Cooling Tower Fan Maintenance and Repair Procedure

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2.1.1 The spare parts of the main and auxiliary equipment are complete, and their quality meets the requirements. 2.1.2 Instruments, meters, and various safety devices are complete, in good condition, sensitive, and accurate. 2.1.3 The foundation and base are stable and reliable; the anchor bolts and all bolt connections are tight, neat, and meet the requirements. 2.1.4 The body is intact, with no obvious defects such as deformation, cracks, or corrosion in the blades. 2.2 Operational Performance 2.2.1 The equipment is well-lubricated, the lubrication system is unobstructed, and the oil quality meets the requirements ； Implement \"five fixations\" and \"three-level filtering\". 2.2.2 There are no abnormal vibrations, noises, or similar phenomena. 2.2.3 The temperature of the rolling bearings shall not exceed 70°C, and the current values shall be within normal limits. 2.2.4 The production capacity reaches the output specified on the nameplate or the rated capacity. 2.3 Technical Documentation 2.3.1 Equipment records, maintenance, and inspection records are complete. 2.3.2 There are equipment history cards. 2.3.3 It comes with installation and operation instructions, as well as a product quality certificate. 2.3.4 The vulnerable parts come with diagrams. 2.3.5 There are statistical records of the equipment’s operating time and cumulative operating time. 2.3.6 The equipment operation procedures and maintenance rules are complete. 2.4 Equipment and Environment 2.4.1 The fans are clean, with no dust or oil residue on their surfaces. 2.4.2 The foundation and base are intact, with the surface and surrounding area kept clean. 3 Equipment Maintenance 3.1 Routine Maintenance 3.1.1 Strictly follow the operating procedures for the position and carefully fill in the operation records. 3.1.2 The operating condition should be checked once per hour to ensure that the current and temperature readings are within the specified ranges. 3.1.3 Strictly implement the equipment lubrication management system. 3.1.4 Maintain equipment and environmental hygiene, and regularly clean off debris on the surfaces. 3.1.5 When a fan has been out of use for an extended period and is put back into operation, it is necessary to check whether all connection points are secure and reliable, as well as whether the gap between the impeller and the duct is appropriate; only after testing during operation can it be used officially. 3.1.6 In the event of abnormal sound responses during operation, stop the machine immediately for inspection and troubleshooting. 3.2 Regular inspection items 3.2.1 Conduct a lubrication analysis once a month to check whether the viscosity, moisture, impurities, etc. of the oil meet the required standards. 3.2.2 Monitor the vibration of the machine body and bearings on a monthly basis, with the amplitude not exceeding 0.20 mm. 3.3 Common Fault Troubleshooting Methods
Common faults and their corresponding troubleshooting methods are shown in Table 2.

Table 2: Common Faults and Troubleshooting Methods
| Fault Phenomenon | Cause | Solution |
|-------------------|-------|----------|
| Vibration of the machine body | 1. Loose fit between the hub hole and the spindle | 1. Re-fit the key and perform grinding repairs.<br>2. Unbalanced blade set, corroded blades, or foreign objects on the blade surfaces | 2. Remove foreign objects and balance the blades.<br>3. Inconsistent blade angles | 3. Adjust the angles.<br>4. Excessively large blade angles | 4. Adjust the angles.<br>5. Loose blade mounting bolts | 5. Tighten the bolts.<br>6. Insufficient stiffness of the base | 6. Strengthen the base.<br>7. Damaged coupling or poor alignment | 7. Repair the coupling and realign it.<br>8. Loose foundation bolts | 8. Tighten the bolts.<br>9. Bent rotating shaft | 9. Straighten the shaft.<br>10. Worn or damaged bearings | 10. Replace the bearings |

High oil temperature inside the gearbox | 1. Blocked lubrication channels in the gearbox | 1. Clear the blockages to ensure proper flow.<br>2. Low oil level or insufficient oil splashing | 2. Fill the gearbox with oil to the specified level.<br>3. Worn bearings | 3. Replace the bearings.<br>4. Incorrect installation | 4. Realign the components properly.<br>5. Lubricant that does not meet requirements | 5. Replace the lubricant.<br>6. Excessively high oil level | 6. Drain excess oil to the specified level.<br>7. Worn gears or gears that were not replaced in pairs | 7. Replace the gears in pairs. |

Oil leakage | 1. Damaged seals | 1. Replace the seals.<br>2. Loose bolts at the sealing points | 2. Tighten the bolts. |

