Soldering copper pipe

Ted

Ted

The pilot formerly known as Twin Engine Ted
Joined
Oct 9, 2007
Messages
30,006
Display Name
Display name:
iFlyNothing
We've been going through the process of replacing the appliances in the house. The dishwasher has been the problem child. First we got a defective one, and now I'm trying to finish up the copper pipe required modifications. The problem I am having is with the solder on the fittings. I have the required swet, propane torch, and solder.

However, I am having a hard time making it work properly. The first time, it all seemed to work great, and I have no idea why. Now I can't get this fitting to seal all the way around no matter what I do. I'm going to buy another fitting (this one was new, but after multiple attempts I'm sure I'm screwing it up somehow).

Are there any tips for how to do this properly? The fitting is, unfortunately, in a bad location to start out. That makes it very difficult to get a good angle with the solder and the torch. However it simply does not want to seal somewhere on the back side, and as such keeps on leaking out of there. It's only a pinhole leak, but of course that's too much.
 
What type of paste flux are you using?
 
Ted - I'm no expert, but I've had good luck making sure the connections are absolutely clean to start with (quick swipe with sandpaper). The other thing I do is use MAPP gas rather than propane. I believe it is a hotter flame, helpful if you are trying to solder into a larger fitting.

Clean fittings, MAPP gas - and the solder just (insert schlippp noise) slides in there nicely.

Tim
 
Cleaning and fit is everything in soldering! Are you able to get both pieces nice and bright and shiny? Are you using a flux paste as well? How is the fit between the pieces - snug or loose - getting solder to fill a big gap is difficult. Getting the male pieces clean is usually pretty easy, the female parts can be a PITA if the access is tough. A small round wire brush like a battery clamp brush or even a gun bore brush can help if the size is close.

Wish there was a magic wand, but it is a matter of preparation and some measure of skill. Is it possible to change them over to compression fittings?

Gary
 
I run 320gt sandpaper on all inside surfaces and all pipe (past where the fitting will end so that the solder will schtick beyond the fitting).
Then flux all surfaces well with plumbers paste.
The only time I've had problems was when I bought fittings with a bit of corrosion on them. Noway, nohow will it adhere to corrosion.
 
If at all possible don't forget to VENT the pipe that you are soldering by opening it to the air at either end. If you don't do this the expanding heated air can push the solder out of the fitting causing pin hole leaks at the fitting.

Good luck..

Jon
 
Ted DuPuis said:
We've been going through the process of replacing the appliances in the house. The dishwasher has been the problem child. First we got a defective one, and now I'm trying to finish up the copper pipe required modifications. The problem I am having is with the solder on the fittings. I have the required swet, propane torch, and solder.

However, I am having a hard time making it work properly. The first time, it all seemed to work great, and I have no idea why. Now I can't get this fitting to seal all the way around no matter what I do. I'm going to buy another fitting (this one was new, but after multiple attempts I'm sure I'm screwing it up somehow).

Are there any tips for how to do this properly? The fitting is, unfortunately, in a bad location to start out. That makes it very difficult to get a good angle with the solder and the torch. However it simply does not want to seal somewhere on the back side, and as such keeps on leaking out of there. It's only a pinhole leak, but of course that's too much.
Click to expand...

Is it dry? Repairing or adding to existing work can be problematic if some water remains in the line. The water prevents the pipe from getting hot enough for good capillary action, the solder doesn't flow into the joint and make a good seal. For a half inch pipe I take half a slice of white bread, no crusts, and roll it into a ball, force it into the pipe to form a plug. That keeps water from cooling the joint while you're sweating the connection. When you turn the water on the bread plug disintegrates. Make sure you use plain, common, tasteless, white "Wonder" type bread. Whole wheat will clog any mesh screens or cone washers it encounters.
 
As others have said, clean is important. Flux all over. Propane is plenty hot, I use it all the time.

I apply heat to one side and the solder to the other - when it melts it wicks all around.

Make sure there is no water in the pipes. If any runs down in the middle of your work, it will quench part of the pipe and you won't get the solder to flow in there. (edit: Mr. Ronachamps bread idea is a good one)
 
Thanks for the advice. The first time I must have done something right, because it all just magically worked. After some phone conversations with Ed and the advice here, I'll give it another shot tonight and hopefully put the saga of the dishwasher to rest. It seems part of the issue is that I need to get it right the first time, because after that it probably just won't work.
 
