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The vertical multi-stage pump is a vertical multi-stage single-suction segmented centrifugal structure. It is a vertical multi-stage medium conveying equipment. The flowing medium (gas and liquid, or a mixture of suspended particles and gas or liquid) is from The root of the blade shaft (inlet) enters, and the medium relies on the high-speed rotating blades to obtain centrifugal force, generating a high pressure and flowing out from the pressure relief port (outlet). Vertical multi-stage pump models mainly include three types: DL vertical multi-stage centrifugal pump, GDL vertical multi-stage pump and CDL/CDLF vertical stainless steel multi-stage pump. They have high efficiency, wide performance range, easy installation and maintenance, etc. Features: Its vertical structure determines that the installation area is small, and its center of gravity coincides with the center of the pump foot, thereby enhancing the operating stability and service life of the pump.
Vertical multistage pump
The purpose of disassembling the vertical multi-stage pump is to find the cause of the fault and inspect, repair or replace parts that have been damaged or have reached the end of their service life. The disassembly of the vertical multi-stage centrifugal pump is a necessary means for maintenance. The maintenance cycle is: minor maintenance, 3 months; medium maintenance, 12~24 months; overhaul, 36 months.
Disassembly steps of vertical multi-stage pump parts
1. Technical requirements before disassembly
(1) Disassemble the segmented multi-stage centrifugal pump as shown in the figure according to the correct procedures and methods.
(2) Special tools and equipment should be used for disassembly as much as possible.
(3) Brutal disassembly is strictly prohibited and parts should be avoided as much as possible.
(4) For parts that are easily mixed, the installation orientation should be marked or numbered and stored after cleaning.
(5) Check the relevant technical information and the last overhaul and intermediate repair records, and ask the operator about the operation of the machine.
(6) Cut off the power supply to ensure safety during maintenance.
(7) Cut off the conveying medium.
(8) Prepare tools, measuring tools and corresponding lifting equipment.
2. Preparation before disassembly
(1) Preparation of dismantling tools and tools: lifting and dismantling tools; special wrenches; screwdrivers; hand hammers; wooden hammers or copper bars; crowbars; cleaning tools and tools, etc.
(2) Testing measuring tools: vernier caliper; magnifying glass; inner diameter micrometer; outer diameter micrometer; feeler gauge; depth vernier caliper; flat plate, etc.
3. Disassembly process methods and steps
(1) Remove the connecting bolts of the flange in front of the outlet valve and behind the inlet valve of the pump on the medium pipeline, and separate the pump from the medium pipeline. Remove the cooling water pipe. Disconnect the coupling between the pump and motor and remove it from the pump shaft.
(2) Unscrew the base bolts of the pump, and at the same time, number the gaskets at each base bolt in sequence and keep them in place when reassembly to reduce the amount of alignment work.
(3) Disassembly of the bearing body. First remove the bearing body connecting bolts on the front and rear sides. Then pull out the bearing bush or bearing together with the bearing frame in the axial direction.
(4) Disassembly of shaft seal. First unscrew the connecting nut between the gland and the pump body. Pull out the packing gland along the axial direction, and then take out all the packing or pull out the mechanical seal.
(5) Disassembly of the balancing device. Unscrew the connecting nut between the tail cover and the tail section, remove the tail cover, and then take out the balance plate axially. Loosen the screws connecting the balance ring to the pump body to remove the balance ring.
(6) Disassembly of the tail section. Remove the balance plate and balance ring. First unscrew the bolt and nut of the rod, pull out the bolt, and then tap the boss of the rear section lightly with a hammer to loosen it and then remove it.
(7) Disassembly of impeller. The impeller and pump shaft have a clearance fit, but they may rust together due to the action of the medium. When disassembling, generally use a wooden hammer to gently tap around the impeller to loosen it, and then pull it out in the axial direction to remove it. If the impeller is rusty on the shaft, soak it with kerosene and then disassemble it. That’s it.
(8) Disassembly of the middle section. Usually, use a pry bar to pry along the two legs in the middle. The middle section can be removed. Then remove the bushing on the pump shaft between the impellers. Then, the entrance sealing ring and guide wheel can be removed from the middle guide wheel. Use the same method to remove the remaining impeller, middle section, and suction cover.
