When will my sweat joints leak?

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dotkayk

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The meter insisted on leaking...not much, but enough to put water in the pipe. I make a swab of pieces of a towel attached to a heavy wire...coat hanger I believe..

I had to replace a garden faucet once, the pipe was the uttermost low point of the plumbing in the house. Closed and opened everything, waited six hours, no matter what there was a slow drip. I used a piece of bread.. mashed it up into a semi-solid bit of dough, stuck it way up the pipe. Once the water is back on the bread flushes out quite easily..

interesting thread. 'In God we trust, everyone else needs to show their data'.
From a theoretical standpoint I'd be inclined to agree with hackney - if taken patiently and the joint heated sufficiently before starting the solder, the pressure should have had time to equalize between the pipe and surrounding air. His experiments seem to confirm this..
 

Ballvalve

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When I was doing hydrostatic testing on high pressure gas pipelines, we often used a grease gun to squeeze up small jobs. Mind you, we also squeezed up miles of 42" pipe and that stuff sure made a mess when it blew.

Good idea. Probably make 5000 psi with a good one. Freezing is safer though, and real world useful. That break of his looks just like a freeze break, so that gives an idea of water expansion power.

The largest dozer tracks get tensioned with a grease filled cylinder and any hand grease pump. You can also fill a grease gun with oil, some dozer track rollers get lubed that way.
 

Hackney plumbing

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I just looked up the burst pressure rating of 1/2 type L copper and it was 3885 psi. The footnote said that was an average burst pressure and none of the samples tested has a burst pressure of no less than 5% of that. 5% of 3885 is basically 194 psi. So my sample mimicked what copper.org said it would hold.

Hard drawn typle L is good for 7,765 psi. Hard drawn type M will go to 6,135 psi burst.

I expected the solder joint to fail.......

Type K will go to 9,840 psi. hard drawn.

In all cases as the copper pipe size increases the burst pressures decrease. Small copper pipe will hold more pressure than big pipe.

Hard drawn will hold more pressure than soft.
 

Jadnashua

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The fitting will act like a reinforcment ring, i.e., sort of like double-thick pipe. Now, the end of a cap would be susceptable like the pipe itself. So, not surprised. There's a lot of surface area in a properly soldered connection, so the bond is quite strong.

The original point of this was not that a joint WILL fail, but that it could. Lots of variables. Lots of flux, (thicker pipe like maybe K), a quality fitting that fits tight without the solder yet applied, and your results might differ.
 

Tom Sawyer

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Yes indeed its a bit of a D.I.L.L.I.G.A.F situation. Joints fail for one reason only and that's improper technique which included the cleaning as well as the soldering process.
 

Hackney plumbing

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Try it with a short section between stops that are closed...unlikely to happen in a large pipe run since the pressure change would be minimal, but in a short section? Yes.

The fitting will act like a reinforcment ring, i.e., sort of like double-thick pipe. Now, the end of a cap would be susceptable like the pipe itself. So, not surprised. There's a lot of surface area in a properly soldered connection, so the bond is quite strong.

The original point of this was not that a joint WILL fail, but that it could. Lots of variables. Lots of flux, (thicker pipe like maybe K), a quality fitting that fits tight without the solder yet applied, and your results might differ.

I think I proved my point based off what you wanted me to do in the 1st post above.

Now since that worked out well your opinion is changing. Now it has to have alot of flux and fit tight.

Want me to do it again with a gallon of flux and beat the fittings onto some K copper?????? What would I need to do after that? Solder it at the bottom of my swimming pool for you? LOL
 
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LLigetfa

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Now since that worked out well your opinion is changing. Now it has to have alot of flux and fit tight.
He's an engineer, so what do you expect? We have our share of them at work that cannot accept that their theory sometimes does not align with reality. I think a lot of it has to do with how you hold your tongue while soldering.:p
 

Jadnashua

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My opinion is based on both theory...in a closed space, heating gas increases pressure...this is a true, valid, repeatable scientific fact; and, other plumbers that I respect have said that it has happened to them. That it didn't happen in this instance does not prove your theory. There are lots of variables, and they all have to align. I stand by the statement that you should have an opening when making the last soldered connection. That the problem doesn't always happen is somewhat irrelevant. What you did prove is that a good joint is quite strong, not that you might get a bad one on occasion if you don't follow the 'rules'. Similar to the 'rule' that you should turn a pvc fitting as you insert it in the socket...you can often get a good, leak-free joint if you don't, but you have a better chance of getting a good one if you do.
 

