Multistage centrifugal pump broken shaft
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Multistage centrifugal pump model: 45TADY100 * 9. The high-pressure lean amine liquid pump has a design inlet pressure of 0.2Mpa, an outlet pressure of 8.7Mpa, a flow rate of 45m3/h, a lift of 876m, and a motor power of 280KW. The shaft broke from the balance plate snap ring. Please ask someone to analyze the reason.
The cross section is quite straight, it's not a short-term problem.
It is recommended to check from the following aspects. 1. Whether the fixing bolts of the equipment foundation are tight ； 2. Alignment problems that may be caused by bearing wear ； 3. Vibration before the shaft is broken, such as impeller fouling and dynamic balance imbalance ； After replacing the new rotor, you should confirm the above precautions to see if the problem can be found. For reference.
You can carefully check whether the undercut is chamfered or the chamfer radius is too small. This is the reason why KSB pumps have short shafts many times.； Another possibility is that the shaft itself is defective. Check whether there is a non-destructive testing report (PT/MT, UT) of the shaft in the pump's completion data. The rest is the reason for the analysis on the third floor.
Is there any corresponding specification for the chamfer radius of the undercut?
You can refer to JB/ZQ4238. Since the cross-section is very flat and it is obviously new, it should have been broken in one go. If part of the cross section is rusty or oxidized, and part is metallic luster, it should be that the shaft is defective at the break point or has been used for a long time and suddenly broke at some point.
There are knife marks and alternating stress during the machining process, and it is estimated that it will break after a few thousand hours.
If the operating conditions are normal, it is a processing defect or material defect.