I'm in the middle of remodeling my bathroom and cannot stop a connection from leaking. What I'm dealing with is an old iron pipe coming out of the slab (circa 1951) and a brass shut off valve for my toilet supply. I capped off the pipe during the demolition stage (which doesn't leak) and now that I'm installing the toilet, I have this leak. The threads don't look good, and some are destroyed. Since this fitting is out in the open, I'd like for it to be neat, but I do need it to not leak, of course. I've unsuccessfully used pipe thread tape and some liquid sealant which was recommended by a guy at the hardware store. Any suggestions or thoughts?
OK, so you've got iron pipe with tapered NPT thread coming out of the slab. And you're using a brass valve for the toilet, which hopefully is also NPT threaded. Make sure of that first.
Second, how are the threads damaged? Were they cross threaded? Were they galled or somehow smashed?
How many wraps of teflon tape did you use? You need 5 wraps at least. NPT threads are fairly deep, so it takes a few wraps of tape.
My suggestion would be to shut off the water and start over. Get a bristle brush and clean all the gunk and old tape off the threads, and out of the valve. Wrap with tape. Crank the new valve down and try it again. If that fails, my next step would be to try a new valve...Your cap held water, so perhaps the problem is the valve.
I'd throw the liquid sealer the hardware store sold you in the trash. Teflon tape will seal them unless they're too damaged to save.
on which part are the threads mess up the pipe or the fitting.If its the fitting get a new one if its the pipe rethread them or run a treader on them lightly to clean them out.I they are damaged you wont get them tight enough to seal no matter how much tape or gunk you put on them