence - it appeared to me that you are using external fillet, stitch welds to join the end pieces, and are using a continuous, seal weld (GTAW process) on the inside surface. Correct?
RE: AWS Process to minimize distortion
RE: AWS Process to minimize distortion
When possible the chambers are structurally welded first and this helps a lot, but so much heat is put into the chamber it seems to distort a fair amount. Between that and actively cooling them we rarely have a problem. [U]What I'm trying to do is write a welding specification and was hoping I could find some AWS standard the clearly outlines good practices. Similarly I am looking for the same thing for weld preparation, precleaning the parts prior to welding and post cleaning after.[u/]
RE: AWS Process to minimize distortion
Have you looked at specifying a continuous fillet weld on the outside of the T-joint versus a 4" stitch weld? Having a continue fillet on the outside surface along with the GTAW seal weld on the inside surface of the T-joints may do the trick to reduce distortion.
RE: AWS Process to minimize distortion
RE: AWS Process to minimize distortion