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Cast Iron Radiator Fittings: Removal Tips?

Stew_5 Member Posts: 23
I'm installing a used cast iron radiator that has the nut-half of the pipe union still in it. Removed one by heating w/ oxy/acetylene torch but am nervous about pushing my luck ("crack!, #%*¥@!!) removing the other two. What are my chances of finding the other side of the existing unions? Nut is 3/4" pipe thread and I'm tempted to just use a 3/4 cu male adaptor..... Probably not a good idea. ?

If I go back to heating to red hot and removing them, any voices of experience out there? Like how big an area around the fitting should I pre-heat w/ torch to prevent cracking?


  • DoRight
    DoRight Member Posts: 7
    There is no better do what been doing- > "heating w/ oxy/acetylene".

    And not to push luck, just do with smaller amount of heat , keep spraying with WD-40 between heating up.
    Once decide go for it, try cool down internal ( this will decrease in size , as hotter-outer will remain bigger due to heat expansion).
    Prevent creack, you should spread heat evenly , maybe reconnect back and let the steam do the job?
    JUGHNE Member Posts: 11,086
    I have never used a torch, inside the house, sometimes the radiator was just power coated etc.
    Spud wrench will seldom work, when it does it is a surprise.
    Saw the spud off leaving a 1/4" sticking out, hacksaw a portion of the spud length wise being careful to not cut iron female threads. Spud is brass, easy to saw, you can feel when you touch the iron. With a small chisel pop that piece of the pie out and the rest of it will collapse inward and unscrew.
    It might be good to clean up the rad threads with a tap or even a black nipple before screwing in the new brass spud.

    It would be very surprising if that union nut has 3/4" NPT threads in it. BWDIK
    j a_2
  • New England SteamWorks
    New England SteamWorks Member Posts: 1,520
    edited October 2016
    "What are my chances of finding the other side of the existing unions? "

    Zip. Zero. Nada. You will need new (steam) radiator valves.

    Never tried a torch. Agree spud wrenches seldom work. 50% if you lay it on it's side and use a big pipe wrench with an even bigger persuader (piece of pipe) it will come out. Cut the union ring off 1st so you gan get a pipe wrench on the nipple.

    Otherwise sawzall surgery. Carefully.

    Also: a bunch of old radiators have reverse threads!
    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
    JUGHNE Member Posts: 11,086
    Going with RI's method, I have had that luck by sawing off just enough to get that nut out of the way, then jamming in a bolt that just fits inside the spud, ( would have twisted the spud internal nubs off with the spud wrench by now).
    The spud having the insert tightly inside would not collapse or egg shape and probably come out easier.
    After this then the saw & chisel comes into play. FWIW
    STEAM DOCTOR Member Posts: 2,020
    Saw and chisel. Go slow. Shouldn't take more then a few minutes. I usually make two cuts inside. Makes the chiseling easier.
    j a_2
  • Jamie Hall
    Jamie Hall Member Posts: 23,526
    I'm with the three folks just above. Works fine, every time, and no risk of cracking.

    With heat -- the risk of cracking is extremely high, unless you heat the whole end section evenly. Anything else... can't possibly recommend heat on cast iron.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • bodybyfisher
    bodybyfisher Member Posts: 1
    I use the "Jim Reed" method (God rest his soul). Spud wrench and 18" or 24" pipe wrench on it and your biggest channel locks (squeeze hard) between the nut and radiator. Pull both simultaneously. Works every time.