threading PVC fitting into cast iron stack

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by ksudar, Jul 21, 2010.

  1. ksudar

    ksudar New Member

    Messages:
    3
    Location:
    northern va
    Hello.. I'm redoing a bathroom and have to replace a section of 1-1/2" galvanized drain pipe, which runs horizontally before it meets the main cast iron stack. Now, I was able to remove all of the galvanized pipe and found a 1-1/2" PVC threaded male coupling that will thread into the cast iron hub. My question is whether this will work, and if so what type of sealant I should use on the threads? Thanks for the help-
  2. jc60618

    jc60618 DIY Junior Member

    Messages:
    88
    Location:
    Chicago
    I use teflon tape and Megalock pipe dope. I also would use a PVC schedule 80 male adapter instead of the regular one.
  3. ksudar

    ksudar New Member

    Messages:
    3
    Location:
    northern va
    thanks for the help... I'll give the pipe dope a try and see if it holds.
  4. shacko

    shacko Master Plumber-Gas Fitter

    Messages:
    561
    Location:
    Rosedale, Md
    What you have will work, I only use pipe compound on them, make sure you clean the metal threads and don't cross- thread it.
  5. asktom

    asktom Member

    Messages:
    515
    Location:
    Victor, MT
    I would use a male adapter on a drain rather than a sch 80 nipple. The nipple reduces the ID of the pipe, creating a place for things to start to clog
  6. ksudar

    ksudar New Member

    Messages:
    3
    Location:
    northern va
    This is what I used - I did look for the sch. 80 fitting but they only carried 1-1/4" and smaller. Luckily the cast iron threads were still in pretty good shape, even though the galvanized piece had rusted out. And I'm pretty sure the old pipe was sloping in the wrong direction too. :rolleyes:
  7. Fireguy97

    Fireguy97 Irrigation Contractor

    The "Rules" of PVC, according to the manufacturers.
    (From another forum, courtesy of TreeMonkey)

    Apollo Company strongly recommends not using plastic piping with metallic ball valves, 4th paragraph down:
    http://www.apollovalves.com/_docs/CautionPage.pdf

    Spears (and more so, Lasco) strongly suggest that you only use sealant, not tape, on threaded PVC fittings. The Lasco link to follow goes in to great detail.
    http://www.spearsmfg.com/how_to/FG-3B-0105_0706_English.pdf

    And finally, Lasco has all kinds of rules about using threaded PVC: Sch. 80 not to be mixed with sch 40, absolutely no tape, etc., with a lengthy explanation of the engineering principles behind it. http://www.lascofittings.com/supportcenter/TheDosandDontsThreadedPlastic.asp

    http://www.lascofittings.com/supportcenter/ThreadedPlastic.asp

    http://www.lascofittings.com/supportcenter/Schedule40threads.asp


    The Lasco site has several more links to info about threaded PVC such as this one:
    Why PVC Threaded Connections Fail:
    http://www.lascofittings.com/supportcenter/WhyThreadedConnectionsFail.asp

    Mick
    Last edited: Jul 23, 2010
Similar Threads: threading fitting
Forum Title Date
Plumbing Forum, Professional & DIY Advice, Tips & Woodford (model 14?) nozzle threading Jun 3, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Plumbing the Hard Way - Threading on Exisiting Risers May 20, 2013
Plumbing Forum, Professional & DIY Advice, Tips & pipe threading tool Mar 14, 2011
Plumbing Forum, Professional & DIY Advice, Tips & Corroded threading help Aug 8, 2009
Plumbing Forum, Professional & DIY Advice, Tips & Copper threading tool Jun 21, 2007

Share This Page