Tag Archives: improve pump efficiency

Save Money on Your Next BB3 Pump Overhaul

How to re-use the worn wear rings for better performance

Axially split, between bearings multi-stage pumps (API Type BB3) are used for some of the most important services in the hydrocarbon processing industry–charge pumps, boiler feed pumps, and product shipping/pipeline pumps.

The repair of these pumps is a great opportunity to upgrade with Vespel® CR-6100 or Boulden B-Series composite wear rings. In many situations, this will also be the most cost-effective way to rebuild the pump.

Cost of Repair
The reason these pumps offer a great value upgrade is because the case rings in axially split pumps can generally be re-used as holders for composite “inserts” as shown in figure 1.

This method of repair saves the cost of purchasing new case rings, or machining full rings with milled features. All of the work can be done on a lathe at the time of repair. First, you machine the inside bores of the existing case rings, throttle bushing, and center bushing. Then, you make the Vespel® CR-6100 inserts, press them in, and then final machine the parts to reduced clearance. This will increase the Lomakin Effect and efficiency of the pump.

Complete the remaining elements of the overhaul as you normally would. When the pump goes back into service, it should be easier to operate, more efficient, and more reliable.

Final Thoughts

If you have a BB3 pump coming through your shop for overhaul, consider upgrading to composite wear parts. Boulden can help you engineer the upgrade to Vespel® CR-6100 or Boulden B-Series and the patented Boulden PERF-Seal® design to ensure long-term reliable success. Contact us today. We have the material you need in stock.

Helpful Links:

Boulden Installation Guide for Vespel® CR-6100

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

2MW Boiler Feed Pump Case Study

Amine Stripping Pump Case Study

Today’s Photo

A rainbow over rolling hills

Andrà Tutto Bene (Everything Will Be Alright)

Comparing Pump Component Composite Materials

There is one material property that can tell you a lot about how a composite material is likely to perform in a pump: The coefficient of thermal expansion (CTE). If the value is too high, the material can deliver inconsistent results in challenging services.

Why CTE?
A low CTE is essential for reliable performance because components like wear ringsthrottle bushings, and vertical pump shaft bearings run with tight clearances. A low CTE allows the material to experience normal frictional heat generation during contacting conditions without significant deformation.

Conversely, it is difficult for a material with a high CTE to maintain a tight clearance. When exposed to normal frictional heat generation or higher temperatures, a high CTE can quickly cause the component to “grow” and close the clearance. When this happens, contact increases, frictional heat generation increases, and premature failure of the component can follow. This is likely what happened to the bushing in figure 1:

Failed vertical pump shaft bushing made from high CTE material

Figure 1: Failed vertical pump shaft bushing made from high CTE material

The difficulty from the user’s perspective is everyone selling materials for pumps claims that their material has a “low CTE.” What this often means is “low CTE relative to other plastics.”
How do you define low CTE?

At Boulden, we define “low CTE” to mean “equal to or lower than the CTE of the metal parts in the pump.” Common metals used to manufacture pumps are carbon steel, 400-series stainless, or 300-series stainless, so we want to be close to or below the CTE for these materials.

Boulden B-Series
Because we think CTE is so important, we developed our B-Series materials with this in mind. If you are currently using PEEK-based components, contact Boulden about upgrading to our B-Series materials. B-835 is our replacement for 30% carbon fiber filled PEEK; B-1050 is our replacement for “abrasive resistant” PEEK blends. B-920 is a non-PEEK proprietary blend, also for potentially dirty services.

CTE of composite materials

Material CTE (in/in/F) CTE (mm/mm/C)
Vespel CR-6100 3.1 5.6
B-920 3.5 6.3
B-1050 5.1 9.2
410 SS 5.5 9.9
Carbon Steel 6.0 10.8
B-835 8.7 15.7
316 SS 8.9 16
30% CF Filled PEEK 15 27

 

Conclusion

A low CTE is critically important to the performance of a composite wear part in a pump and one of the reasons Vespel® CR-6100 has proven so reliable over the past 20 years. Boulden-supplied materials also offer ease of machining, simple installation practices, and material availability. Boulden keeps the material you need in stock and can supply raw material or machined parts including our patented PERF-Seal® with rapid delivery.

If you want to make your pumps more reliable, easier to operate, safer, and more efficient, contact Boulden today. We can help you choose the best material for your application and provide detailed design assistance.

