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Thread: ABS into cast iron hub with neoprene gasket HELP

  1. #1

    Default ABS into cast iron hub with neoprene gasket HELP

    I had to replace my bathroom floor, and in doing so removed the closet flange under the toilet, as well the lead pipe connecting the flange to the cast iron soil pipe. (Lead was joined with lead/oakum, which took me decades to pull out. ) Now I have a length of ABS I need to run from the flange to the cast iron hub. I was told a neoprene gasket, which fits on the inside of the bell, would be the best option. But godd*mn if it isn't impossible to squeeze the ABS into the gasket once the gasket's inside the hub.

    Anyone have any advice on this? I thought about some kind of lever, or using a come-along to ratchet it down in there, but the joint is in a very tight space, and right above an elbow -- so no room to maneuver much of these machinations.

    None of the local plumbers will come out for this minor job -- or if they will, not until three months from now. Help!


  2. #2
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
    Blog Entries

    Talking cut the hub off

    the best option is to just go get a cast iron cutter and cut the hub off

    then put a 3 or 4 inch fernco fitting on the end of the cast

    and tie in the pvc to it.....

    Now beating that plastic into the hub can be done if you use some

    sort of lubricant (lots of bear grease) and a short piece of pvc pipe to hit with

    a sledje hammer and 2x4 to keep the pipe from shattering.

    then coupling onto the pvc ppe you have beat into

    the hub.....

    its lots and lots of funn and very manly....

    I try to avoid it at all costs
    Last edited by master plumber mark; 09-03-2006 at 07:43 PM.

  3. #3

    Default yeah, but

    Thanks Mark. The issue with cutting the cast iron is that it's an elbow -- a very short one at that. And there's no real room to cut it, either -- especially not using one of those giant cutters. In addition, that elbow feeds into another segment of cast iron, which I could pull out as well, but then I'm back to square one if I just pull off the elbow.

    I lubed the sh!t out of the ABS and the gasket, but that didn't help much. Or at all, really. And there's no room for sledge hammers and such -- I'm right under the floor, with about 4 or 5 inches between the pipe's top end and the subfloor. Though I guess I could get a longer section of ABS and just cut it off at the top once I've jammed it into the neoprene...

  4. #4


    There was just a recent thread on cutting cast iron. Here's the link:


  5. #5


    Verdeboy -- I'm an Albuquerque kid myself. Nice to see some Nuevo Mexicanos among the forumites...

    Thanks for the link, but after reading it I'm especially sure that cutting the cast iron won't work. Too small a space for the snap cutter, and too small to get a grinder or saw blade all the way around the diameter. (Plus, there's a whole lot of other piping right nearby that I'd have to remove and then replace in order to get a clear shot at the cast iron.)

    So far it sounds like the neoprene gasket is the wrong idea, but I'm still crossing my fingers...

  6. #6
    Engineer PhilUpNorth's Avatar
    Join Date
    Sep 2005
    Montreal, Canada

    Default Document on Compression-Gasket Joints


    At the end of the PDF file at the link below which I saw just today, you'll see some of the tooling and methods that are used to install fittings with compression-gasket joints. I hope it helps.



  7. #7

    Default So where can I find that tool?

    Thanks for the link, Northern Phil. The manual features a special pulling tool for joining with neoprene -- basically a big lever that braces against the bell of the hub. They of course recommend their own brand, the "Charlotte Pipe pulling tool part #EPT-920." But likely there are other, similar tools out there.

    Anyone have an idea where I might find, rent or borrow one of these things?

    Not-so-Northern Phil

  8. #8
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default pipe

    Cutting the hub off would leave you with an unusable curved piece of pipe/fitting to try to connect to. The joint is designed to be tight, but if you have the wrong sized insert, such as one for cast iron pipe, it could be too small for your ABS.

  9. #9

    Default right gasket size?

    Thanks HJ. Agreed about cutting the pipe. As far as having the right fitting, is there a list somewhere that lays out proper sizes or model numbers? Or should it say somewhere on the gasket itself?


  10. #10
    Master Plumber-Gas Fitter shacko's Avatar
    Join Date
    Jan 2006
    Rosedale, Md

    Default Gasket

    Like someone else said, you have to check the gasket. You don't have XH stamped in any of your iron, do you? If so a standard gasket won't work. You have to make sure the the plastic is square, file the outside edge on a slight taper, and use a lot of soap [dish soap is fine]. Lots of luck.


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