Leaking radiator flanges

tkos115

As the cold weather has been setting in here in the northeast I have been trying to make sure my steam system is up to par for the winter. Other than some vents that don't seem to close all the way, I have noticed that two of my radiators are hissing and leaking at the flange where they connect to the valve that comes up through the floor. I have tried tightening them as much as I can by rocking the radiators back and forth as I tighten it. They are a little better but still leak a little, and it is not leaking at the valve shaft that you would turn to open or close it. My plan tomorrow is to unbolt them completely and inspect the flanges. Other than maybe using some steel wool or a scotch pad, is there anything else than can be used if they still leak? Someone mentioned using a small amount of high heat RTV on the flange to help seal any imperfections. Is that OK to use if they still leak, or is there something better?

This is on a one pipe steam system as well



Thanks for your help!

KC_Jones

We may have a terminology issue here. There isn’t a flange on a radiator or valve. Perhaps a picture of what you’ve got and where it leaking would help us understand a little better what your issue is.

tkos115

Yeah sorry I guess that I mean is the connection between the radiator and the valve that's attached to the steam pipe coming through the floor. I will take a picture and post shortly.

tkos115

It is leaking at that nut, if I remember correctly there is a conical fitting that seals the connection.

Jamie Hall

I think -- without looking at the pictures -- that what you are talking about is a union. Unions depend for their seal on the two faces of the union being absolutely smooth and clean -- no scratches, no gunk. Clean. You can take them apart and clean and polish them, but absolutely no abrasives of any kind should be used. When you put them back together, some suggest a very thin smear of dish soap. Otherwise, no sealants or pipe dope or anything of the sort.

All that said, what unions will not do is take up any lateral, up and down, or angular misalignment. Make sure that the spud going into the radiator is exactly lined up with the pipe from the valve and the union and that the union is coming together. Then, and only then, tighten the holding nut. And it doesn't need to be gorilla tight. Just tight.

EBEBRATT-Ed

Some "Never Seize' on the union faces and, on the threads, may help. Some call it "anti-seize" an auto parts store will have it. You might put some Teflon tape on the union threads at this point it's whatever works

That nut looks like it has been worked over pretty hard. Could be out of round. Everyone uses pipe wrenches on the unions (me included I confess) but being brass a smooth jaw wrench is the best.

To change the union, valve and spud you have to change the whole thing they come as a matched set.

Big Ed_4

There are no threads left either , time for a new setup....

retiredguy

If all other attempts to completely seal that union fail, I would smear a thin film of high temp silicone on the face of the mating surfaces. Be careful to only coat the mating surfaces with no extra that could get into the piping or valve parts. Tighten the union and let sit a couple days for the silicone to set up. Oh yes, when using a pipe wrench on those brass union nuts loosen the jaws so the teeth of the wrench do not cut into the brass nut when you pull the wrench or go buy a flat jaw pipe wrench.

RTW

When I had that problem, the plumbing supply house I use suggested the same solution as "Retired Guy" opinion above. It worked and never had another problem. Only difference is I used a thin film of pipe dope, but I see that is NOT recommended in another post

Jamie Hall

If you put something other than dish soap or never seize on the mating faces, such as pipe dope or high temp silicone or some such, make sure the film is then and very very even. It's a last ditch solution.

One other thing. As noted, the union nut is soft -- almost always brass -- and it's very easy to squish it or break it. Tightening it beyond hand tight plus half a turn is NOT going to help.

tkos115

I do have some good news, I was able to take it apart and clean both side of the union with some steel wool. I was certain that I was still going to have a leak on one of my radiators because it is slightly pitted in one spot. After cleaning it I put a little dish soap on the union and threads and tightened it up. I have run the heat through 3 or 4 cycles since and currently no leaks at any radiators. Now I just need to replace the leaking vents on them and I should be good to go.


Thanks everyone for the input, fingers crossed nothing else leaks.