Boulden B-1050 Vertical Pump Shaft Bearings

Last fall, a power plant needed to replace the vertical pump shaft bearings on their cooling water intake pump. They contacted Boulden to find a solution.

Service Conditions

The cooling water intake pumps at the plant pump brackish water from the local harbor. The salty water creates corrosion issues, the silt in the water creates abrasion issues. The line shaft bearings are exposed to potentially high loads from the pump at an operating speed of 1500 rpm.

Boulden B-1050 cooling water intake bearings

Boulden B-1050 cooling water intake bearings

Bearing Design

Boulden selected B-1050 for the application due to its excellent dimensional stability, resistance to abrasive wear in dirty water conditions, and high load carrying capability. Unlike most plastic or composite materials used for this application, B-1050 has a coefficient of thermal expansion less than carbon steel. Boulden has found that a coefficient of thermal expansion less than carbon steel is probably the most important material property for the reliable performance and ease of design of a composite bearing or wear ring. For a complete data sheet, contact Boulden today.

Some key properties of B-1050 are shown in Table 1:

Boulden B-1050 key properties

Boulden B-1050 key properties

 

 

Tough, wear resistant shaft bearings from Boulden

Boulden supplied the B-1050 bearings mounted in Duplex Stainless shells. The old bearing spiders were corroded and needed to be re-machined; therefore, the shells were machined to fit after the modification to the spiders. The bearings ran against a 7″ (180 mm) diameter shaft. One line shaft bearing design was 9″ (225 mm) long; the other was 11″ (270 mm) long. The components were manufactured in a few weeks, delivered and installed without issues.

Conclusion

If you are looking for better materials for your vertical shaft bearings, contact Boulden. Consider B-1050 for your cooling water pumps, waste water pumps or other services where you need the ability for the bearings to run in potentially dirty service plus survive off design conditions such as running dry. We have a portfolio of materials with B-Series and Vespel® CR-6100, so whatever your vertical shaft bearing application, we can help.

For consultation on the best material for your application or design assistance, contact Boulden today. We have the material you need in stock and can supply raw material or machined parts with rapid delivery.

How to drill a hole into a solid Vespel® CR-6100 rod

A quick tip for the machine shop

Recently, a pump repair shop bought some 2″ solid rods of Vespel® CR-6100. This was their first purchase of solid rods and they asked for instructions to machine the I.D. to size. Below is the method we use in our shop at Boulden:

Step 1: Drill Pilot Hole 0.375–0.500″ (10-12 mm) through the center of the bar

How to drill a hole into a solid Vespel CR-6100 rod

Step 1: Drill Pilot Hole 0.375–0.500″ (10-12 mm) through the center of the bar

Step 2: Use a spade blade (or larger drill bit) to enlarge the hole

How to drill a hole in a solid Vespel rod

Step 2: Use a spade blade (or larger drill bit) to enlarge the hole

 

 

 

 

 

 

 

 

 

 

 

Step 3: Final machine with boring bar

How to drill a hole in a solid Vespel rod

Step 3: Final machine with boring bar

 

 

 

 

 

 

 

 

 

 

 

Until Next Time

If you have a pump in your shop where you would like to improve reliability, efficiency, avoid seizing, or reduce vibration, consider an upgrade to Vespel® CR-6100 wear rings with the Boulden PERF-Seal® design. Whatever the pump geometry, Boulden can help you fit the parts into the pump, make drawings and machined parts for you, or simply help you with tips and tricks to use in your shop. Contact us today.

 

Helpful Links:

Boulden Installation Guide for Vespel® CR-6100

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

2MW Boiler Feed Pump Case Study

Amine Stripping Pump Case Study

 

Today’s photo

Kebab grill in Turkey

The master of the kebab grill, Ankara, Turkey

 

 

 

Measuring Your Pump

Which information is needed in order to upgrade your pump to DuPont™ Vespel® CR-6100?

Pump Measurement Review

Using Vespel® CR-6100 wear parts with reduced clearance can help your pumps be more reliable, efficient, and easier to operate. Which measurements and which process data do we need to assemble for the upgrade?

Dimensions Needed for a Quote

Let’s start with the 3 dimensions we need to determine material sizes and availability shown in Figure 1:

  • “R” Outside diameter of the rotor running against the Vespel® CR-6100
  • “B” Inside diameter of the bore the Vespel® CR-6100 will press into
  • “L” Length of the bore
  • Alternative: the O.D., I.D., and Length of the existing parts

If we have those 3 dimensions for each part plus the quantity of each part required, we can provide a quote. Contact us if you have any questions.

