The guys at the local feedstore will replace the old valves with a new
OPD for about the same price as a new tank. They remove the old valve
using a fitting that will attach to the valve. That fitting is welded
to a piece of pipe about four feet long.
They don't use any heat, and without purging the tank. Obviously they
do let all the pressure out.

CYA This is not a recommendation to use their procedure.


Dan