Join 3" ABS to 3" PVC

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by derry, Dec 26, 2011.

  1. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
    I need to join a 3" ABS pipe from the toilet to a 3" PVC sewer pipe under a concrete slab.
    OD for PVC is 3.25" approx, and 3.5" for ABS. What is the best way to do this?

    It was glued before but leaking. If I'm using glue again I'm planning to use a standard 3" ABS coupling with an ABS bushing adapter as a reducer to connect the PVC pipe. Is it correct? (I'd use transition cement (PVC to ABS) to join the PVC pipe to the ABS bushing)

    I can also use a Fernco but I don't know which one (model?) AND if I should use a PVC bushing to increase the OD for the PVC pipe.

    Thanks.
    Last edited: Dec 26, 2011
  2. kreemoweet

    kreemoweet New Member

    Messages:
    371
    Location:
    Seattle. WA
    You'd best determine EXACTLY what type of pipe you're dealing with. I don't know how things are in Canada, but around here
    legal PVC and ABS pipe used for sanitary drain, waste, and vent applications are exactly the same sizes. There might
    be a proper adapters to join the different sizing-standards pipe you apparently have.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,308
    Location:
    Yakima WA
    Couple of things. First, ABS and PVC connections are not made with glue as we normally thing of glue. These are plastic materials, but are made from different chemicals. The so-called glue is actually a solvent that when applied to the pipe and fitting surfaces actually liquify the surfaces briefly. When the pipe and fitting are slipped together, the two surfaces combine and form a chemical weld. Since PVC and ABS are different chemically, the solvent for one does not work on the other. There is however a solvent that will work on both, but you have to be sure you get the right can. The other way to connect them is with a banded coupler. When most people refer to a "Fernco," they are thinking of the neoprene sleeve with hose clamps on each end. These can not be used above ground as the will not provide a solid connection. That's why the banded coupler. Whether using the special solvent or the banded coupler, you must be sure the size of the coupler is correct.
  4. Chad Schloss

    Chad Schloss Member

    Messages:
    328
    Location:
    USA
    The 3.25" PVC that I have worked with is called Schedule 30, thin wall pipe. There are transition adaptors to go to schedule 40 PVC, which is the normal, thicker stuff. Not sure about joining to ABS. I'm just a diy'er, not a plumber.
  5. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
    The ABS pipe is black, 3" ID - 3.5" OD.
    What I suppose is PVC is white, it's written sewer on it, 3" ID - 3.25" OD.

    I bought a 3" white PVC coupling and the white pipe fits perfectly in it, however the ABS pipe is too big for it.
    If I put this part http://www.canadiantire.ca/AST/brow...20P/Bow ABS Sewer Adapter, 3-in.jsp?locale=en
    in a 3" ABS coupling, then I can connect the white pipe in this bushing, it fits tightly although the pipe can easily touch the bushing's stop (I mean without cement the pipe is fully engaged in the bushing).

    The cement I'd use is this one: http://www.oatey.com/Channel/Shared/ProductGroupDetail/166/ABS_to_PVC_Transition_Green_Cement.html
    but I saw some codes don't accept this so it seems it can fail (?).

    I'd rather use a Fernco or both if possible. In my case it's below ground so I suppose I can legally use any Fernco PL to PL 3 x 3, but which one would you use?

    Chad it seems you're right, this will help to ask for the right pipe since I need to extend it.
    Thanks.

    Edit: I'm not sure but I don't think the Fernco 1056-33 is neoprene (I saw it's flexible PVC). The Proflex is made of neoprene.
    Last edited: Dec 27, 2011
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,068
    Location:
    Maine
    A 3" two band Fernco is the way to go
  7. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    You're trying to connect DWV piping to sewer piping.

    The PVC sewer piping isn't supposed to be inside the house.

    Stop trying to glue them together.
  8. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
    I'm not surprised. A lot of things were wrong in the plumbing. The most funny was a backwater valve not even glued or attached to the sewer pipe.
    It would be difficult to correct this problem because right now the water table is above the sewer pipe out of the house.
    Last edited: Dec 27, 2011
  9. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
  10. Chad Schloss

    Chad Schloss Member

    Messages:
    328
    Location:
    USA
    you can use schedule 30 here where I live. our house from 2005 has it throughout the house. I don't like it, but it's here.
  11. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    That is unfortunate.
  12. Chad Schloss

    Chad Schloss Member

    Messages:
    328
    Location:
    USA
    yep.. the main lines are all sched 30 and sched 40 connects to it. I think they used it because it fit inside a 2x4 wall, instead of using the correct material and bumping the wall out slightly. it works, it's just a little more noisy than i would like.
  13. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Strange, so you have couplers all over the place?
  14. Chad Schloss

    Chad Schloss Member

    Messages:
    328
    Location:
    USA
    i have a finished basement, and the main line in encased in a drywall covered buildout so I can't see that. I can see the upstairs piping in the utility room, which is sched 30 there. I can see the wye coming from the kitchen sink is a genova 61032 pictured here: http://www.doitbest.com/PVC wye-Genova Inc-model-61032-doitbest-sku-416990.dib

    i don't see any transition fittings to connect to the 2" coming from the sink. i see a clear type of glue on the 3.25" bristol pipe, and a purple glue on the 2". maybe it's a 2" schedule 40 fitting on the 3x3x2 wye pictured there?
    Last edited: Dec 27, 2011
  15. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
    If it can help someone, I called the Fernco company and they said I should use the 1056-33 or 1056-33RC. The PROFLEX shouldn't be under a slab. The 1056-33 can go over a sched30 PVC without bushing to increase its outer diameter.
  16. derry

    derry New Member

    Messages:
    16
    Location:
    Quebec
    Last edited: Dec 28, 2011
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