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Thread: replacing cast iron sewer with plastic

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  1. #1

    Default replacing cast iron sewer with plastic

    I am trying to replace some old (perhaps 60 or more years) cast iron sewer line that rns into my basement with plastic. I went to Lowes and they have like 3 different brand and colors of pipes that says "sewer" on them .. they were white, green, and gray in color .. i ended up buying the white one because it was the cheapest ($8 / 10 feet pipe).. here are my questions:


    1- Do the colors mean anything? What type do u recommend?

    2- I have 2 use those black flex rubber coupling that have those screw rings (sorry don't know proper name) in a couple of places .. how tight can i make them? i am afraid that i should have bought the more rigid pipes since i have to use these type of coupling

    3- what is the best way to cut the old cast iron pipe .. i am afraid that it would crack .. specially at the end where it eventually goes under the ground ..

    Thanks for your help and suggestions.

  2. #2
    In the Trades Bob NH's Avatar
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    If you bought white sewer pipe that doesn't say "Schedule 40" or DWV; if it is that thin white stuff that is similar to the kind that has holes in it and used for french drains, then you should take it back and get some that at least says DWV.

    Another way you can check is to see if it fits a DWV fitting such as a Wye or Tee.

    And your clamps should have a piece of metal that covers the full length of the rubber cylinder.

    If it is the right pipe, you will not be able to break it with the clamps.

    You can cut the pipe with a chain cutter/snapper device, or you can cut it with an abrasive wheel on an angle grinder. I have also occasionally cut a piece with a very good and heavy duty saber saw. You could probably also do it with a SawZall. I would be more inclined to use a saw or grinder device near the concrete where the consequences of breaking the pipe into the floor are severe.

  3. #3

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    Bob . .thanks for the reply .. no it does not say DWV or schedule 40 .. it does say "sewer line" on it .. i guess i just return it and get the good stuff to be on the safe side .. i am selling the house and want to make sure it will work later .. what does DWV mean anyway?

    Also, a couple of my clamps have that metal piece around them so i should be good there .. but i am also using a flex rubber 3 way (t shape) and U shape one .. r those ok to use?

    also, i am having a very hard time finding all the pieces that i need .. like transfering a 2 inch pipe to 4 inch .. is it because lowes oe ********* don't have all the stuff? where should i look for my parts?

    Thanks for all the help.

  4. #4
    In the Trades Bob NH's Avatar
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    DWV means Drain Waste Vent.

    I'm not a pro at DWV plumbing, and I'm not familiar with rubber Tees and U shapes, and would suspect that they are not acceptable. You should await feedback from the pros in that area.

    You should be able to find 4x2 reducers and such in PVC (the white stuff) or ABS (the black stuff); whichever is used in your region.

    You should search some of the older posts here under plumbing to find some examples and pictures. I'm a little concerned that you are on your way to cobbling something together without knowing the right way to do it. It will look like hell to a new buyer if you don't get it right.

    Those rubber couplings should have metal wrap their full length, as well as screw clamps at the end.

    You would usually use those only where you need to adapt from cast iron to PVC or ABS, and use cemented fittings at all other places. And you can't mix PVC and ABS; use one or the other.

    It would be good if you could post some photos and/or sketches here and get suggestions before you start cutting cast iron.

  5. #5
    Plumber Cass's Avatar
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    You didn't mention how much pipe you are trying to replace and we can't see the scope of the work. By the questions asked I would recomend you get a few estimates at having the work done by a plumber. If nothing else you will have an idea of what amount of work realy needs to be done. Don't be afraid to ask questions. Replacing 1 small peice of pipe could end up being a nightmare if you end up having something go wrong that you didn't forsee and then dont have the knowlage or tools to deal with it.

  6. #6

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    Bob, Cass ... i did get an estimate about 6 months ago and it was about $1500 .. the parts will not cost me more that $200 and i can not imagine taking me (a non-professional) more than 10 to 12 hours, IF I have all the right parts!!!! .. basically .there are 2 iron pipes (one 3" and the other 2") that come from the bathroom and kitchen area from the upper floor (10 feet apart) into the basement where they feed into a 4 inch cast iron pipe that runs almost parallel to the basement floor (well, it is sloped and 20 feet later runs into the ground).. it is this pipe that needs to be replaced.

    .. since the house is being sold "as is" and the buyer is aware of all that is wrong with it, i am just doing this learn something new .. for me it is just a matter of getting the right parts (and learning proper names for the parts) .. i have jumped into much larger projects .. i will try to take some pictures tonight and post .. thanks again.

