Shield pump repair technology

1 Regular Maintenance of Shielded Pumps In order to avoid and reduce sudden damage to the shielded pump, the shielded pump requires regular service. In case of bearing monitor "alarm", must be immediately overhaul. Chemical plant is generally continuous operation, shielding pump regular maintenance only when the device is scheduled to stop. Most shield pumps can be serviced once a year. Shielding pump repair method is: Disassemble the shield pump: first clean up the parts, and then make an apparent inspection of them, whether there is any exception. Then measure the size of the key parts, electrical inspection of the motor windings.
(1) mechanical inspection, u- \; q "U0} & v measured graphite bearing aperture and sleeve shaft diameter, and look at their mating surfaces such as the finish of graphite bearings and bushings with the gap exceeds a predetermined inspection criteria. (0.55-11kw with clearance, diameter difference of 0.4 ?, 15-45kw with the gap, the diameter difference of 0.5?) Or with poor surface finish, the need to replace the bearing, sleeve or thrust plate .0 t% @ $ W ) Check the upper and lower outer stop of the impeller and the size of the inner diameter of the buckle and the pump seat matched with them. Whether these two clearances are within the range specified in the inspection standard, When the need to replace the parts or take other measures (such as: surfacing, set) to meet the requirements of the gap, otherwise it will affect the performance of the pump, flow, lift, axial balance, etc. {6 y / R. B0 j ! w observe the inspection set, the apparent state of the rotor shield sleeve, with particular attention to whether there is any abnormal weld, if necessary, should be for testing, leak detection. 'S, D, x0 A3 After long-term operation, the rotating part The balance may change, so it is necessary to connect the rotor Equalizer and other rotating parts assembled together to do dynamic balancing test.
(2) Electrical Check 8 A / S # A2 X2 z, o. I DC Resistance Check: The unbalance of three-phase resistor should not exceed 2%. 4 n! H3 r: b0 G6 c 'S) S Insulation resistance check: Shielding pump motor winding insulation resistance can generally reach more than 100MΩ. Such as less than 5MΩ need to analyze the reasons for insulation is damp, or shielding the leak if there is no problem, such as leakage through the stator shield no problem, then purely moisture insulation, the need for drying treatment, such as stator shield has a problem, You need to change the shielding sleeve. Rehabilitative overhaul of shielded pump * I0 D2 d6 B i9 G. h 'o / In case of shielded pump damaged by winding or shield, recovery overhaul is required. Damage is generally divided into two types: one is the stator shield is good, and the stator winding occurs on the ground, phase breakdown, winding inter-turn short circuit, overload caused by the winding burn. The other is due to damage to the stator shield to make the medium invade the stator winding stator winding damage. In either case, replace the stator coil and shield sleeve. Since the shield pump structure is special, the stator winding replacement becomes more complicated, the stator shield and the both ends of the shield must be removed to remove the stator winding. After the winding is repaired, The new shielding sleeve and sealing plate must be reworked with special material requirements and high production precision.
(1) The stator winding is replaced with the ordinary motor, except that the insulation level is higher, and the H-level insulation is mostly used. QY polyimide enameled wire, slot insulation, slot wedge, bushing, lead wire and impregnated paint, etc. are required to use H-class insulation materials. Replacing the winding principle is: as it is, especially the number of turns of the coil can not be arbitrarily changed, the number of turns will significantly affect the main performance of the motor, the wire diameter is as close as possible to the original total area, the winding form, the coil span do not change .
(2) the replacement of shielding sleeve shielding shield is to repair the shielding pump difficult and special, is to ensure the quality of repair shield pump key To achieve the original level, we must pay attention to the following aspects.
(A) Material Selection of Shielding Sleeves In the losses of shielded pump motors, the stator shields wear out at a loss, sometimes up to 2 to 3 times the iron loss , After repair shield sleeve loss should be maintained at its original level. 3 C * \ 9] (f% f stator shield loss PB is proportional to the thickness of the shield sleeve, inversely proportional to the resistivity of the shield sleeve material ρ. Shield sleeve material must be non-magnetic material with good mechanical properties and corrosion resistance , In order to reduce the eddy current loss to choose a large coefficient of resistance of the material thickness should not be too thin, to affect the mechanical strength, should not be too thick, too thick will increase the loss of shielding sleeve shield mask imported most of a shield with a containing Nickel content of more than 50% called Hastelloy-c special stainless steel material, the performance of this material can fully meet the above requirements, and its resistivity than the general stainless steel 1Cri8Nig9Ti double, that is, the shield sleeve loss is normal stainless steel 1/2 of material.
(B) Making Shielding Shields The fabrication process for shield shields should be the most difficult and critical part of shielding pump recovery overhauls. Shielding sleeve dimensional accuracy and shape tolerance requirements are higher, welding quality requirements of the weld is also very strict. From the unwinding of the size of the calculation, cutting, straight seam welding, full circle, press fit, girth welding, leak detection and so have a certain degree of technical difficulty. The effective gap between the stator and stator of the shielded motor is generally only 0.5 ~ 1.0. Therefore, it is required that the shielding sleeve should not only be pressed into the stator core and the rotor core but also be close to the core. Only in this way can there be enough between the stator and the rotor Effective clearance.
(C) The overall stator leak detection; After completion of the stator seal plate and the chassis welding, press the shield sleeve and the shield sleeve to complete both ends of the girth welding, the overall stator Leak check. The method is: the cavity between the base and the stator shield is filled with a pressure of 0.5? / C ?, and then the overall immersion in the water stator, in the event of leaks, the bubbles in the water, which is a simple The effective leak detection method.
(3) Final assembly and inspection test After completion of the stator and rotor repair, ready qualified graphite bearings, bushings, thrust plates, seals, etc. can be After the assembly is completed, turn the rotor by hand, the rotation should be uniform and flexible, the rotor should have a certain amount of axial movement, and its displacement should be within the scope of maintenance standards: shielded pump power kw 0.55 ~ 3.7 5.5 ~ 11 15 ~ 45 Axial movement? 0.9 ~ 1.5 1.4 ~ 2.0 1.8 ~ 2.5 'k4 Q + e0 _ "u" n After the completion of assembly, check the DC resistance and insulation resistance, etc., that the normal electrical performance, the shield pump immersed in the water tank as a whole (Junction box to be on the water, the water can not enter the junction box) to do electric test (at this time the pump outlet can be covered) to observe the current, running sound, vibration and other anomalies. If the test conditions can do Pump performance test is better.

Galvanized Steel Strip

Galvanized steel strip is the cold rolled or hot rolled, long and narrow strip of steel with different degrees of plating on a layer called (zinc, aluminum) raw materials. Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. Complex physical and chemical reactions occur between the substrate of hot dip galvanized steel strip and molten bath to form a corrosion-resistant zinc iron alloy layer with compact structure. The alloy layer is integrated with pure zinc layer and strip substrate. Therefore, it has strong corrosion resistance.