Where should I cut and connect the Galvanized Pipe?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by froddan, Jul 16, 2007.

  1. froddan

    froddan New Member

    Jun 14, 2007
    I need to replace some 1 1/4" Galvanized pipe with 1 1/2" PVC because I will install a second lavatory sink.
    In the picture you can see the scenario, and I'm trying to decide where I should cut the galv pipe and connect the PVC.
    What would be the best/easiest option?
    Underneath the wall, a Galv pipe probably 1 1/2" or 2" is going horizontally all the way to the main stack of 3" cast iron.

    The pipe on the left is 1 1/4 and that is the section that needs to be replaced.
    I would like to connect the PVC at the reducer bushing on the upper right, but don't know if I can get the existing galv pipe off without sawing it...it seems to be really really tight.

    I also need to connect to the horizontal pipe below.
    Any thought on what the best connection(s) would be?

    Thank You!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I think it would be best to take out all of the galvanized. You can probably cut it off then with a BIG wrench, unscrew it out of the CI hub. Depending on what you find, you may be able to screw in a PVC fitting, then replace the rest with PVC. Galvanized is a pair, so take it out while you can.
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  4. BAPlumber

    BAPlumber Plumber

    Jul 18, 2007
    Journeyman Plumber, business owner
    Vashon, Washington
    I'm not seeing your picture very clearly. I'd cut out whatever I needed and replace using shielded transition couplings (Mission bands). If your replacing a 1.25" drain you'll have to replace all the 1.25" to avoid a restriction from 1.5 to 1.25.

  5. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Jun 18, 2007
    Plumber, self employed
    Licensed Grump
    I would strongly recommend removing all galvy drainage, also as BaPlumber stated, You can't increase to 1-1/2" and connect to 1-1/4" ...you'd have to replace all 1-1/4" to where it connects to the stack...future clogs in waiting if you do that.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Where are the pictures?
  7. froddan

    froddan New Member

    Jun 14, 2007

    Here is the one picture, and I have removed all the galv pipe above ground and replaced the vent pipe with 1 1/2" ABS.
    I am now working underneath the subfloor where the tub-shower drain, which is 1 1/2" galv pipe, connects to the sink drain and then runs about 3 feet to the main stack.

    I am replacing as much of the galv pipe with ABS, but I cannot reach all of it, so I'm planning on using 1 1/2" no-hub couplings.
    I realize that 2" would probably be better, but with a couple of cleanouts and very rare use of this tub and sinks, would I be fine with 1 1/2" ?

    To clarify the pictures: The photo is obviously the pipes for the double sinks.
    The drawing is what it looks like underneath the subfloor. Tub-shower drain connecting to sink drain and then it goes to the main stack.


    Attached Files:

  8. geniescience

    geniescience Homeowner

    Nov 27, 2005
    humid summers hot, humid winters cold
    1.5" diameter is fine. Fine.

    If the run is long, long, long, then 2" is better. Otherwise 1.5" is sufficient and is not in any way at or near the lower limit of carrying capacity needed to drain a tub or shower.

    That is all I can add, for now. (Can't figure out completely yet what your other questions are asking.) Others will get to your other questions raised.

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