【Haichuan Chemical Valve Management】Series Posts--How to match the hardness of the ball and seat in ball valves? If mismatched, it is scrapped directly

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Proper management of valves is the foundation for stable operation. Everyone is welcome to engage in discussions and share insights on this series of posts: 【HaiChuan Chemical Valve Management】 series of posts: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=5719309 ---------------------------------------------------------------- Disclaimer: The content contained in this article is intended solely for technical exchange and reference purposes only; it does not constitute any form of professional engineering advice, design basis, or operational guidance. ----------------------------------------------------------------------------------- How should the hardness of the ball valve ball and the seat be matched? If the mating is incorrect, the component is discarded; the metal sliding contact surfaces need to have a certain hardness difference, otherwise seizure can occur easily. In practical use, the hardness difference between the valve ball and the valve seat is generally 5–10 HRC, and this difference in hardness enables ball valves to have a longer service life. Due to the complexity of ball processing and the high costs associated with it, and in order to protect the ball from damage and wear, it is common to choose a ball hardness that is higher than that of the valve seat surface. There are two commonly used hardness combinations for the contact surfaces between the valve ball and the valve seat: ① The surface hardness of the valve ball is 55HRC, while that of the valve seat is 45HRC. The surface of the valve ball can be treated with supersonic spraying using STL20 alloy, and the surface of the valve seat can be clad with STL12 alloy. This hardness combination is the most widely used in metal-sealed ball valves, and it can meet the requirements related to normal wear in such valves ； ②The surface hardness of the valve ball is 68HRC, while that of the valve seat is 58HRC. The surface of the valve ball can be treated with supersonic spraying of tungsten carbide, and the surface of the valve seat can be treated with supersonic spraying of STL20 alloy. Such hardness levels make these materials well-suited for use in the coal chemical industry, offering high wear resistance and a long service life.