1. Tough Composite Pump Bearings
Prove Their Value at Power Plant
Retrofitting DuPont™
Vespel®
CR-6100 for line-shaft bushings and wear rings
in condensate pumps at Nevada Power sharply reduces vibration, protects
shaft against damage.
When a large four-stage condensate pump failed in August 2006,
DuPont was enlisted to help Nevada Power replace worn line shaft
bushings of carbon graphite with Vespel®
CR-6100 parts without re-
placing the throat bushing. Vibration immediately dropped essentially
to zero. In April 2007, a faulty impeller caused the pump to fail again. It
was discovered that the brittle carbon graphite throat bushing was de-
stroyed, but the tough Vespel®
CR-6100 bushings survived with only
a slight increase in shaft clearance. If they had failed, severe damage
to the pump may have occurred, with repair costs estimated at more
than $50,000.
Based on this experience and on sharply reduced vibration, DuPont
helped Nevada Power’s maintenance team replace carbon graphite
line-shaft bushings, wear rings and the throat bushing with Vespel®
CR-6100 in three additional pumps that deliver condensate to boiler
feed pumps.
The pumps are 700 hp (522 kW) Ingersoll Rand 27APKD-4 four-
stage, deep-well units fed by a wet well. The process fluid is water
condensate at 110 to 120°F (43 to 49°C).
Benefits Gained
Reduced vibration. Relying on both the outstanding anti-seizing,
anti-galling performance and the precise machinability of Vespel®
CR-6100, the maintenance team installed bushings and wear rings
made to tight clearance, a key factor in reducing vibration (chart at
left). Bushing clearance was just 0.008 in (0.2 mm). The wear rings,
which have an ID of 9.375 in (238 mm), have clearance of 0.012 in
(0.3 mm). Vibration and accompanying wear and tear on pump seals
and bearings remain low over time thanks to the low friction and high
wear resistance of Vespel®
CR-6100.
Increased reliability. The tight wear ring clearance allowed by Vespel®
CR-6100 reduces NPSHR (net positive suction head required). This
reduces the risk of cavitation and improves reliability.
Damage protection. The toughness of Vespel®
CR-6100 helps pre-
vent damage to the shaft and other pump components in the event of
impeller failure or other process upsets.
End User
Nevada Power Company
Charles Lenzie Generating Station
Las Vegas, Nevada USA
For more information, visit
pumps.vespel.dupont.com

2. Americas
DuPont™
Vespel®
Pencader Site
Newark, DE 19714-6100
Tel: 800-222-VESP (222-8377)
Fax: (302) 733-8137
DuPont do Brasil, S.A.
Alameda Itapecuru, 506
06454-080 Barueri, SP Brasil
Telephone +55 11 4166 8542
Fax +55 11 4166 8720
Asia Pacific
DuPont China Holding Co, Ltd.
15th Floor, Shui On Plaza
333 Huai Hai Road (Central)
Shanghai 200021, China
Telephone +86 21 6386 6366
Fax +86 21 6386 6333
DuPont Kabushiki Japan
Sanno Park Tower 11-1
Naguta-cho 2-chrome Chiyoda-ku
Tokyo
100-6111 Japan
Tel: +81-3-5521-2773
Fax: +81-3-5521-2777
Europe / Middle East / Africa
DuPont de Nemours
(Belgium) BVBA-SPRL
Engineered Parts Center
A. Spinoystraat 6
B-2800 Mechelen
Belgium
Tel: ++32 15 441384
Fax: ++32 15 441408
vespel.dupont.com
Wear ring, part of bowl assembly of vertical pump, delivers high reliability and
durability, thanks to toughness, wear resistance and anti-galling, anti-seizing
performance of DuPont™
Vespel®
CR-6100.
Material Selected, and Why
Vespel®
CR-6100 meets this application’s
need for bushings and wear rings that can
reduce vibration and provide resistance
to process upsets. The composite
material’s anti-seizing and anti-galling
performance, low coefficient of friction,
high PV capacity, low wear rate and low
coefficient of thermal expansion make it
a perfect choice for rotating equipment
in power plants and many other
environments.
In-stock availability of Vespel®
CR-6100
from the regional distributor was another
key factor in its initial use within a pump
requiring immediate repair.
Let’s Talk
We have the right materials, technology
and technical resources to help you
design and manufacture superior parts
and systems. Please contact the nearest
DuPont representative for your country.
The data listed here fall within the normal range of properties, but they should not be used to establish specification limits nor used
alone as the basis of design. The DuPont Company assumes no obligations or liability for any advice furnished or for any results obtained
with respect to this information. All such advice is given and accepted at the buyer’s risk. The disclosure of information herein is not a
license to operate under, or a recommendation to infringe, any patent of DuPont or others. DuPont warrants that the use or sale of any
material that is described herein and is offered for sale by DuPont does not infringe any patent covering the material itself, but does not
warrant against infringement by reason of the use thereof in combination with other materials or in the operation of any process.
CAUTION: Do not use DuPont materials in medical applications involving implantation in the human body or contact with internal
body fluids or tissues unless the material has been provided from DuPont under a written contract that is consistent with DuPont policy
regarding medical applications and expressly acknowledges the contemplated use. For further information, please contact your DuPont
representative. You may also request a copy of DuPont Policy Regarding Medical Applications, H-50103-2, and DuPont Caution Regarding
Medical Applications, H-50102-2.
Copyright © 2008 DuPont. The DuPont Oval Logo, DuPont™
, The miracles of science™
, and Vespel®
are registered trademarks or
trademarks of E.I. du Pont de Nemours and Company or its affiliates. All rights reserved. K-16832-2 (11/08) Printed in the U.S.A.