The reason why the valve stem and stem nut of the gate valve cannot be made of stainless steel at the same time is that there is interaction between them, which may lead to premature wear and seizure.

The valve stem is not only a moving and load-bearing component during the opening and closing process of the valve, but also a sealing component. At the same time, the valve stem is subjected to the impact and corrosion of the medium, and also generates friction with the packing. Therefore, when selecting valve stem materials, it is necessary to ensure that the valve stem has sufficient strength, good impact toughness, and corrosion resistance at the specified temperature. The valve stem is a vulnerable component, and when selecting, attention should also be paid to the mechanical processing performance and heat treatment performance of the material.