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Why I dislike di-electric unions... (ME)

Mark Eatherton1
Mark Eatherton1 Member Posts: 2,542
These are worth a few million. Cast iron flanges on Kent BTU meter, galvanized steel nipples and EPCO dielectric unions on 1-1/2" copper pipe. 25 years young.



  • Al Letellier
    Al Letellier Member Posts: 781
    dielectric unions

    You should see the ones I took off a 40 gallon gas water heater the other day...talk about plugged!!! No maintenance on this unit whatsoever. No wonder it only lasted 4 years.
    Have you ever found a dielectric union where the gasket lasted more than a few years, or better yet, survived being taken apart???

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  • Terry_4
    Terry_4 Member Posts: 42
    Yeah, but

    look how clean the copper is, and from the photos apparently no degradation of the wall thickness (i.e. no electrolysis) which is really what we're trying to protect against with dielectrics, right?

  • Phil_8
    Phil_8 Member Posts: 42
    di-electric unions

    What do you recommend when connecting disimiliar metals?
  • Jim Walls
    Jim Walls Member Posts: 49

    Phil, I would recommend using dielectric nipples, such as victaulics #47,,,,,, Anvil,formerly Gruvlok has them, and there are others
  • [Deleted User]

    think about it this way,,what are the valves made of on a steel piping system...the international plumbing code allows brass as a converter fitting from steel to copper....altho only some states operate under the ipc.
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542

    ELectrolysis always acts upon the lesser noble metal. If this were a true disimilar metal connection, the galvanized nipple, or the cast iron flange would deteriorate, not the copper.

    I recommend the use of yellow brass nipples for eliminating any disimilar metal mixes in open, potable water systems. In closed loop oxygenless systems, they are not necessary and generally create more problems due to leaking gaskets etc..

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