2" stainless pipe weld test 6g

by jared
(evadale, texas, usa)

i recently took a weld test on 2" sch 40 stainless pipe in the 6g position and failed. i haven't done a lot of stainless welding. i used 3/32 tungsten and tig wire.

i was told i had a lot of undercut in the weld which is why i failed. i need help on any tips to pass this test. what amperage should i use? i was welding on 50 amps. should i turn it up after the feather edge is melted away with the root pass?

the fixture used to hold the pipe is a piece of angle iron, what is the best way to make sure i have a uniform gap? thanks



yes you should probably increase the amperage after the root pass. probably to around 65 for the second pass and up to around 70-80 for the rest.

to get a uniform gap, you can use 1/8 wire and pull it out after the first tack and then eyeball it to make sure it stays even.
you may even want to leave the wire spacers in until after the second tack is done 180 degrees from the first tack weld.

i usually make some spacers out of weld wire and just grind the sides flat so that after tacking , i can just turn the spacer a little and it pulls right out.
it will be hard to get the wire out .

if your undercut was on the cover pass try using a tighter arc and really watching the edge of the bead as you go to make sure it fills.

make sure and let the pipe cool between passes.
getting in a hurry is what kills most stainless welding tests.

good luck,


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Sep 21, 2015
3" sch 80 NEW
by: Anonymous

hi I'm due to take a 6g test ,could anyone give my some advice on what to set the gap at amps for root weld & size of wire thanks.

Jul 10, 2010
tig welding stainless
by: Anonymous

I understand a little of your situation.
1.3/32'' tung is good on sch 10 s.s. pipe up to 20''
2.Your i.d. root condition is commonly reffered to as suck back.
3. In regard to your particular malady heat and speed are your friends. Do you walk the cup if not you should start to train yourself in this.
What I believe is occuring is that you are going too slow staying in one area too long and that is why you are getting this problem turn your amperage up reduce your gap to 3/32''max.remember wide gap makes you want to use less heat and widens what is your filler metal area. Not a good thing, increases other chances for issues.good luck from eric

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