3.4 Emergency Shutdown
An emergency shutdown must be carried out in any of the following situations. 3.4.1 Abnormal loud noise from the fan ； 3.4.2 Sudden severe vibration of the fan ； 3.4.2 The current continues to rise beyond the rated value without decreasing. 4 Maintenance Cycle and Scope 4.1 Maintenance Cycle The maintenance cycle and categories are shown in Table 3. Table 3: Maintenance Cycle and Categories for Cooling Tower Fans Maintenance Category Minor Repair Major Repair Maintenance Cycle 6 months 12–18 months If condition monitoring techniques enable predictive maintenance, this restriction can be waived upon approval from the relevant authorities. 4.2 Maintenance Tasks 4.2.1 Minor Repairs 4.2.1.1 Inspect and tighten the foundation bolts. 4.2.1.2 Check whether the back caps and fastening bolts of the blades are loose, and whether the blade angles have changed. 4.2.1.3 Inspect or replace the lubricating oil, and clean the dirt and debris accumulated on the blades. 4.2.1.4 Check the alignment of the coupling and replace the rubber ring. 4.2.2 Major Overhaul 4.2.2.1 Includes minor repair tasks 4.2.2.2 Remove blades and hubs to check for defects such as corrosion, deformation, and cracks ； Adjust blade angle ； If necessary, a static balance test should be conducted on the assembled blade set. 4.2.2.3 Disassemble the reducer to check the wear condition of components such as gears, bearings, and the reducer body, and repair or replace any damaged parts. 4.2.2.4 Inspect and repair the drive shaft and coupling, and align them properly. 4.2.1.5 Inspect and repair the machine base and foundation, check or replace the foot bolts, and verify the levelness of the machine body. 4.2.1.6 Apply anti-corrosion and moisture-proof treatments. 4.2.1.7 Motor inspection, repair, and refueling. 5 Maintenance Methods and Quality Standards 5.1 Brief Description of Maintenance Methods 5.1.1 Blade assembly: Marks must be made during disassembly, and these marks should be used to reposition the blades correctly upon installation after maintenance. During installation, remove the gland on the upper part of the gearbox output shaft (impeller), wipe the conical portion of the output shaft clean, apply oil to it, and fit the sleeve over the impeller shaft. Install the gland, tighten the bolts, and compress the profile. The method for adjusting the blade mounting angle is as follows: The tools required for measuring angles are a ruler and a protractor. First, set the protractor to the specified angle, then place the ruler at the position where the blade mounting angle is to be measured. Position the protractor on top of the ruler, and rotate the blade until the horizontal bubble on the protractor is centered. After all the blade angles have been adjusted and the bolts tightened, check the blade installation angles again. 5.1.2 If the groove depth of the shaft journal exceeds the specified value, it can be repaired by grinding and spraying. 5.1.3 Use a dial indicator on the machine tool to check the shaft’s radial runout, straightness, roundness, and cylindricity. 5.1.4 Check the tooth surface contact using the coloring method. 5.1.5 Use the lead pressure method or dial indicator to detect gear meshing, tip clearance, and side clearance. 5.1.6 During the major overhaul of the reducer, the method of using kerosene to fill gaps is employed to check for defects such as sand holes and cracks in the housing. 5.1.7 Use a level to check the levelness of the machine body on its horizontal plane. 5.1.8 Special removal tools and presses should be used for the disassembly and assembly of rolling bearings ； During bearing heating and assembly, the oil temperature should not exceed 120°C; assembly should be carried out after immersing the bearings in the oil for 10–15 minutes. Direct heating with flames or direct hammering of the bearings is strictly prohibited. 5.1.9 Check the wear condition of the bearing using feeler gauges, dial indicators, or other methods, in accordance with the clearance requirements for rolling bearings. 5.2 Maintenance Quality Standards 5.2.1 Blade Assembly 5.2.1.1 The inclination angle error of each blade as it rotates around the axis shall not exceed 0.5°. 5.2.1.2 End face runout at the outer edge of the blade set ≤ 50mm ； Radial runout ≤ 8.0 mm. 5.2.1.3 After the hub and blades are assembled, a static balance test shall be conducted, requiring that the residual unbalance value at the outer edge of the blades be no greater than 25g. 5.2.1.4 Hub radial runout ≤ 6mm ； End face runout ≤ 6mm. 5.2.1.5 The gap between the outer edge of the blade and the wall of the air duct shall be 30–45 mm, and this gap shall be consistent throughout. 5.2.2 Reducer 5.2.2.1 Spindle a. The spindle must be free of cracks, and the shaft journals must not have any defects such as scratches or pitting; the roughness of the shaft journals should be Ra1.2 ； b. The straightness of the main shaft’s centerline is 0.015 mm/m at the journal areas and 0.04 mm/m in other areas; c. The roundness and cylindricity of the journal areas are 0.02 mm ； d. The inclination of the keyway centerline with respect to the axis centerline is 0.03 mm/100 m ； e. The axial play of the spindle is 0.06–0.08 mm. 5.2.2.2 Helical bevel gears and helical spur gears a. The gear mating surfaces must be free of corrosion pits and cracks, with a surface roughness of 1.6 ； b. The contact patch of the gear pair mesh shall meet the requirements in Table 4. Table 4: Requirements for the contact patch of gear pair meshing. Inspection location: Contact patch; Minimum percentage along the tooth height: ; Minimum percentage along the tooth length: Helical bevel gears: 60, 60; Helical spur gears: 35, 60. c. The wear of the gears shall not exceed 10% of the original tooth thickness ； d. The tip clearance for gear meshing is (0.2–0.3)m (where m is the module), and the side clearance is 0.13 