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 only5' of water head so pressure is extremely low.
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