Multistage pump
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Why should multi-stage pumps not be turned or have their shafts rotated without the bearing housing in place?
The rotor sinks; for materials prone to seizure, locking up is likely to occur
The rotor sinks and the mouth ring makes contact; at this point, turning the disk has caused friction on the mouth ring. In mild cases, the gap between the mouth rings increases, while in severe cases, direct locking occurs
Before the bearing housing was installed, the rotor and the casing were severely out of alignment, causing friction at the points where they met; it’s likely that the rotor couldn’t be rotated at all!
Without rotor support, radial misalignment can lead to wear between the mouth ring and other components. If a major overhaul is required, it is recommended to perform a minor rotor replacement on the pump
The impeller is fully seated on the mouth ring, so it cannot be turned
What to do with the guide vane sleeve and seal ring? What to do about the mechanical seal?