On Feb 20, 7:55 am, nick hull wrote:
I have a gate valve with a small leak I need to fix. The valve is
stainless and in good condition but has a very small leak when closed
tightly. It's a 3" valve with a non-standard flange so replacement is
out of the question. The valve will be seldom operated and I could live
with a fix that sealed the valve tight and allowed the valve to be
opened ONCE (for a fire hose connection).

The big complication is that the valve is welded together and cannot be
taken apart.

I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

I don't have lots of experience, but every gate valve I have seen (5
or 6 of them) leaked some when closed. I think that the silicone
sound like a good idea, but I would think that the downstream side
would be better since any (even your low) water pressure would force
the gate into the silicone rather than away from it.

Carl Boyd