A Case Study presented at the 20th International Pump Users Symposium, Houston, TX, USA. March, 2003

1. USER CASE STUDY ABSTRACT
20th International Pump Users Symposium
TITLE:
Reliability Improvement of End Suction Pump in Severe Service
through Engineered Component Upgrade
ABSTRACT:
An end suction pump for amine service at an Ammonia plant was successfully
upgraded by improvement of its components.
Two 290 kW (390 HP) pumps, turbine/motor driven, rated for 262 m3/hr (1,153
gpm) and 271 m (889 ft), operate in severe service conditions due low NPSHA and
part-load operation. The equipment exhibited rough operation with high vibration
and an elevated repair frequency by recurrent fatigue failure of shaft, severe wear
ring rubs, impeller corrosion/erosion, mechanical seal leakage and bearing
damages..
After a catastrophic failure, involving pump and electric motor, that caused an
emergency plant shutdown, an upgrade for the pumps was engineered. The
objective was to overcome design weaknesses and incorporate features to
increase reliability. Impeller deficiencies were identified and corrected and its
metallurgy improved to endure severe cavitation/recirculation damage. The power
end was completely redesigned, incorporating larger shaft and bearing housing
stiffness, together with a material upgrade, oversized bearings and lubrication
enhancements.
As a result, a failure frequency as large as 9 a year has been eliminated since the
upgrade and the pump presently accumulates 3 years of continuous operation.
An outstanding improvement in reliability was obtained together with considerable
savings in investment & maintenance costs.
AUTHOR:
César A. Morales Casanova
Rotating Equipment Specialist
PDVSA – Pequiven
Morón Petrochemical Complex
Edo. Carabobo
Venezuela

2. ®
20th International Pump Users Symposium
March 17-20, 2003. Houston, Texas
RELIABILITY IMPROVEMENT
OF END SUCTION PUMP
IN SEVERE SERVICE
THROUGH ENGINEERED COMPONENT
UPGRADE
César A. Morales Casanova
Rotating Equipment Specialist
PDVSA - Pequiven
Edo. Carabobo - Venezuela

3. CONTENTS
• Objective
• Conditions of service – Amine recovery system
• Pump failures
Experience of continued low reliability
Problem areas – Original design
Remedial actions – Historical review 1980 – 1997
Catastrophic failure – 1998
• Preliminary analysis – Recurrent pump failures
• Problem analysis
Factors associated to low reliability
Correlation of causes for low reliability
• Pump upgrade
Objectives
Areas of attention
Summary of main improvements
• Upgraded pump test
Objectives
Results of performance testing
Test conclusions
• Upgrade results
Cost – lead time comparison
Current upgrade progress – end 2002
Reliability improvement
• Conclusions
• Lessons learned
• References

4. OBJECTIVE
A successful experience of reliability
improvement of two process pumps,
through the application of a cost-effective,
“in-house” engineered component upgrade
is presented.
The solution can be used as a reference to
yield better mechanical performance of
existing equipment in similar services.

5. SITUATION OVERVIEW
AMINE RECOVERY SERVICE
FCV
C-754 C-752 PUMP RATINGS:
PCV
Q : 262 m3/hr (1,153 GPM)
H : 271 m (889 ft)
N : 3550 RPM
PC-752A/B P : 290 kW (390 HP)
MAIN PUMP “A”
Turbine Driven
STAND-BY PUMP “B”
Motor Driven

6. PUMP FAILURES
EXPERIENCE OF CONTINUED LOW RELIABILITY
OPERATION PROBLEMS:
10
PC-752B High Vibration
9
8 PC-752A Low Capacity
7 Product Leakage
6
5
4 FAILED COMPONENTS:
3
2 Impeller
1 Wear Rings
0 Shaft
1995 1996 1997 1998 1999
Bearings
Mechanical Seal

7. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN

8. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
WEAR
RINGS

9. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
SEVERE RUBBING AT WEAR RINGS - 1996

10. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
WEAR
RINGS
SHAFT

11. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
SHAFT FAILURE AT IMPELLER END - 1992

12. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
WEAR
RINGS
SHAFT
IMPELLER

13. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
EROSION W/R RUB
SEVERE IMPELLER FAILURE - 1992

14. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
WEAR
RINGS
SHAFT
IMPELLER MECH. SEAL

15. PUMP FAILURES
PROBLEM AREAS - ORIGINAL DESIGN
WEAR
RINGS BEARINGS
SHAFT
IMPELLER MECH. SEAL

16. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT ACTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut
1994 Wear Rings Increase in wear ring clearances
1995 Impeller Incorporation of 3 partial vanes
1996 Impeller Impeller trim to pump “B”
1997 Impeller Trimming of vanes at inlet
Bearings 5313 thrust bearing replaced by 7313

17. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds

18. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1980
PINS INSTALLED BETWEEN IMPELLER SHROUDS

19. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread

20. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1986
CAPSCREW M 24
NC TO NF

21. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut

22. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1992
IMPELLER NUT M 38 NF
CAPSCRW
M 24 NF

23. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
Pump “B”
SHAFT FAILURE AT IMPELLER END - MAY 1999

24. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut
1994 Wear Rings Increase in wear rings running clearance
1995 Impeller Incorporation of 3 partial vanes

25. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1995
IMPELLER PATTERN WITH 3
PARTIAL VANES ADDED
EROSION CONTINUED

26. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut
1994 Wear Rings Increase in wear rings running clearance
1995 Impeller Incorporation of 3 partial vanes
1996 Impeller Impeller trim to pump “B”

27. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1996
00 200
200 400
400 600
600 800
800 1000
1000 1200
1200 1400
1400 Q [GPM]
Q [GPM]
340 Publ Head 1120
1120
340 Publ Head
Publ Head
3550 rpm φ 385 mm
3550 rpm φ 385 mm Publ Head
Corr Head
Corr Head
1060
1060
320
320
30% 1000
1000
300
300
PUMP “A” Imp φ385 mm RATED
RATED
940
940
H [ft]
H [m]
280 @ 3200 rpm POINT
H [ft]
H [m]
280 POINT
880
880
BEP
BEP
260
260
PUMP “B” Imp φ348 mm 820
820
@ 3550 rpm
240
240 760
760
OPERATING
220
OPERATING
RANGE
RANGE PROCESS FLOW
220 700
NOT700
REACHED
200
200 640
640
00 50
50 100
100 150
150 200
200 250
250 300
300 350
350
Q [m3/hr]
Q [m3/hr]
IMPELLER TRIM OF STAND-BY PUMP “B”

28. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1996
00 200
200 400
400 600
600 800
800 1000
1000 1200
1200 1400
1400 Q [GPM]
Q [GPM]
340 Publ Head 1120
1120
340 Publ Head
3550 rpm φ 385 mm
3550 rpm φ 385 mm Corr Head
Corr Head
1060
1060
320
320
1000
1000
300
300
940
940
RATED
RATED
H [ft]
H [m]
280
H [ft]
POINT
H [m]
280 POINT
PUMP “B” Imp φ370 mm 880
880
@ 3550 rpm BEP
BEP
260
260
820
CAVITATION 820
240
240
760
760
OPERATING
OPERATING
RANGE
RANGE
220
220 700
700
200
200 640
640
00 50
50 100
100 150
150 200
200 250
250 300
300 350
350
Q [m3/hr]
Q [m3/hr]
IMPELLER TRIM OF STAND-BY PUMP “B”

29. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut
1994 Wear Rings Increase in wear rings running clearance
1995 Impeller Incorporation of 3 partial vanes
1996 Impeller Impeller trim to pump “B”
1997 Impeller Trimming of vanes at inlet

30. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1997
VANE TRIM AT IMPELLER
INLET TO REDUCE NPSHR
IMPROPERLY EFFECTED

31. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
YEAR COMPONENT DESCRIPTION
1980 Impeller Installed pins between shrouds
1986 Shaft Impeller capscrew replaced to fine thread
1991 Impeller Local manufacture of impellers
1992 Shaft Impeller capscrew replaced by a nut
1994 Wear Rings Increase in wear rings running clearance
1995 Impeller Incorporation of 3 partial vanes
1996 Impeller Impeller trim to pump “B”
1997 Impeller Trimming of vanes at inlet
Bearings 5313 thrust bearing replaced by 7313 BG

32. PUMP FAILURES
REMEDIAL ACTIONS – HYSTORICAL REVIEW
1997
THRUST BEARING UPGRADE FROM 3313 TO 7313 BG

33. PUMP FAILURES
CATASTROPHIC FAILURE – PUMP “B”
SEPT 1998

34. PRELIMINARY ANALYSIS
RECURRENT PUMP FAILURES
SEPT 1999
Unsuccessful efforts to improve reliability.
Solutions mainly focused in the consequences
rather than the causes for the problems.
Improper procedures contribute to failures.
Complex problem with multiple correlated
causes and failure modes.
Global solution required.

35. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SEPT 1999
OPERATIONAL
• Low NPSHA

36. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SUCTION CONDITIONS - 1999
PLUGGING OF
PLATE COOLER
FCV
C-754 C-752
PCV
INOP.
FILTER
TEMP INCREASE & PC-752A/B
REDUCTION OF SUCTION
PRESSURE
MEA RECOVERY SYSTEM

37. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SUCTION CONDITIONS - 1999
DESIGN REVISED 1997 MEASURED
Fluid 20% MEA 30% MEA 30% MEA
Temp [ºC] 92 95 – 99 99
SG 0.965 1.015
VP [kg/cm2 a] 0.78 1.05
Suct. Press. [kg/cm2 g] 0.60 0.50 0.25 – 0.60
Flow [m3/hr] 228 – 262 200 – 220 200 – 220
NPSH A [m] 9.00 4.90 2.45 – 5.90
NPSH R [m] 6.50 4.00 ? 4.00 ?
NPSH MARGIN 38% INSUFFICIENT NONE

38. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SUCTION CONDITIONS - 1999
DESIGN REVISED 1997 MEASURED
Fluid 20% MEA 30% MEA 30% MEA
Temp [F] 198 203 – 210 210
SG 0.965 1.015
VP [psia] 11.1 14.9
Suct. Press. [psia] 8.5 7.1 3.5 – 8.5
Flow [GPM] 1000 – 1153 880 – 970 880 – 970
NPSH A [ft] 29.5 16.0 8.0 – 19.3
NPSH R [ft] 21.3 13.1 ? 13.1 ?
NPSH MARGIN 38% INSUFFICIENT NONE

39. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SEPT 1999
OPERATIONAL
• Low NPSHA
• Part load operation

40. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
PART LOAD OPERATION - 1999
EROSION &
SHROUD
SEPARATION
EVIDENCES OF RECIRCULATION AT DISCHARGE

41. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SEPT 1999
OPERATIONAL
• Low NPSHA
• Part load operation MAY
CONTINUE
• Process disturbances
(flow/pressure surges)
MAINTENANCE
• Inoperative pipe supports
- Transmission of pipe forces
- Excessive deflection

42. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
MAINTENANCE PROBLEMS - 1999
INOPERATIVE PIPE SUPPORTS

43. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SEPT 1999
OPERATIONAL
• Low NPSHA
• Part load operation MAY
CONTINUE
• Process disturbances
(flow/pressure surges)
MAINTENANCE
• Inoperative pipe supports
- Transmission of pipe forces EASILY
- Excessive deflection CORRECTED
• Improper procedures

44. PROBLEM ANALYSIS
FACTORS ASSOCIATED TO LOW RELIABILTY
SEPT 1999
MANUFACTURING DEFICIENCIES
• Shaft (own shop)
• Impeller (local mfr)
PUMP
PUMP
DESIGN WEAKNESSES
UPGRADE
UPGRADE
• Dated 1969
• Hydraulics
• Component Stiffness
• Choice of Materials

