pipe welding

[Jorville]

I am not a TIG welder but have been around a lot of it and worked as a fitter for TIG welders on SS and other special alloys. In my younger pipefitter days I was a certified ASME pressure piping and pressure vessel welder using both O/A and manual arc. We never saw any advantage to TIG welding mild steel. For production work it is too slow. Up to 4" schd 80 pipe O/A was a one pass weld and arc it was 3 passes for butt welds. I could run circles around arc welders using O/A on pipe up to 4". Socket weld fittings were a PIA with O/A. Over 4" it can be done but it is too hot for me and was a 2 pass job. There were times though when we did O/A on large pipe when it was not feasible to set up for arc on a couple joints. One time I was required to O/A 6 and 8" vertical runs every 10' for 4 stories in position; all horizontal welds which are the hardest position to control the puddle, especially with a #6 Victor short bend tip. To each his own. Glad that is long behind me.

Ron

Tractor SeaBee, I am a little to a lot rusty on O/A welding. But I did make a hydraulic tank out of sheet metal and O/A welded the corner joints. I never bothered to leak test the tank because I was satisfied with the weld I put in. This manifold I want to build will have a lot of smaller pipe fittings welded to it also. I want to tig weld it all. I think I can do it with a little re-fresher welding.

 

[Tractor Seabee]

Tractor SeaBee, I am a little to a lot rusty on O/A welding. But I did make a hydraulic tank out of sheet metal and O/A welded the corner joints. I never bothered to leak test the tank because I was satisfied with the weld I put in. This manifold I want to build will have a lot of smaller pipe fittings welded to it also. I want to tig weld it all. I think I can do it with a little re-fresher welding.

Jorville, sounds like time is not an issue but you just want to do it for the pleasure. That is an honorable endeavor. In the past I believe most steel tigging I saw was done with CO2 shield gas. Key to success is getting that root pass in full penetration and solid weld metal well fused, especially for high pressure use. No fun in grinding out a leak spot and redoing; so, have fun!

Ron

 

[joefromga]

No tig should be done with c02. Pure argon only. Some heavy aluminum can be argon helium mix.

 

[nybirdman]

Thanks for the tips nybirdman, I know I am rusty at this. Most of my Tig experience is on aluminum. I figure on doing some refresher welding on 3/16" flat bar beveled and open root before I start this. Four of my joints will be 1-1/2" pipe. Many years ago I gas welded pipe and that all looked good. Changing the heat source to something that won"t spit once in awhile should be a big plus.
Where I worked we had a crew come in and weld maybe 1-1/2 " stainless pipe maybe schedule 20 for a 1200 PSI line. That welder did not gap the pipe. It was a tight butt weld with argon purge. I asked him how he got 100% penetration and he said he watched for a fish eye. Could I ask a dumb question, and say what is a fish eye. Or is it too hard to explain?

If you have your heat set right;the puddle will look like a swirling mass of molten metal(like a fish eye),had to describe.Maybe 1/8" in diameter.
On schedule 20 stainless they probably butt tight and fused the first pass and did a second with stainless filler,of course purged.
I worked in a new brewery for 14 months Tigging schedule 5&10;one pass only and no filler rod.Joint looked like a pencil line(I could see then!)
I found TIG aluminum much harder than stainless or mild steel.

 

[chuck172]

If you have your heat set right;the puddle will look like a swirling mass of molten metal(like a fish eye),had to describe.Maybe 1/8" in diameter.
On schedule 20 stainless they probably butt tight and fused the first pass and did a second with stainless filler,of course purged.
I worked in a new brewery for 14 months Tigging schedule 5&10;one pass only and no filler rod.Joint looked like a pencil line(I could see then!)
I found TIG aluminum much harder than stainless or mild steel.

I think what your seeing in beer welding is a swirling piece of contamination. I think it's tungsten. It looks like your seeing the eye of a hurricane. The slower you go, the more you penetrate, the faster the swirl. It is very hard to describe.

 

[chuck172]

Jorville, many phases of pipe welding are complicated. Takes much practice, years. It's tough to get the answers your looking for on a tractor forum.

 

[Tractor Seabee]

No tig should be done with c02. Pure argon only. Some heavy aluminum can be argon helium mix.

I screwed up the sentence structure; sorry. I meant to say "CO2 as shield for mild steel. Yes Argon with some minor other mixed in rare gases for some materials is the normal shield gas and purge gas. I could be very wrong on the CO2 as it has been 30 years from the trade. Argon is very expensive so experiments were always happening using cheaper gasses and mixtures with Argon. Big jobs; the Argon was in a large tank in liquid form that gassed off like CO2 and LPG. I remember guys got their walking papers for over using Argon. That was the fitters job to keep the flow on/off/proper for the joints.

Maybe Shield Arc will weigh in on the CO2.

Remember us old guys have long term memory losses.

Ron

 

[Jorville]

I screwed up the sentence structure; sorry. I meant to say "CO2 as shield for mild steel. Yes Argon with some minor other mixed in rare gases for some materials is the normal shield gas and purge gas. I could be very wrong on the CO2 as it has been 30 years from the trade. Argon is very expensive so experiments were always happening using cheaper gasses and mixtures with Argon. Big jobs; the Argon was in a large tank in liquid form that gassed off like CO2 and LPG. I remember guys got their walking papers for over using Argon. That was the fitters job to keep the flow on/off/proper for the joints.

Maybe Shield Arc will weigh in on the CO2.

Remember us old guys have long term memory losses.

Ron

Ron, even for mild steel argon is used. I am not sure what straight co2 is used for. A lot of Mig will use a 75/25 mix. I think that is 75% co2 and 25% argon. We used a tri mix for stainless, don't remember the percent but that had argon, co2, and some helium in it. One fellow put that 75/25 on his tig machine, was welding mild steel and the welding process made a strange sound and just did not weld right. 100% argon fixed the problem.

 

[Shield Arc]

Maybe Shield Arc will weigh in on the CO2.

Ron

No Ron I never heard of CO2 being used for Tig welding, only Mig. Like stated above a lot of
guys use a helium argon mix for aluminum. I keep a bottle of 100% helium for thick alumium welding. But now I have a spool gun I don't use the helium much.

 

[nybirdman]

Tig requires pure Argon,on stainless we used Nitrogen for a purge(inside).