sch.10 stainless pipe gaps

By Kix

Date 02-10-2009 16:25

1/8" gap, 1/8" wire, it's faster!

By js55

Date 02-10-2009 18:00

For Sch 10?

By pipehog (**)

Date 02-10-2009 18:30

3/32 wire 3/32 gap works good for me also but alot of guys i know use 5/32 gap for everything.

By Kix

Date 02-10-2009 19:24

Your 1/8" gap would end up being a 1/8" 3/32" filler combo anyway due to gap shrinkage.:-) 1/8" on your 1st 2 quarters and 3/32" on your last 2 quarters. 4" sched 10 pipe and below doesn't need a gap or filler rod at all.

By Kix

Date 02-10-2009 19:18

Yeah, for the bigger diameters. ;-) I know what you were thinking.

By mightymoe (**)

Date 02-11-2009 22:15

I've welded a bunch of 3" and 4" 304 sch 10 pipe. We just butt it tight and fuse the root, adding filler wire to any gaps from a poor fit.
It was all VT.

By scrappywelds (***)

Date 02-12-2009 02:19 Edited 02-12-2009 02:22

in the papermills where i broke out. 5/32" gap with 1/8" wire , backfeeding anywhere from 2" to 48" was the normal. 2" and under was 1/8" or 3/32" gap. stainless steel has a bad gap shrinkage. Always heard that fusing the root after prolonged heating and cooling cycles the root will crack. Don't know if it was true, but I have cut alot of old welds out with root cracks that the root bead was very tight (like fused). now that being said I do fuse my socket weld roots. Another point of stainless steel pipe on the fitting aspect when you do all your take-outs and calculations for pipe layout, don't take into count the gap size at all if you don't want to be short, atleast thet was allways my experience.

By mightymoe (**)

Date 02-12-2009 02:40

with a gap you know you're getting penetration.
How many passes do you run on sch 10?

By scrappywelds (***)

Date 02-12-2009 23:19

3 ROOT, FILL, AND CAP

By medicinehawk01 (**)

Date 02-12-2009 23:53

I usually have the pipe prepped the usual way, but with a slight land (1/16"-Max.) and then butt it together and fuse the root keeping a 1/16" rod handy incase there is a gap or it starts to open up any. On the root pass I would run 70-75 DCSP and minimize the occillation of thr tungsten. You have to really look at the puddle, you can see the the puddle "swirling" aand that generally means you are penetrating. You have to be moving quick enough to keep the heat from building up , yet slow enough to get penetration. Once your rooted, I turn the heat between 60- 68 amps.
I welded miles of pipe in them paper mills and I have really changed my technique from the early days of big gaps. It works for sure and may even be necessary, but I have welded 24"- schedule 10 (last summer)and it was in there. The interesting thing I like about minimal gaps is the you can get a really clean (sliver) root, IMO.
Be well,

Hawk

By Stringer (***)

Date 02-14-2009 05:22

Being kinda slow the last month or so I've spent my days running experiments with sanitary methods, and according the the forty something dollar pamphlet AWS calls D18.1:1999 the joint is prepared with no more bevel than 10% of wall thickness, so really it's a square face butted up tight. I've had great success with pulse and a positioner. No filler. Trick is to watch so carefully that the cap isn't above flush. If it is then there's LOP. If I try this in a fixed position I can't do it. It's the devil to follow the tiny crack, for one thing, and the pulse just gets in the way because you need to vary the heat as the joint gets hot. Usually I get undercut or concavity on the outside if I run hot enough to get a root. I've taken some 3/4 samples, shined 'em up and wear as a ring. People can't believe it's done on one pass and looks like friction welding. Of course, they've never seen orbital, either.

By js55

Date 02-16-2009 13:44

medicinehawk is right. You can see by puddle characteristics if you have penetration(the glassy swirl). Not unlike being able to see good fusion with consumable inserts by the collapse/rise of the puddle.
Travel speed is everything though. You need a good consistent motion and a consistent travel speed once you establish your pen.
I used to like grinding a flat spot on my gas lenses to help minimize aspiration and allow a little easier cup rocking. At least it worked for me. Others didn't like it.