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Thread: Concrete to PVC

  1. #1

    Default Concrete to PVC

    I have a concrete tube 8" ID (more or less) and a PVC tube 8" OD (more or less). I want to put the PVC tube inside the concrete tube and get a good seal. I was thinking a combination of a donut and a coupling device. Any suggestions?

  2. #2
    Plumber jimbo's Avatar
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    Seal against what? something getting in? something getting out? how much pressure?

  3. #3

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    Itīs about 60 psi of pressure and of course I want the seal to prevent water from leaking out.

  4. #4
    In the Trades Bob NH's Avatar
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    This would usually be a municipal distribution system problem.

    I assume that the concrete pipe is fully rated for pressure. If it is rated pipe, there should be standard joints for it. If it is not pressure rated pipe, then you should not attempt putting pressure in it.

    The standard jooint is probably a gasketed joint with some kind of tie rods to take the axial loads at bends and tees.

    If it is a straight run, then there is no axial load. Consult with an engineer who has access to the standards for that kind of pipe.

    The axial joints would have to be held with some kind of restraint-resisting block at all turns. The axial force will be on the order of 3000 pounds.

    You might have to get some kind of engineered adapter if it is not standard. It is not difficult but it will be relatively expensive.
    Last edited by Bob NH; 06-18-2006 at 10:36 AM.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default pipe

    IF it is 60 psi, then it is not concrete, rather Transite asbestos pipe. The only transition that will work is a Dresser type, (Baker, Dresser, etc.), with the proper reducing gaskets on both sides. You will have to know the approximate o.d. of the transite because the o.d. varied according to the pipe's class, so that the proper gaskets and coupling will be furnished.

  6. #6
    Plumber jimbo's Avatar
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    Well, simply put this is just out of my league. Out of curiosity, what are you working on that has a 6" line pressurized to 60? Is this a community main as others implied?

  7. #7

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    Sorry if I misled. The psi I just assumed was 60 but now Iīve been told that itīs much less. Itīs an underground drainage network running through some pasture fields and it comes out at a drop off. At this exit Iīve built a 25000 liter tank and I want to fill the tank with the water that comes out of this concrete tube. The tank rim is about 1 meter 20 cm above the concrete tube. Iīve been thinking to put the PVC tube into the concrete tube and then reduce it from 8" to 4" and then put a 4" Tee and reduce again to two 2" tubes that will go up at about 60 degrees to the tank rim approximately 2 meters from the concrete tube. The water during the rainy season (June-November) comes out of the concrete tube between 4"-6" constantly. In order to get the water to get enough pressure to get up to the tank I believe I must have a very good seal where the PVC and concrete tube unite. I hope this clarifies my question and any help will be greatly appreciated.

  8. #8
    In the Trades Bob NH's Avatar
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    Since is is a drainage pipe, it works by gravity. You don't want to put anything on the end that will restrict the flow. That will defeat its drainage capability.

    Of course, if you own the whole pipe, and no responsibility for draining water from an adjacent site, that is your choice. If water is going into that pipe from some other property, you can't put any restriction on the end.

    If it is on your own property, you are probably going to make a flood if you raise the end by 1.2 meters.

  9. #9

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    I also plan to use a 8" Wye with one side going to the tank with the reducers and the other to continue draining the pasture with a globe valve to open and shut the drainage or to fill the tank.

  10. #10
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Pressure won't be a problem (about 2.5 psi, according to the back of my envelope), but as Bob points out, nothing upstream below the level of the top of the tank will be drained as long as you're diverting the outflow up to the tank. Valve plan will work, but some sort of float valve to automate the process would would be more appealing.

  11. #11
    In the Trades Bob NH's Avatar
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    " . . . and it comes out at a drop off. "

    Since the outlet is at a dropoff, the elegant solution is to build a water wheel or other device that is powered by the main flow during high water times, and have that wheel drive a lift to fill the tank with maybe 10% of the total flow. When the tank is full, it runs over, but who cares. Requires no attention and never restricts the flow.

  12. #12
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default ooooh, I like that!

    But a Q&D energy conservation analysis says we're not going to be able to pump all the water up into the tank. How much of the watershed is in fact above the level of the tank? A neat project nonetheless; post pictures when it's done.

  13. #13

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    Bob,
    Thatīs a very good point. Iīll investigate how this could be implemented. Thanks for your insight and to everyone who chipped in.

  14. #14
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default An alternative

    How far upstraem do you have to go to be able to tap into the drain system at a point above the tank level? I'm thinking just run a second pipe from there directly to the tank, and let the lower portion of the drainfield continue to drain through the original pipe.

  15. #15

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    Mikey,
    Another very good point. Iīll also investigate this possibilty.

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