I can't see how this coating would reliably mend bad joints....is he a licensed plumber? I would get a plumber in to check the situation out.

It IS possible you have "aggressive" water which has corroded your pipes, you should have a water quality check. I don't know much about softeners but with properly treated water, copper pipes and joints should last indefinitely.

If there is indeed a problem I don't know if the coating will help (although if it works I suppose it'd protect the copper) but like I said, I doubt it would help joints that are bad. It might be better to re-run all your pipes if they're that bad, with a view to ensuring the water's not going to attack them. Plastic might be less susceptible but the water quality problem would still be there (and the joints and elbows are still metal) and I'd have to wonder how good the stuff is for your health.

The way you describe this, "Â a joint in the water pipe in the kitchen popped loose. He had applied almost no pressure to it and in fact remarked that it could have come apart at almost any time" suggests that these joints were never soldered to begin with.

When a pipefitter makes up a series of joints, it is common to put them together (dry-fitting) for the purpose of fitting the lengths and rotation of a group of fittings and nipples. When all is ready, the joints are prepared and soldered. Since the contractor was doing demolition, he would not necessarily be a plumber or even very familiar with plumbing.

At this point, I would want to see the joints and determine whether they were finished. While it is unlikely that a system would not reveal a leak from Day One, once that occurs, the likelihood of it continuing to hold pressure would increase with time, as water-borne deposits fill the jointÂs voids.

This is more likely to be seen in a drain, where there is virtually zero pressure. But you call it a Âwater pipe. That is usually understood as Âsupply. If my guess is accurate, you should be more comfortable knowing that these are probably the only two instances of the condition.

Pinoke

When you say "finished" I gather you mean "soldered". I'll ask him. I'm hoping he kept the evidence, since I assume one can tell by looking at the joint. Hard to believe a builder would skimp that way, but then builders do the darndest things to save a few pennies here and there.

And I agree about the coating business: I can't imagine that would do a thing to help a problem with improperly finished joints. There was a lot of building going on at the time this house was built. I can easily imagine that inspectors could have been sloppy or worse.

Trekker,
This condition would have been accidental  not skimping. Yes, get the parts. It will be very obvious whether there is solder in the joints that came apart. I would have to say, no. It is not uncommon (especially for a newbie) to make a sweat joint that has a void; and so a leak.

[Remember, folks, even LazyPup was a kid in the Â60s. Do-wah; do-wah; do-wah; ditty! (Sorry. Got carried away.)]

But that joint would virtually never fall apart. In fact, once tested with water (supposed to be air) getting it apart for re-work is the hardest thing to do, sometimes. But even that joint will show obvious signs of solder adhesion, including any lack of it leading to a leak.

In the case IÂm describing, there will be no solder (I believe.) It is possible to cut pipe with a wheel-cutter, which will create a nice smooth radius where the straight pipe diameter turns to the cut face; i.e., Âthe corner or circular edge that is created when a cylinder is sectioned.

Then, if this nipple is inserted into a fitting, which will have been formed with a tool that also has a radius (this time, to avoid sharpness) the mating radiuses (radii) can be jammed together in such a way that they actually close the joint, mechanically.

That is Âpossible. And to some extent, it is likely to occur. But it is not the intended closure of the joint. It is the infusion of solder that fills the capillary which seals the joint and provides such strong mechanical strength that, when stressed mechanically, the pipe is far more-likely to fail than the sweated joint.

One could twist a soldered joint or pull it. And they would find that the joint will survive when the pipe and fittings are wrecked.

Pinoke

The reality is that if you have a water line with even the slightest flaw in the sweated joint, you will get a noticeable, high-powered, pinhole spray. A joint that is not soldered or only partially soldered would always send out large amounts of leakage under normal water pressure. So it's hard to say what the story is without seeing the joint.

I've done several poor, sweated joints over the years and they always have two characteristics: they spray water, and they're buggers to get apart so they can be re-done.

I hope this is not a "silly question," but, how does a joint actually work. I know after it is cleaned and fluxed and heated, the solder "melts" into the mico space between the pipe and joint. But what is actually holding it tightly together...an adhesive bond (ie. the solder "sticks" to the metal) or a mechanical bond (ie. the space is filled tight making it anchor the parts together). Just curious. I have done many piping jobs in the home, but just wondering.