Or you could just cheat and use a big honkin' compression fitting...
 
Ted DuPuis said:
Thanks for the advice. The first time I must have done something right, because it all just magically worked. After some phone conversations with Ed and the advice here, I'll give it another shot tonight and hopefully put the saga of the dishwasher to rest. It seems part of the issue is that I need to get it right the first time, because after that it probably just won't work.
Click to expand...

The advice you've received WRT cleaning and venting is spot on. The only thing I can add at this point is that you must prevent any water from reaching the joint while soldering. This isn't normally a problem with new plumbing work but when tying into existing lines you either have to remove all traces of water upstream for several feet or block the pipe. A trick I've used in such cases is to stuff some bread into the existing pipe a few inches. This will absorb and/or block any water dripping into your soldering operation and will dissolve and wash out once the joint is completed. It might be a good idea to flush the bread out before connecting the other end to the dishwasher though, the supply valve in the washer might not like the bread.
 
Another thing to check is that the flux is not water based - that crap is for the pros.

Clean joint (sandpaper on external surface, wire brush on internal surface), good flux, and proper heat application will produce a good joint.
 
gismo said:
The advice you've received WRT cleaning and venting is spot on. The only thing I can add at this point is that you must prevent any water from reaching the joint while soldering. This isn't normally a problem with new plumbing work but when tying into existing lines you either have to remove all traces of water upstream for several feet or block the pipe. A trick I've used in such cases is to stuff some bread into the existing pipe a few inches. This will absorb and/or block any water dripping into your soldering operation and will dissolve and wash out once the joint is completed. It might be a good idea to flush the bread out before connecting the other end to the dishwasher though, the supply valve in the washer might not like the bread.
Click to expand...

Agree on Lance's comments and the others above. I've used bread with great success on sweating copper pipe. I've also found that it sometimes takes longer to heat the joint than you might expect, especially if there's a heat-sink attached to the pipe (a stud, dirt for an underground pipe, etc.).

You said it's in a bad spot - are you sure you're able to get the pipe really clean? It's harder to clean oxidatation after you've tried to sweat it.
 
Clark1961 said:
Another thing to check is that the flux is not water based - that crap is for the pros.

Clean joint (sandpaper on external surface, wire brush on internal surface), good flux, and proper heat application will produce a good joint.
Click to expand...

Some other hints for anyone new to soldering.

1) Use just enough heat to get the job done. Too much heat can oxidize the copper and solder, too little and the solder won't flow into the joint. MappGas is hotter than Propane which can make the job go more quickly but it's also makes it much easier to overheat.

2) When the temp is just right the solder will wick into the joint, even if that means going up hill. Too cold and it will bead up (forms round balls and won't flow). With experience you get to "know" when the pipe is hot enough to feed in the solder. Newbies tend to apply solder as soon as it will melt when touching the pipe, or worse yet they will melt the solder with the flame. If you aren't sure when to add solder, apply heat for 10 seconds then briefly touch the solder to the joint, if it doesn't get "sucked in" heat another 5 seconds and try again.

3) Don't let the two parts of the joint move (rotate or in-out) while feeding solder or for another 15-30 seconds while the joint cools. If it does move you should probably heat and separate the joint then clean everything up and start over.
 
Ted DuPuis said:
The dishwasher has been the problem child.
Click to expand...
They always are. Confined space, persistent wet, hot/cool cyclic environment. The added bonus is they give you excess length of copper with flared ends. The quick solution is to kink, er, I mean coil that excess pipe and jam it into a confined space. Be smart, delete the copper and get a ABS flex hose. This will require adapters on the fittings at both ends but you'll be way ahead of the game.

The problem I am having is with the solder on the fittings.

However, I am having a hard time making it work properly. The first time, it all seemed to work great, and I have no idea why. Now I can't get this fitting to seal all the way around no matter what I do.
Click to expand...
See confined space. Your problem is you are in uncomfortaable position so you are impatient. You are rushing. The trick is getting the pipe to the required temp. This requires time. Go into Zen Mode as you chant the mantra, Do it right the first time.

Again, go with the ABS plastic flex hose and fittings.
 
gismo said:
Some other hints for anyone new to soldering.

