How to choose an erosion-resistant valve

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Erosion is one of the severe operating conditions and has always been a challenge in field applications. In cases of severe erosion, the lifespan of the valve is extremely short; it ranges from 1 to 2 months at the shortest, and at most 3 to 6 months at the longest. In applications such as hydrogenation catalytic units in the petrochemical industry and copper slurry adjustment in mineral chemistry, the erosion problem is particularly prominent. At present, no valves with exceptional resistance to erosion have been developed; addressing this issue requires a comprehensive consideration of factors such as valve structure, selection of erosion-resistant materials, and anti-erosion measures, in order to find targeted solutions. I. Main causes of erosion Erosion mainly occurs in situations with large pressure differences and in media containing particles. In such situations, the flow velocity of the fluid at the throttle opening of the valve is extremely high, carrying a large amount of kinetic energy; this energy can quickly carve out streamlined grooves on the surfaces of the valve core and seat, thereby damaging the sealing surfaces and causing the valve to malfunction or become unusable. Especially when the valve operates at a low opening degree, the throttling gap is smaller, the fluid velocity is higher, the erosive damage is greater, and thus the service life of the valve is shorter. Therefore, erosion-resistant valves should avoid operating at low opening degrees as much as possible. II. Selection of valve body structure: All throttling surfaces that impede the flow of the medium will be subjected to relentless erosion by the medium. Avoiding is the simplest and most effective way. Therefore, from the perspective of valve structure, a valve that minimizes changes in fluid direction should be chosen; a straight-stroke angular control valve is a traditional solution that provides such a flow path. Some rotary valves, such as V-ball valves, eccentric rotary valves, or fully functional ultra-lightweight control valves with a V-shaped throttle structure, provide nearly straight-through flow paths and offer excellent erosion resistance. At the same time, the throttle openings should be as concentrated and rounded as possible (to reduce the number of times particles come into contact with the valve components and to minimize turbulence), thereby slowing down the flow velocity of the fluid over the throttle surface and reducing erosion of that surface by the medium. III. Selection of erosion-resistant materials: For the valve core and valve seat sealing surfaces, which are most susceptible to damage due to medium impact, materials as hard as possible should be chosen while still maintaining toughness, such as wear-resistant alloys applied by surfacing, in order to enhance the valve’s resistance to erosion damage. When erosion is particularly severe, the guide surfaces as well as the eroded valve body surfaces should also be cladded with wear-resistant alloys to improve reliability and service life. IV. Selection of erosion control measures (1) Avoidance is a simple and effective method. Straight-stroke valves have complex flow paths and are subject to erosion at the bends ； The valve core remains in the throttle position, being directly subjected to the erosion caused by the high-speed fluid, with no way to avoid it. Therefore, straight-stroke valves are not suitable for use. Angle-type control valves can effectively address this issue, but the valve disc is subject to erosion at the center; the best options in terms of erosion resistance are fully functional ultra-lightweight valves, eccentric rotary valves, and \"V\"-type ball valves. (2) Try to avoid operating at low opening degrees; efforts should be made to keep the valve operating at an opening degree of 60–70%. If the medium contains a large amount of solid particles, the normal opening degree should be increased to 70–80% in order to reduce the number of times the particles impact the seals, slow down the flow rate, mitigate erosion damage, and extend the service life of the valve. (3) Use wear-resistant materials. (4) Use an actuator with high stiffness and high thrust (torque). (5) In situations with severe erosion, there are often impure media present, which frequently leads to blockages; therefore, when selecting a suitable solution, attention must also be paid to preventing such blockages. V. Selection of valve types for erosion-resistant valves: (1) Fully functional ultra-lightweight control valves; (2) Eccentric rotary valves. (3) “V”-shaped ball valve (4) angle valve