Angle Valve Pipe thread sealant - Help!

Joined
Jan 9, 2010
Messages
23,887
Location
Los Gatos, CA
I replaced the flush valve in a newer toilet and noticed how old the multi-turn angle valve was. It was hard to break torque.
Our house is old, 1962. We had the bathroom remodeledyears ago, the guy should have, IMO, refreshed the plumbing.

So I took it apart; it was a 4" brass nipple and pipe thread valve.
Got a Brass craft 1/4 turn angle valve, new brass nipple and supply line. I used the grey Teflon tape Home Depot had next to the valves.
There is a tiny leak at the angle valve, not even a drip. Maybe it will dry up? It's pretty tight.

What is the proper sealant? What do you recommend?
I appreciate your help!
 
I replaced the flush valve in a newer toilet and noticed how old the multi-turn angle valve was. It was hard to break torque.
Our house is old, 1962. We had the bathroom remodeledyears ago, the guy should have, IMO, refreshed the plumbing.

So I took it apart; it was a 4" brass nipple and pipe thread valve.
Got a Brass craft 1/4 turn angle valve, new brass nipple and supply line. I used the grey Teflon tape Home Depot had next to the valves.
There is a tiny leak at the angle valve, not even a drip. Maybe it will dry up? It's pretty tight.

What is the proper sealant? What do you recommend?
I appreciate your help!
So the connection we are talking about is 1/2 NPT? Correct?

Don't use tape unless you are a pro with protape. Use Teflon paste, it's all I ever use.

That said, with NPT taper, almost all fittings made in China, some will just leak. No matter what sealant and too tight is WORSE.

But first, pictures and if not NPT, what are we talking about here?
 
So the connection we are talking about is 1/2 NPT? Correct?

Don't use tape unless you are a pro with protape. Use Teflon paste, it's all I ever use.

That said, with NPT taper, almost all fittings made in China, some will just leak. No matter what sealant and too tight is WORSE.

But first, pictures and if not NPT, what are we talking about here?
Yes, 1/2 NPT. Seems to be leaking more. Now I wonder if it is leaking behind the wall.

PXL_20250527_233609113.webp


PXL_20250527_233634304.webp
 
Teflon tape and paste style thread sealant on top of it is the only way. Ive tried one or the other and have always had issues. My old plumber buddy told me tape then dope and I haven't had a leak since.
 
If I may be Captain Obvious, make sure the leak isn't from the valve stem. I quit using the 1/4 turn valves because I had two develop leaks after about 5 years and there is no way to tighten the seal around the stem to stop the leak.
 
If I may be Captain Obvious, make sure the leak isn't from the valve stem. I quit using the 1/4 turn valves because I had two develop leaks after about 5 years and there is no way to tighten the seal around the stem to stop the leak.
Thanks for the tip; yes, the leak is from the nipple valve threads. Gonna get some Blue Monster unless @Pablo instructs me differently.
 
If I may be Captain Obvious, make sure the leak isn't from the valve stem. I quit using the 1/4 turn valves because I had two develop leaks after about 5 years and there is no way to tighten the seal around the stem to stop the leak.
Yep..would be nice to have a packing gland instead of an oring. When I started using the quarter turn ball type years ago clockwise was on. I found that on when I had turned the service valve back on and heard water runnin from somewhere..had not installed supplies yet and the water was flowing out from both stops. I now always check them...clockwise off..
 
It is possible that the valve has been over-tightened and started a hairline crack in the threads. The walls of the valve where the threads are cut are very, very thin and it doesn't take much to split in that area.

If you cannot get the leak to stop, consider getting a new valve and resist the BITOG (aka 'Murican) mentality of "If something is good, more of it must always be better" effort to over-torque the valve onto the pipe nipple.
 
Back
Top Bottom