The maintenance procedures for centrifugal submersible pumps are here for everyone to learn together*

Thread Content

Table of Contents 1 General Provisions 2 1.1 Scope of Application 2 1.2 Brief Structure Description 2 1.3 Equipment Performance 2 2 Integrity Standards 2 2.1 Parts and Components 2 2.2 Operational Performance 2 2.3 Technical Documentation 2 2.4 Equipment and Environment 2 3 Equipment Maintenance 2 3.1 Routine Maintenance 2 3.2 Regular Inspection Items 2 3.3 Methods for Handling Common Faults 2 3.4 Emergency Shutdown 3 4 Maintenance Periods and Tasks 3 4.1 Maintenance Periods 3 4.2 Maintenance Tasks 3 5 Maintenance Methods and Quality Standards 3 5.1 Pump Casing and Cover 3 5.2 Base Plate (Pump Seat) 4 5.3 Pump Section 4 5.4 Pump Shaft 4 5.5 Bushings 4 5.6 Impeller 4 5.7 Rolling Bearings 4 5.8 Couplings 5 5.9 Packing Seals 5 6 Commissioning and Acceptance 5 6.1 Preparations Before Commissioning 5 6.2 Commissioning 5 6.3 Acceptance 5 7 Safety Precautions for Maintenance 5 7.1 Safety Precautions for Maintenance 5 7.2 Safety Precautions for Repair 6 7.3 Safety Precautions for Commissioning 6 1 General Provisions 1.1 Scope of Application These regulations apply to the maintenance and repair of YB, YM, and YH steel centrifugal submersible pumps; other centrifugal submersible pumps can be used as a reference. 1.2 Brief structural description: The corrosion-resistant submersible pump is a single-stage, single-suction submersible centrifugal pump. Its main components include the pump body, pump cover, bottom plate, pump segments, pump shaft, impeller, shaft sleeve, coupling, bearings, and support bushings. 1.3 Equipment Performance The equipment performance is shown in Table 1. 2 Integrity Standards 2.1 Parts and Components 2.1.1 Parts and components are complete and intact, with quality meeting the requirements. 2.1.2 The foundation and base are firm and intact, with quality meeting the requirements. 2.1.3 Piping, valves, and supports are installed properly with clear markings; 2.1.4 Corrosion protection meets the required standards. 2.2 Operating Performance 2.2.1 The equipment operates smoothly without noise, and the current does not exceed the rated value. 2.2.2 Pressure and flow are stable, and temperatures in all sections are normal. 2.2.3 Strictly implement the lubrication management system of “five fixations” and “three-stage filtration”. 2.2.4 The equipment’s output capacity meets the specifications stated on the nameplate or satisfies the production requirements. 2.3 Technical Documentation 2.3.1 The technical archives are complete, and the data is accurate and reliable. 2.3.2 Random certificates and product instruction manuals are complete. 2.3.3 The equipment assembly drawings and diagrams of vulnerable parts are complete. 2.3.4 Complete operation records are available. 2.3.5 Maintenance and acceptance records are complete. 2.3.6 Maintenance and repair procedures, as well as operating procedures, are complete. 2.4 Equipment and Environment 2.4.1 The equipment should be clean, with no dust, grease, or debris on its surface or around it. 2.4.2 There are no leaks or drips from the equipment and associated pipelines. 3 Maintenance of Equipment 3.1 Routine Maintenance 3.1.1 Check for any abnormal vibrations or noises in the equipment. 3.1.2 Check whether the pressure, flow rate, and temperatures of various components are normal, and keep records. 3.1.3 Strictly implement the lubrication management system of “five fixations” and “three-stage filtration”. 3.1.4 Regularly inspect the packing seal; replace it promptly if the packing leakage exceeds the specified limits. 3.1.5 Regularly check whether the connection bolts in various parts are loose or experiencing vibration due to looseness. 3.1.6 Check whether the shaft sleeve cooling water pipe is unobstructed. 3.1.7 Check all sealing points for any signs of leakage. 3.1.8 Keep the equipment tidy at the end of each shift. 3.2 Contents of regular inspections 3.2.1 Inject lubricating oil into the bearings once a month, and clean and change the oil every three months. 3.2.2 Conduct a comprehensive inspection and operation of the pump once a month. 3.3 Common Fault Resolution Methods
The common fault resolution methods are shown in Table 2.

