Introduction to Globe Valve

Globe valve, also known as stop valve, is a forced sealing valve, so when the valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters the valve from below the valve disc, the resistance that the operating force needs to overcome is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve stem The diameter of the valve must be large, otherwise the valve stem will bend. According to the connection method, it is divided into three types: flange connection, thread connection and welding connection. Since the emergence of self-sealing valves, the medium flow direction of the stop valve has been changed from the top of the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, but the force to open the valve is large, and the diameter of the valve stem can be adjusted accordingly. reduced. At the same time, under the action of the medium, this form of valve is also tighter. my country's valve "three modernization regulations" have stipulated that the flow direction of stop valves should always be top-down. When the stop valve is opened, the opening height of the valve disc is 25% to 30% of the nominal diameter. The flow rate has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the stop valve should be determined by the stroke of the valve disc.
The opening and closing part of the stop valve is a plug-shaped valve disc. The sealing surface is flat or conical, and the valve disc moves linearly along the center line of the valve seat. The movement form of the valve stem, (common name: concealed stem), also has a lifting and rotating stem type, which can be used to control various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. flow. Therefore, this type of shut-off valve is very suitable for shutting off or regulating and throttling. Since the opening or closing stroke of the valve stem of this type of valve is relatively short, and it has a very reliable shut-off function, and because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating flow.