DuPont™ Vespel ® CR-6100 PFA Carbon Fiber Reinforced

Vespel® CR family provides excellent chemical resistance in refineries or chemical processing. They offer high-creep resistance for seals, run-dry capability for wear rings for pumps and easy machinability for tight-tolerance parts like ball-valve seats.The CR-6100 grade of DuPont™ Vespel® parts and shapes is a composite material consisting of carbon fibers held in a PTFE® fluorocarbon resin matrix (PFA/CF Reinforced Composite, 20 wt% random x-y oriented carbon-fiber). Vespel® CR-6100 has been installed in thousands of pumps in refineries, chemical plants, power plants, and other fluid processing facilities since 1996. It has replaced metal and other composite materials used for pump wear rings, throat bushings, and line shaft bearings to help users increase pump reliability and performance. The properties of Vespel® CR-6100 help to reduce the risk of pump seizure and allow internal rotating-to-stationary part clearances to be reduced by 50% or more.

Features & benefits

Because total water flow in the main CWT increased by more than needed to compensate for the decommissioning of the smaller CWT unit, additional savings in energy (in electricity and steam) of over $200,000 per year were achieved.

The full decommissioning of the smaller CWT led to savings in electricity and maintenance that were estimated to be over $400,000 per year (at $0.06 per kWh). The cost to overhaul five pumps and one spare pump has been fully paid with the energy savings of just one year. If avoidance of yearly maintenance costs of the smaller CWT unit were included, the savings figures would be even larger.

With smaller clearances made possible by Vespel® CR-6100, water recirculation and turbulence has been reduced, increasing flow and discharge pressure. The combined result of pump overhaul resulted in an improvement in pump efficiency of about 8%.

Higher efficiency

The operator measured a 3% gain in pump efficiency over the pump manufacturer’s performance test curve.

No seizures, no repair costs to date.

As of January 2011, the pump has operated for three and a half years without a single seizure failure. That has saved $65,000 in annual repair costs that would have been needed with metal wear components, adding up to nearly $200,000 in three years

Extending the benefits

Based on the proven 3% efficiency gain and run-dry capability of Vespel® CR-6100 parts in this particular situation, the operating company installed CR-6100 parts in the pipeline’s eight additional pumps

Long life

The pump continued in operation for the next six months, completing its planned production cycle. During this time, there was no noticeable change in pump vibration or efficiency. At the end of the cycle, the pump was disassembled to inspect the rotor (see photo). The Vespel® CR-6100 parts had survived the incident with no measurable wear, and there was no damage to the pump rotor

Increased safety

The operator reported that the continued operation of Vespel® CR-6100 parts during the process upset helped significantly in avoiding a release of hazardous material.

Run-dry survival

Shortly after installation of the Vespel® CR-6100 parts, a control problem caused the pump to run “blocked-in” with both suction and discharge valves closed for 38 minutes. After the pump was shut down and cooled, operators were surprised that the rotor still turned freely. They then replaced mechanical seals, checked alignment, and returned the pump to normal operation.

Vespel® CR-6100 offers improved performance versus other wear ring materials

Vespel® CR-6100 is based on a fluoropolymer, which gives it broad chemical resistance and a low coefficient of friction. These characteristics coupled with its high temperature resistance and low thermal growth make Vespel® CR-6100 a suitable candidate for a wide range of applications. 

• The durability of Vespel® CR-6100 aids installation and machining, and stays tough during operation.

Reduced vibration

With Vespel® CR-6100 parts, the pump runs with much less vibration than previously

Pump performance and reliability are significantly improved.

• Because Vespel® CR-6100 is non-metallic, has a low coefficient of friction, and excellent dimensional stability, it can withstand short-duration off-design conditions such as start-up, slowrolling, low-flow, cavitation, or run-dry situations. The pump remains available for service, resulting in potentially lower repair costs. 

• With these characteristics, clearance at wear components can be reduced. This results in efficiency gains which lead to significant operating cost reductions, particularly when applied to populations of pumps. • Improved reliability: Pumps with reduced clearance also exhibit lower vibration levels and reduced cavitation. Seals and bearings last longer, and MTBR increases.

Sharply lower operating cost and increased efficiency

Increased efficiency achieved with the clearance reduction enabled by Vespel® CR-6100 parts made it possible to operate at full capacity with a single pump instead of two. The elimination of the second pump saved $100,000 per year in operating cost. In addition, the pump now draws 5% less amperage, saving $6200 annually based on a typical North American power cost of $0.06/kWh.

Applications

1.A large hydrocarbon processing facility in Central Alberta was using a nine-stage horizontally split-between-bearings pump (right photo) with 12-chrome stationary and rotating wear components to feed water to a boiler.

2.DuPont™ Vespel® CR-6100 is used for I.D.-mounted (in compression) wear components in nearly all centrifugal pump types in non-abrasive process services up to 500 °F (260 °C).

3.Pump Components • Wear rings • Line shaft bearings • Inter-stage bearings• Throat bushings• Pressure-reduced bushings

4.Pump Services Vespel® CR-6100 has been used in thousands of pumps in a broad range of hydrocarbon, chemical and water services. Some applications include: • Boiler feed • Condensate • Propane • Butane • Ethylene • LPG • Diesel • Gas oil • Sour water• Naphtha• Gasoline• MEA• DEA• Sulfuric acid• Ammonia• Hydrofluoric acid• Caustic• Lube oil

5.Pump Types • Overhung horizontal • Between bearings• Vertical• Multistage

The operator of a pipeline in the Southwestern U.S. was searching for a case ring material for pumps that would enable improved operating efficiency, increase equipment reliability and avoid the seizing or galling problems encountered with metal components.