TIG welding copper pipe instead of soldering/brazing?

[plamauski]

setting up an airline system for an air compressor. Was going to use black pipe but I had this crazy idea of using copper and TIG welding it. I know it's crazy and most people braze or solder their copper pipes but I enjoy TIG and thought it would be a good chance to practice (never welded copper) Other than time factor, is there any reason not to do this?

I am not the greatest TIG welder but I do alright, have a dynasty 200dx, took comm college welding 10 years ago and have been a hobbiest since then...

[lstilts]

As long as you get the heat right, the cooper won't know the difference. Brazing is probably faster. What kind of filler will you be using? I use sil-fos 5 normally it works well with copper & makes a good strong joint.

[Shox Dr]

Apart from been a bitch, no not really. If you've mastered thin Stainless Steel <0.035 (0.9mm) then welcome to the next level

[fran...k.]

Common copper pipe is where a lot of the recycled copper goes. It is my understanding if you want to weld copper it should be deoxidized copper which doesn't have recycled content. I don't know about stuff like 10% nickel copper pipe which I came across some of. Perhaps someone could say I am wrong or elaborate.

fran

[plamauski]

Well I haven't "mastered" the thin stainless, I can make it hold water but it don't look pretty like zap or ZTfab or the other guys who I am convinced are actually robots.

I was thinking of just using solid copper electrical wire for filler (stripped and cleaned of course)

I think I'll try it on a few small pieces before going all-out. Main reason for the idea is I don't have threading tools for black pipe, don't have a gas torch for brazing, and basically just enjoy TIG and excuses to practice it.

Any other tips input ideas or criticism is welcome.

[plamauski]

Originally Posted by fran...k.

Common copper pipe is where a lot of the recycled copper goes. It is my understanding if you want to weld copper it should be deoxidized copper which doesn't have recycled content. I don't know about stuff like 10% nickel copper pipe which I came across some of. Perhaps someone could say I am wrong or elaborate.

fran

Oh yeah, that's another question I forgot - if the normal copper plumbing stuff will suffice as I had also heard it is recycled and may have impurities. I guess if I try a few small pieces I will be able to report back if it welds ok. Anyone tried it already?

[Oldiron2]

Originally Posted by plamauski

Well I haven't "mastered" the thin stainless, I can make it hold water but it don't look pretty like zap or ZTfab or the other guys who I am convinced are actually robots.

I was thinking of just using solid copper electrical wire for filler (stripped and cleaned of course)

I think I'll try it on a few small pieces before going all-out. Main reason for the idea is I don't have threading tools for black pipe, don't have a gas torch for brazing, and basically just enjoy TIG and excuses to practice it.

Any other tips, input, ideas or criticism [are] welcome.

Assuming you're using a reasonable sized copper pipe, I would suggest a propane torch and the silver solder ( eg Sil-Fos ) which is commonly used in refrigeration systems. Much easier then TIG and gives gas-tight joints too. Standard lead solder remelts easier though, in case you ever expect to pull the system apart, and does as well at sealing if applied correctly.

The extruded copper pipe is very pure; cast fittings may be less so.

[jakeru]

Originally Posted by plamauski

setting up an airline system for an air compressor. Was going to use black pipe but I had this crazy idea of using copper and TIG welding it. I know it's crazy and most people braze or solder their copper pipes but I enjoy TIG and thought it would be a good chance to practice (never welded copper) Other than time factor, is there any reason not to do this?

I am not the greatest TIG welder but I do alright, have a dynasty 200dx, took comm college welding 10 years ago and have been a hobbiest since then...

Welding hard copper tubing will anneal it, at least near the weld. This will make the tubing softer in that area (easier to bend or deform), albeit more ductile (less likely to crack while being deformed.) It will make the tubing behave like the soft copper tubing that comes in a roll (which is annealed.)

Soldering will allow hardened copper tubing to maintain it's full "hardened" tensile strength, provided that you don't *severely* overcook the tubing or the solder.

Brazing I don't know whether it typically anneals copper tubing or not; I would guess that it would but pehaps is possible to accomplish without annealing the tubing; I am not sure and it may depend which type of brazing filler rod / technique you use.

[plamauski]

I picked up a few pieces last night and tried it out. Went better than expected overall...but had some issues. I could def tell it softened up alot after welding. My filler was too big (12ga solid wire) for the L type tubing I got. I used basically the same setup as steel, 1.5% lanth, no idea what amps as I set it for 100 and used the pedal. Really hard to manage heat. But I did get a few decent beads just running flat on a small piece of tube. It is obviously not practical (ok we knew that from the start) but it is fun so I will probably play around some more.

For soldering, I forgot I do have a propane bernzomatic somewhere, wonder if it would be up to the task?? Never tried soldering/brazing and this is a good time to learn that too.

I read something about soldered/brazed copper having issues when painting, something about flux residue or something. Probably just BS but the tig welds I did looked clean inside the pipe, even the one that got too hot and almost dropped through lol.

Oh btw all the pipe and fittings I got are made in USA, havent tried welding on the fittings yet just some of the pipe. (3/4" L type)

[lstilts]

I've always used sil-fos, if I remember correctly propane alone, would not get hot enough to make a decent joint, so we always used MAAP gas. I never even thought about using copper wire for filler. Do you have any pics of your welds made with copper filler?

[plamauski]

Originally Posted by lstilts

I've always used sil-fos, if I remember correctly propane alone, would not get hot enough to make a decent joint, so we always used MAAP gas. I never even thought about using copper wire for filler. Do you have any pics of your welds made with copper filler?

No pics yet, will borrow a camera this weekend and snap a few shots after I get some smaller wire too. I was working on a different project until pretty late and only ran a few beads on the copper before going to bed.

I looked all around for copper tig wire before realizing most hardware stores sell bare copper wire. Seems to work well so far. I did give it a quick stroke or 2 with some sandpaper then acetone first.

[JohnR]

There's a few threads about welding copper pipes on here. Copper has the highest thermal conductivity of anything you're likely to come across. I've tried it once half-heartily and it somewhat reminded me of aluminum as far as heat soak and backing the amps as the puddle progresses..

[plamauski]

Yes kind of like aluminum but harder, need a ton of heat to get it started but need to back off quick and move fast. If you pause for a sec or over saturate with heat or it all wants to melt like wax.

[pipefitter72]

used to weld copper backup fixtures for purging the back side of welds with argon on aircraft parts.It fuses easily...the only time i used filler we used tin snips to cut small strips of copper sheet to make filler rods. and used vise grips to hold the strips because of heat transfer. Sil-fos will anneal the copper. A solder joint is incredibly strong and easy to make. You want to heat the joint and periodically remove the flame and touch the solder to the joint.When the joint is hot enough the solder will melt.Do not melt the solder with the flame.just keep the joint hot enough with the flame and the run end of the solder all around the joint as it melts capillary action will draw the liquid in the joint. But it would be more fun to tig it..lol

[pipefitter72]

and be sure to sand the copper and put flux on both pieces if your gonna solder....not necessary for sil-fos.