When will my sweat joints leak?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jok, Jan 29, 2012.

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  1. LLigetfa

    LLigetfa DIYer, not in the trades

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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.
     
  2. Hackney plumbing

    Hackney plumbing Homeowner

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    I appreciate that you appreciate the project,thank you. The pipe failed at 3800 psi. I will test all types of pipes and fittings but I have to consider the testing source is a busy business and they dont have the time to rig up the test hose at a moments notice.

    I was very surprised it held up to 3800 psi......I expected "somthing" to fail at a much lower pressure.

    I really do not have a big need to test at high pressure so I'm not in the market to buy a high pressure test rig. The most I pressure my systems up for a test is around 200 psi and thats with pex,I do that with a rex wheeler hydrostatic hand pump.....but it is broke right now. I let it freeze like a big dummy. I had some stuff testing and forgot about it then the weather changed on me.
     
  3. dotkayk

    dotkayk New Member

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    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..
     
  4. ballvalve

    ballvalve General Engineering Contractor

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    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.
     
  5. Hackney plumbing

    Hackney plumbing Homeowner

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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.
     
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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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.
     
  7. Tom Sawyer

    Tom Sawyer In the Trades

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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.
     
  8. ballvalve

    ballvalve General Engineering Contractor

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    I plumbed my house with hard copper 'L', so I think I'll turn up my pressure to 3500PSI and have a real shower.
     
  9. Hackney plumbing

    Hackney plumbing Homeowner

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    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
     
    Last edited: Feb 17, 2012
  10. LLigetfa

    LLigetfa DIYer, not in the trades

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    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
     
  11. ballvalve

    ballvalve General Engineering Contractor

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    I use my tongue to gauge when the copper is just the right temp to add the solder. Good for dieting also.
     
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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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.
     
  13. dlarrivee

    dlarrivee New Member

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    What is that joke about engineers and revisions... lol.
     
  14. Hackney plumbing

    Hackney plumbing Homeowner

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    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.
     
  15. Hackney plumbing

    Hackney plumbing Homeowner

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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
     
    Last edited: Feb 17, 2012
  16. Tom Sawyer

    Tom Sawyer In the Trades

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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.
     
  17. Hackney plumbing

    Hackney plumbing Homeowner

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

    jimbo Plumber

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    POLL: will this thread be over before his joint leaks???
     
  19. Tom Sawyer

    Tom Sawyer In the Trades

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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
     
  20. Hackney plumbing

    Hackney plumbing Homeowner

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    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.
     
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