Welding Tips and Tricks

Putting together some parts for a commercial work boat. The material is 304 stainless. I am putting sch 40 stainless pipe 2.5 ID to the 1/4" stainless plate. I have 3/32 red tungsten and 3/32 308 filler wire. I am looking for a ball park amperage, these welding calculators are talking upwards of 200 amps. My machine max s out at 200 amps.

You won’t need that much, not by a long shot.

The “rule of thumb” of 1amp/0.001 is voided with Stainless and Aluminum. Stainless required much less, aluminum much more.

I use about 65-70% for stainless, but really dial it in once I get the torch and puddle running. Position, joint, application… all play a key part in amperage used.

If it's a tig fillet weld you're talking about and you want a decent single pass, 160amp will get you there. Use a big cup to stop greying out at those hi amps. You'll have a fast travel speed too.

Coldman wrote: ↑Sat Jan 22, 2022 2:40 am If it's a tig fillet weld you're talking about and you want a decent single pass, 160amp will get you there. Use a big cup to stop greying out at those hi amps. You'll have a fast travel speed too.

you sure?
6.4mm ??
my miller calc says over 250 amps for single pass.

edit: sch 40 stainless pipe 2.5 ID, ~5mm, calc says 175-225 amps for fillet weld.
still should be possible with 200 amp machine.

Have done so in the past. Also did it at 180amps which worked fast and well but the bead comes out grey. Personal preference I guess.

tweake wrote: ↑Sat Jan 22, 2022 3:57 am edit: sch 40 stainless pipe 2.5 ID, ~5mm, calc says 175-225 amps for fillet weld.
still should be possible with 200 amp machine.

It won’t take anything more than 175 amps. I have done plenty of Sch 40 stainless. A couple of things to bear in mind- is there a bevel on the end of the pipe where it joins? Sch 40 stainless has a wall thickness of about 0.203, and at 70-80% of the rule of thumb, you’re right in the wheelhouse of 160 amps.

Even though he has a 200 amp machine, duty cycle might be an issue, but I have never hit it with TIG welding because of all the stop-starts.

A #8 cup, especially if you can walk the cup. Otherwise, I’d be up at a #10-#12 and flowing argon at 25-30cfh.