Hackney plumbing

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My opinion is based on both theory...in a closed space, heating gas increases pressure...this is a true, valid, repeatable scientific fact; and, other plumbers that I respect have said that it has happened to them. That it didn't happen in this instance does not prove your theory. There are lots of variables, and they all have to align. I stand by the statement that you should have an opening when making the last soldered connection. That the problem doesn't always happen is somewhat irrelevant. What you did prove is that a good joint is quite strong, not that you might get a bad one on occasion if you don't follow the 'rules'. Similar to the 'rule' that you should turn a pvc fitting as you insert it in the socket...you can often get a good, leak-free joint if you don't, but you have a better chance of getting a good one if you do.

This has nothing to do with a theory or who told you what that you respect. The fact is a joint is not air tight until after its soldered.....at this time all the expansion has already taken place.

The test I did was fact. No theory to it.

Dont swet it(pun intended) your not the 1st enginner who was wrong.

I connected a low pressure gauge and video taped it. I then was accused of having a bad joint so I subjected the piece to its burst pressure that was 3800 psi. The solder joint held.

This has nothing to do with pvc......but I'm sure I could teach you a few things about that also.

I suggest sticking with what you know best because no matter how much you read on this or any other plumbing forum is going to make up for your lack of actual experience in the field.
 

Hackney plumbing

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I also challenge anyone to find were it says when you solder one end MUST be open to atmospheric pressure.......Find it in print and show me were it says this must be done and its a valid source of information. Chatrooms dont count....LOL

You cant.

Solder joints are made by capillary action. Capillary action best works when the capillary space is .002-.005 with .004 being ideal for soldering copper. Get out of that range and you may have trouble. A joint can be too tight just like it can be too loose.

ADD> And I'm done talking about until sombody does find it. Believe what you want. I've proved it over the past 30 years to myself and I proved it here with tests.

So
 
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Tom Sawyer

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Seems like a whole lot of time and effort spent on something that doesn't matter. Of those plumbing related issues I care about, soldering copper with the end closed up ain't even in the top 25.
 

Hackney plumbing

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Seems like a whole lot of time and effort spent on something that doesn't matter. Of those plumbing related issues I care about, soldering copper with the end closed up ain't even in the top 25.

Pick one of those 25 and create a thread that everyone will think matters.
 

Tom Sawyer

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I dunno...TM has a way of dragging things out for weeks and weeks....LOL

Here's the thing though. Why take all that time to do the testing when you can just go to copper.org and get all the facts there? Besides which, who's got a water pump or has city water coming in a 3000 psi?

Back to the soldering thing. If done with care and patience you can indeed solder a closed line and if you still don';t think you can then give it a try. When you are done, take it apart and see if the solder ran around the pipe and the fitting. Here's the deal though. I have done it on many times with no problems and a few times it leaked. Why it leaked I could care less about. Might have been poor technique or it might have been moisture in the pipe. Either way, if I can leave an end open I'm going to because those joints never leak. OK Jimbo, you can close her down now LOL
 

Hackney plumbing

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I dunno...TM has a way of dragging things out for weeks and weeks....LOL

Here's the thing though. Why take all that time to do the testing when you can just go to copper.org and get all the facts there? Besides which, who's got a water pump or has city water coming in a 3000 psi?

Back to the soldering thing. If done with care and patience you can indeed solder a closed line and if you still don';t think you can then give it a try. When you are done, take it apart and see if the solder ran around the pipe and the fitting. Here's the deal though. I have done it on many times with no problems and a few times it leaked. Why it leaked I could care less about. Might have been poor technique or it might have been moisture in the pipe. Either way, if I can leave an end open I'm going to because those joints never leak. OK Jimbo, you can close her down now LOL

Here is the thing though,I wasn't testing the pipe I was testing the joint that I made in the video. A question came up about if it was a good joint or not. I think 3800 psi proved it was "Ok". LOL

Yeah Jimbo close it down...its not going the home teams way.
 

Tom Sawyer

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I recall somewhere there is something that tells you the strength of a soldered joint but for the life of me I can't find it anymore.
 

Hackney plumbing

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I recall somewhere there is something that tells you the strength of a soldered joint but for the life of me I can't find it anymore.

It doesn't state the strength of a solder joint I made that was suppose to be a complete failure. Now would it?

Did you even read the thread?

Thats like telling the inspector...."I dont need to test my pipe because the manufacture already tested it" LOL
 
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