At 1/4 slope should water completely evacuate the drain lines?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by sazerac, Nov 18, 2019.

  1. sazerac

    sazerac New Member

    Joined:
    May 29, 2019
    Location:
    San Diego
    I'm replacing some cast iron pipe with ABS and I've got a two-way cleanout, then a combo, which then goes to a 3"->2" reducer and a 45 elbow. The slope looks correct, I've measured it several times and it's almost exactly 1/4" per foot. When I run some water down the combo I notice the water goes down the drain but a decent amount pools and is visible down the two-way cleanout. is this expected or is my measurement off or something else? I'm aslo getting quite a bit of drip out of the coupler, it's a 3000-33/CP-33, so it should be correct. I haven't fully torqued it yet, but it seems pretty tight. Thanks! IMG_0982.JPG IMG_0983.JPG
     
  2. James Henry

    James Henry In the Trades

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    There might be some waste in the bottom of the pipe holding the water back or the pipe no longer has grade. put a hose in the combo and turn it on full for 4 or 5 minutes. If the two way clean out doesn't back up it's probably nothing to worry about. put your level on the cast iron pipe and check it for grade.
     
    Last edited: Nov 18, 2019
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  4. plumber69

    plumber69 In the Trades

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    The cast has to be really clean on the ouside where the clamp goes. A file helps
     
  5. plumber69

    plumber69 In the Trades

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    Or you may have a split in the cast
     
  6. sazerac

    sazerac New Member

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    May 29, 2019
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    San Diego
    There's still a tiny bit of clay/rust compound stuck to the edges around the pipe. I used a wire wheel on a drill, a razor, and god knows what else. I'll try a file next.
     
  7. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    You could use some silicone plumber's grease to help the rubber flow into the crannies. I would try just tightening first, to see if that solves the problem on its own.

    Regarding standing water, is that maybe 1/8 of an inch? I would not worry about that.
     
  8. sazerac

    sazerac New Member

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    May 29, 2019
    Location:
    San Diego
    It looks like it might be 1/8 inch. Soil here is mostly clay and the cast iron is 50 years old so I wouldn't be surprised if it's lost some grade over the years. I intend on repiping everything at some point, but it's not in the budget yet. I just want to make sure I've gotten rid of all the cast iron in the parts of the house that will be remodeled so I don't have to tear everything up again.

    I ran the hose down the combo for quite a while and no back up. Some of the turbulence that you can see in the cleanout threw me off because it almost looked like it went the other way, but I sprinkled some stuff that floats and it went it's merry way down to the sewer.

    Thanks for all the tips!
     
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Retired Systems engineer for defense industry.
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    New England
    Smaller than 4", calls for at least 1/4"/foot, but once you get to 4" or larger, they allow 1/8"/foot. But, any flat spots or bellies can create issues.
     
  10. Tuttles Revenge

    Tuttles Revenge In the Trades

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    Oct 15, 2014
    Theres no Perfect in retrofitting to underground sewer. The ground moves and changes.

    Cleaning the crap outta the outside will help reduce drips, which you should be able to get. But removing the tar coating exposes the cast and will rust that much faster. Hercules makes a product called Griiiiip (might have one or two less i's) that is great for covering exposed cast iron and a side beneftit of forming gaskets on questionable pipe surfaces. Use it sparingly and treat it like a contact cement.
     
  11. mliu

    mliu Active Member

    Joined:
    Feb 7, 2007
    Location:
    Colorado
    You need to clean around the entire outer surface of the cast iron pipe to the depth of insertion into the no-hub. Considering how shallow the trench looks under the pipe (perhaps it's just hard to see from the photo), it appears you didn't get a wire wheel under the pipe to clean the bottom surface. The pipe should be a smooth as possible. One way to do this without a lot of clearance under the pipe is to get a long strip of coarse emery cloth, slide it under the pipe, and work it back and forth to smooth the pipe. This is easier than a file and you don't risk putting flat spots or gouges in the pipe.

    After you mechanically clean the pipe really well, wipe it off with a rag soaked in mineral spirits and let it dry. Then apply Black Swan No-Hub Sealant to the outside of the pipe and then slide your no-hub onto the pipe (apply the sealant to the cast iron pipe ONLY; do not apply to the ABS side). The no-hub sealant will fill any leak paths in the surface of the cast iron pipe caused by rust or other damage. This stuff is a bit expensive, but it will ensure a no-leak seal. No one wants sewage leaking in or around their house.

    After you have sealed and tested your joint to be leak-free, then you can apply a seal coat to the outside of the cast iron pipe to stop rust around the area of your repair.

    I would not recommend putting any silicone plumber's grease on the pipe. Doing so will prevent you from applying any sealant to the pipe, either inside the no-hub, or on the outside of the pipe to prevent rust.

    [​IMG]
     
    Tuttles Revenge likes this.
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