45. PROBLEM ANALYSIS
CORRELATION OF CAUSES FOR LOW RELIABILITY
IMMEDIATE NOTICEABLE EXPECTED
MAIN CAUSES CONSEQUENCES
EFFECTS EFFECTS FAILURE
OPERATION
• Plugged Filters / Coolers • CAVITATION • IMPELLER EROSION • VIBRATION • IMPELLER
• Too low NPSHA • INTERNAL • IMBALANCE INCREASE • WEAR RINGS
• Part load operation RECIRCULATION • LARGE LOADS • NOISE • SHAFT
• Process disturbances • TURBULENCE • LARGE STRESSES • LOSS OF • BEARINGS
• VIBRATION • LARGE DEFLECTIONS CAPACITY • MECH. SEAL
MAINTENANCE • SEAL LEAKAGE
• INCREASE OF • SEVERE RUBS
• Inoperative pipe supports NPSHR • LOSS OF RUNNING
• Improper wear ring materials • PIPE FORCES CLEARANCES
• Improper vane trim at inlet • STRESS RISERS • SHAFT FATIGUE
• INSUFFICIENT • LOSS OF FUNCTION
MANUFACTURE
MAT PROPERTIES
• Improper part. vane position
• MAT OF SIMILAR
• Insufficient shaft fillet radii GALLING
TENDENCY
DESIGN
• Deficiencies in hydraulics
• Insufficient stiffness
• Inadequate shaft end design
• Choice of materials

46. PUMP UPGRADE
IMPLEMENTATION OF SOLUTIONS
OBJECTIVES:
Identify & solve design weaknesses.
Correct component manufacturing deficiencies.
Incorporate modifications for improved
reliability.
Withstand tough operating conditions with low
NPSHA.
Manufacture of new parts, pump refurbishment,
stand testing & performance adjustment to
requirements by a qualified supplier.

47. PUMP UPGRADE
AREAS OF ATTENTION

48. PUMP UPGRADE
AREAS OF ATTENTION
IMPELLER

49. PUMP UPGRADE
IMPELLER IMPROVEMENT
BEFORE AFTER
VANE CORRECTIONS

50. PUMP UPGRADE
IMPELLER IMPROVEMENT
MANUFACTURING MATERIAL:
BEFORE ORIGINAL NEW
AISI 304 18Cr-16Mn
AFTER
VANE LEADING EDGE / MATERIAL IMPROVEMENT

51. PUMP UPGRADE
AREAS OF ATTENTION
IMPELLER
WEAR
RINGS

52. PUMP UPGRADE
WEAR RINGS IMPROVEMENT
MANUFACTURING MATERIALS:
IN USE NEW
DESIGN
(1999) ALT 1 ALT 2
AISI 304 AISI 304 +
IMPELLER AISI 304 18Cr-16Mn
Stellitted Cr. Plating
CASING AISI 304 AISI 304 18Cr-16Mn AISI 304
WEAR RINGS MATERIALS

53. PUMP UPGRADE
AREAS OF ATTENTION
IMPELLER
WEAR SHAFT
RINGS

54. PUMP UPGRADE
SHAFT IMPROVEMENT
L
D
DESIGN SAME MFR MFR 2 MFR 3
API 610 Ed. APPLIED
(1969) 7th 8th 8th
L [in] 10.91 12.25 11.25 11.50 11.18
D [in] 2.480 2.937 2.625 2.440 2.953
L3 / D 4 34.3 24.7 30 43 18.4
Improvement – 39% 14% – 20% 86%
SHAFT FLEXIBILITY COMPARISON

55. PUMP UPGRADE
SHAFT IMPROVEMENT
R 5/32” R 1/4”
MANUFACTURING MATERIAL:
ORIGINAL NEW
INCREASED TO AISI 304 AISI 420
M48x2 FROM M38x2
R 1/32”
KEYWAY CORNER RADIUS
SHAFT END / MATERIAL IMPROVEMENT

