Marking SS for TIG...

[Trip59]

So I'm about to start on a piece for a friend, going to practice a bit first on some scrap of the same size/material, but there are two welds I'm just not sure about.

This is for a cooling fitting, lower radiator hose goes on each end. I need to run a bead around, to replicate the flare on the original. Not a big deal, surface, no through penetration needed, just keeps the hose on, but it does need to be the same distance all the way around.

I thought about making a fixture for the torch and then rotating the piece on it's own fixture, but it seemed like a PITA for two welds. Started thinking about the best way to mark it so I could follow it visually, but was concerned about introducing anything into the weld area. What should I use to mark it, a nice scratch, soapstone, sharpie... something else? Or do you think it's not overkill to fixture it and rotate the piece and manipulate the filler under a fixed torch?

[Rambozo]

So I'm about to start on a piece for a friend, going to practice a bit first on some scrap of the same size/material, but there are two welds I'm just not sure about.

This is for a cooling fitting, lower radiator hose goes on each end. I need to run a bead around, to replicate the flare on the original. Not a big deal, surface, no through penetration needed, just keeps the hose on, but it does need to be the same distance all the way around.

I thought about making a fixture for the torch and then rotating the piece on it's own fixture, but it seemed like a PITA for two welds. Started thinking about the best way to mark it so I could follow it visually, but was concerned about introducing anything into the weld area. What should I use to mark it, a nice scratch, soapstone, sharpie... something else? Or do you think it's not overkill to fixture it and rotate the piece and manipulate the filler under a fixed torch?

Depending on how you can position it in a vise or on the bench, I usually just stack up a few pieces of wood to prop my torch hand on so I can hold a set distance. It's a quick and dirty way of getting a semi fixed torch height. I weld through sharpie marks all the time with no signs that is does anything on either steel, stainless or aluminum. I doubt I could reliably see a scribe mark anymore.

[Trip59]

Depending on how you can position it in a vise or on the bench, I usually just stack up a few pieces of wood to prop my torch hand on so I can hold a set distance. It's a quick and dirty way of getting a semi fixed torch height. I weld through sharpie marks all the time with no signs that is does anything on either steel, stainless or aluminum. I doubt I could reliably see a scribe mark anymore.

Appreciate it!

I was thinking of setting it up almost like a hand turned welding lathe, propping I can handle and just do it in a couple repositions.

I know what you mean about seeing, it's a lot harder to see than it was 13 years ago, going to try with my reading glasses next time, see if that helps, else I'll buy some cheaters.

I'll give the sharpie a try. I tried welding a straight line the other day and it was straight, but I missed my endpoint by 1/3 the distance, wound up drawing closer to me regardless of how I positioned.

[Paul Moir]

How thick is the metal roughly?

The bead takes the place of a hose barb? If it is and you need it relatively smooth, you could just lay the bead and then give it a "wash" with the torch, where you just run the torch over your bead to give it a fused-like finish. If it's getting machined into a barb then just put on lots of filler: it doesn't matter what it looks like as long as you don't undercut or miss something.

I use sharpies too. They seem to sort of disappear as you get close to them. If that's a problem, I would "scribe it" with an angle-grinder & cutting disk, Giving it a nice easy to see mark. Soapstone is kind of useless for stainless.

[Trip59]

Yup, but not a barb per se, we're talking about 2" diameter pipe, this is just the flared bump like you have on radiator bungs on cars. I don't have a bead roller, nor do I know anyone with one and a die that small, so I figure a 3/32 or so bead around the outside would do what I need.

If I could machine it, I would, but it's a bent pipe to begin with and my lathe doesn't swing 3' would be nice though

Good info on the sharpies, if you're saying it's not an issue, I'll run with it. Like I said, these aren't full penetration welds and the bead is less than critical, so all is well.

[Paul Moir]

Ha! Swinging a radiator, that would be something to see eh?

I think for what your doing it'll work no problem. No need to fixture it: just do a few short welds. Stainless is pretty easy, just only a little harder to do than steel. It insulates more so heat builds up in the weld area faster. It also expands more than stainless with heat. Those gang up on you and cause warping, and makes welding thin stuff a little difficult. Shouldn't be an issue with what you're doing though.

The only thing is if you penetrate to where the stainless gets to melting on the back side, ugly, nasty "popcorn" will form without a back purge (argon on the back side). If the wall thickness is over ~1/16" it shouldn't be a problem for someone with a little experience.

[Rambozo]

I did the same thing for some steel turbo plumbing with large tubes. The guy I was working with came up with a slick way to make them come out nice and even. We just took a piece of 1/8" filler rod and bent it into a ring that fit tight on the pipe, then welded it right where the rod met the open end of the pipe. With good control of the heat we were able to avoid breaking down the outer edge of the ring, so it came out great and was very consistent. Something else that just occurred to me, since your's is stainless, is that by welding from the edge like that you will have argon shielding flowing over both the inside and outside, so you won't need to backpurge, and will keep the corrosion resistance intact.