joining PVC to CI

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by ksuwldkat, Jun 7, 2009.

  1. ksuwldkat

    ksuwldkat New Member

    Messages:
    2
    I have CI coming up from the floor, and I'm trying to join the PVC main stack to the CI pipe. I've tried using no hub couplings, but the joint keeps leaking around the CI, and the bands keep slipping down the coupling toward the CI. I'm not sure if the CI is slightly too small for the coupling. Is there something I can use to increase the thickness of the CI, perhaps that silicone tape material? I have considered a rubber fernco, but after reading on here that appears to be against code. Any suggestions?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    22,324
    Location:
    New England
    Is the part coming out of the floor a hub, rather than a straight piece of pipe?
  3. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Pictures are a plus.
  4. Terry

    Terry Administrator Staff Member

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    15,419
    Location:
    Bothell, Washington
    If the cast iron pipe measures 4-1/8" OD, then the proper no-hub coupling will be a Copper x Cast Iron transition.

    Some old cast iron is the outside dimension of copper pipe.
  5. ksuwldkat

    ksuwldkat New Member

    Messages:
    2
    I'll see if I can get a photo. Cast comes out of the slab, then there is a hub, and about 6" of CI before I'm trying to make my joint. I talked to someone from Fernco, and they suggested it might be service cast? and suggested using a flexible coupling, perhaps using the metal sleve from the proflex around the flexible coupling if it will fit and I want to be extra cautious. The diameter of the CI is 4.3". It's very close to the same diameter as the pvc
    Last edited: Jun 9, 2009
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