Bearings in chemical centrifugal pumps are core transmission components, bearing both radial and axial loads from the rotor. Failures can cause downtime at best, or even production interruptions or accidents at worst. Mastering scientific bearing maintenance methods is crucial to extending equipment life and reducing operation and maintenance costs.

一、Daily inspection: real-time monitoring of operating status

Daily inspection is the basis of maintenance, which can detect early abnormalities in time and avoid the expansion of faults.:

1.Appearance inspection: Daily inspections focus on checking whether the bearing end covers and sealing parts are leaking. If the lubricating oil leaks, it is necessary to check whether the seal is aging, damaged or the end cover bolts are loose; at the same time, check whether there are cracks or deformations on the bearing outer ring and bearing box surface. If any problems are found, stop the machine immediately for inspection and maintenance.

2.Temperature monitoring: The normal operating temperature of the bearing should be controlled between 30°C and 70°C (adjustment based on the model and operating conditions). Use an infrared thermometer to measure the surface temperature of the bearing seat regularly. If the temperature suddenly rises to over 80°C, it is necessary to analyze the causes such as insufficient lubrication, bearing wear, rotor imbalance or concentricity deviation and deal with them in time.

3.Vibration and noise detection: Bearing abnormalities will be accompanied by vibration and noise. Place a stylus close to the bearing housing and listen for a normal, even buzzing sound. If there are unusual "clicking" or "rustling" sounds, or if the vibration rate exceeds 6.3 mm/s (which requires quantification using a vibration detector), the machine must be shut down and disassembled for inspection.

4.Lubricating oil inspection: Check the lubricating oil level in the bearing box regularly to ensure that it is at 1/2-2/3 of the oil mark. If it is insufficient, add oil of the same type; observe the color and transparency of the oil. Normally it is clear and transparent or light yellow. If it is black, turbid, has impurities or odor, it needs to be replaced immediately.

二、Lubrication management: ensuring efficient operation

Lubrication can reduce bearing friction and wear and lower the temperature. It is necessary to follow the principle of "correct selection, standard addition, and regular replacement".：

1.Lubricant selection: Choose based on the centrifugal pump's operating temperature, speed, load, and media environment. For bearings operating at temperatures ≤60°C and medium speeds, choose calcium-based grease. For bearings operating between 60°C and 120°C and with high loads, choose lithium-based grease (highly resistant to high temperatures and water). For speeds >3000 r/min, use 46# or 68# machine oil. When conveying corrosive media, choose an anti-corrosion lubricant.

2.Lubrication method and dosage: Oil bath, drip oil and grease lubrication are three commonly used methods. Oil bath lubrication requires controlling the oil level. Too high will increase resistance and raise temperature, while too low will result in insufficient lubrication. During grease lubrication, the amount of grease filled in the bearing box should be 1/3-1/2 of the internal space of the bearing. Too much grease will result in poor heat dissipation, while too little will result in insufficient lubrication. Use clean tools when adding lubricant to avoid mixing of impurities and ensure that the lubricant covers the rolling elements and raceways.

3.Replacement cycle: Grease lubricated bearings should be replaced every 2000-3000 hours; oil lubricated bearings should be replaced every 1500-2000 hours. If the equipment is in a high temperature, high dust or corrosive environment, the replacement cycle will be shortened by 1/3-1/2. Before replacement, the bearing box and the inside of the bearing must be thoroughly cleaned to avoid mixing of new and old lubricants.

三、Cleaning and maintenance: prevent contamination by impurities

In chemical production environments, impurities such as dust and media leakage can easily enter the bearings and require regular cleaning.：

1.Cleaning the outside of the bearing box: Wipe off the oil and dust on the outside of the bearing box every week to ensure good heat dissipation; check whether the ventilation holes (if any) are blocked. If blocked, clean them in time to prevent the temperature inside the box from being too high.

2.Bearing disassembly and cleaning: Bearings need to be disassembled and cleaned when they are inspected or lubricated. Use specialized tools such as a bearing puller to disassemble the bearing, avoiding forceful handling. Rinse the bearing with kerosene or diesel fuel, and remove stubborn stains with a soft brush (not a hard brush or sharp tools). After cleaning, allow the bearing to dry or blow dry with 0.2-0.3 MPa compressed air. Check for cleanliness before reassembly and lubrication.

3.Seal maintenance: Check whether the skeleton oil seal, O-ring and other seals are aging, deformed, cracked or worn. If they fail, replace them with the same type of seals in time; clean the impurities in the sealing groove to ensure that the seals are installed in place and the seal is reliable.

四、Regular replacement: avoid aging failure

Bearings are wearing parts and will wear and fatigue after long-term operation. They need to be replaced regularly.：

1.Determine the replacement cycle: The service life of bearings is generally 8000-12000 hours (needs to be adjusted in combination with material, working conditions and maintenance quality). Even if there are no obvious faults, it is recommended to replace bearings nearing or reaching their service life to prevent unexpected failures from impacting production.

2.Standardize the replacement process: select bearings that are consistent with the original model (pay attention to the accuracy grade and clearance), and do not use inferior or incompatible products. Before assembly, check the dimensional accuracy and surface roughness of the shaft neck and bearing seat hole, and repair any wear and deformation first; use heating(80℃-100℃) or pressure method during assembly to avoid forceful knocking; after assembly, check whether the axial clearance is appropriate and whether the rotation is flexible and without sticking.

五、Fault diagnosis and troubleshooting

1.Bearing overheating: First check the lubricating oil level and status, add oil if insufficient, replace if deteriorated; then check whether the bearing assembly is too tight, adjust if the clearance is small; if ineffective, check the rotor balance, coupling concentricity, or bearing wear, cage damage, and repair or replace them as needed.

2.Abnormal bearing noise:"Rusting" sound may be caused by insufficient lubrication or impurities entering, and the lubricant needs to be replaced and cleaned;"clicking" sound may be caused by damage to the rolling element or raceway, and the bearing needs to be replaced immediately;"buzzing" sound accompanied by vibration may be caused by rotor imbalance or non-concentricity of the coupling, and the balance needs to be corrected or the concentricity needs to be adjusted.

3.Bearing leakage: If the end cover leaks, check whether the seal is damaged. If damaged, replace it, and tighten the loose end cover bolts (pay attention to the torque to avoid bolt breakage or end cover deformation). If the bearing box mating surface leaks, check whether the sealing gasket is intact. If aged, replace it, and clean the mating surface impurities to ensure that the sealing surface is flat.

In short, the maintenance of chemical centrifugal pump bearings needs to be combined with daily inspection, lubrication management, cleaning and maintenance, regular replacement and troubleshooting to form a complete system to reduce the failure rate and ensure continuous, safe and efficient operation of chemical production.