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1. A common problem with throttle control valves is blockage, which often occurs in newly commissioned systems and at the beginning of operation after major repairs. Weld slag, rust, and other debris in the pipes can cause blockages at the throttling areas and guide sections, preventing smooth flow of the medium. Additionally, if the packing is tightened too much during valve maintenance, it increases friction, resulting in the valve not responding to small signal inputs while over-reacting to larger signal inputs. Clogging solution: The bypass line or control valve can be quickly opened and closed, allowing the debris to be flushed away by the fluid through the bypass line or ball valve. Another method is to use pipe wrenches to clamp the valve stem, and under applied signal pressure, turn the valve stem in both directions to allow the valve core to pass over the jammed area. If this is not possible, increase the air supply pressure and boost the driving power; moving up and down several times will resolve the issue. If no action is taken, it will need to be dismantled. 2. Leakage: 2.1 Internal leakage of the valve, and the valve stem is of inappropriate length. The air release valve: the valve stem is too long, and the distance that the stem can move upward (or downward) is insufficient; as a result, there is a gap between the valve disc and the butterfly valve seat, preventing full contact and leading to poor sealing and internal leakage. Similarly, the valve stem of the air shut-off valve is too short, resulting in a gap between the valve core and the valve seat; this prevents proper contact and leads to poor sealing and internal leakage. Solution: The valve stem of the control valve should be shortened (or lengthened) to adjust its length appropriately, so as to eliminate internal leakage. 2.2 Packing leakage. After the packing is inserted into the stuffing box, axial pressure is applied to it via the gland. Due to the plasticity of the filler, a radial force is generated, causing it to make close contact with the valve stem; however, this contact is not very uniform. In some areas, the contact is loose; in other areas, it is tight, and there are even some areas where there is no contact at all. During the operation of a gate valve, there is relative movement between the valve stem and the packing, and this movement is called axial motion. During operation, under the influence of high temperatures, high pressures, and fluid media with strong permeability, the packing gland of control valves is also a part where leaks occur frequently. The main cause of filler leakage is interfacial leakage; in the case of textile fillers, seepage also occurs (the pressure medium leaks outward through the tiny gaps between the filler fibers). Interfacial leakage between the valve stem and the packing is caused by the gradual decrease in the contact pressure of the packing, as well as the aging of the packing itself; under such conditions, the pressurized medium leaks outward through the gap between the packing and the valve stem. Solution: To facilitate the insertion of the packing, chamfer the top of the packing box, and place a corrosion-resistant metal protective ring with a small clearance at the bottom of the packing box (the contact surface between the globe valve and the packing must not be inclined) to prevent the packing from being pushed out by the medium pressure. The metal surfaces of all parts of the stuffing box that come into contact with the packing must be finely processed to improve surface smoothness and reduce packing wear. Flexible graphite is chosen as the packing due to its excellent airtightness, low friction, minimal changes over time, low wear and degradation, ease of maintenance; the friction remains unchanged after the gland bolts are tightened again. It also boasts good pressure and heat resistance, is not affected by internal media, and does not cause pitting or corrosion in the metals that come into contact with it within the valve stem and stuffing box. In this way, the seal of the valve stem packing gland in the pressure relief valve is effectively protected, ensuring the reliability and durability of the packing seal. 2.3 Leakage due to deformation of the valve core and valve seat. The main cause of leakage at the core and valve seat is the enhanced corrosion resulting from casting or forging defects during the production of the control valve. The passage of corrosive media, as well as the scouring by fluid media, can also cause leakage in control valves. Corrosion mainly occurs in the form of erosion or cavitation. When corrosive media pass through the control valve, it causes erosion and impact on the materials of the valve core and seat, resulting in these components taking an oval or other shape. Over time, this leads to a mismatch between the valve core and seat, the creation of gaps, and leakage as a result of poor sealing. Solution: The key is to ensure proper selection of materials and maintain high quality for both the valve core and the valve seat. Choose corrosion-resistant materials, and firmly reject products with defects such as pitting and sand eyes. If the valve core and seat are not severely deformed, they can be polished with fine sandpaper to remove any marks and improve the smoothness of the seal, thereby enhancing its sealing performance. If the damage is severe, a new valve should be replaced.