56. PUMP UPGRADE
AREAS OF ATTENTION
BEARING HOUSING
IMPELLER
WEAR SHAFT
RINGS

57. PUMP UPGRADE
BEARING HOUSING IMPROVEMENT
ORIGINAL NEW
1” NEW
CAST IRON A216 WCB
5/8” ORIGINAL

58. PUMP UPGRADE
BEARING HOUSING IMPROVEMENT
IMPROVED BEARING HOUSING

59. PUMP UPGRADE
AREAS OF ATTENTION
BEARING HOUSING
IMPELLER BEARINGS &
LUBRICATION
WEAR SHAFT
RINGS

60. PUMP UPGRADE
BEARINGS & LUBRICATION IMPROVEMENT
6216 M 7314 BECBM
HSG BORE TOL:
HSG BORE TOL:
+0,06 / +0,04 mm
+0,045 / +0,025 mm
FINISH GROUND

61. PUMP UPGRADE
AREAS OF ATTENTION
BEARING HOUSING
IMPELLER BEARINGS &
LUBRICATION
STUFF. BOX
WEAR COOLING SHAFT
RINGS

62. PUMP UPGRADE
SUMMARY OF MAIN IMPROVEMENTS
BEFORE AFTER
• PARTIAL VANES MISPOSITIONED EXTENDED & CORRECTED
• MAIN VANES AT INLET IMPROPER TRIM TRIMMED IN PATTERN
IMPELLER
• VANE LEADING EDGES (ALL) ROUNDED & THINNED IN PTRN
• MATERIAL AISI 304 18 Cr – 16 Mn
1 AISI 304 + Cr / 18Cr-16 Mn
WEAR RINGS • IMPELLER / CASING AISI 304 / AISI 304
2 18 Cr-16 Mn / AISI 304
• L3/D4 34.3 18.4
• END THREAD SIZE / FILLET RADIUS M38 + FILL. RAD. 3/32” M48 + FILLET RADIUS 5/32”
SHAFT
• RADII AT SHOULDERS / CORNERS 3/32” AT END / SHARP KW 1/4” AT END / 1/32” AT KW
• MATERIAL AISI 304 AISI 420
• THICKNESS AT TRANSITION PIECE 16 mm (5/8”) 25 mm (1.0”)
BEARING HSG
• MATERIAL CAST IRON CAST STEEL A216 WCB
BEARINGS • RADIAL / THRUST 6215 / 7313 BG 6216 M / 7314 BGM
LUBRICATION ENHANCED / CIRCULATING
MECH. SEAL • STUFF. BOX COOLING NO YES
COUPLING GEAR/LUBRICATED DISC PACK / NON-LUBR.

63. UPGRADED PUMP TEST
STAND-TESTING OF UPGRADED PUMP
OBJECTIVES:
Determine actual performance for modified
impeller.
Quantify actual NPSHR.
Reduce effects of adverse operating conditions:
• Trim impeller of pump “B” to reduce part
load operation.
• Rework impeller, if required, to help
prevent cavitation.
Guarantee trouble-free operation at the plant.

64. UPGRADED PUMP TEST
RESULTS OF PERFORMANCE TESTING
00 200
200 400
400 600
600 800
800 1000
1000 1200
1200 1400
1400 Q [GPM]
Q [GPM]
340 Publ Head 1120
1120
340 Publ Head
Test Head
Test Head
1060
1060
320
320
BEP
3550 rpm φ 385 mm
3550 rpm φ 385 mm
BEP
1000
1000
300
300
ORIGINAL
ORIGINAL 940
940
RATED
RATED
H [ft]
H [m]
280
H [ft]
H [m]
280 POINT
POINT
880
880
BEP
BEP
260
260 REVISED
REVISED 820
820
RATED
RATED
POINT
POINT
240
240
760
760
OPERATING
OPERATING
RANGE
RANGE
220
220 700
700
200
200 640
640
00 50
50 100
100 150
150 200
200 250
250 300
300 350
350
Q [m3/hr]
Q [m3/hr]
HEAD VS FLOW – FULL SIZE IMPELLER

