The globe valve is a forced sealing type valve. So when the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve below the disc, the resistance that the operating force needs to overcome is the frictional force between the valve stem and the packing. Generally, because of medium presuure under the disc, the force to close the valve is greater than the force to open the valve, so the valve stem's diameter must be large enough, otherwise the valve stem may bend failure.