1) Use just enough heat to get the job done. Too much heat can oxidize the copper and solder, too little and the solder won't flow into the joint. MappGas is hotter than Propane which can make the job go more quickly but it's also makes it much easier to overheat.

2) When the temp is just right the solder will wick into the joint, even if that means going up hill. Too cold and it will bead up (forms round balls and won't flow). With experience you get to "know" when the pipe is hot enough to feed in the solder. Newbies tend to apply solder as soon as it will melt when touching the pipe, or worse yet they will melt the solder with the flame. If you aren't sure when to add solder, apply heat for 10 seconds then briefly touch the solder to the joint, if it doesn't get "sucked in" heat another 5 seconds and try again.

3) Don't let the two parts of the joint move (rotate or in-out) while feeding solder or for another 15-30 seconds while the joint cools. If it does move you should probably heat and separate the joint then clean everything up and start over.
Click to expand...

Since you're giving lessons.......

Does the flux burn off and have to be reapplied, or does it survive direct flame while heating the copper?
 
Steve Foley said:
Since you're giving lessons.......

Does the flux burn off and have to be reapplied, or does it survive direct flame while heating the copper?
Click to expand...

The flux will liquify and clean the joint just prior to the solder application. If the flux burns off (there will be a black residue) then ya get start all over.

It's pretty simple, heat the base of the socket portion of the joint, watch the flux liquify, heat just a bit more, apply solder in a quick swipe around the joint, cheat and wipe excess solder with rag, and allow to cool.

A little clarification: heat the socket portion of the joint, not the pipe which sticks into the socket. Try to get the flame all the way around the socket on the portion of the socket closest to where it tapers down to the body of the pipe. The heat will draw the solder all the way into the socket and create a very good joint.

Only very rarely will the flame need to be directed to the pipe which is inserted in the socket. Sometimes it helps when heating a joint which has the socket inverted (on top of the pipe which sticks into the socket).
 
Last edited:
All good tips. I'd only add: Clean the female part of the fitting, too. Have a cotton rag or sock handy to wipe the joint. Since you are going at this for the umpteenth time, I might even buy a new fitting rather than try to clean the old.

(I prefer MAPP, too)
 
The thing that I find bites most would-be solder amateurs on copper pipe is the requirement to get the metal clean. Not just kinda clean, not sorta clean, not mostly clean - CLEAN. As in sandpaper or nylon scratch pad until it's SHINY SHINY clean, and then DON'T TOUCH IT. Do the same for the inside of the female fitting. Use good flux, assemble them, heat them with the torch at varying angles to get a good flow of heat, and the solder will wick into the entire joint when it's hot enough.

The biggest problem I see people run into is looking at a store-bought new fitting and assuming it's CLEAN because it's shiny. Not true.
 
I agree with the tip of removing the barcode/price sticker. Even if its 1/4" from the joint, its going to burn and flow, contaminating everything.
 
Let'sgoflying! said:
I agree with the tip of removing the barcode/price sticker. Even if its 1/4" from the joint, its going to burn and flow, contaminating everything.
Click to expand...
It always ticks me off when stores put those stickers on, especially when the glue won't let go easily. In the days before everything had to have it's own barcode this wasn't a problem but now it's a PITA. If you need more than a couple fittings it's worth a trip to a real plumbing store instead of the local Menards.

As to reusing a fitting, IMO that should be the last resort, especially the female end. You not only need to get the inside nice and shiny, you pretty much have to remove all traces of solder or the joint can't be hand fitted.

I think the question about burning up the flux has been answered, but I wanted to add that coating the surfaces to be soldered with flux immediately after cleaning them up will delay the inevitable oxidation. That's what the flux is for, it prevents oxidation while the part is being heated. Without flux the bare copper will oxidize quickly and the solder will not wick very well when oxidation is present, nor will if form a good bond.
 
why is sweating a joint so much damned fun?!
and screwing it up so frustrating!

You can read about it and see the videos, but the only way to truly learn it is to make all the mistakes once, yourself! Glad flying isn't quite like that!
 
