Mating steam radiator to valve - see pix


  #1  
Old 01-22-19, 07:30 PM
D
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Mating steam radiator to valve - see pix

This 100 year old radiator was working fine for years and it all of a sudden started leaking water where the radiator nut tightens on the valve. I tightened the nut but it still leaks slowly. (The radiator is pitched correctly, there is a new vent on the other end...)

So I cleaned the threads on the right and on the nut inside, as best as I can. And I cleaned the beveled area.

I want to do a good job. How best to seal this up on the (1) threads on the right. And (2) do I apply anything to the beveled area?

I have teflon tape and I have these other pipe dope - see second picture. If I use teflon tape, how many times around the thread, and if on the bevel, how many times?

Best,
Dave
 
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  #2  
Old 01-22-19, 08:03 PM
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d,
How big a wrench are you using on this. Get at least an 18" or 24" pipe wrench.
Since the mating of the rounded part inside the threaded end is the seal and no pipe is needed it will not hurt to put some on the threads and on the smooth part if you want. If you want to try Teflon start a couple threads in and wind in the direction of the tightening nut(clockwise) so ir doesn't unwind when tightening nut, and go around a couple of times.

Sometime over time the smooth or nutted end gets out of round and when taken apart doesn't quite seal after but with the dope and the right wrench it will usually stop. DO NOT be afraid to lean on the wrench if needed.
 
  #3  
Old 01-23-19, 02:51 AM
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I do not know how or with what you cleaned that union but you should have only used 00 to 0000 steel wool. The use of sand paper or a wire brush will scratch the mating surfaces of the union and will usually allow them to leak. So, what to do now; get some steel wool and redo both surfaces of the tapered ends of both fittings (the outside of the left fitting and the inside of the right fitting). Pay particular attention to that little brass looking area just passed the tapered part. Go to a home supply store or an auto parts store and buy a tube of RTV silicone. Add a thin coating of the RTV silicone to the mating surfaces of the fitting . Adding anything to the threads will not help to seal the joint. Tighten the joint with a crescent type wrench and not a pipe wrench. A pipe wrench will distort the fitting. Tighten the nut well and let the fitting sit overnight if you can. One last thing, since you have indicated that this is a 1 pipe steam system, the radiator valve must be fully open or closed and not partially open..
 
  #4  
Old 01-23-19, 07:42 AM
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Hi Steamboy,

I had cleaned everything with alcohol and a rag and a plastic stiff brush. But it might have been cleaned improperly in the past. Yep I now see no need to teflon tape the threads. And yep the valve is always fully on except those rare occasions it needs to be turned off, like the below...

(1) I will finish the cleaning of the beveled and almost perpendicular mating surfaces with 00 or 0000 grade steel wool.
(2) RTV silicon. Should be soft or medium grade?
(3) Yep, OK, Let it set overnight with the valve shut for the RTV silicon to dry

Best,
Dave
 
 

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