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Thread: Cast Iron Drain Modification Needed

  1. #1
    Engineer PhilUpNorth's Avatar
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    Default Cast Iron Drain Modification Needed

    OK. My turn with a cast iron and ABS problem. Its pretty simple, really. I've got this cast iron Y piece into which a kitchen drain is connected. The problem is that the 2" ABS that feeds into it (on the attached picture, that's the connection at the top, just after the 45 degree elbow) is pretty much horizontal over a distance of about 20 feet, so needless to say it needs to be unclogged maybe once every 6 months. To fix this problem, I reckon that I should lower the kitchen drain connection by 5 or 6 inches which should give me enough slope. I've never played with cast before, but the job seems to be pretty straightforward to me:

    1) With an angle grinder, I'll cut the straight piece that sits between the cast 4x4x2 and the 4x4x3 Ys, maybe a couple of inches below the hub. I think I've got enough room for this all around.
    2) I'll get rid of the remaining piece of straight pipe, and of the 4x4x3 below it.
    3) I'll permanently cap the 2" connection on the 4x4x2
    4) With a hubless coupling, I'll join the shortened cast iron piece to a small section of 4" ABS below it, which will then be joined to a new ABS 4x4x2 (which will now be at the correct height), followed by another piece of 4", followed by a new ABS 4x4x3 for the lower connection...

    Am I missing anything, here, or is this the extent of it? Any trap, pitfall, etc. I have to be aware of? Thanks for any suggestion or comment.

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

    You did a good job of photographing the cast iron, but I would rather see the 2" sink drain. If it is like I am guessing, then just removing that adapter, etc., into the "Y" and replacing it with 2" street 45 into a No-Hub coupling would drop the pipe several inches. But that section of cast iron with the duct tape on it probably should be replaced if the duct tape is covering a crack.

  3. #3
    Plumber plumber1's Avatar
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    Default

    It couldn't hurt to put a clean out in the ABS under the sink, in fact you might be glad you did someday.

  4. #4
    Engineer PhilUpNorth's Avatar
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    Default So, How Do I Disassemble Cast Iron

    Thanks for the reply, HJ and Plumber1. As you had suspected, the straight piece is cracked... I had just hoped that the crack would start low enough that I could amputate the straight piece and still have enough material to use a hubless coupling on it. But, as you can see on the attached picture, the crack goes right up to the hub, so a hubless coupling probably wouldn't perfectly cover and seal the crack. I guess the issue now is that I've got to remove the cracked cast iron part. Any idea how I can do that? Do I have to remelt the lead (given the mass of cast iron around it, I doubt that I could do this with propane or MAP), or can a combination of hub cutting/grinding at strategic locations and brute force do the trick?

    Thanks

    Phil
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  5. #5
    Master Plumber-Gas Fitter shacko's Avatar
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    Default Cast iron repair

    If you own a 4 1/2 angle grinder that would be the thing to use with a cut off wheel. Cut into the bell [thats where the lead is] untill you contact the lead, make as many slices around the bell that you can, then use two hammers, one is a backer and hit until the pieces break off. As old as that pipe is the wye probably has a spigot on the bottom, you will have to cut that off also. I would also recommend a Fernco or Mission coupling instead of the no-hub band thats on there now. Luck.

  6. #6
    Engineer PhilUpNorth's Avatar
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    Default So What's Keeping All Of This Up?

    As always, contributors of Teerylove.com, thanks for the advice. One last question on this drain of mine, and then I'll leave you alone for a while: What's going to happen once I remove the two cast iron wyes, and suddenly a two-foot gap appears between the ABS at the bottom and the top cast iron elbow (which has got two floors worth of other cast iron on top of it)? Will it be:

    (1) The whole cast iron drain pipe located above the new gap "quickly" comes down a couple of feet because the removed piece was what was holding it up and it ain't there no more, or
    (2) The cast iron above remains above because something else (like brackets, clamps, etc.) is holding it nice and steady inside my walls.

    Is the smart money on shoring up the drain properly before doing anything to what's underneath it? Or, rather, would you think something like "Nah! that 4" ABS isn't strong enough to hold up his cast iron, so something else must be doing the job!"

    Thanks

  7. #7
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default

    I think the smart money is on shoring up the drain properly before doing anything to what's underneath it, in spite of the appearance that it's being held up by other mysterious forces anyway -- probably various bends and such.

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