To extend the service life of a control valve, one effective approach is to start with a larger opening, such as 90%, at the beginning of operation. This helps prevent cavitation and erosion on the spool head, which can lead to damage over time. As the valve deteriorates, the flow increases, causing the valve to close gradually until it is fully damaged and no longer functional. By starting with a large opening, the valve can be used more efficiently throughout its lifespan. Additionally, this method reduces the intensity of erosion, extending the valve’s life by 1 to 5 times compared to operating at a medium or small opening. For example, a chemical plant that implemented this strategy saw a two-fold increase in valve life. Another method to improve valve life is by reducing the pressure drop (S) across the valve. This involves increasing the system’s total pressure loss so that less pressure drop occurs across the control valve itself. As a result, the valve can operate at a larger opening, which reduces cavitation and erosion. Practical steps include installing an orifice plate after the valve to absorb some of the pressure loss, or closing a manual valve in series with the control valve to achieve a more optimal operating position. This method is simple, efficient, and particularly useful when the valve initially operates at a large opening. A third technique involves narrowing the valve's opening by reducing the diameter of the valve body or replacing the seat with a smaller one. For instance, changing from DN32 to DN25 or replacing the valve seat with a smaller size can increase the working opening and reduce wear. During an overhaul at a chemical plant, replacing parts like DGL0 with smaller components resulted in a one-time improvement in valve life. Transferring the location of damage is another strategy. By shifting the point of severe wear away from the sealing surface and throttle area, the valve seat and sealing surfaces are better protected. This can significantly prolong the valve's operational life. Increasing the throttling channel length is also an effective way to extend valve life. This can be done by thickening the valve seat or enlarging the seat hole to create a longer path for the fluid. This not only delays sudden flow expansion but also moves the cavitation and erosion away from critical areas. Some valves are designed with stepped or wave-shaped seats to increase resistance and reduce cavitation. This method is commonly used when upgrading older valves or introducing high-pressure systems. Changing the flow direction can also enhance valve longevity. When the flow is directed toward the open side, cavitation and erosion mainly occur on the sealing surface, leading to rapid damage. However, if the flow is directed toward the closed side, the erosion occurs after the valve seat, protecting the sealing surface and the valve root. This method can extend the valve's life by 1 to 2 times, especially in open-flow applications. Using special materials is another way to improve durability. Anti-cavitation and anti-erosion materials, such as 6YC-1, A4 steel, Lai Steel, and cemented carbide, can be used to create throttling elements that resist damage. For corrosion resistance, materials like rubber, PTFE, ceramics, Monel, and Hastelloy are suitable. These materials provide both mechanical and physical resistance, making them ideal for harsh environments. Finally, modifying the valve structure can significantly increase its lifespan. This includes using multi-stage valves, anti-cavitation valves, or corrosion-resistant valves. Choosing a design that inherently resists wear and tear can greatly improve performance and reliability.

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