(9) Removal of long rod bolts. The front, middle and tail sections of the segmental multi-stage pump are fixed together by a number of long bolts to form a complete pump body. These bolts are also called long rod bolts. When the long rod bolts are tightened, the axial sealing surfaces between each section are closely fitted to prevent the pressure medium in the pump chamber from leaking outward. If the tightening force of long bolts is too large, it will cause damage to the parts; if the tightening force is too small, the sealing surface will leak. Some manufacturers give the pre-tightening force value of long-rod bolts in the instructions. When assembling after repair, just tighten the bolts according to the specified value; most manufacturers do not give the pre-tightening force value of long-rod bolts, which requires on-site During maintenance, make sure the tightening force is moderate based on the comparison of tightening lengths before and after disassembly and assembly. The simple way is to number each long bolt and its matching nut in sequence before disassembly, for example, number 1, 2, I3,… in the clockwise direction, and number the other end in the counterclockwise direction, and put the bolts correspondingly. The bolt holes are also numbered accordingly to ensure that the bolts and nuts are still reinstalled in their original places. Polish the bolt end face and nut end face with emery cloth. For the same bolt, measure the length of the nut exposed at both ends.
When assembling, use the same method to measure the sum and calculate the value so that the value is equal to the value before disassembly. Example of recording the protrusion amount of the long rod bolt of a segmented multi-stage centrifugal pump. After measuring and recording, start to remove the long rod bolts. When removing the long bolts, be sure to keep two bolts 180° apart to prevent the front, middle, and rear sections from suddenly falling apart and damaging the rotor or other parts. In order to prevent the middle section from falling and bending the pump shaft, temporary support should be added to the lower side of the middle section when the long rod bolts are removed.
(10) During the disassembly process, the shaft will be in a cantilevered state after several middle sections are removed, so as to avoid bending of the shaft. Therefore, temporary reliable supports should be installed. also. The disassembled impeller, key, guide vane, middle section and other parts should be numbered and stored one by one. After disassembly, the bearings, shafts, mechanical seals, etc. should be cleaned with kerosene, checked for damage, excessive wear or deformation, and decided whether to repair or replace them. Remove the gaskets between each section to remove rust.
4. Inspection after disassembly
(1) After cleaning the disassembled parts, macroscopic inspection and measuring instruments will detect scrapped parts and store them separately.
(2) Check out the parts to be repaired. After marking or numbering, classify and group them for safekeeping.
Disassembly steps of vertical multi-stage centrifugal pump water pump motor
1. Vertical multi-stage centrifugal pump disassembled water pump:
Because there are different manufacturers and models of water pumps, the structure of the pump body is also different; however, there are roughly two steps for disassembling and repairing the water pump. One is to remove it level by level from bottom to top, and the other is to remove it level by level from top to bottom. The following is an example of dismantling one level at a time (from bottom to top).
(1) Close the inlet and outlet valves, drain the water in the pump body, and mark each stage of disassembly.
(2) Use a drawing code to pull out the coupling on the pump body, remove the cover nut, take out the bearing cover lever, remove the bearing, shaft seal or packing packing. When disassembling the magnetic ring mechanical shaft seal, it is strictly prohibited to pry or hit hard. .
(3) Remove the screws connecting the pump body outlet to the pipe network, and unscrew the fixing bolts between the pump body and the base. Use hemp rope to tie 2/5 of the pump body. Lift the water pump away from the base and slowly lower it. When lowering the pump, remember not to bend the pump shaft. Place the pump flat on the ground wooden board.
(4) Unscrew the pump shaft tail nut, remove the shaft sleeve, and then remove the impeller. (It is strictly prohibited to hit the shaft sleeve and impeller with a hammer directly during the disassembly process.) Finally, take out the casing.
(5) After the first-stage sleeve, impeller, and casing are removed, the shaft should be debonded before disassembling the next stage. (The pump shaft below 35mm cannot be used as a force-bearing tool to move the water pump).
