Tag Archives: CR-6100

Case Study: Repeat Failures of Boiler Feed Water Pumps

Vespel®CR-6100 centrifugal pump components

Boiler Feed Pump Seizing Problems

The low lubricity of boiler feed water along with operational challenges can lead to pump seizures. How do you avoid the problem? Or, if it happens, what is the best way to solve the problem? This case study is about repeat seizures of two, new, 1.2 MW boiler feed water pumps operating in a refinery. The pumps were fitted with metal wear parts, ran at 2980 rpm, and experienced failures immediately after commissioning.

The Tale of the Terrible Boiler Feed Pumps

Here is a brief summary of the problems this site faced with their boiler feed pumps:
  1. The first failure was due to pump seizure, the original failure analysis suggested the pumps failed due to sand or debris lodging into the close clearance between rotating and stationary wear parts. The filters on the suction strainer were changed to a finer mesh to limit particle size which could enter the pump.
  2. Soon after, one of the pumps seized again–this time, the metal parts had galled before start up and the pump could not be rotated by hand. The clearances at the wear rings, center bushing, and throttle bushing were increased.
  3. The pumps seized again.
  4. Repeated start-up attempts against seized pumps had also damaged the pump motors.

The failure analysis led the engineers to re-check the entire design and installation of thepumps:

  • Re-checking the design basis of the pumps
  • Re-checking the materials of construction
  • Re-checking assembly and rotor run-out
  • Re-balancing the rotor
  • Performing a new pump rotordynamic analysis
  • Verifying soundness of foundation and that pipe strain within limits
  • Evaluation of operational practices and function of the minimum control valve

Minimum Flow Valve Problem

Ultimately, the site realized the minimum flow valve was not functioning properly, leading to low flow rates at start up. The low flow rates caused localized flashing inside the pump and the metal parts would seize.

Their corrective action was to change the minimum flow valve, increase the clearance at the center bushing, throttle bushing, and wear rings, and “upgrade” to a “non-seizing” metal alloy. Because they increased the clearance at all of the internal parts, they ran a new rotor dynamic analysis to verify that the rotor would remain stable.

How Much Did It Cost?

Between repeated pump repairs, motor overhauls, engineering resources to troubleshoot and re-verify the design, the problem undoubtedly cost hundreds of thousands of dollars. If start up was delayed or the site lost production, the losses were probably in the millions.
The solution was also extremely expensive. The clearance at the pump wear parts was permanently increased. We’ll generously assume the increased clearance resulted in a 2% efficiency loss. Assuming a power price of $0.12/kw-hr, this loss of efficiency will cost about $50,000/year. Over the life of the pumps, the site will lose another million dollars or more!

Avoid Pump Seizure By Using Vespel® CR-6100

If the site had specified Vespel® CR-6100 wear parts when the pump was ordered, the pump would not have seized. Most likely, the pumps would have made it through the low flow transients without issue and all of the efforts above could have been avoided. The motors would not have been damaged, and they would not have had to increase the internal clearances. Even after the first seizure occurred, they could have easily converted to Vespel® CR-6100 and saved time, effort, and cost. The small adder to specify Vespel® CR-6100 would have saved several hundred thousand dollars at a minimum.

Furthermore, because Vespel® CR-6100 does not seize, clearance at the wear rings, center bushing, and throttle bushing could have been reduced, resulting in an efficiency gain instead of an efficiency loss. So, instead of losing $50,000 per year in operating costs, the site could have saved at least $50,000 per year–a net $100,000 annual savings from using Vespel® CR-6100. Combined with the Boulden PERF-Seal® design, the pump would be more reliable, easier to operate, and more efficient than a pump with metal parts and increased clearance.

Conclusion

If you are buying or overhauling a boiler feed water pump, specify Vespel®CR-6100 for all of the stationary wear parts (the rotating parts will remain metal). You’ll have a better pump that is easier to operate with a lower life cycle cost due to higher efficiency. If you have an existing pump that seizes, contact Boulden today. We can help you solve this problem in just about any pump service.

If you simply have an urgent repair and need a great material fast, we have a large inventory of material in stock and can supply raw material or machined parts with very short lead times. If you have dimensions, quantities, and basic service conditions, simply request a quote. We’re here to help you!

Case Study: Upgrade of Boiler Feed Water Pumps

Boiler Feed Water pump upgraded with Vespel® CR-6100 componenets

BB5 boiler feed water pump upgraded to Vespel® CR-6100 with the PERF-Seal® design for the wear parts

Last week, we wrote about a boiler feed pump case history where the customer paid dearly because they didn’t use Vespel® CR-6100. Repeated failures due to pump seizure led them to increase the clearance at the wear rings, resulting in a lifetime of lower efficiency and higher operating costs.
Published right next to that unfortunate history was another boiler feed case study where the site and the shop involved took a set of 50-year-old boiler feed pumps and made them run better than when they were new. Unlike the first case history, they used Vespel® CR-6100.