Dimensions for designing a Vespel CR-6100 part

Figure 1: Dimensions for designing a Vespel CR-6100 part

 

Dimensions to Design

To design parts for fabrication, we will need the dimensions of the mating hardware. While many wear parts have a simple O.D., I.D., and Length profile, some parts have additional features for which we will want the dimensions:

  • Some pump wear rings have profiles like an “L”, “T”, or “Z”. In those situations we need to know each of the diameters and widths of any of the “shoulders” or “ribs” of the parts
  • Is the pump axially or radially split?
  • Are any of the parts are axially split?
  • For vertical pump shaft bearings, it will be helpful to know if there is any groove profile required-spiral grooves, axial grooves, how many, what diameter, how deep…
  • What is the existing material and clearance of the vertical pump shaft bearings?

Process Conditions

Vespel® CR-6100 works in most process services. It is manufactured from Teflon™ PFA and carbon fibers, so it is chemically resistant to nearly all process chemicals and it has a broad temperature range. There are only two general limitations:

  • Temperature range is cryogenic -300 F (-200 C) to 500 F (260 C)
  • Avoid abrasive slurries, slops, and bottoms services

To design the parts, the pump operating temperature is required in order to determine the correct press fit for the Vespel® CR-6100 parts.

Differential Pressure

If the components are going into a high-energy pump, such as a multi-stage horizontal charge pump or boiler feed water pump, we recommend that the patent-pending Boulden PERF-Seal™ design be used on all horizontal multi-stage pumps. The PERF-Seal™ design is fabricated from Vespel® CR-6100 and increases the efficiency gain and rotor damping associated with the upgrade. If the PERF-Seal™ is not used, we will need to know the differential pressure across the components in order to verify that they are designed correctly.

PERF-Seal™ center bushing from a boiler feed pump

PERF-Seal™ center bushing from a boiler feed pump

 

Conclusion

In the ideal situation, you can supply the dimensions of the parts required, the pump cross-sectional drawing, and the API data sheet for the pump. From this information, we can confirm that the service is a good fit for Vespel® CR-6100, quote the material or machined parts required, and make a recommendation on how to install Vespel® CR-6100 into the pump.

Please feel free to contact Boulden with your application details and dimensions. We’ll be happy to provide a budget estimate or a fixed quote depending on the information available. Once you decide to go forward with the upgrade, we have whatever material you need in stock in the USA, Europe, and Singapore.

Helpful Links:

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

3MW Boiler Feed Pump Case Study

 

Today’s Photo:

Petronas Towers, Kuala Lumpur, Malaysia

Petronas Towers, Kuala Lumpur, Malaysia

 

How to get Vespel® CR-6100 in a new pump?

Frequently Asked Question:

“Are the OEMs using Vespel® CR-6100?” is a question we hear every month. The answer is definitely, “yes.” All of the major API pump manufacturers use Vespel® CR-6100 for both new pumps and aftermarket upgrades.

A related question: “If Vespel® CR-6100 is so great, why don’t the OEMs include it as a standard material?”

To answer that, we need to look at how pumps are usually purchased…

Most pumps are sold into projects. The EPC contractor generally selects the pump with the lowest price which meets the bid specification. Therefore, if the bid spec allows bronze or cast iron wear rings, the OEM will probably quote bronze or cast iron because they are the cheapest materials. These materials might result in a higher life-cycle cost, but procurement personnel will not care if their decision is driven by the initial price.

Put it in the Bid Spec

If you want to maximize your pump reliability and efficiency, specify Vespel® CR-6100 for the stationary wear components in your next project. When it is part of the specification, the OEMs are happy to quote and supply Vespel® CR-6100.

If your company does not allow using brand names in the project specification, you can use the generic description for Vespel® CR-6100 from API610, Table H.3: PFA/CF reinforced composite, 20% mass fraction random X-Y oriented carbon fiber. For clarity, you can add the note “one example of which is DuPont™ Vespel® CR-6100.”

Direct Questions to Boulden

If there are any questions from the Project Engineer, EPC contractor, or OEM, please ask them to contact Boulden. We will be happy to answer any questions they have and make sure that the Vespel® CR-6100 is used correctly throughout the project.

