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I. Analysis of vibration causes: The vibration and noise of control valves can be roughly classified into mechanical vibration, cavitation vibration, and hydrodynamic vibration, depending on the factors that cause them. Mechanical vibration: Mechanical vibration can be divided into two states based on its manifestation. One condition is the overall vibration of the control valve, that is, the entire valve vibrates frequently on the pipeline or base, and this is caused by the intense vibrations of the pipeline or base, which in turn cause the whole control valve to vibrate. It is also related to frequency; that is, when the external frequency is equal to or close to the system’s natural frequency, the energy of the forced vibration reaches its maximum value, resulting in resonance. Another condition is the vibration of the control valve’s disc, which is mainly caused by a sudden increase in the flow rate of the medium, leading to a sharp change in the pressure difference across the control valve and resulting in severe oscillations throughout the valve. Cavitation vibration: Cavitation vibration mostly occurs in control valves of liquid media. The fundamental cause of cavitation is the acceleration of fluid flow and the decrease in static pressure within the control valve, which leads to the vaporization of the liquid. The smaller the opening degree of the control valve, the greater the pressure difference before and after it, which increases the likelihood of fluid acceleration and cavitation; correspondingly, the pressure drop due to flow obstruction becomes smaller. Hydrodynamic vibration: The throttling process of the fluid within the valve is also a process in which it is subject to friction, resistance forces, and disturbances. When turbulent fluid passes through a control valve with poor flow conditions, vortices are formed, and these vortices break away as part of the wake generated by the continuing flow of the fluid. The formation and influencing factors of this vortex shedding frequency are highly complex and exhibit significant randomness, making quantitative calculation very difficult; yet objectively, there is a dominant shedding frequency. When this dominant shedding frequency (including higher harmonics) approaches or matches the structural frequency of the control valve and its associated components, resonance occurs, causing the control valve to vibrate and generate noise. The intensity of the vibration depends on the strength of the dominant shedding frequency and the degree of consistency in the direction of the higher harmonic fluctuations. II. Solutions: Through the practical use of control valves and theoretical analysis, it can be shown that there are many factors that cause vibration and noise in these valves. These factors interact with each other, and many of them occur simultaneously, which makes it more difficult to reduce vibration and noise in control valves. A comprehensive consideration of aspects such as the valve’s material, structure, and fluid dynamics is necessary. 1) Increasing stiffness method: For oscillations and minor vibrations, the stiffness can be increased to eliminate or reduce them; methods such as using springs with higher stiffness or switching to piston actuators are feasible. 2) Increase damping method: Increasing damping means increasing the friction against vibrations; for example, the plug of a sleeve valve can be sealed with an “O” ring, or graphite packing with high friction can be used. This can help to eliminate or reduce mild vibrations to some extent. 3) Increasing the guiding dimensions and reducing the clearance method: Shaft plug valves generally have small guiding dimensions, and the clearance between the various components of such valves is usually large, ranging from 0.4 to 1 mm; this condition facilitates the occurrence of mechanical vibrations. Therefore, when mild mechanical vibrations occur, the vibrations can be reduced by increasing the guiding dimensions and decreasing the fit clearance. 4) Method of eliminating resonance by changing the shape of the throttling element: Since the so-called source of vibration in control valves occurs at the throttling area where flow is rapid and pressure changes sharply, changing the shape of the throttling element can alter the frequency of this vibration source, making it easier to resolve the issue when resonance is not severe. The specific method is to turn the valve core surface by 0.5–1.0 mm within the vibration opening range. In a factory residential area, a self-acting pressure control valve was installed; resonance caused humming noise that disturbed the workers’ rest. By grinding 0.5 mm off the surface of the valve core, the resonant humming noise disappeared. 5) Method of eliminating resonance by replacing the throttling element: ① Change the flow characteristic, from logarithmic to linear, or from linear to logarithmic; ② Replace the type of valve core. For example, changing the plug type to a \"V\"-groove valve core, changing the double-seat valve plug type to a cartridge type; replacing the windowed cartridge with a cartridge having small holes, etc. In a nitrogen fertilizer plant, a DN25 two-seat valve experienced frequent breakage at the connection between the valve stem and the valve disc. After identifying resonance as the cause, we replaced the linear-characteristic valve disc with a logarithmic one, and the problem was resolved. For another example, a laboratory in a certain college used a DN200 sleeve valve; the plug of this valve rotated violently and could not be used. After changing the sleeve with openings to one with small holes, the rotation stopped immediately. 6) Replace the type of control valve to eliminate resonance: Control valves with different structural designs have inherent frequencies that vary naturally; replacing the type of control valve is the most effective way to eliminate resonance at its root. A valve that experiences severe vibration – intense shaking (which can damage the valve in severe cases), strong rotation (to the point where the valve stem may break or twist), and produces loud noise (reaching over 100 decibels) – will see immediate improvement once it is replaced with a valve that has a significantly different structure; the intense resonance disappears miraculously. In the new expansion project of a vinylon plant, a DN200 sleeve valve was selected, and all three of the aforementioned phenomena occurred: the DN300 pipeline vibrated, the valve plug rotated, and the noise level exceeded 100 decibels. The resonance occurrence rate was between 20% and 70%. Given this high level of resonance, a double-seat valve was used instead, and as a result, the resonance disappeared and the valve operated normally. 7) Method of reducing cavitation vibration: For the cavitation vibration caused by the collapse of cavitation bubbles, it is natural to seek ways to reduce cavitation. ①The impact energy generated by the bursting of bubbles is not allowed to act on the solid surface, especially on the valve core, but is instead absorbed by the liquid. Sleeve valves possess this feature, which allows the plug-type valve core to be replaced with a sleeve-type one. ②All methods to reduce cavitation should be employed, such as increasing throttling resistance, raising the pressure at the throat, and using staged or series pressure reduction. 8) Avoid vibration caused by external wave impacts: External wave impacts can cause vibration in the valve, and this is something that must be avoided during the normal operation of control valves. If such vibration occurs, appropriate measures should be taken.