Is it necessary to perform rotor dynamic balancing on single-stage pumps?
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Version 8 of API 610 describes the dynamic balancing of rotors as follows: The following rotors should be subjected to two-plane dynamic balancing at low speeds: 1. Multi-stage pumps (3 stages or more); 2. Single-stage or two-stage pumps with a maximum rotational speed exceeding 3800 r/min. The sequence for assembling and correcting the balance of such rotors should follow ISO 5406. When performing balancing, the rotor does not include the coupling sleeves or the rotating components of mechanical seals. However, in practice, many companies require that single-stage pumps also undergo rotor dynamic balancing. Version 8 of API 610 does not specify such a requirement, and this type of dynamic balancing is irreversible – it only proves that the rotor was in a balanced state at the time of balancing. Once the pump is disassembled and reassembled, its balance is lost. What are everyone’s thoughts? Is it necessary to perform rotor dynamic balancing on single-stage pumps?
I know that many manufacturers, especially some small private factories, do not perform dynamic balancing on the rotors of single-stage pumps; generally, only static balancing of the impeller is carried out.
Version 8 of API 610 specifies clearly the range for the dynamic balancing of rotors. Pumps of grade 1 or 2 with a maximum rotational speed exceeding 3800 r/min do not require dynamic balancing. Most commonly used centrifugal pumps are equipped with two-pole or four-pole motors, and their rotational speeds do not exceed 3000 r/min or 1500 r/min. So, dynamic balancing is not necessary.
Generally speaking, companies that place emphasis on quality have requirements that are higher than the standard specifications. For single-stage cantilever pumps with an impeller diameter of more than 360 mm, it is advisable to perform dynamic balancing, as this helps to reduce vibration and extend the pump’s lifespan. The so-called unrepeatability refers to the fact that when the precision of dynamic balancing is high, both the residual weight and angle change after reassembly. But in any case, the magnitude of the change will not be very large; it will still remain within the standard range
Where I work, this isn’t done; generally, we only measure the shaft dimensions, the degree of vibration, and the clearance at the impeller’s mouth ring. If all the key dimensions are within the specified range, then it can be installed right away.
It should be done when the pump leaves the factory, but generally not during maintenance.
Our company usually installs the impellers purchased directly. If excessive vibration of the pump is detected, a static balance test is conducted on the impeller.
The reply on the 3rd floor is correct; I’ve learned it
It is generally not done; dynamic balancing is considered in the event of a failure
For ordinary centrifugal pumps, we only perform static balancing during maintenance.