Soldered Joint Faulire Rate?

So I tried all afternoon to solder some copper pipes to a new valve and hook that up to my existing plumbing. I practiced sweating copper yesterday and it was so easy and I did a great job... but today not good at all.

My last three joints did not work at all. The solder melted but it never sucked into the joint, whats up with that? The pipe was cherry red but the solder just would not stick.

Now I'm worried about my other joints that I think look good. After I turn the water back on and if they are not leaking what is the chance that they will not leak? Should I rip everything out and start over? I'm really worried that my joints will fail in a year or so... does that happen?

Did you do the basic prep on those joints?

--clean each joint with emery cloth or brush, then don't touch the cleaned area
--use fresh, good quality flux on both parts of the joint
--heat the JOINT, not the pipe
--touch the solder to the gap and it will suck the solder right in when the joint is at the right temp.

In my case, I had a run of bad luck and it was because I was heating the PIPE instead of the joint. That doesn't work.

If you have ANY water whatsoever in the pipe, capillary action will never occur.

You should have the valve open as well.

I cleaned and prepped the heck out of those fittings and end... everything was so shiny and pretty. I tried my best to heat the fittings and not the pipe too...

Old flux, maybe?

You incorrectly heated the joint and burned away the flux prematurely, that is why your molten solder just dripped off the tubing.

The previous answers all have merit. My guess is too much heat, possible old or poor quality flux, and perhaps some moisture. When you heat a joint, you should only heat it until the solder flows when touching the joint. In other words, hold the solder against the joint while heat the fitting so when it is hot enough the solder will melt and flow into the joint. If a valve is involved, open it. If there is moisture present in the pipe, the solder will not flow because the moisture will turn to steam and cool the joint before it is hot enough to melt the solder.

It is correct to heat the pipe first then move the heat to the fitting. It the pipe was red hot then you had way too much heat for soft soldering, you burned the flux and the joint. On small joints (1/2 and 3/4) you can get away with heating just the fitting but the proper way is to heat the pipe first. If you put the tip of the flame right where the pipe enters the joint at the bottom and at about a 45 degree angle up into the joint it is almost guarenteed to be successful. Too much heat will burn off the flux and the pipe will oxidize, guarenteed bad joint.

Thanks guys... what about my other joints that seem to be okay, is there a possibility they have been contaminated too and need to be redone? Will they fail prematurely?

if possible pump it up with a hydrostatic tester. I've known some people to fill the line with water then pump it up with an air compressor when they didnt have a hydrostatic tester. Pump it up to about 100lbs and see if it holds 15-30 min,

If you have a "bead" of solder around the tubing where it goes into the fitting, then it is IMPOSSIBLE to tell what the joint looks like inside the fitting. You could have a thin band of solder underneath the bead, untinned channels inside the fitting, or any of many other defects. Whether they will fail eventually, is also impossible to tell ahead of time. I had a customer who dropped a can of peas on a copper pipe in his cabinet and it fell apart because of a bad joint made TWENTY YEARS ago. Using the "New" water soluble fluxes requires much greater care with the heating to prevent burning it. No matter what size tubing you work with you ALWAYS heat the fitting socket and let the heat flow from there to the tubing.

If I have a ring of solder around the joint and I re-heat the joint will the solder just flow into it? Or will it not work because there is no flux?

If you burned most (all) of the flux out of the inside of the connection, reheating it won't resolve the problem. If you turned the water back on, you absolutely need to take it apart, clean, and re-do. The only reliable thing is to take it apart, clean things up, and start over. A big pain. On my last DIY'er job, I had to buy some new flux...don't remember the brand, but it was horrible. I could not get a good joint. I bought a different brand of flux, and all of the joints went together without any problems. They specify a water soluable flux, the old stuff wasn't (and I think it worked better, but left a taste in the water for a bit until flushed out - took longer than the water soluable stuff). What I found worked best for me was the tinned flux. This has powdered solder mixed into the flux. Worked very well. When you don't do this every day, you need the easier solution...try some tinned flux, it may really help.

The solder will NEVER flow into the joint and "repair" it. Once the joint is contaminated, by water, burnt flux, or anything else, the solder will not flow into that area, nor would it bond to the copper/brass if it did.

Thank you all for putting up with my silly DIY questions, I really appreciate it. I hope this will be my last question…

How do I remove the soldered joints? I will replace all of the copper to copper elbows and couplings, but my main concern is the joints on the new valve. I really do not want to destroy it while trying to remove the soldered copper pipe.

So what is the best way to ensure that I get all of the solder out? And if I can’t get it all out and there is still a thin layer of solder inside the valve do I just apply flux and solder the new copper pipe to it?

BTW it is a brass shower valve… all internals have been removed.


Thanks again!!!

Often, it's easiest to just cut out the bad joints and patch in new. You may need a repair coupling (this is a normal coupling without the stop in the middle...make sure to mark or measure so you get decent overlap on both pieces of pipe). Once you can get a straight pull on the pipe into the valve, you should be able to heat it up and pull it out with a pair of pliers. If you are lucky, you'll get enough solder out so you can re-insert a new piece of pipe. Otherwise, if the valve body is free, tap the end on a block and most of the excess will come out. It's hard to wipe the inside without burning yourself. On electronic stuff, they have solder suckers and solder wick (braided wire), but never used that on plumbing stuff. They probably make a reamer, but I've not seen one. A steel brush will get some of it and clean up the insides (and outside of the pipe). If the valve body has a good full coat of solder, reflux it, and you could probably heat it while pushing in the pipe, but it's better to get it in there first, then heat it. You risk a cold solder joint, which can look good, but be bad.

Heat the joints and pull them apart as SOON as the solder is soft enough to release them. Heat the tubing and wipe the solder off of it. Then just clean and flux it as if it were a regular piece of tubing. ANY spots that do NOT have solder on them will be the places where you could have had a leak.