Tech Enthusiast | Ways to Increase the Lifespan of Control Valves (8 Methods)

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Methods to extend the lifespan of control valves (8 methods) 1) Extending lifespan by operating at high opening degrees: Have the control valve operate at its maximum opening degree from the start, such as 90%. In this way, damages such as cavitation and erosion occur on the head of the valve core. As the valve core is damaged, the flow rate increases, causing the valve to close a little more; this process of continuous damage and gradual closing ensures that the entire valve core is utilized to the fullest extent, until the root of the valve core and the sealing surface are damaged and the valve can no longer be used. At the same time, when operating at a large opening, the throttle gap is larger, reducing erosion; this increases the lifespan by more than 1 to 5 times compared to operating the valve at intermediate or small openings from the start. If a chemical plant adopts this method, the service life of the valves is doubled. 2) The method of reducing S to increase the operating opening and extend lifespan: By reducing S, the losses in the system other than the control valve are increased, which leads to a lower pressure drop across the valve. To ensure that flow passes through the control valve, its opening must be increased; at the same time, the reduced pressure drop across the valve lessens cavitation and erosion. Specific methods include: installing a orifice plate behind the valve to create pressure drop through throttling ； Close the manual valve connected in series on the pipeline until the control valve reaches an optimal operating position. For when the valve is initially selected to operate at a small opening degree, this method is very simple, convenient, and effective. 3) The method of reducing the diameter to increase the operating opening and extend lifespan involves increasing the operating opening by reducing the valve’s diameter; specific approaches include: ① Replacing the valve with one of a smaller diameter, such as changing from DN32 to DN25 ； ②The valve body remains unchanged; only the spool and seat with a smaller seat diameter are replaced. During a major overhaul of a chemical plant, replacing the throttle element dgl0 with dg8 doubled its service life. 4) The method of shifting the damage location to extend lifespan involves moving the areas most severely damaged to less critical positions, in order to protect the sealing surfaces and throttling surfaces of the valve core and seat. 5) Method of increasing the service life by enlarging the throttling channel: The simplest way to do this is to thicken the valve seat, thereby increasing the diameter of the valve seat hole and creating a longer throttling channel. On the one hand, it can delay the sudden expansion that occurs after throttling in a flow-blocking manner, thereby shifting the location of failure and keeping it away from the sealing surface ； On the other hand, it increases the throttling resistance, reduces the degree of pressure recovery, and thus attenuates cavitation. Some designs feature stepped or wavy shapes in the valve seat hole, aimed at increasing resistance and reducing cavitation. This method is often used on the high-pressure valves in new installations and when upgrading old valves, and it is also very effective. 6) The method of changing the flow direction to extend service life: In the flow-open configuration, the flow moves in an open direction; cavitation and erosion mainly affect the sealing surfaces, causing rapid damage to the root of the valve core as well as the sealing surfaces of the valve core and the valve seat ； In the flow-blocking type, flow moves in the direction of closure; cavitation and erosion occur after throttling, below the valve seat sealing surface, which protects the sealing surface and the root of the valve element, thereby extending its service life. For valves designed to be used in a flow-diverting manner, when extending their lifespan is a significant concern, simply changing the direction of flow can double or triple their service life. 7) To improve durability by using special materials, in order to resist cavitation (damage in the form of honeycomb-like spots) and erosion (streamline-shaped grooves), special materials resistant to cavitation and erosion can be used to manufacture throttle components. Such special materials include 6YC-1, A4 steel, Stellite, and cemented carbide. To resist corrosion, materials that are more resistant to corrosion and possess certain mechanical and physical properties can be used instead. This material is divided into two categories: non-metallic materials (such as rubber, PTFE, ceramics, etc.) and metallic materials (such as Monel, Hastelloy, etc.). 8) The method of improving lifespan by changing the valve structure involves altering the design of the valve or using valves with a longer service life, such as multi-stage valves, anti-cavitation valves, and corrosion-resistant valves. Coal chemical industry black water control valve