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Can you connect copper to black pipe?

Hey_Obie Member Posts: 66
I have an old oil hot water system that I want to modify and break into zones. The whole system is black steel pipe.   I bought 4 brass zone valves which I am going to attach to 1 1/4 copper manifold that I need to make.


The question is: 'Is it OK to connect threaded copper to black steel.  I was at Home Depot and the guys working there said that over time, they can leak.  Their solution was to buy Dielectric couplers.

Should I be concerned?




  • Chris M_2
    Chris M_2 Member Posts: 67
    You Can

    You can connect the two, and will most likely be fine.  The possible leaks that the Home Depot guys were talking about come from the two different metals being in contact with each other, which causes corrosion. To be absolutely safe, take their advice and use dialectric couplers, but you'll probably be fine without them. 
  • Hey_Obie
    Hey_Obie Member Posts: 66
    Pipe Dope?

    Is there a pipe dope that would reduce the chance of corrosion between the metals?
  • Jim Bennett
    Jim Bennett Member Posts: 607
    edited March 2010
    Copper to steel.........

    I've never had much luck with dialectrics. Use a brass nipple or adapter between the copper and steel and you'll be fine.

    Good luck,

    Jim Bennett
  • eluv8
    eluv8 Member Posts: 174
    copper to black pipe

    I have seen copper to black pipe installed and they were not leaking yet. I personally always felt it was best to be safe and use a brass coupler. Better to be safe and do it once than have to worry that you left a problem on a job to be fixed by another.

    I used dielectric unions for a while and had problems getting them to seal. They always seemed to like to come loose and weep or corrode. Brass there is no questions, it done.
  • Hey_Obie
    Hey_Obie Member Posts: 66
    Brass is golden

    Brass it is.  Thanks guys
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Not a problem

    We transition from black steel to copper on every job ( hot water , closed systems ) , using the basic copper to male or copper to female adapters .

    We also remove the old equipment that had the same transitions for decades . Never see leaks at these adapters or any dielectric buildup whatsoever .

    We do from time to time see leaks due to the fitting not being tight enough or not enough thread sealant . Which is why we solder a small piece of copper into the adapter then retighten while it's still hot .  
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