[coldman]

Any tips on what gap to start with, amps, wire size etc would be very much appreciated.

[TamJeff]

Is this structural, or plumbing of some sort?

[Otto Nobedder]

Yeah, more information would be helpful. Last 1/2" I butt-welded was sch. 160 Stainless.

What material? What service? There must not be a WPS, or you wouldn't be asking.

I correct myself... Last 1/2" I welded was sch. 80 carbon socket weld in dry steam service.

Please tell us a little more about what you are doing.

Steve S

[coldman]

Hi guys, sorry I should have given more info. It will be pressure gas pipe, low carbon steel seamless. I want to work up a procedure for this spagetti pipe, I have not done any small bore stuff before and need to get going with it. Last night I tried a 60 degree single v-but, 1/32" land, 1/8" gap, 80amp on the pedal, 2-passes, 3/32 wire + tungsten. Result - not too pretty but sound weld. Over penetration, cap needs prettying up. Any advice to help me zero in would be great. Thanks.

[Otto Nobedder]

My gut reaction (personal preference, as we all tend to do it a little different), is to tighen the gap to 3/32 as well, to avoid overpenetration. Unless you need to backfeed the wire at some point, having a gap your wire can't fall through (after the tacks shrink the gap slightly) will help control over-penetration. I also prefer a 37.5* bevel, for a 75* vee, for improved visibility of the root in awkward positions, as well as a wider cap, which I find easier to control on small-bore pipe. I free-hand all small pipe, though, so if you walk the cup, the narrower vee might be the better choice for you.

I'd be comfortable with the other parameters you've set. (Though I usually set the machine much higher and only use part of the pedal... a habit from needing a thumb-wheel remote for some welds.)

Your mileage may vary...

Steve S

[coldman]

Thanks Steve,
I tried reducing gap, over-peno not as bad, I will try closing the gap a little more see to what that does.
Increased prep angle, cap is much prettier now.
Cheers.

[Otto Nobedder]

If a further reduction in gap isn't productive, consider more "land" for more heat-carry away from the root. Either, or a combination of both, may be the solution.

If you're building a procedure others will follow, you'll want to experiment with the limits anyway, so you're not forcing another welder with another style to follow one single set of parameters. A WPS is intended to give "ranges" that can achieve the desired result, so a welder qualifying on the procedure can adjust toward his "comfort zone", and hopefully pass the test. For example, some will prefer a 1/16" gap and land, with, perhaps, 1/16" wire for the root. In developing a procedure, once you find one combination that produces the desired result, you've got to work the variables to find the limits of what works.

If you're just developing a reliable procedure for yourself, throw all that long-winded stuff out the window...

(And you may already be familiar with all this. If so, forgive me for preaching to the choir, and let others read it.)

Steve S