I need to fabricate a fitting that is a shortened 1″ dia L+R nipple (RH thread cut off) to a steel coupling.I spoke to a plumber and he said that stick welding was ok but he thought that MIG was not.But he wasn’t sure.I have an industrial 200A mig but no stick welder.Does any one have any idea behind the plumbers logic.I might add that I am caperable of welding and can get good penetration of that thickness.
Thanks Jako
Replies
As long as your're welding steel to steel any method is fine. Don't even try to weld iron to just won't take.
Thanks for the help US and forrest
Don't even try to weld iron to just won't take.
Do you mean cast iron?
If you preheat cast iron to at least 900 degrees you can use nickel rods in an arc welder, but I have seen some big messes done that way.
My fab shop predominately uses silicon bronze wire feed that will pretty much weld any dissimilar metals----- had some copper coils that had black iron nipples---- funky as heck.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
Your right Bill, I meant to say cast iron is very hight tech to weld in any way or form.
I often mig 1/2" IP to mild steel, for spacers and mounts. Never been a problem - I just make sure it's all bright.
Forrest
Edited 2/10/2008 2:07 pm ET by McDesign
is black iron pipe, iron or steel. I need to weld some too..two ways to screw up concrete 1) concrete driver 2) concrete finisher
Black iron pipe is steel .Most fittings are mallerable cast iron but I have got steel couplings and nipples that are ok to weld
Almost all metal is weldable in some way shape or form.
Almost all production shops use wire feed to weld pipe.
Welding a nipple to a coupling is doable, but make sure that the coupling is malleable iron or steel & not cast.
Steel is iron with less impurities.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
Edited 2/10/2008 4:26 pm ET by plumbbill
Lincoln electric has a great forum and tech section online for all things weldable. You'd be surprised what some of the special purpose rods can do.
However, this might be one of the questions that if you have to ask it, you probably want to be extra careful with what you do or have it done at a shop. I've see so many good looking welds crack from stresses created during the welding process that I wouldn't trust the metal unless the manufacturer's specs came along with a new fitting, and I wouldn't trust the welder unless he has a track record of working with those materials.
If you were a client I'd say no way since who picks up the bill if the weld cracks while you're on vacation? Black pipe must be gas line? What happens when gas lines crack?
Even if I suggested against it and you forced the issue and I allowed it and it failed you would have a decent case against me. Since I knew it was a bad idea and let the plumber install it I'd be on the short list of who's being sued along with the plumber. No thanks.
I'm guessing you are trying to modify a fitting instead of having a section of pipe reworked in the normal fashion. Almost always better to simply have the pipe reworked.
Best of luck
Beer was created so carpenters wouldn't rule the world.
After looking at your original post that would be a good spot to do a socket weld.
Take a die grinder to the coupling until the nipple slides in then weld the over lapping joint.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
what I want to do: I salvage a pile of black iron, some of the threads are screwed up. I want to run air lines in my shop. Too cheap to re thread.two ways to screw up concrete 1) concrete driver 2) concrete finisher
That pipe is the standard you see welded for air, steam, hydronics et al.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
NO BUTT WELDING.
Bevel the ends.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
Basic hand threading equipment isn't too expensive if you buy used, and it is a whole lot easier than trying to weld it... assuming your air lines are the standard 1/2, 3/4 or 1 inch variety.
To the best of my knowledge, pipe nipples with left and right hand threads on the same piece are quite difficult to find outside of a specialty shop.
Commercially available fittings that do what you want have a threaded side and the other side is machined to accept the black pipe without threads. A fillet weld is then made along the shoulder of the fitting and the pipe... at least that is what it looked like- I suppose they threaded pipe into standard filltings and welded over that.
The pieces are *not* butt welded together.
A better solution would be to cut the existing 1" pipe in place, rethread in place, install a union (or coupling if it is in a wall), then proceed with the proper length pipe nipple. One inch pipe is no big deal to do by hand.
Just to give you the background. It is a hydronic heating system with a cast iron rad,on the 3rd flr .Typical of installations of this type the rad has LH female threads.Originally one inch risers came out of the floor ,into a 90 and were connected to the rad with 2 1/2 inch LH/RH nipples (avoiding unions).I now want to replace that set up with new bronze 90 deg valves that have a union (Don't say expense cos I got a box of about 20 free,new yet 60 -70 years old. I tested them @35psi ).The union will be threaded into the coupling which is to be welded to the nipple (the shortest LH/RH nipple available is now 2 1/2 in) and I need to cut 1 in off the R/H end.I need the LH threads to fit the rad.Secondly I cannot move the risers Anyway thanks for the tip, I will check the wholsale for the weldable coupling