  7. #7
    DIY Senior Member SteveW's Avatar
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    Quote Originally Posted by switchex

    Also, a couple of my clamps have that metal piece around them so i should be good there .. but i am also using a flex rubber 3 way (t shape) and U shape one .. r those ok to use?

    also, i am having a very hard time finding all the pieces that i need .. like transfering a 2 inch pipe to 4 inch .. is it because lowes oe ********* don't have all the stuff? where should i look for my parts?

    Thanks for all the help.

    Just to be clear about this, there are 2 different types of flexible connectors for DWV pipe. The standard, approved kind consists of a simple "rubber" (probably actually a synthetic material) cylinder, which is covered by a stainless steel band, which is held on by 2 screw clamps. It joins 2 straight pieces of DWV pipe together and is widely used and accepted.

    The fittings you are referring to above are actually whole "joints" -- wyes, tees, etc., -- made out of that "rubber" material. I've seen 'em at the home stores. They certainly look tempting, but I suspect they may not be code (I'm not a pro so don't know for sure). I would recommend NOT using these, unless one of the pros here can vouch for them.

    RE: where to buy "stuff," if you live in a big enough town, you may have access to a professional plumbing supply house like Ferguson's. I've been to my local Ferguson's several times, and while I feel a little like a fish out of water (not being a pro, and it shows!), they have generally been helpful, and they certainly stock fittings, tools, valves, etc. which you will NEVER see at a regular home store. Much better quality stuff in general (and of course more expensive).

  8. #8

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    hire a professional, this work is way out of scope for a DIY. This is plumber grade material.

  9. #9
    DIY Senior Member coach606's Avatar
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    Default maybe, maybe not...

    He could be right about hiring a pro. But like I said, I did mine. The chain cutter is not very hard to use, nor were the riser clamps. Measuring, cutting and gluing in a pvc wye with shielded no hub couplers was also a fairly easy DIY'er job.

    I'd be worried about crushing the pipe near the part that goes into cement, but I'm not sure that's even an issue. Seriously, the snap cutters were EASY to use. Just wrap the chain around your marks and ratchet it tight until you hear a little 'thunk.'

    If you can properly support the pipe with riser clamps and the pipe snaps (as I believe most do) you should be fine. Hey, if you're not comfortable hire a pro. But I think a DIY'er can do it. I don't believe it's way out of scope. If things go well it's actually pretty easy.

    If the pipe crushes, it would have happened to the plumber, too. So you might was well take a shot before calling him. Mine was 80 years old and snapped easy. I think a plumber will try snap cutters first, too.

    If you want to research and are comfortable, it is something a DIY'er can do in my opinion.

  10. #10
    DIY Junior Member Stainedrat's Avatar
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    Quote Originally Posted by mn_nobody
    hire a professional, this work is way out of scope for a DIY. This is plumber grade material.

    I have to laugh at this remark. It is a simple job that I could have done before I became a "Professional"
    Coach says the truth. Make sure you support the pipe with riser clamps.
    The Rubber flexible connectors are of two types. You have the simple connector which is commonly referred to by its major name brand (FernCo) and has 2 hose clamps on it. I recommend you avoid these. Use the No-Hub band connectors (rubber connector with a metal shield and 2-6 hose clamps) and only use these at your transition points. Make sure you use schedule 40 PVC Pipe for the new material. The Green pipe is not rated for the job you want it to perform. The Gray Pipe is more than likely Schedule 80 and much more pipe than what is needed.

    As coach says the snapcutters are easy they are but even a "professional" can crush and old pipe with the snap cutters. When you cut the CI by the concrete floor I recommend you use an abrasive tool such as an angle grinder to cut the pipe. This will ensure you don't destroy the pipe and in turn have to do more work than you want. Make sure you use proper PPE (personal protective equipment) i.e. safety glasses, face shield, leather gloves, etc when grinding on the pipe.

    Leave the support on the pipe you are not removing, it will be better for everyone in the long run.

    One more thing. Selling a house as-is is fine but make sure you disclose what you know regardless, because in this day and time as-is doesnt necessarily protect you from lawsuits.

    And frankly if it was me and I was selling the house as-is I'd leave it for the new owners. No sense in spending money on someone else's house.

  11. #11
    DIY Junior Member plumber66's Avatar
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    use a grinder and a wafer style cut off wheel to cut the cast. understand that the cast is going to be heavier than it looks. use dwv-drain waste and vent pvc to replace make sure you hang the pipe every 4' and use the proper size fernco couplings to tie the cast and pvc together. there is nothing worse than hearing a cast line crush under the load of a pair of soil pipe snappers. If the pipe was good it probably would not be leaking and then i would say rent a pair of snappers. read the lettering on the pipe you are buying somewhere it is going to say dwv or sch 40 go or even cell core you can use any one but the pipe will be white in color.

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