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  1. #1
    Join Date
    Dec 2013
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    2

    Question How long will rubber PVC-to-cast iron adapter last?

    Just watched the segment "Underground master bathroom" where Richard uses a rubber adapter to tie the new PVC into the old, existing cast iron drain pipe, all of which will be covered in cement for the buildout. My first thought when I saw this was "Gee, won't the rubber eventually corrode and leak, making for a very expensive & intrusive repair?"

    How long can that type of connector reasonably be expected to last?

  2. #2
    Join Date
    Jan 2010
    Location
    Northern Virginia
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    1,165

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    Quote Originally Posted by mcdorman4 View Post
    Just watched the segment "Underground master bathroom" where Richard uses a rubber adapter to tie the new PVC into the old, existing cast iron drain pipe, all of which will be covered in cement for the buildout. My first thought when I saw this was "Gee, won't the rubber eventually corrode and leak, making for a very expensive & intrusive repair?"

    How long can that type of connector reasonably be expected to last?
    The way to think about this is to realize that the joint is under no pressure, and the mass of the iron and the under-slab location means there is no movement to disturb the seal. Generally, under those conditions, rust forms a very good tight seal over time. With the coating of slime, there is little oxygen to degrade the rubber, and it's probably silicone rubber at that. Even cast iron is going to rust through eventually, so if it was halfway through its lifetime, the repair should be good for the remaining 40 years.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  3. #3
    Join Date
    Jul 2010
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    SoCal
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    6,472

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    This product is a proven one. It's virtually "lifetime".

  4. #4
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    I checked the manufacturers website and was quite impressed by the quality of the products and the high number of national and international codes their products meet.

    In my 30 years I have never seen one fail or hear of a corroded one.

  5. #5
    Join Date
    Dec 2013
    Posts
    2

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    Excellent -- I wouldn't have expected those answers. It's good to know that should last a long time. Thanks for responding, folks!

  6. #6
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,589

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    Just be sure to tighten the bands according to manufacturer-specified torque values. No, I don't know what the torque specs are.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  7. #7
    Join Date
    Jan 2008
    Posts
    2,041

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    I've never seen one fail without excessive strain or movement involved. Even then, the failure scenario is usually a joint sliding apart and it can be just as easily slid back together, this time supporting the piping better. These "Fernco" couplers (generic trade name) do have a specified torque value, but I have fared well by watching the band as it tightens, and when it has well compressed the rubber I stop there. Over-tightening may cause a split or a clamp failure; under-tightening may cause a leak but that is easily repairable with a bit more tightening, so err on the loose side. On older cast iron pipes that are pitted or have casting flaws where it's going I slather a bit of silicone where I expect the problem to happen but keep that local since silicone is slippery and will keep the Fernco from 'biting' the pipe, allowing the fitting to slide off more easily. On PVC I also like to use primer and let it dry before assembly- this seems to enhance the 'bite'. I'm not sure if the rubber will like wet primer which may deteriorate it. These are rated for inaccessible locations which means that you should never need to deal with them again when they are installed correctly.

    Phil

  8. #8
    Join Date
    Sep 2008
    Posts
    94

    Default Re: How long will rubber PVC-to-cast iron adapter last?

    Well mine is leaking... It is connecting a 3 inch PVC Pipe to a 3 Inch Cast Iron. It has been in place for less than 10 years and is now leaking, it is from about 5 ft down from the wood floor joists to the old cast iron and is behind the old cement utility sink in my basement... So all I can say is that it is never bumped or anything and yet it is leaking. I asked about this mid 2013 wondering if there was a longer one and all said there was only the one I had installed when the cast iron drain started leaking about 8 ft away where the drain from the toilet tied into the tub drain. And the pipes are supported... I am have yet to replace the coupler because I will need to sand the cast iron pipe to smooth it out because that is where you see the rust stain where the water is running down the pipe to the floor.

    So again it sounds good but they can leak and mine worked for about 7 or 8 years and then just started leaking this last summer...One would think if it was going to leak it would have sooner not this long after being put in place...

    So 40 years is not true at least not here...

    MMeehan

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