The pump suction is from river water to discharge to water boxes of steam condenser. It’s a vertical shaft, 2,100 discharge bore mixed flow pump. It’s driven by an 1650 KW vertically mounted motor with a rated full load rpm of 372. Rated flow rate of the pump is 29,000 m3/hr

1. Prepared by
Md. Shaha Jalal
Maintenance Technician
In a Largest Multinational
Company

2. History
The pump suction is from river water to discharge to water boxes of steam condenser. It’s
a vertical shaft, 2,100 discharge bore mixed flow pump. It’s driven by an 1650 KW
vertically mounted motor with a rated full load rpm of 372. Rated flow rate of the pump is
29,000 m3/hr.
Specification of the Equipment
Pump Specification
Manufacture HHI
Model Number 1800VKNM
Type Vertical Wet Pit
Capacity 29,000 m3/h
Total differential head 14.6 m
Pump speed 372 rpm
Efficiency 86.0%
Direction of rotation from motor driven end Clock wise
Motor Specification
Rated kW 1650KW
Motor Type HRQ7 806-76V
Rated Voltage 6600 V
Phase 3 ᶲ
Full load amperes 224.6
Pole 16
RPM 372
Ins. Class F
HZ 50
BRG. (DE/NDE) NU244M/AV12SNT
WT 25 Ton

3. Before Maintenance Equipment vibration data
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Motor & Pump
1 2 3 4 5 6 7
H,V,A (mm/s)
Data no.
Base line
Motor D/E H
Allowable
Just tolerable
MOTOR D/E V
MOTOR D/E A
Motor NDE H
Motor NDE V
Motor NDE A
Pump DE H
Pump DE V
Pump DE A
Pump NDE H
Pump NDE V
Pump NDE A

4. Dismantling Procedure
The motor-pump assembly was disassembled with the following steps:
The stop gate was inserted into the intake basin with the help of gantry crane.
3 submergible pumps (ф4” & ф3”) were being placed inside the intake basin to
continuously pump out water.
Note: before inserting the gate, it’s important to grease the slots of the gate; the slots
will guide thru the railing inside the basin.
The pump was then stopped and motor was isolated.
Pump was decoupled from the motor and lift of the pump was noted as 9.5 mm

5. Note: there are 6 stud bolts and 6 reamer bolts in the coupling. Space nut is screwed to
the pump shaft and pump end hub is keyed to the shaft which drops down after loosening
the coupling bolts.
Cooling water lines had been removed.
The motor and motor pedestal was sequentially removed by gantry crane
3 gland packing were removed by screw driver.
Gland and upper bearing housing were removed afterward; all these were lifted
using eyebolt-shackle-belt assembly of appropriate sizes.
Elbow cover was lifted (after removing tow center pins) by the crane up to when
the top spider hoisted over the column pipe as it was to be supported by H-beam
underneath.
Elbow cover and upper shaft tube were unfastened sequentially.
Note: There is a distance ring which rests between elbow cover and upper shaft tube
which must be handled and kept safely.

6. Note: There is a tapering part in every leg of the spider and this side would face the
downside while assembling.
Upper spider along with the intermediate shaft tube was then dismantled after
lifting the resting assembly as long as the lower spider was supported similarly.
The upper shaft was then separated from the lower shaft by dismantling the line
shaft coupling & thrust ring using special tool as seen in the figure.

7. Lower spider, lower enclosure tube, discharge bowl and impeller were then taken
out altogether and spider-tube was dismantled in similar fashion.
Discharge bowl was separated from the impeller-shaft assembly by removing the
stopper ring.
Note: Match marking is provided in every part disassembled.
Shaft was disassembled separated from the impeller using an extractor.
Note: Impeller washer must be removed first before extracting impeller from the shaft
using special tool (mechanical jacking).
Casing wear ring was pulled using hydraulic jack & a fabricated special jack with
nearly 100 bar of pressure. Impeller wear ring was extracted by tapping &
unscrewing it.

8. Dummy Inspection
Dummy inspection refers to
checking whether discharge bowl
seats in its slots after assembling
it with only shaft tubes, spiders
and elbow cover.
After assembling all these and
tightening the elbow cover on its
bolts; a gap of 3 mm found
beneath the discharge bowl on its
seating slots. It had to be
compensated. A shim of 3 mm
was ordered instantly with same
shape of distance ring from
nearby workshop of stainless
steel.
Findings
Followings were the findings on disassembly:
After dismantling the whole pump it was observed that all the Ferro form bearings and
their related shaft sleeves (Upper, Upper Intermediate, Lower Intermediate and Lower)
surface were damaged (out of clearance). Its gland shaft sleeve and packing was out of
use. Casing and impeller wear ring surface scratched badly and clearance between them
were found high and irregular

9. Shaft Run out
We took shaft run-out and found the reading unusually high at one point for the upper
shaft. We also checked the upper shaft reading there also found one high reading at one
point.
Final run-out reading is attached here:
Dial gauge readings corresponding to the points on lower shaft
Dial gauge readings corresponding to the points on upper shaft

10. Assembly
Whole assembly was just the reverse of disassembly.
Before assembling, Ferro-form bearings were taken out and replaced by new one. We also
replace 3nos of (Packing, Inter and lower sleeve) shaft sleeves. Bearing clearances after
assembly are listed below:
Dimension of Bearing
SL Description ID OD Bearing Housing ID Length
1 Feroform Bearing (Upper) 205.65 mm 250.37 mm 250.08mm 295 mm
2 Feroform Bearing (Inter) 205.69 mm 250.30 mm 250.06mm 295 mm
3 Feroform Bearing (Inter) 205.70 mm 250.40 mm 250.09mm 295 mm
4 Feroform Bearing (Lower) 205.70 mm 250.35 mm 250.07mm 295 mm
Dimension of Shaft Sleeve
SL Description ID OD
1 Packing sleeve 189.91 mm 204.99 mm
2 sleeve(Upper) No Change
3 Sleeve (Inter) No Change
4 Sleeve (Inter) 189.90 mm 204.93 mm
5 Sleeve (Lower) 189.89 mm 204.93 mm

11. Greasing to all spider leg sides, O-ring grooves.
Plating Molykote to the bolts, studs, sleeves, thrust rings, impeller washer, shaft
coupling & all other mating surfaces etc.
Tightening the bolts in a crisscross pattern like the following:
Alignment
After reinstalling motor pedestal and motor, gap between motor coupling and pump
coupling was kept 9.65 mm by turning the space nut toward the motor hub ensuring the
required gap.

12. A steel scale was kept stood vertically in the hub surfaces and motor jacks were adjusted
to bring the required alignment.
When the centreline of the pump & motor was confirmed, the hubs were coupled with
reamer bolts. Now the tip clearances (radial clearances of the impeller and impeller liner
in the suction bell) were recorded. The values are:
POS E W N S
1 1.77 1.6 2.95 1.65
2 1.97 1.8 1.9 2.11
3 1.8 1.76 2.05 1.9
4 1.95 1.98 2.9 1.85
Tip clearances were judged good. Now relative position of the shaft assembly against
static elbow cover-brg housing-gland was adjusted by adjusting motor. After adjustment,
alignment readings are as follows:

13. Test run
After test run vibration data was measured and found ok.