Table 2: Phenomenon, Cause, Resolution Method
Phenomenon | Cause | Resolution Method
-------------|-------|-------------------
Excessive power consumption | 1. Packing pressed too tightly
2. Friction between impeller and casing
3. Misalignment of motor shaft and pump shaft centerline
4. Bent or tilted pump shaft | 1. Adjust the packing gland
2. Adjust the axial clearance
3. Align the coupling
4. Adjust or replace the pump

Failure to pump liquid | 1. Clog in the suction pipe or inlet
2. Liquid level below the working impeller
3. Air in the pipeline
4. Incorrect motor rotation direction | 1. Remove the blockage
2. Fill the tank with liquid
3. Remove air from the pipeline
4. Reverse the motor rotation direction

Insufficient flow rate | 1. Worn impeller
2. Clogs in the inlet and outlet pipes
3. Excessive wear of the impeller seal ring
4. Impeller detachment | 1. Replace the impeller
2. Clean the inlet and outlet pipes
3. Replace the seal ring
4. Reassemble the pump

Pump vibration with noise | 1. Misalignment of motor shaft centerline and pump shaft centerline
2. Friction between impeller and pump body
3. Excessive bearing clearance
4. Bent shaft
5. Worn or corroded impeller, unbalanced rotor | 1. Align the centerlines of both shafts
2. Adjust the clearance
3. Replace the bearings
4. Straighten the shaft
5. Replace the impeller or balance the rotor

Overheating of bearings | 1. Improper bearing assembly
2. Lack of oil or incorrect oil quality in the bearing housing
3. Worn or corroded bearings
4. Motor shaft and pump shaft not aligned | 1. Reassemble the bearings
2. Clean the bearings, add oil, or change the oil type
3. Replace the bearings to stop leakage
4. Align the centerlines of both shafts