In short, if you want Vespel® CR-6100 wear rings, vertical pump shaft bearings, or throttle bushings in your new pumps, all you have to do is ask–i.e. spell it out in the bid spec. Until next time, if you need any material for your pumps, we have a wide range of sizes in stock and ready for immediate shipment.

Helpful Links:

Boulden Installation Guide for Vespel® CR-6100

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

2MW Boiler Feed Pump Case Study

Amine Stripping Pump Case Study

 

Today’s Photo

Lanzarote, Spain

Lanzarote, Spain

Upgrading Pumps With Composite Wear Components: Part 3

Part 3: Reduce Clearance – Improve Pump Efficiency

Welcome to Part 3 in our series on upgrading pumps with composite wear parts.

In the first part of this series, we discussed how upgrading your pumps with composite wear parts can help avoid galling and seizing. 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 creates 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.

Today, we will discuss how reducing the clearance in your pump also improves pump efficiency.

Centrifugal Pump Background

According to a major centrifugal pump OEM, energy consumption accounts for 44% of the life cycle cost of a centrifugal pump. You can reduce this cost by upgrading the wear components to a composite material like Vespel® CR-6100 and reducing the clearance in your pump.

The specific components where you want to reduce the clearance are the pump wear rings, inter-stage rings, center-stage bushing, and throttle bushing. These components form the barriers between high-pressure and low-pressure areas within the pump. The differential pressure across these components creates internal recirculation within the pump, resulting in a loss of pump efficiency (Figure 1).

Loss of pump efficiency

Leakage past the wear rings (QL) creates efficiency loss

 

 

 

 

 

 

When you upgrade these components to Vespel® CR-6100, you can typically reduce the clearance by 50% compared to the API minimum for metal parts. If you reduce the clearance by 50%, you reduce the internal recirculation by approximately 50%, leading to a significant efficiency gain.

Which Pumps Produce the Biggest Gains?

If we consider only efficiency gains, horizontal multi-stage pumps usually offer the best return on investment from an upgrade to Vespel® CR-6100 with reduced clearance. These pumps have multiple leak paths across wear rings, inter-stage rings, center bushings, and throttle bushings. Because they have many stages, these pumps also tend to consume a lot of power. Consider the following cases where process plants have reduced the operating costs of their multi-stage horizontal pumps:

  • A power station upgraded a 3MW boiler feed water pump with Vespel® CR-6100 along with the Boulden PERF-Seal™ design and reduced clearance and recorded a 7% efficiency gain compared to a newly rebuilt pump with original clearances.
  • A refinery upgraded their hydrocracker charge pumps with Vespel® CR-6100 along with the Boulden PERF-Seal™ design and reduced clearance and recorded 4% more throughput to their hydrocracker-a hugely profitable upgrade.
  • A product pipeline company upgraded their LPG shipping pumps with Vespel® CR-6100 and reduced clearance, resulting in a 4% efficiency gain.

Another area to consider is process pumps which are marginally undersized, requiring parallel pump operation to achieve 100% of the target process rate. Sometimes, a modification as simple as reducing the wear ring clearance can get you back to one-pump operation with a full-capacity spare pump.

The PERF-Seal™

To further increase the efficiency gain associated with reduced clearance, the components can be modified with the Boulden PERF-Seal™ design. Internal testing has shown that the PERF-Seal™ creates an additional reduction in flow across throttle bushings, center-stage bushings, and wear rings beyond what can be achieved with reduced clearance alone.

Conclusion

When you eliminate the metal-to-metal contact surfaces in your pumps and use Vespel® CR-6100 stationary wear components, you can then reduce the clearance. This reduction in clearance improves pump efficiency and lowers the operating cost of the pump. Numerous field examples exist where customers have saved tens of thousands of dollars on their annual pump operating costs with this simple upgrade.

If you have a pump where improved efficiency will save you money, 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.

Today’s Photo

Cape Town, South Africa

Cape Town, South Africa

Upgrading Pumps With Composite Wear Components: Part 2

Part 2: Reduce Clearance – The Lomakin Effect

Welcome back to our series on upgrading pumps with composite materials. In part 1, we discussed how using composite materials like Vespel® CR-6100 in your pumps allows you to eliminate the metal-to-metal contact points in the pump and minimize the risk of pump seizure:

  • In the shop during assembly
  • In the field during alignment
  • During slow-roll, start-up, and shut down
  • During off-design events like dry-running or low flow

Reducing Clearance – The Lomakin Effect

Minimizing the risk of seizure in your pump sets the stage for reducing the clearance at the wear parts in your pump. Reducing clearance can be a significant pump reliability upgrade due to a phenomenon known as the “Lomakin Effect“.