First of all we must determine what type of joint was it? A solder joint or a compression joint?

The solder actually sticks to the metal, somewhat like glue (if not exactly) - if you look at a perfect joint (if, like me you only do plumbing occasionally, a pre-soldered fitting, the ones with the solder already provided in a groove in the fitting will show it best - you'll see a seamless tapering silver line where the solder melds to the copper, or in electronics soldering. The joint physically, should appear seamless.

I wish I knew the physics of the bonding but basically it's a bit of both, I guess, in answer to your question - vacuum and the fact the space is tightly filled also contributes to the bond, hence it's also mechanical. In practice a good soldered joint ought to be stronger than the surrounding pipe, since the fitting's usually a good deal thicker and stronger than the pipe.

With a bad joint of course, it's where it WILL fail.

Thanks, guys. Part of the problem is that I am not a plumber, nor is my contractor (although he does some plumbing work and certainly knows a lot more than I do). You did answer one question, which is whether or not a water softener can be hard on the pipes: I take that as a "no." When I find out more, I'll explain what happened.

Is this house on a well? I had the same thing happen in a house built in the 40's that we owned. The well water was so aggressive (sulphur water) that when I went to replace the piping, some of the joints just popped apart. The water had ate through the solder joints. The pipe was thin in places also. A sulphur removal system was put in and a softener. Get the PH of the water analyzed and checked for other contaminents.

ThatÂs pretty interesting. I didnÂt know copper was available in the Â40s. It could be that such material was in the Âinfancy and there was no history of failure to set standards to.

Pinoke

Copper pipe initially became available in 1932 but due to the stock market crash of 1929 and the great depression that followed there were very few housing starts. While the USA didn't officially get into the second world war until 1941, nonetheless we were supplying arms and munitions to Russia and England as early as 1939 so copper was in short supply because it was being used to make brass casings for military ammunitions.

Copper piping did not come into common use until 1946 or 47.

If I remember correctly the house was built after WWII. We purchased it in 1983 and the Person who built it stopped by and told us when it was built. He was a very wealthy retired hog farmer. Before he passed, he donated money to the local university to build a very large hockey rink for the school.

He said he had to go clear to kentucky to get the wood for the house. It was cut by a sawmill. When I gutted the house I found a lot of 2 by 4's with bark on them. House is located in NW Ohio.

It was the original water lines. The line to the toilet was brass soldered to the copper. No valves on any of the plumbing.

With the aggressive water I put in all CPVC. The old copper was pretty decent shape except for a couple of elbows that seperated when I pulled it out. Probably fell apart from the lead solder. Probably used 60/40 lead -tin.

Lead solder is more resistant to corrosion than copper.
Somehtng else is going on for joints to actually pull apart.

I would geuss you have a water chemistry issue. While lead solder is usually very stable a few organic acids (acetic acid)will dissolve it over time. I would inquire with your neighbhors and local water supplier to see if other problems have been reported. If it were mine, I'd probably replace any readily accessible joints. If a catastrophic failure would cause a lot of damage I would invest in a leak detector with automatic water shutoff, otherwise I'd double check my HO insurance policy and hope for the best.

Soldering is a chemical bond, with a metal alloy forming at the interface between copper and the solder. So its more like a glue, rather than a caulk

If you had joints that easily slipped apart it is much more likely that they were subject to freezing at some time in the past and the expansion of the ice mechanically forced the solder bond to break. While this generally results in a leak in some rare instances it does not leak but the joint is weakend.

I have to amend my view of failing joints. Today my neighbor called and asked how to shut off the water to the house because she thought she had a leak in the garage. When I took a look at what was going on, I saw that she had a frost free hose bibb in an unheated wall and there was a length of copper pipe that extended from that to a coupling. the copper pipe was showing about 1/2" of shiny solder. I can only theorize that it froze when we got down to 15 deg F last week, it was a bad joint, and the ice forced the pipe out of the coupling, but not completely. Surprisingly, the joint was only dripping because it hadn't totally failed yet. She had her plumber come over to cut out the joint and resolder everything. When I asked him how often he'd seen something like that, he said it was the first time...and he was at least 50 years old.

...and I should add that her plumbing was only about 5 years old.

"acetic acid"

Eats copper faster than lead.