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OT - Foam insulation for plumbing pipes causing corrosion?

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  • OT - Foam insulation for plumbing pipes causing corrosion?

    I am dealing with some corrosion and leaks of galvanized water pipe in the home and it made me wonder if the china split foam slip on insulation may be acidic or otherwise contributing to the problem. A quick search brought up a bunch of schollarly papers about this.

    Wondering what our resident plumbers and others may know about this. Thanks.

  • #2
    We used split wrap but it was rock wool, it was required the pipe be spiral wrapped with denso tape first to protect it from moisture same for black and galv
    i personally hate denso but it works, gets all over you
    https://www.denso.net/products/denso...tum%20compound.
    mark

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    • #3
      Originally posted by Glug View Post
      I am dealing with some corrosion and leaks of galvanized water pipe in the home [...].
      Galvanized water pipe? I thought that they stopped using it so long ago that all of it that had been used had rusted away. When does yours date from?

      Comment


      • #4
        I had some of that foam insulation on cold water pipes which are copper, and developed a leak(maybe 2). I concluded that what happened was condensation occurred under the insulation on the pipe surface, and caused the corrosion. Took the insulation off the cold water pipes as it is not needed anyway. No issues since.

        Might relate to your experience…

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        • #5
          The galvanizing on standard pipe mostly protects the outside from corrosion when buried: galvanic activity at the joints and all of the compounds in drinking water attack the pipe from the inside.

          Best materials for water pipe are copper, CPVC, PEX & SS.
          Avid Amateur Home Shop Machinist, Electronics Enthusiast, Chef, Indoorsman. Self-Proclaimed (Dabbler? Dilettante?) Renaissance (old) Man.

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          • #6
            The insulation , as mentioned above in passing, is not needed on cold water pipes. They are the ones that might have corrosion from condensation. If anything condenses on your hot water pipes, that is the least of your issues.

            I've got galvanized pipe that is 90 years old, and still working fine. Biggest problem with galvanized pipe is buildup of deposits from the water. That will kill it long before corrosion, usually.

            I DO have corroded galvanized pipe right now. But it is 90 years old, and was installed as DRAIN pipe from an upstairs sink. Intermittent wet and dry conditions in the drain (like tidewater) is the worst. And even that lasted 90 years.

            Copper isn't bad, although much of it was put in with lead solder, if that bothers you. We had flat out lead pipe water supply, the solder is minor. But the lead pipe had so much hard water buildup that it was more like stone pipe..... not an issue.

            The Pex etc, well, it depends on the fittings. All plastic goes bad. Chlorine in the water makes it go bad faster. Old fittings were basically defective, since they would fail long before the pipe would.

            So the old PEX fittings will fail, and give your walls a nice internal wash-down, probably while you are on vacation. Not great. So new PEX installs by folks who know what they are doing, may be OK for a few decades anyhow. Old original PEX installs are failing now, from what I am told by plumbers.

            PVC works OK, even though it does not last as long as metal.

            One thing that plumbers apparently do not know or care about these days, is water pipe grounds. They will happily install copper in the middle of the water supply pipe, with a carefree lack of any concern for the fact that the house wiring is no longer properly grounded.

            Yes, you are supposed to have a rod driven, for new installs, but decades back, the water pipe was sufficient.
            CNC machines only go through the motions.

            Ideas expressed may be mine, or from anyone else in the universe.
            Not responsible for clerical errors. Or those made by lay people either.
            Number formats and units may be chosen at random depending on what day it is.
            I reserve the right to use a number system with any integer base without prior notice.
            Generalizations are understood to be "often" true, but not true in every case.

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            • #7
              Originally posted by J Tiers View Post
              [...]
              One thing that plumbers apparently do not know or care about these days, is water pipe grounds. They will happily install copper in the middle of the water supply pipe, with a carefree lack of any concern for the fact that the house wiring is no longer properly grounded.

              [...]
              I suspect that you don't mean that. Maybe "they install PEX"?

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              • #8
                Originally posted by Bob Engelhardt View Post

                I suspect that you don't mean that. Maybe "they install PEX"?
                I mean just what I said.

                If you install copper in the middle of an iron pipe run, you are going to use dielectric unions, unless you are a total numpty. Those break the connection, if you did not know that.

                I would HOPE, but do not know, that installing PEX they would be aware of the issue. It's the idea of installing metal pipe in a metal pipe run..... but with insulating unions, that does not get through...... "is there a problem?".
                CNC machines only go through the motions.

                Ideas expressed may be mine, or from anyone else in the universe.
                Not responsible for clerical errors. Or those made by lay people either.
                Number formats and units may be chosen at random depending on what day it is.
                I reserve the right to use a number system with any integer base without prior notice.
                Generalizations are understood to be "often" true, but not true in every case.

                Comment


                • #9
                  Originally posted by Glug View Post
                  I am dealing with some corrosion

                  Wondering what our resident plumbers and others may know about this. Thanks.
                  I am not a plummer Mr. Glug. I have worked on the plubming for my house for 23 years. It all fails to some extent at some point. I hate plumbing work, not good at it.


                  This is more concerning...
                  "galvanized water pipe "

                  That is a bigger problem.. JR

                  Comment


                  • #10
                    Originally posted by ChazC View Post
                    The galvanizing on standard pipe mostly protects the outside from corrosion when buried: galvanic activity at the joints and all of the compounds in drinking water attack the pipe from the inside.

                    Best materials for water pipe are copper, CPVC, PEX & SS.
                    Galvanizing on pipes is both on the inside and outside and helps prevent corrosion anywhere. Only issue is when they cut the threads they are not galvanized and that is where 90% of the leaks occur. Galvanized pipe needs that special dielectric union when mixed with copper on the same run and the pipe also tends to lime up. PEX is the way to go.
                    Retired - Journeyman Refrigeration Pipefitter - Master Electrician

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