Abstract: Improved self-grinding valve is provided with corrosion-protecting features and an improved floating coupling between the valve stem and valve disc whereby, when the valve disc is brought into contact with its seat, a selected rotation of the valve disc will produce a grinding of the seat, followed by a disengagement of the valve stem from the valve disc. When this disengagement takes place, the full torque load of the stem can be imposed upon the valve disc to obtain the desired seating of the same. The valve stem is advantageously comprised of improved telescoping and theadedly engaged sections that operate to relieve the forces used to hold the valve disc against the seat upon the initial opening of the valve whereby the amount of torque required to ultimately rotate and free the valve disc from its seat is materially reduced and seizing of the valve disc relative to its seat avoided.