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Galvanized pipe on wet return

Changing a boiler today what are the consequences of galvanized pipe on wet return obviously it was something somebody had left over from a job

Comments

  • Jamie HallJamie Hall Member Posts: 13,182
    Galvanized pipe rusts. Remarkably rapidly. The possible consequences are slow returns from the rust clogging things up and, eventually leaks. If possible I'd replace it either with black iron or, since it's a wet return, copper.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Steve_210Steve_210 Member Posts: 590
    Yes I know how to replace it with copper just didn’t know what the consequences were thanks
  • Steve_210Steve_210 Member Posts: 590
    Strange galvanizes is used outside because it doesn’t rust
  • retiredguyretiredguy Member Posts: 268
    I was told by the "old timers" that the galvanized coating would be compromised by boiler water with a low PH and that is why galvanized pipe was never used in a boiler system.
    delta T
  • mikeg2015mikeg2015 Member Posts: 1,178
    Worse, in some cases the galvanized flakes off. I believe hte low PH speeds up corrosion as mentioned. It has poor chemical resistance in general. That’s by it’s sort of OK for potable water, but not as good as plastic or copper.

    Galvanized still rusts outdoors, only much, much slower than plain steel that rusts instantly the protective film of machining oil is gone.

  • Jamie HallJamie Hall Member Posts: 13,182
    Remember too that galvanized pipe is usually steel, not iron. Steel rusts like mad once the galvanic coating is breached. Black iron rusts very slowly.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Steve_210Steve_210 Member Posts: 590
    Correction yes galvanized will rust but much slower a lot of codes required galvanized for outdoor gas pipework
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