This document summarizes a study evaluating the long-term performance of composite wear rings in centrifugal pumps at a Sunoco refinery. It found that replacing metal wear rings with composite ones reduced repairs by 45%, vibration by 25%, and seal leaks by 70% initially. After 4+ additional years, repairs remained low, mean time between repairs increased, and vibration levels and seal leaks stayed reduced, showing the reliability benefits were sustained long-term. Some early composite failures occurred but were addressed by improving pump assembly procedures.

1. Evaluating the Long-Term Performance of
Composite Wear Rings in Centrifugal Pumps
Robert Aronen, Boulden International: Robert Aronen is the Managing
Director, EMEA, for Boulden International in Luxembourg. Since 2002, he has been
developing the market for the composite material DuPont™ Vespel® CR-6100 in
centrifugal pump applications. His prior work includes 4 years as a rotating equipment
engineer in the refining industry and 6 years as an engineer for Flowserve, Fluid Sealing
Division.
Mr. Aronen received a B.S. degree (Mechanical Engineering, 1991) from Rose-Hulman
Institute of Technology.
Martin Russek, Sunoco: Martin Russek is a Rotating Equipment Reliability Engineer at
the Sunoco, Philadelphia Refinery. He has worked in several rotating equipment
reliability roles for Sunoco at their 3 refineries in the Northeast since 1999. He has been
responsible for numerous pump, compressor, and turbine upgrades. Prior to his work in
the refineries, he was a Systems Engineer and Maintenance Engineer for Public Service
Electric & Gas Company. He has a Level II vibration certification and is an INPO certified
Systems Engineer.
Mr. Russek received a B.S. degree (Mechanical Engineering, 1989) from Trenton State
College.

2. Background
• Refinery instituted a reliability improvement
program to install composite wear rings as a
standard upgrade to all bad-actor pumps
• Initial results were published at 2007
International Pump Users Symposium
• This Case Study provides long-term results
after more than 4 years of running time

3. Program Scope
61 Centrifugal Pumps
Temperatures from 65 ⁰F (17 ⁰C) to 475 ⁰F (246 ⁰C)
Hydrocarbon, Acid, Amine, Water, Caustic services
Multiple API horizontal and vertical pump types
Intermittent (tank farm, product transfer) and
continuous process services

4. Which Components?
Horizontal Pumps Vertical Pumps
Stationary wear rings Stationary wear rings
Inter-stage rings Bowl bearings
Center-stage bushings Line-shaft bearings
Throttle bushings Throat bushings
Throat bushings

5. Why Composite Wear Rings?
• No metal-to-metal contact
– Avoid seizure
– Survive process upsets
• Reduced Clearance
– Lomakin Effect
– Lower vibration
– Reduced shaft deflection
– Lower NPSHR

6. Material Selected: PFA/CF Composite
Key Properties
Coefficient of thermal expansion (x-y)* 3.1 X 10-6 (in/in/⁰F) ASTM E-831
5.6 X 10-6 (mm/mm/⁰C)
Temperature Limit* 500 ⁰F (260 ⁰C) ASTM D-648
Limiting PV* 278000 (psi-ft/min) Falex test
9.7 (Mpa-m/sec)
Chemically compatible with everything in the refinery
Favorable machining and installation characteristics
*Source: DuPont™ Vespel® CR-6100

7. Definitions
Repair Any work order—includes seals, bearings,
vibration issues, wear ring seizure, inability to
make rate, etc… with an associated cost
Overall Average of 111 vibration data points from the
Vibration 25 horizontal pumps within the study
population.
LDAR Seal Leak Detection and Repair (LDAR) program,
Leaks which monitors single mechanical seals in VOC
(volatile organic compound) services.

8. Results from Original Study
2003—2006
Factor Studied Change
Number of Repairs 45% Reduction
Overall Vibration 25% Reduction
LDAR Seal Leaks 70% Reduction
*Source: Aronen, R., Boulden, B., and Russek, M., 2007, “Driving Pump Reliability
Forward with Advanced Composite Wear Rings,” Proceedings of the 23rd
International Pump Users Symposium, Turbomachinery Laboratory, Texas A&M
University, College Station, Texas, pp. 15-19.

9. Long Term Results: 2000—2009

10. Annual Repairs
(Population 61 Pumps)
60
50
40
Annual Repairs
Composite Repairs
30
Metal Repairs
20 Conversions
10
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

11. MTBR Before and After
(Population 61 Pumps)
90
80
70
MTBR (Months)
60
50
Composite MTBR
40
Metal MTBR
30
20
10
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

12. Overall Average Vibration
(Population 25 Horizontal Pumps)
0.20
0.18
0.16
Overall Vibration (ips)
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
-12 -6 -1 1 6 12 18 24 30 36 42 48 54
Months Before/After Installation of Composite Wear Rings

13. Annual Seal Leaks in VOC Service
(Population of 12 Pumps)
7
6
5
4
3
2
1
0
Before Composites After Composites

14. Specific Examples

15. Boiler Feed Water
Pump Type BB3
3 Pumps
Operating 230—250 ⁰F
Temperature (110—120 ⁰C)
Speed 3550 RPM
MTBR Before 15 Months
MTBR After 41 Months*
* One pump had 3 lube oil system failures which were included in calculation,
otherwise MTBR would have increased to 163 months

16. Flare Knockout Drum
Pump Type VS7, 4-stages
2 Pumps
Operating 212 ⁰F (100 ⁰C)
Temperature
Speed 3550 RPM
MTBR Before 15 Months
MTBR After 122+ Months

17. Gasoline Transfer
Pump Type OH2
4 Pumps
Operating Ambient
Temperature
Speed 3550 RPM
MTBR Before 17 Months
MTBR After 120 Months

18. Debutanizer Reflux
Pump Type OH2
2 Pumps
Operating 100 ⁰F
Temperature (38 ⁰C)
Speed 3550 RPM
MTBR Before 22 Months
MTBR After 107+ Months

19. Limitations
• In 2005 and 2006 there were some premature
composite related repairs—failure soon after
start-up due to mechanical interference from
reduced clearance
• Pump concentricity standards and checks after
assembly were improved to address failures
• Vertical pump shaft bushing minimum clearance
was also adjusted to be 0.002” (0,05 mm) larger
than 50% of API minimum to avoid assembly
issues

20. Conclusions
• Composite upgrade program improved reliability
• Repairs, vibration levels, and seal leaks decreased
• Reducing clearance requires superior
concentricity
• Previous “bad actors” have run more than 5 years
with zero failures
• Multi-stage pumps and pumps with start/stop
operation showed the largest reliability
improvements