The Chairman
Chairman of the Board
If the valve is CLOSED, there is no pressure on the outside of the valve. There is absolutely no need to drain the tank. Almost all valves use a #10 O-ring to seal the stem: use lots of lube. Sometimes, the gland nut hasn't been tightened down. See if that's the case first, but if it isn't just install a new 10 oring on the stem, making sure what's left of the old o-ring is out of there. This is a two minute fix.