Your Wear Rings are Bearings

During pump operation, the flow created by differential pressure across the wear parts in the pump (wear rings, throttle bushings) creates a force called The Lomakin Effect. The force arises from an unequal pressure distribution around the circumference of the component during periods of rotor eccentricity. This force counteracts shaft deflection in the pump.

Figure 1 shows how shaft deflection creates this force. As the fluid enters the clearance between the rotor and wear component, it accelerates as it passes from the high pressure end to the low pressure end. Due to the eccentricity of the rotor, there is more clearance on one side of the wear part than the other. There will be more flow and a locally higher velocity on the side of the wear ring with more clearance and lower velocity on the side of the ring with less clearance. Higher velocity results in lower pressure; lower velocity results in higher pressure, creating a net corrective force which acts in the direction opposite of the shaft deflection.
In other words, when your pump experiences shaft deflection, there is a hydraulic “stiffness” (Lomakin Stiffness) which is generated to counteract the shaft deflection.

The Lokamin Effect

Figure 1: The Lokamin Effect

 

 

 

 

 

 

 

Using Vespel® CR-6100 you can typically reduce the clearance at the pump wear rings by 50% compared to the API recommended minimum for metal wear parts. The Lomakin Stiffness is inversely proportional to clearance; therefore, a 50% reduction in clearance doubles this force.

Potential benefits for your pumps include:

  • Less shaft deflection
  • Lower vibration levels
  • Fewer mechanical seal leaks
  • Longer bearing life

Which Pumps?

The Lomakin Effect is generally beneficial to all centrifugal pumps, but some pump types often show significant vibration reductions and reliability improvements with reduced clearance:

  • Multi-stage horizontal pumps
  • Older overhung pumps with long, thin shafts (high L/D ratios)
  • Two-stage overhung pumps

Conclusion

Reducing the clearance at the wear components can be a major reliability upgrade for your pumps. The reduced clearance increases The Lomakin Effect which improves pump rotor stability. The net result is a pump which runs with potentially lower vibration, fewer seal leaks, and longer bearing life.

Reducing the clearance also increases pump efficiency, which we will discuss in Part 3.

Until then, if you are working on a pump with a long, thin, flexible rotor, contact Boulden to discuss upgrading the wear parts to Vespel® CR-6100 and reducing the clearance. We have a huge stock of Vespel® CR-6100 standard sizes in the USA, Europe, and Singapore available for immediate delivery to your workshop.

For application and installation details, download the Boulden Installation Guide for Vespel® CR-6100.

Today’s Photo

Le Louvre, Paris, France

Le Louvre, Paris, France

Upgrading Pumps With Composite Wear Components: Part 1

Part 1: Minimize the Risk of Pump Seizure

Welcome to our series on upgrading pumps with composite materials. Over the next few months, we’ll cover the basics of why and how to use composite materials, specifically DuPont™ Vespel® CR-6100, to make your pumps more reliable, efficient, and safe.

Metal Parts Seize

Centrifugal pumps contain contact points between rotating and stationary parts. Most designs use replaceable wear components at these contact points: wear rings, inter-stage rings, throttle bushings, center-stage bushings, vertical pump shaft bearings, throat bushings. In the past, both the rotating and stationary parts would typically be metal.

With metal rotating and stationary components, there is a risk of galling or pump seizure. Galling can cause your pump to stick during assembly in the workshop, during alignment, or when the pump is slow-rolling in the field. This is a nuisance which can cause costly delays, returning the pump to the shop for disassembly, clean-up, re-assembly, and a return to the field. If a pump seizes during full-speed operation due to running dry, low flow, valve failure, bearing failure, shaft breakage, or another off-design scenario, the welding of metal parts together will generally cause the pump to stop abruptly, causing severe pump damage along with the potential for safety and environmental impacts.

Vertical LPG Pump with metal shaft bearings

Vertical LPG pump with metal shaft bushings seized, shaft broke, impellers and bowl assemblies destroyed.

