The valve stem is subjected to tension, pressure and torsion during the opening and closing of the valve, and is in direct contact with the medium, and there is relative frictional movement between the valve and the packing. Therefore, when selecting the material of the valve stem, it must be guaranteed. At room temperature, there is sufficient strength, good impact toughness, scratch resistance and corrosion resistance.
The valve stem and the ball joint and the contact between the valve stem and the valve body should have an anti-static mechanism to prevent static electricity from collecting on the sphere. The valve stem is designed to be protected from “blowing” under working pressure, and the flange on the valve stem is protected from blown by an annular ring to reduce the coefficient of friction.