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OT, plumbing, plastic to cast iron.....

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  • OT, plumbing, plastic to cast iron.....

    Situation is leaks in the old galvanized kitchen sink drain pipe running across the basement ceiling to the main cast iron sewer pipe. Because the galvanized pipe doesn't have much slope it's rusted through and has small leaks along it's length, it needs replacement. The joint where the pipe meets the cast iron is one of the old type using oakum, caulked with lead.

    Is there a modern alternative to the molten lead type joint to seal a plastic replacement pipe to the cast iron? A trip to Home Depot with the question yielded me a blank stare when I mentioned cast iron sewer pipe.

  • #2
    Yeah. They make neoprene transitions with SS strap clamps between them. They also deteriorate over time.


    • #3
      Fernco adaptors

      I assume you are going into a cast iron hub (bell) in which case a rubber adapter is available. "Fernco" makes a rubber "donut" for this. Plumbing wholesalers should stock them. I've also used 100% silicone calk with good results. I've even seen one poured with lead that appeared to work. I'd recommend that method for anyone who enjoys wearing his shoes on the wrong feet.


      • #4
        I had to do something like that, about 30 years ago, at my first house. Memory is dim, but I seem to recall I bought some stuff called "plastic lead," which was some goop sort of like plaster, for just the situation you describe.

        Anyway...if you go to a place that really knows about plumbing, they ought to be able to help you out. You aren't the only person who has ever run into this problem.
        Try to make a living, not a killing. -- Utah Phillips
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        • #5
          Adapting ABS (plastic) to Cast Iron....

          OK, several of the guys have mentioned the 2 popular methods. Fernco or Cremco couplings (rubber) are probably easiest. That's what I use (plumbing pays the bills). Just make sure that the replacement pipe enters the hub of the T or Y that you pull the old piece of galv. out of. Otherwise stuff will hang up and clog the drain.
          If you want to do one of the cold-caulked joints, I think the stuff is called PC III. Pick out the old lead and asbestos, get an ABS (plastic) caulk adapter, caulk around it and pipe your sink drain as needed.
          If the slope is too small and you can't change it, maybe add a cleanout too.
          Hope that helps.


          • #6
            I added a second story to my house a few years ago. We installed PVC for all the waste drain lines.
            Here is a shot of how the new PCV pipe was tied into the old cast iron pipe.

            The plumbers cut out a section of the cast iron pipe using a chain like cutter that had cutting disks in the middle of the chain links. They tightened the chain and the compression of the cast iron pipe made a very clean precise cut. I had never seen this technique before.
            I have not had any leaks or problems.
            Messy basement blanked out of the picture.

            Last edited by fixxit; 04-23-2006, 03:58 PM.


            • #7
              If the galv pipe enteriing the CI hub is still good for at least 2" outside the hub, all you need to do is cut the pipe 2" away from the hub, deburr the end in and out, and connect your new pipe (any type, CI, plastic, galv) to the stub with a "No Hub" coupling.

              Those are the stainless band clamp couplings in Fixxit's picture.

              They are relatively cheap, very good and removeable.
              The clamps should be tightened to 60 inch pounds.
              Plumbers use a special torque wrench for that.
              You can use a 5/16" nut driver and it will be fine.
              The rubber gasket is neoprene.
              Be careful not to overtigten it, its easy to break the worm drive clamps.

              If the galv pipe is rotted all the way into the hub, then cut the pipe off leaving about 1/4'" stub then slit the stub legnthwise, squeeze the now split pipe then pull out, then remove the lead and oakum with a scraper or chisel or screwdriver.

              You will have to place a new stub in the hub.
              I would recommend a piece of CI pipe.
              You will have to caulk (pack) in the oakum (oiled hemp) into the hub till its packed tight to about 1/2" deep, then you can either pour lead, pack in "lead wool" or just use your favorite epoxy.
              The caulking is done with caulking irons.
              If you don't have such or don't know what they look like, a thin blunted cold chisel or short piece of flat bar about 1/2" x 3/16" will work well.
              If pouring molten lead it must be caulked in after cooling.
              Lead wool becomes solid lead when caulked in properly.

              When the stub is set, just connect the new pipe with a "No Hub" coupling.