The 50-Year-Old Pumps

The boiler feed pumps were originally installed in 1970 with 1.1MW electric motors. They are 8-stage BB5 pumps with 80 bar (1200 psi) differential pressure. Over many years of wear, erosion, and mechanical seal failures, the pumps needed to be overhauled.
The internal wear components were found to be running with clearance more than double the API design values for metal wear parts. The excessive clearance at the balance drum created high-velocity flow and erosion at the pump discharge cover. The seal design was outdated and the seal flush design was not correct. Some of the old pump components had very poor concentricity.

What They Did

The pump internals were repaired as needed. Obsolete parts were re-engineered and restored to good concentricity. The seal was updated and flush plan was corrected.
For the wear components, Vespel® CR-6100 wear rings, inter-stage rings, and balance drum bushing were installed with the patented Boulden PERF-Seal® design. Clearance at the wear components was reduced to approximately 50% of the API minimum values for metal parts. To save time and money in the shop, the existing metal wear components were re-machined and used as holders for the Vespel® CR-6100 components.

Results

Compared to the worn out condition, the pumps gained 15% efficiency after the overhaul. Depending on the local power price, this represents $100,000–$150,000 per year in lower operating costs.
Compared to the original design curve, the pump is 4% more efficient than when it was new, representing $30,000-$40,000 of lower operating costs. Maintaining this efficiency in the coming years will result in hundreds of thousands of dollars of savings.

Conclusion

If you are buying or overhauling a boiler feed water pump, specify Vespel®CR-6100 for all of the stationary wear parts (the rotating parts will remain metal). You’ll have a better pump that is easier to operate with a lower life cycle cost due to higher efficiency. If you have any pump where you are looking to increase efficiency, contact Boulden today. We can help you increase pump efficiency in most pumping services.
If you have an urgent repair and need a great material fast, we have a large inventory of material in stock and can supply raw material or machined parts with very short lead times. If you have dimensions, quantities, and basic service conditions, simply request a quote. We are here to help you.
Until next time, stay safe and healthy. And don’t use metal parts in your boiler feed water pumps.

A Look at Life Cycle Costs – Part 3: Unplanned Events

Typical Life-Cycle Cost For A Pump System Infographic

Typical Life-Cycle Cost For A Pump System

Today we take a final look at the above graph. We have already looked at Energy and Maintenance costs. Today we look at Operating, Environmental, and Downtime Costs.

When you upgrade pumps with composite materials like Vespel® CR-6100, Boulden B-Series, or Metcar® composites, you eliminate the metal-to-metal contact points in the pump, which essentially eliminates the risk of pump seizure. The pump is far more likely to survive running dry at start-up or during off-design events.

Benefits of Upgrading Pumps With Composite Materials

These are hidden bonuses to upgrading your pumps with composite materials. High quality composite materials act like a safety net in your pump, and sometimes, the savings from this benefit pay for all of the composite upgrades your company will ever do. Consider the following case studies:

Case Study: Condensate Return Pumps

Many years ago, a refinery upgraded the vertical pump shaft bearings in one of their 3 condensate return pumps to Vespel® CR-6100. The other two pumps had their original bronze bearings. The pumps were located in the hot well of a condensing steam turbine. The turbine was driving a critical compressor in one of the refinery process units.

Something happened which changed the pressure in the hot well and the pumps started operating in a vacuum intermittently for 9 hours. The two pumps with bronze bushings seized and had to be removed from service. The pump with Vespel® CR-6100 survived and allowed the process unit to continue operating. An upgrade which cost about $2000 likely saved the refinery millions.

Case Study: Potassium Carbonate Pumps

Plant operators heard a loud noise coming from a hot potassium carbonate pump. They were concerned because if potassium carbonate is released into the atmosphere, it creates a respiratory hazard. They shut down the pump and switched to the spare.

When the pump arrived in the shop, they found a piece of metal had broken from a valve and lodged in the pump impeller. Fortunately, during the previous repair, the maintenance shop had upgraded the pump to Vespel® CR-6100 case rings. During the incident, the pump did not seize, the seals didn’t leak, and a potentially major incident was likely avoided. A $3000 upgrade to the wear rings likely saved hundreds of thousands of dollars.