65. UPGRADED PUMP TEST
RESULTS OF PERFORMANCE TESTING
00 200
200 400
400 600
600 800
800 1000
1000 1200
1200 1400
1400 Q [GPM]
Q [GPM]
500
500
Publ Pwr
Publ Pwr Test Pwr
Test Pwr 140
140
Publ Eff
Publ Eff Test Eff
Test Eff
400
400 120
120
AVAILABLE MOTOR POWER
AVAILABLE MOTOR POWER
100
100
Power [HP]
300
Power [HP]
300
80
80
η (%)
η (%)
200
200 60
60
40
40
100
100
20
20
OPERATING
OPERATING
RANGE
RANGE
00 00
00 50
50 100
100 150
150 200
200 250
250 300
300 350
350
Q [m3/hr]
Q [m3/hr]
PWR & EFF VS FLOW – FULL SIZE IMPELLER

66. UPGRADED PUMP TEST
RESULTS OF PERFORMANCE TESTING
00 200
200 400
400 600
600 800
800 1000
1000 1200
1200 1400
1400 Q [GPM]
Q [GPM]
340 Publ Head 1120
1120
340 Publ Head
3550 rpm φ 385 mm
3550 rpm φ 385 mm Test Head
Test Head
1060
1060
320
320
1000
1000
300
300
ORIGINAL
ORIGINAL 940
3550 rpm φ 350 mm 940
3550 rpm φ 350 mm RATED
RATED
H [ft]
H [m]
280
H [ft]
H [m]
280 POINT
POINT
880
880
BEP
BEP
260
260 REVISED
REVISED 820
820
RATED
RATED
POINT
POINT
240
240
760
760
OPERATING
OPERATING
RANGE
RANGE
220
220 700
700
200
200 640
640
00 50
50 100
100 150
150 200
200 250
250 300
300 350
350
Q [m3/hr]
Q [m3/hr]
HEAD VS FLOW – TRIMMED IMPELLER

67. UPGRADED PUMP TEST
RESULTS OF PERFORMANCE TESTING
6,5
6,5 11,5
11,5 16,5
16,5 21,5
21,5 26,5
26,5 31,5 NPSH [ft]
31,5 NPSH [ft]
260
260
Test NPSH
Test NPSH 1,4
1,4
3550 rpm φ 350 mm
3550 rpm φ 350 mm
Suction press @ oper. cond. [kgf/cm² g]
Suct Press
Suct Press
255
255
1,2
1,2
250
250 1,0
1,0
3% DROP
3% DROP
0,8
H [m]
0,8
245
245
0,6
0,6
MIN REQ'D = 0,50 kgf/cm² g
MIN REQ'D = 0,50 kgf/cm² g
240
240
(( 7,1 psig ))
7,1 psig 0,4
0,4
235
235
60% MARGIN
60% MARGIN 0,2
0,2
230
230 0,0
0,0
2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10
NPSHR 3% = 3,4 m (11 ft)
NPSHR 3% = 3,4 m (11 ft) NPSH [m]
NPSH [m]
NPSHR @ 220 m3/h (970 GPM) – TRIMMED IMPELLER

68. UPGRADED PUMP TEST
TEST CONCLUSIONS
Performance of modified impeller was determined
Head: Larger due to partial vanes
BEP: Coincident at 300 m3/hr (1320 GPM)
Efficiency: Coincident with original
NPSHR: 15% lower than expected
Adjustments for revised conditions of service:
Pump “A”: Full-size impeller @ 3150 rpm
Pump “B”: 91% dia impeller @ 3550 rpm
Min suct. press.: 0.5 kgf/cm² g (7.1 psig)
Required NPSH Margin: 60%

