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Mysterious cracks in no hub cast iron pipe

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  • Mysterious cracks in no hub cast iron pipe

    Here in Central Calif, we have had some way above average rainfall, and with lots of rain comes leaks not detected before. I do service plumbing on 13 school sites and am running into cracked 3" and 4" no hub C.I. pipe on horizontal runs of roof drain piping. The cracks are long (sometimes 6 feet!) and are always near the top of the pipe in the 10:00 o'clock or 2:00 o'clock position. The buildings are 20 to 30 years old and State inspected and built origionally. The pipe has proper pitch, and supported correctly, no excesive dirt buildup was on the bottom of the pipe. Most piping is run above heated spaces so I don't think freezing was the issue. I'm kind of stumped on this one and would love some of your input.

  • #2
    Re: Mysterious cracks in no hub cast iron pipe

    Read:

    http://www.ridgidforum.com/forum/showthread.php?t=21904

    Comment


    • #3
      Re: Mysterious cracks in no hub cast iron pipe

      Thanks for the link Chemeng, hopefully some others will chine in with some more updated info. The replies in the link are from different possible causes, in the meanwhile I will try replacing the bad runs with pvcdwv pipe.

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      • #4
        Re: Mysterious cracks in no hub cast iron pipe

        I'm not a plumber, but can you run ABS/PVC in commercial?

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        • #5
          Re: Mysterious cracks in no hub cast iron pipe

          Originally posted by Chemeng View Post
          I'm not a plumber, but can you run ABS/PVC in commercial?
          Yes, abs and pvc dwv can be run on commercial not over 2 stories, according to local codes. Also to some degree the schools are not subject to inspections everytime something is changed. I can change the piping and no one will question it.

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          • #6
            Re: Mysterious cracks in no hub cast iron pipe

            I work on some old homes in S.F. 1920 and 30s. The old cast on vents crumbles when removed. They never see water,except a little rain. They go before the drains,kept wet.
            The cracks in the thread are located on top only. Anyone think dryness plays a role?
            I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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            • #7
              Re: Mysterious cracks in no hub cast iron pipe

              Originally posted by plumb4life View Post
              Yes, abs and pvc dwv can be run on commercial not over 2 stories, according to local codes. Also to some degree the schools are not subject to inspections everytime something is changed. I can change the piping and no one will question it.
              Commercial:
              Our inspectors don't allow abs/pvc in the framing.Sometimes we can run it underslab and stub through with plastic.

              Residential:
              Anything over two floors cast iron.

              Mostly roof drains that are rarely used or overflows that have never seen water that are cracked.
              Luckily I had "Snap Shot Rickey" with me on the last one I saw last June.

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              • #8
                Re: Mysterious cracks in no hub cast iron pipe

                i was told a story about it that makes some sense

                the cast will rust and as the cast rust, the rust will push against itself and create pressure as it grows larger.

                95% of the time it's from roof, area, planter drain pipe. very rarely from sewer lines.

                rick.
                phoebe it is

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                • #9
                  Re: Mysterious cracks in no hub cast iron pipe

                  I replaced a 4" cast iron vertical pipe for a 2nd floor bathroom, this summer, in a house which was approx. 55yrs old. It was cracked wide open vertically for about 4ft., 1 whole section basically. I've seen this several times too.
                  After seeing everyones theories, I was thinking that this customer had just got back from 3 week vacation in Hawaii, & they have condo there, so they go often. So the drying out of pipe makes sense to me.

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                  • #10
                    Re: Mysterious cracks in no hub cast iron pipe

                    I just don't think that the drying of the pipe will do that, as I have had to replaced cracked NH and CI on both the vert and horiz sanitary drain piping. I just figured the pipe had its time and needed to be replaced, bad batch of pipe, etc.

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                    • #11
                      Re: Mysterious cracks in no hub cast iron pipe

                      Originally posted by Plumbducky View Post
                      I just don't think that the drying of the pipe will do that, as I have had to replaced cracked NH and CI on both the vert and horiz sanitary drain piping. I just figured the pipe had its time and needed to be replaced, bad batch of pipe, etc.
                      I would think that the pipe would start leaking slowly in spots, if it was just wear and tear. This crack I had in pipe was almost big enough to put my fingers into. So something causes it to, what seams like, expand big time. Rick had a good theory about the rust too, because it may rust & scale up more when it is allowed to dry.

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                      • #12
                        Re: Mysterious cracks in no hub cast iron pipe

                        That may be the case, but if that is true wouldn't the pipe be plugged?

                        Usually when I see it is about a 1/2" crack in the top or wider and sometimes it is just chunks missing. I am just saying

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                        • #13
                          Re: Mysterious cracks in no hub cast iron pipe

                          I would think that if seasonally used C.I. pipe is subject to cracking before its 50 year plus design life, that the Great Round Table of the UPC and and the other code writers would change the code for other materials to subsitute the C.I. as long as the burn issue wasn't a problem.

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                          • #14
                            Re: Mysterious cracks in no hub cast iron pipe

                            Hey just an idea, but in alberta, canada we insulate all of our rain water leaders for this very reason so the cast doesnt get shocked....warm environment cold water. i think it has something to do with the particles that cast iron is composed of non-malleable material.

                            Just another guess.....

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                            • #15
                              Re: Mysterious cracks in no hub cast iron pipe

                              Originally posted by Chemeng View Post
                              I'm not a plumber, but can you run ABS/PVC in commercial?
                              In most cases no, due do flame and smoke spread issues if there is a fire. As in all questions like this though each jurisdiction will approach this differently.

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