PVC Inside Metal Pipe

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jandrew, May 30, 2008.

  1. jandrew

    jandrew New Member

    Messages:
    4
    Hi All,

    Well Google led me here, hopefully it's fate.

    I discovered a leak under my kitchen sink. The lead was at a connection between PVC pipe connections just after the "U" (not a plumber so don't know the terminology, but it's the place where rings end up if they go down the drain :eek:). Anyway, the root cause was pressure from a blockage either at the metal pipe coming out of the wall or somewhere between the house and the street.

    When I disconnected the PVC from the metal pipe in the wall I discovered a PVC pipe had been glued/gunked/welded/jammed inside the metal pipe and there is a large amount of really thick, sticky, black sledge inside. Is that normal?

    So the questions are:

    How do I get the PVC out?

    How do I attach a new PVC pipe to the metal wall pipe? (it's not brass or copper, so I'm guessing steel).

    Thanks,
    John
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,360
    Location:
    Yakima WA
    The U shape is the P trap. All drains require one. They are what prevent sewer gas from entering the house. Yes, they sometimes will save a ring, but that's not their primary purpose. You can get replacements at any hardware store or plumbing shop. It is likely your drain is 1-1/2" galvanized steel. When you get the new one, pay very close attention to how it is assembled. The drain end slides into the drain pipe and is secured and sealed by a rubber gasket and a brass ring. The rest to the assembly is done in a similar fashion. These need to be only slightly more than hand tight, so don't horse on the nuts, and do not use any type of sealant. The tubes slide and swivel so there should be no problem in fitting everything together. Sometime a tube may have to be shortened, but a simple hacksaw does the job. There are also extension tubes of the rare occasions additional length is needed, but in the majority of the cases, the standard set will be all you need. The black goo is pretty normal.
  3. jandrew

    jandrew New Member

    Messages:
    4
    Thanks Gary,

    The steel pipe is 2" OD, and threaded.

    "do not use any type of sealant"

    and there's the rub. The person who did this originally used something to "glue" the PVC to the inside of the steel for the entire 4" (approx) length from thread to inside wall T joint. To make matters worse, the PVC pipe glued inside the metal pipe also had the 90degree bend to attach to the P trap.

    Needles to say the connector and part of the PVC pipe shattered (inside the pipe) while trying to loosen the connector. It was obviously a problematic installation as all of the nubs but one on the connector had been scraped off by previous tightening and/or loosening procedures.

    Here's my plan, see if you think it's feasible.

    Chisel out the old PVC
    Use a wire brush to clean the inside of the metal
    follow your instructions

    Which leaves me with one question, how do I connect the 2" metal to the current 1 1/2" PVC assembly?

    Thanks,
    John
  4. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,360
    Location:
    Yakima WA
    It will require some demo on the wall to access the stub coming out of the tee, but I would open the wall and get a pipe wrench on the stub and replace it. Patching drywall is not too difficult and located where it is, the patch doesn't have to be 100% perfect. Do use either Teflon tape, plumbers' pipe dope, or both on the connection to the tee. The no sealant refers to the trap assembly. As I reflect on this, I'm thinking you probably don't have pipe wrenches, the removal of that stub will be difficult at best. With all of those things in mind, I think you should consider hiring a plumber to deal with this.
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