 

Eliminate the Metal-to-Metal Contact Points in Your Pump

At a very basic level, the reason to upgrade the wear components in your pumps to composite materials is because composite materials are completely dissimilar to metal. Due to the totally different material compositions, metal-to-composite contact does not result in seizure like metal-to-metal contact.

So, our first objective when we are upgrading our pump with composite materials is to eliminate the metal-to-metal contact points within the pump. When using Vespel® CR-6100, the rotating parts will typically remain metal and the stationary parts will become Vespel® CR-6100. With this simple change, we now have metal-to-composite contact points in the pump and the risk of seizure is minimized.

Vespel® CR-6100 wear ring

Horizontal LPG pump ran dry with Vespel® CR-6100 case rings. No damage to impellers, case, shaft, or bearing housings.

 

 

 

 

 

 

 

Conclusion

Eliminate the metal-to-metal contact points in your pumps by upgrading the stationary components to Vespel® CR-6100. This simple upgrade will minimize your risk of pump seizure, eliminate nuisance repairs from pumps galling during alignment or slow-roll, and will help mitigate the risks and damage due to off-design operational events including dry-running operation.

Because the risk of pump seizure is minimized, you can now safely reduce the clearance at the wear components, setting up several additional benefits. We’ll talk about reducing the clearance in Part 2.

Until then, if you have had troubles with a pump which galls or seizes, contact Boulden to discuss upgrading the wear parts to Vespel® CR-6100. We have a huge stock of Vespel® CR-6100 standard sizes in the USA, Europe, and Singapore available for immediate delivery to your workshop.

For application and installation details, download the Boulden Installation Guide for Vespel® CR-6100.

Today’s Photo

Fresh coconuts

Fresh Coconuts – Terengganu, Malaysia

The Final Installation Steps: Length and Clearance

Upgrading pumps with composite wear componentsSetting the final dimensions of your DuPont™ Vespel CR-6100 component

Review

We have discussed how to measure your pump, prepare the metal parts, and establish the press fit for your Vespel® CR-6100 installation. The final two dimensions you need to establish are the part length and the clearance.

The Part Length

Vespel® CR-6100 has an extremely low coefficient of thermal expansion in the radial plane (perpendicular to rotation). This is one of the principal reasons it performs so well in centrifugal pump components. The low coefficient of thermal expansion is achieved through the use of radially-oriented, long carbon fibers.

Conversely, the coefficient of thermal expansion along the axis is relatively high. Therefore, the part length for a Vespel® CR-6100 component should account for the axial thermal expansion at operating temperature. Table 4 of our installation guide provides the details on how to make this adjustment.

Table 4 of our installation guide provides the details on how to make this adjustment.

The Clearance

The clearance for the part is set depending on the diameter and component type. Tables 2a and 2b in the installation guide show the clearance recommendations for horizontal pump components such as pump wear rings, throttle bushings, center bushings, inter-stage rings, balance bushings, and throat bushings.

Tables 2a and 2b provide recommended minimum clearance for horizontal pump components.

Tables 3a and 3b show the clearance recommendations for vertical pump components like vertical pump shaft bearings, wear rings, and throat bushings.

Tables 3a and 3b provide recommended minimum clearances for vertically suspended pump parts.

The best way to set the clearance is to press the component into place, and then final machine the bore to the desired clearance. This is shown in steps 5a-7a in our installation guide, pages 8-9.

Where final machining after the press fit is not practical, you can design the component to have the correct clearance after the press fit. For most component geometries, you can assume the Vespel® CR-6100 will reduce at a 1:1 ratio with the press fit. This method is shown in steps 5b-7b in our installation guide, page 9.

Some sites have implemented a hybrid method. They measure the inside diameter of the Vespel® CR-6100 case wear ring after installation, and then machine the metal impeller wear ring to set the desired clearance.

Conclusions

Installing Vespel® CR-6100 is an easy upgrade to make your pumps more reliable, safe, and efficient. Follow the steps in our  installation guide and you can make your pump even better than the day it was new. If you need material, Boulden carries inventory of stock sizes in the USA, Europe, and Singapore.

Until next time, please feel free to contact Boulden with your application details or to request a quote. We’ll be happy to answer any questions you might have.

 

Helpful Links:

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

3MW Boiler Feed Pump Case Study

Today’s Photo

Rock of Gibraltar – was one of the Pillars of Hercules and was known to the Romans as Mons Calpe.

 

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