Compressor maintenance record, with pictures and text

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C-1401B-Z Booster Maintenance Report 1. First maintenance: Fault symptoms and analysis: The C-1401B-Z booster stopped operating due to a fault on ----- year ---- month ----- day; after it was completely disassembled, attempts were made to rotate the shaft, but this proved difficult； Upon inspection through the outlet, signs of friction were found on the drive side end plate. Re-measuring the clearances in various areas revealed that in some locations on the drive side, the clearance was less than the minimum value of 0.55 mm specified by the standards. A detailed inspection was carried out; it was found that the rotor on the drive side was worn, with certain areas turning blue in color, which indicates that foreign objects may have entered between the rotor end face and the end plate, resulting in wear of the rotor. As shown in the figure below: Maintenance process: 1. Manually grind the worn areas and high spots on the drive-side rotor and the end surfaces of the end plates, striving to ensure that the end surfaces are flat and smooth, with no obvious grooves or burrs. 2. Clean the material from the surface of the rotor and the cavity, and blow it away using compressed air ； 3. Considering that the wear on the rotor and end plates on the drive side has an impact on the bearings as well, the bearings on the drive side were replaced: NU313 (2 units) and NF313 (1 unit) ； The non-driving bearings were not replaced ； 4. Adjust the clearances of various components to the standard value ranges: the clearance between the rotors should be 0.50 mm, the clearance between the non-driving end face of the rotor and the end plate should be 0.40 mm, and the clearance between the driving end face of the rotor and the end plate should be 0.70 mm. Test results: Testing was carried out after reinstallation on site; the vibration and noise levels were satisfactory, with bearing vibration ranging between 0.5 and 0.6 mm/s, and operation was normal ； Operating time: After successful trial operation, the equipment ran for about 7 days. During inspections, it was observed that the vibration gradually increased, reaching around 5 mm/s, with a tendency to keep rising. Judging from the sound, the vibration on the side not connected to the drive was more significant. 2. Second maintenance: As the vibration levels of the booster pump showed an increasing trend, the equipment was disassembled again. By observing the surface of the rotor and the end plates through the outlet, no signs of significant wear were detected ； The gaps in various areas were rechecked, and there were no significant changes compared to before ； Judging from the operating conditions, the situation on the non-driving side is not good. Since the bearings on the driving side were replaced during the last maintenance, it was decided, after discussion between the equipment technicians from both sides, to replace the bearings on the non-driving side as well. After replacing the bearings and reinstalling everything, testing was carried out; however, the vibration level remained high, at around 6 mm/s, which is clearly abnormal. After about 10 minutes of operation, since the situation did not improve, the machine was stopped for further inspection and repair. It is presumed that the bearings on the non-driving side were not the root cause of the high vibration levels during the last maintenance. 3. During the third repair, the turbocharger was removed from the site as a whole and manually rotated; there was a sound similar to slight impacts from the rotor. ①Initially, it was suspected that the synchronization between the meshing of the synchronous gears and that of the rotor was not proper, resulting in an inaccurate phase of the rotor during operation and prone to minor collisions. This could be due to problems with the installation of the synchronous gears, or wear on those gears, which increased the meshing clearance and caused the rotor to lose synchronization. The above issues were resolved by replacing the gears with new ones and adjusting their installation ； ②During the manual turning of the rotor, it was observed that the movement of the driving rotor was not very smooth, with a feeling of sticking or resistance; it is presumed that the rotor shaft is bent. The runout of the rotor shaft ends was measured using a dial indicator, and the value was around 0.05, which is within the acceptable range, thus ruling out the possibility of a bent rotor shaft ； ③It is speculated that the jamming during the rotation of the drive rotor may be due to misalignment of the bearings used for positioning and supporting the shaft. Since there are three bearings on the drive shaft, the first bearing at the outermost end of the drive side, the NF313, was inspected. After removing the bearing, it was found that some of the rollers on its surface had signs of metal flaking, and the raceway surface of the bearing’s outer ring also showed signs of wear, as shown in the figure below ； : ④ After removing the NF313 bearing, the rotor was turned manually, and the problem of jamming occurred no longer; this indicates that the root cause of the issue was the damage to this bearing ； Maintenance process: 1. Replace the drive-side bearings and oil seals, NU313 (2 units) ； NF313 (1 unit) ； Oil seal TC 85X110X13 (2 pieces) ； TC 70X95X13 (1 piece) 2. Replace the synchronizing gear ； 3. Adjust the clearances between various components: the clearance between the non-driving rotor and the end plate should be 0.40 mm, the clearance between the driving rotor and the end plate should be 0.70 mm, and the clearance between the rotors in contact with each other should be 0.50 mm ； The clearance between the gear teeth is 0.08 mm. Testing process: Testing was carried out after reinstallation on site; the vibration and noise levels were satisfactory, with the vibration of the bearings on both the driven and non-driven sides ranging between 0.5 and 0.6 mm/s, indicating normal operation ； Speculative analysis of the reasons for the rapid wear of the NF313 bearing: 1. Foreign objects may have entered the bearing, causing wear on the rollers and the raceways of the outer ring; the metal coatings on the surfaces of the rollers and the raceways are damaged, and over time this damage worsens, leading to increased vibration ； 2. There may be some deviation when installing the bearing. When the bearing rollers, cage, and inner ring are inserted into the outer ring of the bearing, slight friction occurs between the rollers and the raceways of the inner ring, resulting in subtle damage to the surface of the rollers as well as to the metal coating on the inner ring. Over time, this damage may worsen, leading to increased vibration ； 3. The bearing rollers themselves may have slight defects. Measures: 1. When replacing bearings, carefully inspect them, especially to check for any defects on the surfaces of the rolling elements as well as the inner and outer rings ； Thoroughly clean the new bearings to prevent dust and other foreign substances from adhering to them ； Turn the bearing by hand to check whether it rotates smoothly ； 2. When installing the bearings, be sure to be careful and follow the procedure. ①The inside of the bearing housing and the shaft should be gently polished clean with sandpaper ； ②Use a dial indicator to check whether the shaft is perpendicular to the bearing housing ； ③Use a micrometer to check the diameter of the shaft and the inner diameter of the bearing inner ring, in order to verify the fit condition ； ④The bearing needs to be heated before installation, and the heating temperature must be controlled ； ⑤Apply some lubricant to the outer ring of the bearing housing and the surface of the shaft before installation, to facilitate the installation of the bearing ； Install the bearings only after all preparatory work is completed. Try to use specialized tools during installation; it is strictly prohibited to use tools such as hammers to strike the bearings directly ； If problems occur during the installation process, stop immediately to check; do not force it ； After installation, manually turn the shaft and carefully check whether the bearings rotate smoothly and if there are any stuck areas. Attached materials: