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Discussion on water pump malfunction and overhaul
- Jul 21, 2017 -

Water pump as a water supply and booster equipment in the water system plays an important role. It is widely used in water supply and drainage in Liaohe oilfield. Aiming at the present situation of water supply and drainage system, this paper mainly analyzes the common running faults and the causes of the centrifugal pump in the process of use, and puts forward the general method of fault treatment, which will be helpful to improve the safety, reliability and efficiency of the pump equipment, and to ensure the efficient use of water supply equipment.

In order to ensure that the unit in good technical condition, better for the people's Living water services, all of the mechanical and electrical equipment in the pumping station, must carry out normal inspection, maintenance and repair, update those difficult to repair the damaged parts, repair those can be repaired parts. Through maintenance and repair can detect problems, eliminate hidden trouble, prevent accidents, ensure the reliability of unit operation, stability, improve equipment integrity and utilization rate, prolong its service life.

Through the maintenance and overhaul of the unit, we can also find out the problems in design and manufacture, accumulate experience, and provide basis for pumping station design, improving management level of pump station and renovation of pump station.

Unit 1 overhaul is not only the key of management, but also the foundation of safe operation. Therefore, the following requirements are put forward for inspection and repair work
(1) Establish and improve the organization of overhaul and maintenance to ensure the smooth conduct of maintenance work. All mechanical and electrical equipment must undergo the assessment of technical personnel and technical workers for maintenance, strictly prohibited operation.
(2) In accordance with the maintenance of equipment, maintenance system or regulation of the period prescribed by the maintenance, strict implementation of standards, so that the host and auxiliary equipment in a good technical state.
(3) Preparation of detailed maintenance plan, do a good job before the maintenance of the preparatory work, carefully fill in the maintenance records, comprehensive collection and repair items consumed materials, spare parts, funds, etc., in order to gradually implement the quota management accumulation of information.
(4) Adhere to the high standards to complete the maintenance tasks, and actively carry out technical and economic contracting responsibility, strengthen the technical inspection and accounting of maintenance work.

The common faults of water pump are divided into two kinds: mechanical failure and hydraulic fault. The major failures that occur during use and their possible causes are as follows:
(1) The pump does not water. The main reasons for this failure are: The water pump is not filled with liquid, the suction water is too high, the suction pipe has air or gas leakage, the liquid temperature is too high, the suction valve is blocked;
(2) Pump vibration. The main causes of this failure are: the pump and the center of the original motive is not within the standard range; the ground angle screw of the pump body is loose, or the foundation is not firm, the bearing cover force is not enough to make the bushing in vivo beating, rotor mass unbalance, rotor natural frequency proportional to excitation frequency, small flow and flow instability, or intermediate recirculation door damage.
(3) Insufficient traffic. The main causes of this failure are: suction valve or impeller is blocked, suction height is too large, too much resistance to enter the tube elbow, the pump body or suction tube leakage, packing place leakage, seal ring wear too large, impeller corrosion, wear.
(4) Insufficient output pressure: The main cause of this failure is: there is gas in the medium, the impeller corrosion or serious damage.
(5) Excessive power consumption: the main causes of this failure are: Packing gland is too tight, packing letter is hot, the coupling collar is too tight;
(6) The bearing is overheating. The main causes of this failure are: centerline migration, lack of oil or oil is not clean, the rotation of the oil ring is not flexible;
(7) Leakage of the seal is too large. The main reasons for this failure are: the material selection of packing or sealing element is not correct, the axle or sleeve is worn, the axle is curved, the center line is displaced, the rotor is unbalanced, the vibration is too large, the dynamic and static ring is corroded, the sealing surface is scratched;

2 The fault should be eliminated in time, not to make the machine "sick" work. Troubleshooting should follow the following guidelines
Clarify the performance-analyze the cause-eliminate it. Before the pump overhaul, the pump must be thoroughly and carefully inspected in order to determine the maintenance project, the bolt repair plan, the main contents are as follows:
(1) Measurement of the vibration of the various parts, bearing temperature. Check the bearings for the same sound and judge the cause.
(2) The combined surface of the pump shell and whether the glen is leaking. Check the running log to understand the current, pressure, running condition and defects under load, and make a good record.
(3) Check the bearing ball and internal and external rings, if found cracks, pitting, peeling, pitting and other defects should be replaced.
(4) Check the outer surface of the sleeve grinding to the original thickness of 1/3 or have obvious groove marks should be replaced.
(5) The fitting clearance between sleeve and shaft is 0.018-0.08mm.
(6) The bending degree of the measuring shaft shall not exceed 0.1mm, the ellipse degree and taper of each axle neck should not be greater than 0.03mm, and the surface without burrs, hemp, groove marks, the thread on the shaft should be perfect, no slip buckle phenomenon.
(7) inspection, measurement of shaft and bearing interference with the surplus, should be less than 0.01mm.
(8) Check the coupling, shaft and key coordination, coupling and the key sides should have no clearance, the top should be left with 0.35mm-0.6mm clearance, coupling with the shaft for the k8/h7 level.
(9) The outer ring of the bearing is K8/H7 level with the outer casing.
(10) Check the packing box inside the surface has no wear and tear, groove (especially axial groove), packing each interface should be staggered 90-180°, elastic appropriate, and have a tight allowance.
(11) Check the impeller diameter to shake no more than 0.3mm.

3 Maintenance Safety Construction technical measures
(1) Before overhaul, the main pump switch must be out of power, hanging "someone work, prohibit transmission" warning signs.
(2) The Inspection tool before commencement is complete and good.
(3) Contact pump workers to confirm that the pump has been cut off, pressure relief. Hang the "Prohibit start" warning.
(4) Close the inlet and outlet valves, isolate the liquid source and ensure that the valve is not leaking.
(5) Open the discharge valve, eliminate the residual pressure in the pump shell, and put the residual liquid inside the pump shell.
(6) Remove the Screw and outlet section of the bearing gland of the outlet, the connecting nut between the three pieces of the packing and the bearing body, and remove the bearing body.
(7) Remove the nut on the shaft, remove the bearing inner ring, the bearing gland and the baffle, then remove the packing.

4 Water pump overhaul needs special attention
(1) The axial channeling clearance of the rotor;
(2) The rocking value of the rotor;
(3) sleeve leakproof apron;
(4) tight-wear bar bolts;
(5) The rotor should not be random disk movement;
(6) Adjusting the concentricity of rotor and stator;
(7) In the school center, consider the amount of thermal expansion.

The failure of the pump during use varies with the environment of use, its maintenance and maintenance methods are also different, should be based on actual production requirements and specific conditions to implement, but also pay attention to the day-to-day use of data collection and accumulation, in order to take timely measures to ensure the normal operation of the pump.


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