Copper to copper, it's been a while but:

1) separate the line
2) boil the water off with the torch
3) check the cuts on the pipe and the joint, smooth if necessary
4) "polish" the lines AND the joint (inside on the joint too)
5) flux the pipes and joint
6) mesh the joint and pipes together
7) start by heating the joint, move slowly from the joint to the pipe edge, back to the joint center, to the other pipe, repeat until flux melts
8) apply solder slow and even around the whole joint, both sides
9) check joint to see it's even and solder wicked all the way around

It's easier than soldering fine pitch. The real skill is the heating with the torch and even application of solder. You'll use more solder than you think, as it should wick into the fitting too. Hmm, 1-1/2 inches per side easy if I remember right.
 
gismo said:
It always ticks me off when stores put those stickers on, especially when the glue won't let go easily. In the days before everything had to have it's own barcode this wasn't a problem but now it's a PITA.
Click to expand...
Boy and how. I'm with you on that PITA. I always wonder why the mfgs don't use fish glue. It's water soluable and any residue rinses away with mild scrubbing. And it sticks like nobody's buisness...as long as it doesn't get wet. heh heh
 
Learn something new every day! Never had I heard of the "Wonder" bread trick for wet work; love it.

I've sweated alot of pipes and all of the points made are on the spot. Clean inside and out (I use emery cloth), don't burn the flux (my typical boo boo), solder flows to the heat, apply heat THEN solder (balls), water based flux sucks, don't light the inside wall of the house on fire (don't ask).
 
I will tell you how this weekend goes, I have a 3/4" 15yo copper pipe leaking somewhere under 6" of a 4500sqft concrete slab. Expect cuss words.
 
I just worked on a slab leak beneath a tile floor at my house a few weeks ago.

A few suggestions if it is a hot water leak..

Do you have cats ? Just look for the spot were the cat now likes to sit and you probably found your leak. If you dont have cats use a non touch thermometer gun to plot out the hottest spots and that should help point to the leak, even doing it inch by inch could narrow it down.

I also plotted out the layout of the pipes under the floor by using the places were I knew they started in the basement and were they ended at the faucets that helped visualize what I was dealing with.

Good luck..

Jon
 
Its cold but I could still use my ultra sensitive digital thermometer, will try it out - tks.
I am told the leak could be quite far from the wet spot thanks to ducting.
 
Let'sgoflying! said:
You can read about it and see the videos, but the only way to truly learn it is to make all the mistakes once, yourself! Glad flying isn't quite like that!
Click to expand...

I made all the mistakes once. Then I made them again. :confused: But even I can learn.

-Skip
 
I don't use flux when sweating pipe/tubing, I use acid. For plumbing small stuff like household stuff, I use a battery terminal brush to get both inside and outside of the fittings, squirt some acid on both,stick em together heat it up, squirt some more acid at the joint and apply the solder.
 
As in "acid flux" ?



Henning said:
I don't use flux when sweating pipe/tubing, I use acid. For plumbing small stuff like household stuff, I use a battery terminal brush to get both inside and outside of the fittings, squirt some acid on both,stick em together heat it up, squirt some more acid at the joint and apply the solder.
Click to expand...
 
Well, I successfully soldered the pipe, and the saga of the dishwasher appears to have come to a close.

Thanks to everyone for the tips - they worked like a charm!

Edit: Specifically, the biggest one I think was focusing the heat on the joint itself, and then also applying the solder on the opposite side of the joint. It then flowed very well, and I kept on applying it until it looked full and then started dribbling to the bottom. The solder joints even look relatively pretty!

I really hope I don't have to do this again anytime soon...
 
Last edited:
iflyatiger said:
As in "acid flux" ?
Click to expand...

You can use a number of things. I sell some Hcl-ZnCl acid that's used for soldering - usually something a little more tough like brass. The issue with the acid, and yes they make acid paste fluxes, is that you need to make sure it is all gone when the job is finished or it can continue to eat away at the copper.
 
Cold will be tougher.. Good luck and let us know how you make out..


Let'sgoflying! said:
Its cold but I could still use my ultra sensitive digital thermometer, will try it out - tks.
I am told the leak could be quite far from the wet spot thanks to ducting.
Click to expand...
 
ha, I have a guy working on it for me, I won't have to lift a finger. :) He starts jackhammering after supper.
 
Let'sgoflying! said:
. . . I won't have to lift a finger. :) . . .
Click to expand...

Not even to write a check? You must have one of those carbon fiber man cards with an Italian flag in the corner. The ones that permit men to get away with saying "fixa my pipe or that cement will be your shooz" :hairraise:
 
You must log in or register to reply here.
Back
Top