Walking the cup

Date 04-23-2007 16:44

Lawrence,
Not sure what you mean by chatter (other than maybe the 'stickiness' you get ont he steel when it gets hot), but gas lense collet bodies for 20's can give you some pretty jumbo cups. When doing fills I always preferred using cups large enough to slide on the bevel edge, more like rotating the cup as opposed to walkin it. 4's an 6's seem awful small to me. I leave actual walking it to the caps when you have some room to move.
If the chatter is sidewall stickiness then sometimes sanding (or even buffing herd)the cups has helped me.

By welder5354 (**)

Date 04-23-2007 23:02

Hi Lawrence, thanks for the info on the 455STT, so i'll see if i can return the favour.
I teach a lot on walking the cup at our facility. First start with using the sch. 80 pipe until you get better control on walking the cup. Practice walking the cup first in the 5g position before u move to other positions. We will be using ER70S-2 or 3 (1/8 C.S.). For the first pass use a number 7-9 cup (if the cup is too small u will get porosity). We also use air cooled torches because we can buy them in flex, which is a lot better for walking the cup. A foot pedal is preferred, but not essential. High frequency is a plus, especially on exotic metals.
We also use gas lenses for all our welding (the smaller gas lense for root passes and maybe pass 2 & 3; then we switch to the larger gas lense>>>3/4 " (19mm).
Set up your coupon, just so that the 1/8 rod doesn't fall inside the pipe (4 tacks). Now in the 5g, position the rod in the root of the joint (a little pressure on the rod [no dipping]; move the torch from side to side using the wrist and don't go too far up the sidewall. Use about 130-150 amps. Make sure your bevel and the top of your bevel has no burrs because u need a smooth sidewall to move your torch side to side and forward.
Try this first and let me know how u r making out before going on to the cap.
DH

By Lawrence (*****)

Date 04-23-2007 23:24

DH,
Thanks, I really do appreciate the tips... My pipe welding days were in the 80's and most of that was schedule 5. I had a very sweaty and humbling day today.

I will strap on the gas lens tomorrow.

Now for fill passes is it preferable to split the beads or use one large walking weave?.

My root gap was closer to 1/16 so I will widen that with a 3/32 spacer on the next run.

Thanks again...

By welder5354 (**)

Date 04-24-2007 02:01

Lawrence, 3/32 gap will not be enought. The proper gap should be 1/8" which in metric is 3.2mm, so i prefer 3mm. 3/32 gap will only give you 2.4mm, which will cause lack of pen.
Don't split the beads until it is necessary. So that depends on your bevel landing. I prefer a bevel landing of between 30-34 deg. I know the morm is 37.5, but this will mean less filler in the joint. Usually after the 3rd filler you may have to split the beads or u can do it all the way with singlr passes, but that depends on the welder. But the cap pass will be one pass, using the larger gas lense.
On the cap pass use you arm more so than your wrist to walk the cup. Try rolling the cup side to side on the cap and at the same time you must progress forward slowly. It will take time and practice for this type of challenge, have fun.
DH

By js55

Date 04-24-2007 13:34

I've found that a tight gap is a little more critical with S-2 than S-6 which wets better. A 1/8 gap is preferrable with a 1/8 rod as the gap will close a bit allowing the rod to rest upon the bevel edges which should be feathered to a knife edge. As confidence and ability are gained the feather edge isn't necessary but still preferrable. And gap is less critical with feather edges than with landings, and less critical with CS and low alloys than with viscous high alloys.
Imagine where the feather edge is underneath your arc and point the arc right at the edge. If you watch someone weld from the inside the puddle will swirl and the hottest point will be the whitest. Its this swirl and whitest point that will break down the edge.
Pointing the arc right at the edge will also ensure your root is wider than the gap enough to make visual inspection easier.

By Kix

Date 04-24-2007 14:28

Yeah i agree with the knife edge cause that is a must. You should use the same rod size as your gap usually starting out with an 1/8" cause thats the easiest to learn on. You should weld your pipe in opposite quarters to help on the closing of the gap witch you will have regardless. As the gap closes go to a smaller rod. You will usually only end up haveing to go to a 3/32 rod, but that depends on how good of tacks you put in and how you weld it.