69. UPGRADED PUMP “A”
PUMP IN SERVICE – MAY 2000
MAIN PUMP INSTALLED SEPT 1999

70. UPGRADED PUMP “A”
PUMP IN SERVICE – MARCH 2002
MAIN PUMP INSTALLED SEPT 1999

71. UPGRADE RESULTS
COST – LEAD TIME COMPARISON
PROS - CONS COST & LEAD TIME
• ENGINEERING $ 3,0 K
Field work • 1 PUMP & DRIVER $ 90,0 K
PUMP required • 2 YR SPARE PARTS $ 5,0 K
REPLACEMENT Larger cost • FOUND. & PIPING $10,0 K
TOTAL: $ 108 K
11 MONTH ON SITE
• ENGINEERING $ 5,0 K
No field work
• BRG HSG PATTERN $ 5,0 K
PUMP • MAIN PARTS $ 17,0 K
required
UPGRADE • MFG, ASSY & TEST $ 12,0 K
Less cost
TOTAL: $ 39 K
11 MONTH FINISHED

72. UPGRADE RESULTS
CURRENT UPGRADE PROGRESS – END 2002
MAIN PUMP “A”
Fully upgraded
STAND-BY PUMP “B”
Partially upgraded
• Impeller & wear rings
• Shaft end design & material
Impeller size increased from 91% to 96% (370 mm)
• Flow requirement not reached
• Measured suct. press.: ≈ 0.25 kgf/cm² g (3.6 psig)
• Full cavitation, NPSH margin < 0

73. UPGRADE RESULTS
RELIABILITY IMPROVEMENT – END 2002
10
10 MAIN PUMP “A”
9
9 PC-752B
PC-752B
UPGRADE "A"
UPGRADE "A"
8
8 PC-752A
PC-752A Fully upgraded
7
7
6
No failures
6
5
5
4
4 STAND-BY PUMP “B”
3
3
2
Partially upgraded
2
1
1 Failures at brgs &
0
0 seal only
1995
1995 1996
1996 1997
1997 1998 1999
1998 1999 2000
2000 2001
2001 2002
2002
Projected savings over 10 years: US$ 900 K
FAILURE HISTORY BEFORE AND AFTER THE UPGRADE

74. CONCLUSIONS
Pump upgrade objectives were successfully
achieved.
Upgrade of existing pump was the best choice
for a cost-effective solution.
In-house engineering allowed a custom design
with some features exceeding current mfr. specs.
Impeller revised configuration is not an optimum
solution, but provided a remarkable service life
improvement.
Detected design deficiencies played an important
role on low reliability, but not on catastrophic
failures.

75. LESSONS LEARNED
In general, improvement of existing equipment
represents lower investment and lead time.
Check your equipment for upgrade opportunities,
specially if they exhibit low reliability.

76. REFERENCES
RELIABILITY IMPROVEMENT OF END SUCTION PUMP IN SEVERE SERVICE
THRU ENGINEERED COMPONENT UPGRADE
Mc. Caul, Colin. An Advanced Cavitation Resistant Austenitic Steel for
Pumps. Corrosion 96, The NACE International Annual Conference and
Exposition. Paper Nº 415, 1996.
Bloch, Heinz P. Improving Machinery Reliability. 2nd Edition. 1988. Gulf
Publishing Company
Bloch, Heinz P. Pump Reliability Improvement Program. Pump Failure
Reduction Programs. PRIME Seminar notes
J.F. Gülich. Selection criteria for suction impellers of centrifugal pumps.
Part 1: The suction specific speed – a criterion for flow recirculation
and pump reliability ?, Sulzer Pumps Ltd, PO Box, CH-8400 Winterthur,
Switzerland.
Summers-Smith, J.D. A Tribology Casebook. P.83. Mechanical Engineering
Publications London and Bury St. Edmunds, 1997.
Pfleiderer, Carl. Bombas Centrífugas y Turbocompresores. Editorial
Labor, 1960.

77. ®
20th International Pump Users Symposium
March 17-20, 2003. Houston, Texas
THANK YOU !