3.4 Emergency Shutdown
Shut down immediately if any of the following occur:
a. When the submersible pump produces abnormal noises ； b. When the liquid level in the tank is below the working impeller of the submersible pump ； c. When the motor current exceeds the rated value and does not decrease. 4 Maintenance Cycle and Maintenance Contents 4.1 Maintenance Cycle The maintenance cycle is shown in Table 3. When the pump power is less than 20 kW, no major maintenance is required; the tasks that were previously considered minor maintenance become part of the major maintenance. 4.2 Maintenance Tasks 4.2.1 Minor Maintenance 4.2.1.1 Check and tighten all bolts. 4.2.1.2 Check and replace the packing. 4.2.1.3 Inspect the cleaning cooling water pipes. 4.2.1.4 Replace lubricating oil (grease). 4.2.1.5 Align the coupling and replace the wear parts. 4.2.2 Medium (major) overhauls 4.2.2.1 includes the contents of minor overhauls. 4.2.2.2 Perform a disassembly inspection to assess the degree of wear and corrosion of various components, and repair or replace them as necessary. 4.2.2.3 Determine the static balance of the impeller and the wobble of the rotor. 4.2.2.4 Check the wear condition of the bearings and replace them if necessary. 4.2.2.5 Check and adjust the clearances of various components such as the impeller seal ring, shaft sleeve, and bushing; replace them if wear is severe. 4.2.2.6 Rust removal and corrosion protection. 5 Maintenance Methods and Quality Standards 5.1 Pump Casing and Cover The pump casing and cover shall be free from defects such as cracks, sand holes, and inclusions. The wall thickness and the machining accuracy of various parts must meet the requirements. 5.2 Base Plate (Pump Mount) 5.2.1 The base plate shall be free of cracks, with a smooth and even surface. 5.2.2 Maintain a coaxiality of Φ0.05mm when assembling the pump body, bearing housing, pump cover, and shaft sleeve. Within the range. 5.3 Pump section: The end face of the pump section shall be perpendicular to the center line of the pipe ； Coaxial with the tube center, with a coaxiality of Φ0.05mm. 5.4 Pump shaft 5.4.1 The pump shaft shall be free from defects such as cracks and corrosion. 5.4.2 The material of the pump shaft and the dimensional tolerances of its various parts shall comply with the drawings; the roundness and cylindricity of the shaft journals shall be 0.04 mm. 5.4.3 The surface roughness of the impeller mounting area and the shaft journals at the coupling assembly shall be 3.2 ； The journal at the location where the rolling bearing is mounted has a surface roughness of 1.6. 5.4.4 The straightness of the pump shaft is 0.05 mm/m. 5.4.5 When assembling the upper and lower shafts, the axial play shall not exceed 1.5 mm. 5.4.6 The offset of the keyway centerline from the journal centerline shall not exceed 0.06 mm, and the skew tolerance shall not exceed 0.03 mm. 5.4.7 The key and the keyway sides should fit tightly together ； Gaskets are not allowed. When the keyway is worn, it can be appropriately enlarged depending on the degree of wear. The increase can only be by one level to the standard size. When the structure and load conditions permit, additional keyways can be created at 90º or 120º to the existing keyway. 5.4.8 After wear of the shaft journal, it can be repaired by electroplating or spraying methods. 5.5 Bushings 5.5.1 The surface of the bushings shall be free from defects such as sand holes, pores, and porosity. 5.5.2 The inner and outer surfaces of the bushing shall be machined. The surface roughness of the contact surface between the bushing and the shaft or sleeve is 1.6 ； The external surface roughness in contact with the filler is 1.6. 5.5.3 The clearance between the shaft sleeve and the bushing shall be in accordance with Table 4: 5.6 Impeller 5.6.1 The surface of the impeller as well as the inner walls of the fluid flow channels must be clean, without any defects such as cracks, sand adhesion, or burrs. 5.6.2 The fit between the turbine shaft hole and the shaft generally uses H7/h6. 5.6.3 The allowable radial runout of the shaft with respect to the outer diameter of the impeller is specified in Table 5: Table 4 – Medium: Alkali, Acid; Clearance: 0.40~0.45, 0.60~0.65. 5.6.4 The impeller must be statically balanced before installation, and the allowable tolerance for static balance is specified in Table 6. When exceeding the values shown in the table, deburring should be performed on the cover plates on both sides of the impeller; the cutting thickness shall not exceed 1/3 of the wall thickness, and the cut area shall meet the uncut area smoothly. 5.7 Rolling bearings 5.7.1 The rollers and raceways of rolling bearings, as well as their inner and outer surfaces, must be free from defects such as pits, pitting, corrosion, etc. The cage is in good condition, the contact is smooth, and there is no noise during rotation. 5.7.2 When assembling bearings, they must be cleaned with a cleaning agent to remove dirt and other residues, after which lubricating grease should be applied before assembly. If the heating method is used, the bearing should be placed in an oil bath at 100–120°C for 10–15 minutes before assembly. Direct heating with a flame is strictly prohibited during assembly. 5.7.3 Special tools or presses should be used for installing and removing bearings; the bearings must not be struck directly with a hammer. 5.8 Couplings 5.8.1 When matching couplings with shafts, H7/J6 or H7/K6 is generally selected. 5.8.2 The alignment deviation between the two shafts and the end-face clearance of the elastic sleeve pin coupling shall comply with the requirements specified in Table 7. 5.8.3 The alignment deviation between the two shafts and the end face clearance of the elastic pin coupling shall comply with the requirements specified in Table 8. Table 7 mm Coupler Outer diameter End face clearance Alignment deviation Radial displacement Axial tilt 70~106 130~190 224~250 310~400 3 4 5 5