The impeller of industrial centrifugal pumps shall not have the following defects: 1. Surface cracks on the impeller; 2. Thinning of the front and rear cover plates due to erosion, corrosion or wear, which affects the strength The wear at the inlet of the impeller exceeds 40% of its original thickness.

If the impeller of centrifugal pumps is damaged, a new impeller should be replaced.

The new impeller should meet the following requirements:

1. The coaxiality of the impeller shaft hole, axis line, and outer axis line at the impeller inlet, the circular runout of the impeller end face, and the parallelism at both ends of the impeller hub should not exceed the specifications in the table.

2. The parallelism between the centerline of the keyway and the shaft hole or axis line shall not exceed 0.3 ‰, and the offset shall not exceed 0.06mm. 

3. The surface roughness of the outer surface of the impeller front and rear cover plates shall not exceed, and the surface roughness of the shaft hole and installation ring shall not exceed The impeller flow channel should be cleaned of sand and burrs to maintain smoothness and flatness. The new impeller needs to undergo a balance test to eliminate its unbalanced weight. The allowable deviation for static balance is shown in the table below. When adjusting the balance using the cutting cover method, the cutting amount should not exceed 1/3 of the cover thickness.

4. The guide vanes shall not have cracks, and the erosion depth shall not exceed 4mm. The length between the island blades shall not be eroded by more than 6mm.