Discussion and analysis on the damage to the metal laminations of the circulating water pump coupling?
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This post was last edited by Huang Zhao on 2019-2-24 at 16:51. I. Basic parameters of the pump: Equipment model: DL0600-705A; Bearing models: SKF/6222C3 on the drive side, SKF/7222BECBM on the non-drive side; Operating speed: 991 r/min; Power: 976 KW; Medium transported: water; Number of impeller blades: 7. II. Type of coupling: Metal laminated flexible coupling； double diaphragm ； Model TD6-3300 ； Material: 301. III. The alignment values for the pump (parallelism and clearance) are both within 0.1 mm ； IV. The maximum vibration during the operation of the pump (at the drive end, non-drive end, in the horizontal direction, and axially) shall not exceed 2.5 mm/s ； V. The distance between the motor and pump half-couplings, as well as the axial clearance of the coupling assembly, should be 0.3–0.5 mm. There are issues with running it ； After the pump has been in operation for about a year, the diaphragms of the couplings start to break; everything else is fine. Out of 40 such diaphragms, 3 to 4 break, and this tendency to breakage increases over time. Could some experts please analyze the reasons for this? Thank you all. In my opinion, the design is the problem; the selected load is too low and the torque is insufficient, resulting in damage to the laminations.
This post was last edited by foam_ZPTK on 2019-2-24 20:16: Poor axis alignment
The rated torque of the diaphragm is 31.5 KNm. The pump’s torque is 9.4 KNm. There is a big difference between the two.
The super version on the upper floor is the correct choice. The motor in question is likely a high-voltage 1120KW motor. According to the sample data provided by Wuxi Chuangming, the TD6-3300 model features a 6-hole coupling with an outer diameter of 385mm, and its rated torque is 31.5 kNm. Through calculations, the actual torque of the coupling is: T=9550P/n=9550*976/991=9.405 kNm. The actual torque is much lower than the rated value; therefore, it’s not due to an error in the design or insufficient strength. Moreover, if there were a problem with the design strength, the breakage would not be clean – there should be signs of twisting instead. Hence, it’s not due to insufficient design strength. Therefore, please look for the causes in the quality of the coupling itself (the material of the diaphragm, its design strength) as well as in the alignment precision. For a coupling of this size, alignment should be sufficient; what is the thickness of each individual piece? It should be at least 0.35 mm or more. Using 40 sheets to form one diaphragm assembly is too much; this results in the overall diaphragm assembly having sufficient strength, but individual sheets lacking sufficient fatigue resistance. It is recommended to change it to an 8-hole coupling
If a coupling with insufficient torque is damaged, will it break at this location? Alignment of the motor and pump, alignment of the motor and compressor – laser alignment devices or the use of three instruments for alignment?
The alignment performed by the laser alignment instrument was accurate, with all values within the 0.10mm range; the instrument displayed a \"green\" color for all of them and showed a \"checkmark\".
The analysis is very reasonable, thank you. Personally, I think the material is a major issue. The pump is a Kaisibi double-suction pump. The motor is from Nanyang Explosion-Proof: 1000KW
Thank you for the reply; I used to think the torque wasn’t enough. But the lamination bolts have never broken; it’s only the laminations that get damaged.
It was located using a laser alignment tool, and it was easy to align.
There are three reasons for your question. One is the coupling alignment issue. The second is caused by pump vibration resulting from pipeline vibration. Third, insufficient inlet flow leads to pump cavitation vibration.
Dynamic balancing issue, caused by tearing