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Cast Iron “Going Bad” ?

AndrewG | Posted in General Discussion on July 12, 2005 08:43am

Today I encountered something new to me, and I’d like to hear from others if they are familiar with it. I had a plumber out for an estimate on installing a washer/dryer in a house that I am moving into. He pointed to the many little stelagtights forming along the bottom of all the cast iron drain lines in the crawl space, and said “your cast iron is going bad”. He went on to caution that I keep an eye out for any leaks that develop, adding that I would most likely have to replace all the cast iron in a few year’s time. He was not fishing for work (he wasn’t interested in doing the work). Anybody know anything about cast iron “going bad” ?

Thanks,

 

Andrew

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  1. jackplane | Jul 12, 2005 08:49pm | #1

    Cast iron naturally will rust in the presence of water.Surface rust doesn't matter but sitting water due to poor slope conditions can lead to bad rusting, pitting etc. Over time the pipe strength is compromised. Your plumber is right.

     

    1. AndrewG | Jul 12, 2005 09:44pm | #3

      I should have added that the house was built in 1969, that the crawl space is 4 feet tall and the waste lines are hangerred from the floor joists and so are no where near standing water (although the crawl space does have more moisture than it should due to inadequate venting), that there appears to be no sign of rusting, and that the stelagtights are not associated with proximity to fittings.

      Thanks,

      Andrew

      1. JohnT8 | Jul 12, 2005 09:53pm | #4

        Andrew, I think the 'standing water' they are referring to is when a horizontal run of the pipe is TOO horizontal.  So the 'stuff' in the pipe doesn't drain very fast and the water (& stuff) tends to loiter more in the pipe and allows it to slowly erode the pipe (from the inside out).

         

        The next flush (or whatever) pushes the stuff along, so it might not be backing up, but its still got water sitting in the pipe.

         

        Whereas on the vertical runs, the water just waves as it goes flashing by and doesn't have time to erode the pipe.       : )

         

        jt8

        In an underdeveloped country don't drink the water. In a developed country don't breathe the air --Jonathan Raban

        Edited 7/12/2005 2:58 pm ET by JohnT8

        Edited 7/12/2005 2:58 pm ET by JohnT8

        1. AndrewG | Jul 12, 2005 10:10pm | #5

          John T8,

          That not only makes sense to me but was the only 'sensible' interpretation of what I read. ON the other hand, ....cast iron pipes rotting out in 36 years?  REALLY ?

          Thanks,

          Andrew

          1. ChemicalLew | Jul 13, 2005 03:24am | #6

            The cast iron in my crawl space is in the same shape - I've noticed a few drips the last couple of trips in there (waiting to rip out a tub and replace the whole line). This particular part of my house was an addition - sometime after the house was built in 1910 - but I'm not sure how old. There was another set of worn-out cast iron drain pipes that had been left in the crawl when I bought the place, so each set of drains probably lasted somewhere around 30-40 years on average.

            Lew

  2. csnow | Jul 12, 2005 09:16pm | #2

    The stuff lasts a very long time, but it will eventually erode thin then pinhole on the bottom of the horizontal runs.  This can take 80 or more years, depending upon water conditions and usage patterns.  Vertical drops will last virtually *forever*.

    If you already have stalagtites, you may have pinhole leaks, though you may also just have a leaky joint.

    If you take out an old horizontal section, you will observe that it is out of round, since the water generally only flows across the bottom half.

    Keep in mind that the same thing happens with PVC.  Even 10 year-old PVC will be noticeably worn away on the bottom.

  3. DanH | Jul 13, 2005 03:35am | #7

    What you're seeing could be from simple condensation on the pipes. In general cast iron pipes should last 50 years or more.

    If you're courageous you can probe the bottom of the pipe in a few places with a screwdriver or icepick. (Pick spots you can easily repair with a compression patch.) Or just "clang" the pipe in various places and listen for a really dull thud indicating it's about rusted through.

    1. User avater
      Sphere | Jul 13, 2005 03:41am | #8

      DING DING DING...

      You win.  That is most likely.  Spheramid Enterprises Architectural Woodworks

      What are dreadlocks made from?

    2. junkhound | Jul 13, 2005 03:55am | #9

      Condensation like Dan says.

      Worked in many Minuteman sites (controlled to 55 F, below water table in many places like Grand Forks), if there were a pinhole leak in a 1/2" thick steel liner weld, there would be a 6 inch stalactite every 6 months, often a 4 or 5 inch high stalagmite on the floor. Maintenance crew were not fond of them. There were often randomly placed little stalactites on equipment that ran intermittently - got warm and the condensation evaporated, cooled off on the condensation and little stalactites formed.

      Helped my brother last month clear the cast iron pipe in or Grandparents house (they built it in 1907) that had been used by my dad for storage for the last 35 years with the water and heat disconnected in central IL.  Cast iron still in good shape, but had to remove a section of vent pipe to shop vac out all the rust that had fallen in over the years and plugged up the elbows, probably about 8 gallons of rust in 60 ft of pipe total - real job to clean it out. If your house was built in '69, the condensate is what it is for sure.

  4. rich1 | Jul 13, 2005 04:18am | #10

    I'll bet you have bad pipe.  Lots of it out there that came bad from the foundry. I've seen cracks in vertical pipes, replaced one today that is less than 10 years old.

    Like was said earlier, be brave, take a screwdriver to it. 

  5. WillieWonka | Jul 13, 2005 06:24am | #11

    You have stalagtites growing from your CI? How old is the house? Can't be more than 100yrs. I thought Stalagtites take 100+yrs to grow about 1/2". Somebodys' lying to us. Then there is that one under the Lincoln Memorial, it's about 8 feet long, somebody is definitley lying to us. Your CI helps prove the point.

    If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME
    1. AndrewG | Jul 13, 2005 05:16pm | #12

      Sorry Pyrotechie, I wasn't intending to be as literal as your interpretation. The plumber referred to stelagtights as mineral formations developing on the bottom of the pipe, extending down (roughly 1/8"). Not knowing what the problem is, much less what causes it, I thought that his description was pretty good. No intention of lying to anyone here.

      About the 100 years, my follow up posting mentioned that the house was built in '69 ( 36 years ago). BTW, I don't know a heck of a lot about stelagtights, but I seen some in New Mexico that were at least 6 feet long.

      Thanks,

       

      Andrew

      Edited 7/13/2005 10:19 am ET by Andrew

      1. Dagwood | Jul 13, 2005 05:42pm | #13

        Our old house had plumbing installed in 1933. I replaced all in 2002 with copper. When I pulled our pipes, they had weakened to the point that I could bend them with my bare hands. They still looked strong, but were in really rough shape. To this day I have a hard time believing it was Cast Iron. When the wrench marked it the metal looked more like aluminium to me. In any case, we had no leaks or stalactites, but the pipes had to go. These were supply lines, the Cast drains are still there for some runs.

        I would go for the screwdriver thing. it will go right through if your pipes are shot.

        DagwoodView Image

        1. BryanSayer | Jul 13, 2005 07:08pm | #14

          It sounds to me like you are describing galvinized pipe, which was often used for the supply lines, and for the part of the drain line (and vent) that goes from the fixture to the main stack. Galvinized pipe can be threaded for the connections at the trap and such, then it was leaded in somehow at the cast iron.I always tell old house people that, if they can, they should replace everything up to and including that lead joint, but that the cast iron will last longer than the galvinized. Particularly the vertical runs.

          1. Dagwood | Jul 13, 2005 08:45pm | #15

            Aha! That solves that mystery.View Image

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