A shut-off valve, also known as a shut-off valve, is a forced sealing valve. Therefore, when the valve is closed, pressure must be applied to the valve disc to force the sealing surface to not leak. When the medium enters the valve from below the valve disc, the resistance that needs to be overcome by the operating force is the frictional force between the valve stem and packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open it, so the diameter of the valve stem should be larger, otherwise it will cause the valve stem to bend. There are three types of connection methods: flange connection, threaded connection, and welded connection.