Case Study: Hydrocracker Charge Pump

Improved efficiency can also translate into increased production. A refinery upgraded their 9-stage hydrocracker charge pump, operating at 6400 rpm to Vespel® CR-6100 wear rings with reduced clearance. This $25,000 upgrade increased unit throughput by 4% creating millions of additional revenue for the refinery over the life of the installation.

Pump Impeller with Vespel CR-6100 wear rings

Conclusion

Upgrading your pumps to composite materials reduces pump life cycle costs by making your pumps safer, easier to operate, more reliable and more efficient. When unexpected events occur or where you can increase throughput, a single installation can save you millions of dollars.

Take a look at the pumps coming into your workshop. Use the repair as an opportunity to make the pump better by upgrading to composite wear parts. Boulden has the material you need in stock and can deliver raw material or machined parts with very short lead times. Get in touch with us today!

A Look at Pump Life Cycle Costs – Part 2: Energy Savings

 

Typical Life-Cycle Cost For A Pump System Infographic

Typical Life-Cycle Cost For A Pump System

Today we continue our look at the above graph. Last week we looked at maintenance costs. Today, we look at energy consumption.

When you upgrade pumps with composite materials like Vespel® CR-6100, Boulden B-Series, or Metcar® composites, you can reduce the energy consumption. Reducing the energy consumption of the pump creates continuous and long lasting savings.

Higher Pump Efficiency = Energy Savings

Composite materials reduce the operating cost of a pump through increased efficiency. Because composite materials do not seize, the clearance at the main wear parts – wear rings, throttle bushings, center bushings, balance drums–can be reduced. These parts separate areas of high pressure and low pressure within the pump and reducing the clearance reduces the internal recirculation across these parts.

The target for this upgrade should be the higher power pumps in the plant, as the payout tends to increase with pump power. Multi-stage horizontal pumps tend to offer the best return on investment because they produce high pressure and the recirculation across many internal components has a significant impact on pump efficiency.

Average Energy Savings Of A Pump Running Full Time

Over the years, many boiler feed pumps, charge pumps, and product shipping pumps have been upgraded to Vespel® CR-6100. It is typical for the efficiency gain from reducing clearance in these pumps to fall within the range of 3-5% compared to the “as new” condition of the pump. So, if you have a 1000 HP (750 kW) pump running full time, the energy savings will likely be in the range of $20,000 – $30,000 per year. If we assume an 8 year run at higher efficiency, savings will accumulate to around $200,000.

Conclusion – Using High-Quality Composite Materials Help With Energy Savings 

In short, using quality composite materials like Vespel® CR-6100 with reduced clearance in your high energy pumps will pay for itself quite easily on energy savings alone. Next month, we’ll discuss some special situations where you can save even more money.

Until then, whatever the temperature, chemical, or operating conditions for your pump, it is likely that Boulden has a non-seizing, non-galling composite material to help you improve your pump efficiency and reliability. Boulden has a large inventory of material in stock and we can supply raw material or finished parts with very short lead times. We can provide all of the technical support required for you to make the upgrade a success.

Contact us today and use your next repair as an opportunity to upgrade your pump.

A Look At Pump Life Cycle Costs – Part 1: Maintenance

Typical Life-Cycle Cost For A Pump System Infographic

Typical Life-Cycle Cost For A Pump System

Most of us have seen a graph similar to the one above. Over the life of an engineered pump, the energy consumption and maintenance will account for the majority of the life cycle cost. So, if you can make your pumps more efficient and more reliable, you will save a lot of money.
Over the years, we have collected several groups of data to suggest how much money you can save from using composite materials in your pumps like Vespel® CR-6100Boulden B-Series, or Metcar® composites. The savings come from two areas–improved reliability and efficiency.

Improved Pump Reliability = Maintenance Savings

Improving pump MTBR has been a primary focus of Rotating Equipment Engineers for decades. Longer life means fewer repairs, lower chance of downtime, and lower risk of environmental or safety incidents. There is no doubt that more reliable pumps save money. The question related to composite materials is how much of an MTBR improvement should be expected from the upgrade?
To answer that question, we have several data sets:
  • Between the years 2004–2006, a refinery upgraded 61 “bad actor” pumps to Vespel® CR-6100. In the 3 years prior to the upgrades, this group of pumps would result in 20-30 repairs. In the 3 years after the upgrades, this group of pumps averaged fewer than 10 repairs per year.
  • Another plant looked at 11 vertical pumps for 5 years before and 5 years after upgrading the shaft bearings and found repairs had been reduced by 64%.
  • Several other data sets have shown dramatic improvements in the overall plant MTBR when the site included Vespel® CR-6100 into their pump reliability improvement program.

