any pipe fitter/welders

[Jorville]

I want to Tig weld the open root on cast steel caps on a schedule 40 pipe. The second weld I am wondering if it should be a 7018, or would another Tig weld be OK. The pipe is schedule 40 black steel, 2 and a 1/2 inch, a couple on two inch pipe and four on inch and a half pipe.

Another welder said to Tig it all, I am thinking the cover passes should be 7018. I think this weld can be done in two passes. What are you guys thoughts on this?

 

[Shield Arc]

I don't see any reason not to Tig weld all the way.

 

[Arc weld]

What are you using them for? 7018 would be faster if you can roll them but I'm not sure if you could do TIG in 2 passes.

 

[Tractor Seabee]

Arc Weld is right. I fitted for a lot of SS process pipe welding. Tigged, always three passes on pipe above 2". What is the end use? Pressure, structural, appearance? Two passes of Tig for appearance you can fill flush (no bead). SMAW is a lot faster from the bottom up on mild steel. We could blow and go SMAW welding with 6010 root and 2 passes 7014. We did OA welding on up to 3" in one pass; hot work but 2-3 times as many welds as SMAW per hour.

Been away from the trade 20 years now so maybe things have changed. Back then Tig on mild steel was unheard of. Left the trade as automatic Tig pipe pipe welding was on the upswing. That was a slow process with keeping track of the settings and doing a lot of coupons for certified work. Tig pipe welders on process work and high tech clean room work were real primadonnas.

Ron

 

[Jorville]

I don't see any reason not to Tig weld all the way.

I was thinking because the butt weld fittings are cast steel it might be better to use 7018, than to use mild steel filler all the way.

 

[Jorville]

This piping is on a hot water heating manifold. It will all be welded on the bench, so I could lay two pieces of angle down and roll the pipe and weld. I am not sure on two passes either, that pipe is not very thick. Two passes with tig most likely would not fill with a cover, but I thought a 7018 might fill it with a slight cover.???????

 

[Jorville]

Arc Weld is right. I fitted for a lot of SS process pipe welding. Tigged, always three passes on pipe above 2". What is the end use? Pressure, structural, appearance? Two passes of Tig for appearance you can fill flush (no bead). SMAW is a lot faster from the bottom up on mild steel. We could blow and go SMAW welding with 6010 root and 2 passes 7014. We did OA welding on up to 3" in one pass; hot work but 2-3 times as many welds as SMAW per hour.

Been away from the trade 20 years now so maybe things have changed. Back then Tig on mild steel was unheard of. Left the trade as automatic Tig pipe pipe welding was on the upswing. That was a slow process with keeping track of the settings and doing a lot of coupons for certified work. Tig pipe welders on process work and high tech clean room work were real primadonnas.

Ron

The end use of this job is a new hot water heating system in my boiler room. What is there now is a 1970's design that I put in, in 1983. I since added two rooms and want to heat them so I need to re-plumb my boiler room. I am using 2016 design and ideas. So there will be a little pressure 12 psi cold and a few more pounds when the water is hot. I would like it to look nice, even though I will probably insulate the piping. All the piping will be welded on the bench so it can be rolled.

I have not done pipe in 30 or more years, did O/A on small pipe and arc on the larger stuff. I did not do a lot of it. I know on SS there need to be an argon purge. Do you think a purge needs to be done on mild steel?

 

[Shield Arc]

Back then Tig on mild steel was unheard of.

Ron talking to different welders who work in the local Navy ship yards. All pipe welding is done with Tig. The welders who work on the submarines amaze me when they have to stick the filler rod through the pipe to weld on the opposite side of the pipe.

 

[chuck172]

I want to Tig weld the open root on cast steel caps on a schedule 40 pipe. The second weld I am wondering if it should be a 7018, or would another Tig weld be OK. The pipe is schedule 40 black steel, 2 and a 1/2 inch, a couple on two inch pipe and four on inch and a half pipe.

Another welder said to Tig it all, I am thinking the cover passes should be 7018. I think this weld can be done in two passes. What are you guys thoughts on this?

What's with the cast steel caps? Must it be cast? Why not reg. mild steel caps. That's your problem, the cast steel.

 

[Jorville]

Shield Arc, There is a u-Tube video on that, and you are right, it takes skill. I personally don't do enough welding now to be at my best.

It had to be a little past three AM on the west coast when you posted this, don't you sleep? Or do you have the same problem that I do.
Have a great day, always enjoy your posts.