How to maintain the pump casing of centrifugal pump？

The pump shell is an energy conversion enclosure, which bears the pressure of the liquid and is affected by the liquid temperature at the same time, and cracks often appear due to the action of mechanical stress or thermal stress, so the pump shell should be inspected regularly. The inspection and repair methods are as follows.

1.Crack inspection:

A simple method to tap the shell with a hand hammer, if there is a mute sound, it means that it has been broken, we should carefully look for the location of the crack. If necessary, it can be checked by magnifying glass or colored flaw detection method, and the location and length of the crack can be determined.

2.The repair method of crack of centrifugal pumps casing.

A.If the crack is in the part where there is no pressure or seal, in order to prevent the crack from expanding, a round hole with a diameter of 3mm can be drilled at the beginning and the end of the crack to eliminate the local stress concentration.

B.If the crack is in the part under pressure, the repair method is as follows.
Before welding, drill a small hole at each end of the crack, then shovel out the groove along the crack, and install bolts on the groove to prevent the nearby material from being pulled apart during cooling shrinkage.

The diameter of the installed bolt should be equal to 40% of the thickness of the weldment and should not be more than 13mm; the distance between the bolts should be 2-4 times the diameter, and the drilling depth should be 2-4 times the diameter (but not drilled through). Cover the thread with a tap, screw up the bolt, first surfacing a layer on the surface, and then gradually thicken evenly. After each welding layer, the welding slag and impurities should be removed before the lower layer can be rewelded. In order to eliminate the internal stress of the welding metal, with the exception of the first layer and the later layer, each layer should be tapped gently with a hand hammer after welding to prevent the weld from cracking.