Average Pump Repair Cost

We can use the study of 61 pumps to estimate the annual savings. The average repair cost of an API pump is about $12,000. Prior to upgrading to Vespel® CR-6100, this site had between 20 and 30 repairs per year–$240,000 to $360,000 annually to repair this group of pumps. After the upgrades, with fewer than 10 repairs per year annual repair costs were less than $100,000. That is a savings of around $200,000 every year. The upgrades to composite materials easily paid for themselves several times over.

Conclusion: Upgrade Pump Parts To Composite Materials

In short, using quality composite materials like Vespel® CR-6100 with reduced clearance in your pumps will lead to a big increase in pump life and significant maintenance savings. Next month, we’ll discuss energy savings.
Until then, whatever the temperature, chemical, or operating conditions for your pump, it is likely that Boulden has a non-seizing, non-galling composite material to help you improve your pump reliability. Boulden has a large inventory of material in stock and we can supply raw material or finished parts with very short lead times. We can provide all of the technical support required for you to make the upgrade a success.
Contact us today and use your next repair as an opportunity to upgrade your pump.

 

Mistakes to Avoid When Upgrading to Composite Pump Components

Upgrading your centrifugal pumps to composite wear parts is one of the easiest, fastest and most reliable ways to make your pumps better. While this upgrade is easy and reliable, there are a few pitfalls to avoid in order to ensure success.

The normal rule of thumb for upgrading to composite materials like Vespel® CR-6100 or Boulden B-Series is to reduce the clearance by 50% compared to API values for metal parts. This can increase pump efficiency and increase the Lomakin Effect in your pump, making the pump more reliable.

#1 Rotor Concentricity

However, reduced clearance requires that the pump be rebuilt to a good standard with a concentric rotor. Just because the Vespel® CR-6100 parts will not seize does not mean that the shop can do a sloppy job. The standard check used for metal parts–that the rotor must turn freely after assembly and coupling in the field still applies. Friction from rotor sag is acceptable, hard mechanical interference from poor alignment of internal parts is not.

#2 Clearance within Vertically Suspended Pumps

As mentioned in item #1, you can reduce the internal running clearance for wear rings. For vertically suspended pump shaft bushings, however, reducing the clearance doesn’t offer much benefit. There is generally no significant differential pressure across these parts. Therefore, reducing clearance at these parts will not increase pump efficiency or do much for rotor stability. If you reduce the clearance of these components too much, you will gain very little and make it very hard to keep the rotor concentric.

internal component parts

internal component parts

Download the Boulden Installation Guide and note the different tables for vertical and horizontal pump wear parts to avoid this issue

There are a lot of problems you can solve when you upgrade your pump to composite wear parts. You can help your pump survive dry running, avoid seizure, reduce cavitation, reduce vibration, help your seals last longer, and improve efficiency. In general, however, the composite materials used for wear parts are not the best choice for services that cause severe erosion of metal parts. The rule of thumb is that if standard metal parts do not show signs of abrasive erosion, you can consider composite materials.

vertically suspended pumps

vertically suspended pumps

#3 Expecting to Solve Abrasive Wear Problems

To put it in perspective, refined products, boiler feed water, chemicals, and utilities are a great place to use Vespel® CR-6100 and Boulden B-Series. For vertical pump shaft bearings in dirty service like wastewater and river water intake pumps, Boulden B-1050 is a good choice. If it is a true slurry service, composites are not the right choice.

Several times over the years skeptical customers have asked us: “We tried black plastic in our pumps 10 years ago. It didn’t work. What makes you think your material will be any different?”

#4 Using a Material with a High Coefficient of Thermal Expansion

Almost invariably, what we find is that the site had used a material with a high coefficient of thermal expansion. One of the reasons Vespel® CR-6100 has proven incredibly reliable is that the coefficient of thermal expansion (CTE) is about 60% lower than carbon steel. The earlier generation of composite materials on the market had CTE values around 3X higher than carbon steel. In practice, a high CTE will make problems in the pump worse–because the material will tend to “grow into” the rubbing or contact in the pump, reduce the clearance, and rapidly fail. Because Vespel® CR-6100 has a low CTE, it does not do this. It remains dimensionally stable until normal operation is resumed.

Boulden believes that CTE is so important, we developed our entire B-Series line of materials to have CTE values very close to or less than carbon steel.

In Conclusion

After 20 years and over 10,000 pumps upgraded with composite materials, problems have been few and far between. Using our experience in application and design, we want to be sure all of your upgrades are successful. We can supply raw material from our inventory, CAD drawings, and machined parts. Boulden has a huge inventory with the best lead times and service in the business. Contact us to upgrade your next pump today.

Today;s photo!

Yummy pie! Stay safe!

Yummy pie! Stay safe!

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