Assembling and dissembling of vertical centrifugal pump (Overhaul)

Cross section view of single stage vertical centrifugal pump :

Dismantling the pump :

1. Remove the distant piece fitted between the pump and motor coupling after removing both motor and pump side coupling bolts and disks.
2. Remove cooling connections to Mechanical seal.
3. Remove casing top cover bolts
4. Once casing cover bolts are removed, pump assembly is free to remove from place along with shaft, bearing housing,bearing, mechanical seal, Impeller and impeller shaft with sleeve.
5. On removing the pump assembly slacking impeller lock nut and remove the impeller from the shaft.
6. Remove shaft key care should be taken for not losing the shaft key.
7. Remove the distance ring.
8. Slacken the holding screw and remove mechanical seals rotating part.
9. Slacken bearing housing bolts fitted on casing cover.
10. Remove the casing cover from the shaft. 
11. Remove sleeve from Shaft.
12. Remove bearing housing cover.
13. Remove bearing retaining cir clip.
14. Remove bearing housing along with bearing.

Checks to be done :

• Condition of the sleeve to be checked. 
• Check the place where mechanical seal is fixed, to find out grooves and markings.
• Impeller, key, shaft, and top cover are kept clean to check the impeller for corrosion, pitting, cavitation, and wear.
• Checking of impeller blade are to be done for narrowing.
• For key check the crack and key way.
• Clearances of sleeve and shaft, impeller and shaft, wear ring,stuffing box throat bushing and shaft.

                   (sleeve and shaft - 0.03 to 0.04mm, impeller and shaft - metal to metal fit to 0.13mm ).

If all are ok , start assembling of pump.

Assembling the pump :

Assembling to be done in reverse order of dismantling.

1. Fast the bearing housing through the shaft and then fit the bearing in housing.
2. Fix retaining cir clip forbearing and apply required grease for the bearing.
3. Fit the bearing housing cover. 
4. Renew the top and bottom o-rings for casing cover.
5. Fix mechanical seals stationary part with the casing cover.
6. Fit the shaft sleeve and pass the casing cover through the shaft.
7. Fix mechanical seals rotary part on the shaft sleeve and tighten the lock screw. 
8. Insert distance ring.
9. Fix shaft key and secure Impeller.
10. Tighten impeller by shaft not and lock plate.
11. Now Impeller assembly is ready for lowering into pump casing. 
12. Lower the impeller assembly and tighten the pump cover with Volute casing.
13. Tighten the bearing housing with casing top cover
14. Connect the cooling pipes for mechanical seal.
15. Opened liquid to casing, purge the casing and confirm mechanical seal is intact without any leaks.
16. On confirming pump is free to turn and mechanical seal not leaking, distance piece for connecting pump and motor coupling can be fitted with coupling discs.
17. Operate the pump and shake the performance, by monitoring its parameters.