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    atticguy's Avatar
    atticguy Posts: 36, Reputation: 1
    Junior Member
     
    #1

    Apr 12, 2006, 04:39 AM
    Is brass an alternative to dielectric union?!
    Good morning speedball,

    I am very clear on the theory of electrolysis and such between dissimiliar metals in solutions. But I have read that one can use brass fittings in leiu of a dielectric device. I find that hard to be true. Brass may have properties which can slightly negate the battery effect, but can brass totally delete the issue? When looking into dielectric unions (galvanized to copper is mostly what I find), I see that even the brass part is separated from the copper partby a washer.

    I am going from galvanized steel piping to brass pex fittings and I question whether I would be OK without the dielectric device. I ask because the pex pamphlet I have (which led to the whole 5/8 conversion fiasco), has me scratching my head again. It says dielectric IS NOT necessary. This isn't about "getting out of" installing these devices, I'm just really starting to question this so called info pamphlet on pex that I got from Menards.:mad:

    Note:I will also be connecting both sets of pipes with a "ground jumper" whether I use dielectric or not, to continue and ground pathways.

    Thanks for your input,

    Louie
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
    Eternal Plumber
     
    #2

    Apr 12, 2006, 06:49 AM
    Hi Louie,
    If you ground the system then I don't see any reason for a dielectric union,

    While Pex had its problems at first they have been corrected. Pex is more "user friendly" to install then copper and plastic will out last copper and that makes this a "no brainer".
    atticguy's Avatar
    atticguy Posts: 36, Reputation: 1
    Junior Member
     
    #3

    Apr 12, 2006, 07:10 AM
    Hey speedball, thanks for the quick reply-

    Now I'm a little confused...

    "if you ground the system then I don't see any reason for a dielectric union"

    I thought these two issues were separate. I was under the impression that the dielectric union was to be used when ANY 2 metals come into contact.

    1)This holds true for galvanized steel and brass does it not?

    Of course grounding will have an influence on the battery effect, but I was under the impression that this was done to have continuous ground in the event of an electrical (major) occurrence.

    2)are you saying that if I was NOT grounding the system that I would have to install the dielectric device?

    Thanks,
    Louie
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
    Eternal Plumber
     
    #4

    Apr 13, 2006, 06:41 AM
    Hey Louie,

    If you will look on top of your water heater you should find The copper supplies are connected to the black iron threads of the heaters boiler without a dielectric union. We have been connecting them for years without and problems with electrolysis.
    "2)are you saying that if I was NOT grounding the system that I would have to install the dielectric device?"
    The system should be grounded if you have water pipes under the slab.

    Cheers, Tom
    Lebite's Avatar
    Lebite Posts: 1, Reputation: 1
    New Member
     
    #5

    Nov 4, 2011, 09:33 PM
    Use Di-electric fittings between all dissimilar metals. I am a forensic engineer specializing in corrosion and I see these issues all the time.

    The reason the copper to steel doesn't corrode too quickly in water heaters is because the water heater has an anode inside of it protecting the steel. Your copper is the cathode and the steel is the anode. If your anode is huge and your cathode is small, corrosion rates will be slow. If it's the other way around, corrosion rates will be fast. If your copper system were isolated from the steel water heater, your heater's anode would last longer and so would the heater.

    Corrosion consists of four parts. 1) Anode 2) Cathode (difference in nobility per galvanic series in "fresh water") 3) Electrolyte (usually water) 4) Metallic path between anode and cathode.

    Remove ANY one of those 4 components and you will stop corrosion. Brass is not a dielectric or insulator or non-conductive material. It is a metallic path and an alloy of copper and zinc. Brasses with over 15% zinc lacking proper amounts of arsenic inhibitors in their composition (0.06% I think it was) and if they are alpha and beta phase instead of annealed pure alpha phase will suffer dezincification in stagnant hot hard waters.
    Milo Dolezal's Avatar
    Milo Dolezal Posts: 7,191, Reputation: 523
    Plumbing Expert
     
    #6

    Nov 5, 2011, 10:51 PM
    Lebite : First, welcome to AMHD. Second, thanks for sharing your expertize with us. It proves to me that life is a continuous process of education. Now I wonder why it is that our Inspectors routinely approve installation of brass fittings in place of di-electric fitting...
    fisher43's Avatar
    fisher43 Posts: 1, Reputation: 1
    New Member
     
    #7

    Feb 23, 2013, 07:01 AM
    My question is this. Why can we use brass ball valves on both copper and steel pipe, but not between the two?
    Ron Rose's Avatar
    Ron Rose Posts: 1, Reputation: 1
    New Member
     
    #8

    Mar 3, 2015, 10:51 AM
    I notice that copper is close to steel in the standard galvanic series and brass is a little further. And, this issue can be quite a large discussion depending on the application. People have done one thing for ships with anodes and even inducing voltages and other applications do not have sacrificial anodes (such as commercial hydronic systems without tanks).

    If you run across any links that can help clear up piping practices, it would be helpful.

    Thanks!
    talaniman's Avatar
    talaniman Posts: 54,290, Reputation: 10853
    Expert
     
    #9

    Mar 3, 2015, 01:10 PM
    Thanks Ron for your input on this subject. It's an old closed post, but hope you stick around the forum to lend your insights, as well as ask any questions you may have.

    Again, thanks, and WELCOME.

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