Part 4: Which services, which machines, which parts to upgrade?
In the first part of this series, we discussed how upgrading your pumps with composite wear parts can help avoid galling and seizing, even when a pump runs dry. Because composite parts do not gall or seize like metal parts, this allows you to reduce the clearance at these components in your pump.
In Part 2, we discussed how reducing the clearance at the wear rings, throttle bushings, and center-stage bushings increases a stabilizing force in your pump called The Lomakin Effect. This force helps to reduce vibration and shaft deflection, leading to longer seal and bearing life in your pumps.
In Part 3, we discussed how reducing the clearance in your pump also improves pump efficiency, leading to a significant reduction in the life cycle cost of the pump.
Today, we start the discussion on how you can upgrade pumps, by looking at the specific services and components to upgrade with Vespel® CR-6100.
Vespel® CR-6100 is manufactured from carbon fibers and Teflon™ PFA resin. It is chemically resistant to nearly all process fluids used in the hydrocarbon processing and petrochemical industries. Vespel® CR-6100 has been used in a wide range products including (but not limited to): refined hydrocarbons, aromatic hydrocarbons, LPG, amines, sour water, caustic, ammonia, MEK, demineralized water, hydrofluoric acid, and boiler feed water.
The temperature range of Vespel® CR-6100 is cryogenic to 500 F(260 C). It has been used in liquid methane and ethane pumps at -230 F (-150 C), along with liquid nitrogen and liquid hydrogen at even lower temperatures. At the upper end of the temperature range, Vespel® CR-6100 has been used in a wide range of hydrocarbon processing services such as gas oil and naphtha.
In general, composite materials are used for refined process fluids and relatively clean utility services. Vespel® CR-6100 is superior to metallic components in avoiding seizure, running with tighter clearance, and resisting wear due to internal contact between rotating and stationary components. Conversely, if you are dealing with a slurry service where abrasive wear is the main problem facing the pump, composite materials have some limitations. Please contact Boulden to discuss your application conditions.
Vespel® CR-6100 will generally be used as the stationary wear parts in the pump. As we noted in the previous parts of this series, our objective is to eliminate the metal-to-metal contact points in the pump and replace them with metal-to-composite contact points. Vespel® CR-6100 is used for the stationary parts because it is stronger in compression than in tension. The rotating parts in the pump remain metal–with no special requirements for surface finishes or hardness beyond the original design of the metal parts.
Table 1 shows which parts are typically converted to Vespel® CR-6100 based on the pump type:
|Overhung Pumps||Between Bearings Pumps||Vertically Suspended Pumps|
|Case wear rings||Case wear rings||Case wear rings|
|Throat bushings||Throat bushings||Throat bushings|
|Inter-stage bushings||Line-shaft bearings|
|Center-stage bushings||Bowl bearings|
|Throttle bushings||Bottom bushings|
Until Next Time
In the next several segments of this series, we will discuss how to install Vespel® CR-6100 by pump type, discussing the differences between radially and axially split pumps, specific considerations for vertically suspended pumps, and some unique situations you might encounter.
Until then, if you have a pump operating at less than 500 F (260 C) where you want to improve the reliability or efficiency, contact Boulden today. We have a huge inventory of Vespel® CR-6100 standard sizes in stock ready for immediate shipment almost anywhere in the world.
For application and installation details, download the Boulden Installation Guide for Vespel® CR-6100