(6) The disassembly methods for the following levels are the same as above. Please pay attention to placing the disassembled components at each level in order; wait until the last level of components is completely disassembled.
(7) The entire work is transferred to grinding the mating surfaces between parts to remove rust and scale. The use of diesel fuel and hazardous substances during the cleanup process is strictly prohibited.
2. Vertical multi-stage centrifugal pump disassembled motor:
(1) According to the actual conditions of the maintenance site (such as installing lifting hooks), hang up the lifting equipment (hoist, wire rope, pull rope).
(2) Check the hook, rope buckle, and hoist lock, and test the lifting center of gravity of the lifting motor;
(3) Remove the motor power cord, remove the screws connecting the motor and the pump body; remove the screws connecting the motor and the water pump coupling.
(4) Lift the motor. When the motor is separated from the water pump by a certain distance, tighten the pull rope and slowly lower the motor (to prevent the center of gravity of the motor from shifting during the lowering process, damaging the equipment and injuring people); wait until the motor is flat. After it is on the wooden board, use the pull code to pull out the coupling, remove the motor fan cover, and take out the fan blades.
(5) Use a megohmmeter to check the insulation of the motor windings and make a record; then mark the disassembly, unscrew the screws of the front and rear end covers of the motor, and take out the end covers.
(6) Check the degree of bearing wear. If you need to replace the bearing, use a pull code to pull out the bearing (pull out the rotor before taking out the bearing, do not damage the stator winding when pulling out the rotor, and take certain protective measures if necessary).
(7) Replace the motor bearings. Methods include: heating method, cooling method, and cylinder direct pressure method.
(8) If the bearing has an outer ring, check the fit between the end cover bearing seat and the bearing. If the fit is not good, the end cover bearing seat needs to be processed. The steps for assembling the motor are opposite to those for disassembling the motor.
(9) Conduct an insulation test on the motor windings before assembling the motor (if the motor windings are damp, they must be dried and dehumidified, and heat-impregnated insulating paint must be added if necessary); the test values are within the specified range and can be used.
3. Vertical multi-stage centrifugal pump assembly metering pump body:
(1) After rust removal, cleaning, and grinding are completed, start assembling the water pump (the order and method of assembly and disassembly are reversed). First, place the level with the bearing horizontally on the wooden strips, then place the level with the water outlet on top, and then place the shaft with a balance drum in the middle of the level with the water inlet and outlet vertically.
(2) Install the first-stage impeller on the shaft and place a waterproof ring on the edge of the housing.
(3) Put the bushing on the shaft, then install the next-stage casing, then install the second-stage impeller, and then install the bushing and next-stage casing to install the N stage in this way.
(4) After installing the last stage, tighten the two reverse nuts.
(5) After completing the above work, hang the pump body on the base and tighten the fixing bolts.
(6) Install the mechanical seal (or install the packing), then install the bearing (pay attention to the direction of the two bearings), and tighten the nut that locks the bearing.
(7) It is advisable to turn the car manually, debug and rotate easily, and install the coupling.
(8) Hang the motor on the chemical pump body, check the distance between the two couplings, which is generally 3~5mm, check the coaxiality of the motor and the water pump, and tighten the connecting bolts between the motor and the pump body.
(9) Check the tightening of all connecting screws of the equipment. Then connect the motor power cord.
Things to note when disassembling vertical multi-stage centrifugal pumps
(1) Before starting to disassemble, the medium in the pump should be completely drained. If it is a corrosive medium, it should be washed with clean water after discharge.
(2) During disassembly, the disassembled shell sections, impellers, keys and other parts should be arranged and numbered in order without confusion. When reassembly, they should generally be reassembled in the original order. Some assemblies can be left undisassembled as little as possible.
(3) Parts should be handled with care, and should not be bumped, broken, or dropped to the ground.
(4) During the maintenance period, in order to avoid accidents caused by someone turning on the power switch or opening the material valve without authorization, the power switch can be locked and a blind plate can be added to the material pipe. ’
(5) Do not loosen the motor anchor bolts to avoid affecting the alignment of the pump during installation.