mm. 5.2.2.3 Reducer housing a. The reducer housing shall be free from cracks and oil leakage ； b. The levelness of the machine body is 0.1 mm/m. 5.2.3 Rolling bearings a. The fit between the bearing and the shaft journal is H7/K6, while the fit between the bearing and the bearing housing hole is K7/H6 ； b. The rolling elements of rolling bearings, as well as the working surfaces of the inner and outer rings, must be smooth, free from defects such as pitting, corrosion, or dents ； The clearance between the roller and the inner and outer rings shall meet the requirements of Table 5. Table 5 Bearing clearance requirements. Location: Clearance requirements – Input shaft bearing: 0.06–0.08 mm; Intermediate shaft bearing: 0.07–0.10 mm; Output shaft bearing: 0.08–0.12 mm. 5.2.4 Drive shaft: 5.2.4.1 The straightness of the drive shaft should be 0.5 mm/m. 5.2.4.2 Alignment of the reducer shaft and drive shaft couplings, as well as the drive shaft and motor couplings ； The radial displacement is 0.5–0.6 mm, and the axial tilt is ±1° ； The radial runout values are all 0.06 mm. 6 Commissioning 6.1 Preparations before commissioning 6.1.1 Check the tightness of the foundation bolts of the frame, as well as the connection bolts between the frame and the fan and motor. 6.1.2 Check whether the lubricating oil level in the tank is appropriate and whether the oil circuit is unobstructed. 6.1.3 The safety devices are secure and complete, with the motor grounding wire connected. 6.1.4 Check whether thermometers, instruments, etc. are sensitive and functional. 6.1.5 Verify that the motor rotation direction is correct. 6.1.6 The maintenance site must meet the requirement of a clean area with all work completed and materials removed. 6.2 Commissioning 6.2.1 Before starting, turn the machine 2-3 times to ensure smooth rotation. Connect the power supply and turn it on once; if there are no issues, then the machine can be started. 6.2.2 No collision between the blades and the air duct. 6.2.3 The temperature of the rolling bearings shall not exceed 70°. 6.2.4 There shall be no abnormal vibrations or noises during operation; the amplitude of vibration of the unit shall not be greater than 0.20 mm, and the maximum vibration speed of the gearbox shall be ≤ 7.10 mm/s. 6.2.5 The current does not exceed the rated value, with fluctuations of less than 5 amperes. 6.2.6 The air volume reaches the output specified on the nameplate or the rated capacity. 6.2.7 The commissioning operation time shall be no less than 2 hours. 6.3 Acceptance: Once the equipment has undergone testing and operates properly, with all technical specifications meeting the required standards, the handover procedures can be carried out in accordance with the established rules, and the equipment can then be put into use in production. 7 Safety Precautions for Maintenance and Repair 7.1 Safety Precautions for Maintenance 7.1.1 It is necessary to strictly follow the process operation procedures and relevant safety regulations. 7.1.2 The equipment shall have a properly grounded wire. 7.1.3 All safety protection devices on the equipment must not be removed arbitrarily. 7.1.4 Before starting the equipment, it must be turned manually and tested briefly. 7.1.5 During equipment operation, it is not allowed to wipe the rotating parts. 7.1.6 It is prohibited to use substandard or deteriorated lubricating oil. 7.2 Safety Precautions for Maintenance 7.2.1 Before maintaining the equipment, it is necessary to clean it thoroughly; once cleaning is complete, the handover procedures for maintenance should be carried out. 7.2.2 Before performing equipment maintenance, the power supply must be disconnected. After a second verification, a “Do Not Operate” sign should be placed at the power source before maintenance can begin. 7.2.3 When using a drill during maintenance, rubber insulating gloves must be worn, and the drill’s casing should be grounded ； Use temporary lighting fixtures with a voltage not exceeding 36 volts. 7.2.4 When hot work is required, the necessary procedures must be followed first; the combustible material content must be verified to be within acceptable limits, and approval in accordance with regulations must be obtained before proceeding. 7.2.5 When lifting and transporting equipment and components, there must be a dedicated person in charge to give instructions, and another dedicated person to operate the lifting equipment. The appropriate lifting ropes must be used, and lifting under overload is strictly prohibited. It is also forbidden for people to walk or stay under the lifted objects. 7.2.6 Maintenance tools, as well as the components that have been removed, cleaned, or replaced, should be placed in designated areas in an orderly manner, to keep the work area clean and unobstructed. 7.3 Safety Precautions for Testing 7.3.1 Testing operations should be carried out in accordance with a testing plan, under the responsibility of a designated person, and under unified command. 7.3.2 The starting and stopping of the equipment shall be carried out by designated personnel, who must hold a \"Safety Operation Certificate\" for that position. 7.3.3 Clear signs indicating that testing is in progress shall be installed, and unauthorized persons are prohibited from entering the testing area. 7.3.4 Before starting the machine, first check whether the rotation direction of the motor is correct. Once the rotation direction is confirmed to be correct, connect the coupling and install the protective cover before attempting to start the machine. 7.3.5 Operate the fan strictly in accordance with its startup procedure. 7.3.6 During testing, pay attention to whether the fan is operating normally. If abnormal vibration and noise are detected or if the current exceeds the rated value, stop the machine immediately for inspection, troubleshooting, and cleanup before attempting to restart it.