Globe valves, one of the most important types of cut-off valves, play an important role in the aerospace field. As an important component of aerospace equipment, globe valves realize functions such as media transportation, cut-off, and regulation. Their sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and laws of the sealing characteristics of typical globe valves has guiding significance for the structural design of valve sealing pairs, thereby improving the sealing performance and reliability of valves.
Valves play an important role in cutting off and throttling the medium in their pipelines. As an extremely important type of cut-off valve, the sealing of globe valves is achieved by applying torque to the valve stem, which exerts pressure on the valve disc in the axial direction, making the sealing surface of the valve disc closely adhere to the sealing surface of the valve seat, preventing medium from leaking along the gap between the sealing surfaces. The sealing pair of globe valves is composed of the sealing surface of the valve disc and the sealing surface of the valve seat. The valve stem drives the valve disc to move vertically along the center line of the valve seat. During the opening and closing process of the globe valve, the opening and closing height is small, making it easy to adjust the flow rate. In addition, it is easy to manufacture and maintain, and the pressure range is wide.
The metal support surface of the valve core of the power station globe valve is designed to match the metal support surface of the valve seat ring, but the contact angles are slightly different. Normally, the valve core has a larger inclination angle than the valve seat ring. This non-matching ring ensures a narrow point of contact, making the axial force of the entire actuator transmit only to a small part of the valve seat, thereby achieving the possibility of the tightest metal-to-metal contact. In most structures, the valve seat ring of the manual globe valve is screwed into the valve body. Rotation of the valve seat ring requires tools to be done in limited space.
Another common manual globe valve guidance type is the valve seat guidance structure. Here, the valve core stem is supported by an upper guide (its function is similar to a packing cover). The outer diameter of the extended part of the valve core head serves as the second guiding surface to guide the valve seat. This means that the lower guide surface is left inside the flow layer, so the process medium is relatively clean. The lower part of the valve core head has an opening, which allows fluid to flow through the valve core head to the valve seat during the valve opening process. Changing the size and shape of these openings will affect the reduction of flow and flow characteristics. Because the length between the upper guide and the lower guide is at the maximum length, the lateral rotary movement caused by the process is not a problem, and the allowable deviation required by this type of guide is not as strict as the double top valve stem guide. This structure reduces the opportunity for any vibration of the valve core during operation. When the valve core and the valve seat are made of the same material, surface wear of the metal may occur during long-term or frequent operation.
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