Replace galvanized drain

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by jtech1, Mar 19, 2014.

  1. jtech1

    jtech1 New Member

    Messages:
    6
    Location:
    NJ
    I have an old galvanized sink drain that runs about 10 feet and threads into the side of the main cast iron waste line (which goes straight down from toilet and 90 out of house).

    The galvanized drain drains very slowly and a snake does not help. I want to replace everything from the sink down with PVC. My question is... should I cut the galvanized drain a foot or so away from the main cast iron waste pipe and attache the pvc there? If so, what should I use, since it would not be threaded. I am concerned with damaging the cast iron pipe if I try to remove the galvanized at the waste pipe, since that would turn this job into a nightmare to replace. Or should the galvanized easily unthread from the cast iron main waste line without issue?

    Second question... there is no vent on this line. The galvanized pipe has a T-off that just 90 deg up and is left open. So, i am sure septic gasses are just flowing into the house. I'd like to put in a vent fitting that allows air in but does not allow liquid or gases out. Do these work? Again, not in a position to run an entire vent line.
  2. SHR

    SHR Member

    Messages:
    96
    Location:
    Minnesota
    Do not try to remove the galvanized pipe from the main line. Cut the galvanized pipe off about 3-4 inches before the main cast iron. Use a shielded coupling

    http://www.fernco.com/plumbing/shielded-couplings/proflex-couplings

    to connect your new PVC pipe to the old galvanized. An AAV valve is what you are referring to and it might work. I try everything possible to avoid using them but they are an option for you.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,480
    Location:
    Cave Creek, Arizona
    If you were to remove the galvanized from the cast iron, there is a good chance you would find that the threads have rusted away and you could not screw a new fitting into it., but that does not mean the existing galvanized connect could not already be ready to fail.
  4. asktom

    asktom Member

    Messages:
    529
    Location:
    Victor, MT
    I'd cut a few inches from the stack and see what you have. If it is reasonably solid use the shielded band. If it is a crumbling rust ball it will need to come out, folks at this site can tell you how to cut it out. AAVs are, in my book, at best, only better than nothing and often equal to nothing. In your case it sounds better than nothing, while doing it right may be a bigger project than you want to get involved with.
  5. jtech1

    jtech1 New Member

    Messages:
    6
    Location:
    NJ
    Thank you all for the advise. I will go the route of the replacement and cutting a few inches away from the main waste pipe.

    I also have another bathroom sink at this property (2 unit rental) that I was not planning on replacing the drain on... also galvanized. There for about 60 years. I think I will probably get it replaced at some point, but it is not as easy to get to. So, for now (I have a tenant moving in this weekend) I need to get the sink flowing. My last tenant never mentioned the sink did not drain properly. In fact, it does not drain at all... I removed the trap and ran a drain auger into the wall. Got about 6 feet in and then stops. Not sure if that is the clog or a 90 bend I can't get around. I need to get this draining for now so my tenant can move in. What other options do I have?
  6. Reach4

    Reach4 Active Member

    Messages:
    2,060
    Location:
    IL
    I would try a BrassCraft Small or Medium Drain Bladder. I don't know if running the auger in 6 feet just cleared out a 3/8 inch hole, or if the first 6 feet of the drain was clear.

    You say "in". If you mean down, that would seem like a more normal clog.

    Not a pro.
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