Improving Reliability and Efficiency of Centrifugal Pumps
Improving Reliability and Efficiency of Centrifugal Pumps
Improving Reliability and Efficiency of Centrifugal Pumps
and Efficiency of
Centrifugal Pumps
No-flow operation of a boiler feed water pump caused these metal wear
rings to weld together requiring extensive repairs. Replacement of
metal parts with DuPont Vespel CR-6100 parts provided better
operation in no-flow conditions.
RAMS
Feature
A better solution is to replace metal wear components with advanced next-generation non-metallic
parts made of composite materials, permitting much
closer clearance between moving parts, and enhanced
run-dry capabilities should a process upset occur.
One of the most
successful and wellproven non-metallic
wear component materials is DuPont
Vespel CR-6100
composite. Vespel
CR-6100 parts are inDuPont Vespel CR-6100 parts
creasingly used in such as wear rings have proven their
thousands of pumps durability and performance benefits in
at facilities operated by BP,
and hundreds of re- pumps
ConocoPhillips, ExxonMobil, Lanxess,
fineries and petro- Shell and Sunoco.
chemical plants around the world. Companies using Vespel CR-6100 include BP, ConocoPhillips,
ExxonMobil, Lanxess, Shell and Sunoco.
These major pump users are testimony to the fact
that installing Vespel CR-6100 wear parts in centrifugal pumps can upgrade the efficiency and longterm reliability of the pump.
reduced to values up to 50% less than the recommended minimums for metal components as specified in API 610/ISO 13709, by replacing the stationary
metal wear parts with Vespel CR-6100 parts, with
the rotating wear component remaining metal. Tighter
clearances improve pump efficiency and reliability.
Ref: Aronen, Robert The Power of Wear Rings: Efficiency, Pumps &
Systems, April 2011
Efficiency Gains
ISO/API Standards
Industry experience with Vespel CR-6100 has
led to inclusion of the material in API 610, 11th
Edition/ISO 13709:2009, Centrifugal pumps for petroleum, petrochemical and natural gas industries. Vespel
CR-6100 is listed in Annex H, Table H.3 of the
standard, under the generic description PFA/CF
reinforced composite.
Reduced Clearance
In practical terms, this means the clearance of wear
ring and bushing components can potentially be
power price of $0.06/kwh). If clearance can be reduced by more than 50%, efficiency gains and savings can be significantly higher.
Reliability Increases
Vespel CR-6100 wear rings with reduced clearance also increase pump reliability. As noted above,
the non-seizing properties and run-dry capabilities
of Vespel CR-6100 help pumps survive off-design
process conditions which could cause metal components to seize.
In addition, reducing the wear ring clearance in a
pump increases hydraulic stiffness and damping,
resulting in lower vibration levels and less wear and
tear on critical pump components like mechanical
seals and bearings. This is known as the Lomakin
Effect, where the wear rings produce dynamic rotor
stiffness in the pump.
results were maintained for several years of operation. The key conclusions of that study were:
Repairs, vibration levels, and seal leaks were
all substantially reduced
Several pumps which were previously troublesome have run for more than five years with
zero failures
Multi-stage pumps and pumps with start/
stop operation showed the most significant
reliability improvements.
RAMS
Feature
DuPont offers a Vespel Application Guideline to help part manufacturers and pump operators in evaluating the optimum interference fit
and clearance. To download the guideline, visit:
(http://www2.dupont.com/Vespel/en_US/
assets/downloads/vespel_cr/
K16392_3VespelCR6100_Guide.pdf)
Conclusion
By replacing metal and or PEEK wear components
with Vespel CR-6100 wear parts pump reliability
and efficiency can be increased, thereby lowering
total system cost.