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A control valve, also known as a regulating valve, operates by receiving a control signal from a control unit. In the automatic control of modern factories, control valves play a very important role, as the production in such factories depends on the proper distribution and control of the flowing media. These controls, whether it is the exchange of energy, the reduction of pressure, or simply the feeding of materials into a container, all require certain final control elements to be implemented. Whether a control valve operates properly is closely related to its maintenance work. There are various types of failures in control valves, and the occurrence of a particular failure can also have different causes. I. Main faulty components of the actuator Different types of control valves, as well as various parts of them, have certain key components that are also prone to failure. 1. Pneumatic and hydraulic actuators a. Diaphragm: For diaphragm-type pneumatic actuators, the diaphragm is the most important component. When the air supply system is functioning properly but the actuator does not operate, it is necessary to check whether the diaphragm is damaged or not properly installed. When there are defects such as sharp corners and burrs on the surface of the metal contact, it can puncture the diaphragm, and the diaphragm must not leak under any circumstances. Additionally, prolonged use of the diaphragm and material aging can also affect its performance. b. Piston: The piston in pneumatic and hydraulic actuators generates the driving force; therefore, damage or wear to the piston is absolutely not allowed. c. Gas (liquid) pipe: This is the pathway through which the input pressure reaches the actuator; therefore, it is necessary to regularly check that it is securely connected and there are no leaks. d. Push rod: Check whether the push rod is bent, deformed, or detached. The push rod must be firmly connected to the valve stem, and its position must be adjusted properly, so as to ensure sufficient travel and the proper closing of the control valve. e. Springs: Check whether the springs are broken. Improper manufacturing, processing, or heat treatment can all cause the spring to break. Some springs may also break under excessive loads. 2. Electric actuator a. Motor: Check whether the motor can rotate, whether it overheats easily, and whether it has sufficient torque and coupling force. b. Servo amplifier: Check whether there is an output and whether it can be adjusted. c. Reduction mechanism: The reduction mechanisms used by different manufacturers vary. Therefore, it is necessary to check whether its transmission components—shafts, gears, worm gears, etc.—are damaged or have excessive wear. d. Torque controller: Check the cause of failure based on the specific structure. Apart from failures of the actuator, the common faults that can occur in the valve body itself are as follows: II. The main faulty components of the valve a. Valve body: It is necessary to regularly check for corrosion and wear on the inner walls of the valve body. Especially for valves used in harsh operating conditions such as those involving corrosive media, high pressure differences, or cavitation, it is essential to ensure their pressure resistance as well as their resistance to corrosion and wear. b. Valve core: Since the valve core is responsible for regulating and shutting off the flow of fluid, and it serves as a movable component that controls the flow, it is particularly susceptible to erosion, corrosion, and impact from particles. It is more prone to damage under conditions of high pressure differences and cavitation; therefore, it is necessary to check whether its various parts are damaged, worn, or corroded, and to determine whether repair or replacement is required. c. Valve seat: The valve seat interface is crucial for ensuring that the valve closes properly, and it is also subject to significant corrosion and wear. Furthermore, due to the penetration of the medium, the internal threaded surface of the fixed valve seat is often corroded and loosened, so this area requires special inspection. d. Valve stem: Check whether the connection between the valve stem, the valve core, and the push rod is loose, and whether there is excessive deformation, cracks, or corrosion. e. Packing: Check whether the polytetrafluoroethylene or other packing materials are aged, lack lubricant, or have deteriorated, and verify that the packing is properly compressed. f. Gaskets and O-rings: These vulnerable components must not crack or age. Through the analysis and handling of common faults in control valves, the failure rate of these valves has been reduced, and their operational lifespan has been extended. This, in turn, has minimized equipment damage and maintenance costs, thereby achieving balance in process production control.