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Thread: cast iron fitting installed in cast iron soil pipe

  1. #1
    DIY Member web_surfer's Avatar
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    Default cast iron fitting installed in cast iron soil pipe

    As a long time reader I have gained a lot of information from this site. Now I have a question that will hopefully be answered. If it has been addressed elsewhere previously please let me know.

    I am adding a cast iron 4" x 4" x 3" upright wye (new Charlotte Pipe) in the 4" vertical cast iron soil stack (approx 60 years old) that runs from the basement floor up through the second floor & then exits through roof. Other than being embedded in the basement concrete floor it was only supported by the pipe running through a 3/4" piece of wood that wrapped around underneath a hub on the first floor. I added a riser clamp on first & second floor. After measuring the the pipe & wye it is apparent that a 4" cast iron to 4" copper coupling is needed (thanks to Terry on this - picked up out of a reply on different thread). Intend on using Mission Rubber CK-44.

    My question is how much should be cut out of the soil stack. If the wye is 8" then how much should be cut out? I notice that the couplings have 1/8" ridge in the middle where the two pieces of pipe meet - so does that mean 8 1/4" cut out? Also, what about future settling on the 2+ stories of pipe above it. I realize that the riser clamps should support the weight, but won't there still be some settling thus squeezing/pinching the middle ridges in the couplings?

    I decided to use the cast iron wye instead of PVC because of concern of the weight that if there is any settling that PVC may not be able to support the settled weight.

    Thanks,

    Matt

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default Y

    Why, if it is a cast iron fitting into a cast iron stack would you need a copper to cast iron coupling, and how would you make it fit? After this amount of time and unless you have a very unusual stack with NO connections to it, there will be NO settling, period.

  3. #3
    DIY Member web_surfer's Avatar
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    Default

    HJ,

    Using the Copper to CI fitting because the new CI fitting has a larger outside diameter than the old CI stack. As a result the Fernco CI to PL, XH CI fitting currently have one end fits the new fitting snug, but other end is way to large for the old pipe. There is quite a bit of excess rubber regardless of which end is used on the old CI.

    Matt

  4. #4
    Moderator & Master Plumber hj's Avatar
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    Default cast iron

    Well, even the thinnest cast iron is MUCH larger than copper tubing. So you are going to have to stretch that copper coupling and the band is going to be "tapered" to cover it. You need a CP-44 which is which is ordinary "cast iron" by XH cast iron.
    Last edited by hj; 06-09-2009 at 12:16 PM.

  5. #5
    DIY Member web_surfer's Avatar
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    HJ

    Thanks for the info.

    Going back to my original question though - how much do I need to cut out of the soil stack for the 8" wye? 8", 8", more, less?

    Thanks,
    Matt

  6. #6
    Master Plumber-Gas Fitter shacko's Avatar
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    Default Cast Iron Tie-In

    Usually 1/8 inch per joint, I would fudge that a little bit due to cast iron known for being uneven. The Fernco or Mission coupling has to be ordered for the types of pipe you are connecting together, and then they will fit correctly.


    "If all else fails, read the directions"

  7. #7
    Moderator & Master Plumber hj's Avatar
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    Default cut

    I always cut at least 1/4" MORE than I actually need just to allow for the unforeseen problems.

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