Tag Archives: Vespel 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 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.

 

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

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.

7 Rules for Using Vespel® CR-6100

Follow these rules and you’ll be on the road to better pump reliability

A Fresh Look

We just completed our series on upgrading pumps with DuPont™ Vespel® CR-6100, getting into details on how to upgrade various horizontal and vertical pump types. We discussed reducing the clearance of the wear rings, upgrading throttle bushings with the PERF-Seal design, and upgrading vertically suspended pump shaft bearings.

Today, let’s try to condense it all down into a short list of guidelines which we can apply to just about any pump. Follow these rules and we can ensure we are using Vespel® CR-6100 properly and improving our pump reliability.

7 Rules for Using DuPont™ Vespel® CR-6100 

  • Stay under the temperature limit of 500 F (260 C)
  • Only stationary parts, mounted in compression
  • Shoulder on the low pressure side to retain the part against differential pressure
  • Avoid extremely abrasive services such as slurries, bottoms, or slops
  • Press fit, clearance, and axial length of part from the Boulden Installation Guide
  • Pump rotor must turn freely when the pump is assembled and ready for commissioning
  • Use PERF-Seal™ design for throttle and center bushings of multi-stage pumps

What do you think?

Did we miss anything? Contact us to let us know your ideas.

Until next time, if you have an application you would like to discuss, contact Boulden. If you need material, we have a huge inventory of standard stock sizes available for immediate shipment.

For details on how to install Vespel® CR-6100 into nearly any pump type, download the Boulden Installation Guide.

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Borobodur, Indonesia

Borobodur, Indonesia

Useful Links for using DuPont™ Vespel® CR-6100

Tools to help you improve your pump operability, reliability, and efficiency

Our favorite material recently passed a milestone. The first pump ever fitted with Vespel® CR-6100 was upgraded 20+ years ago in November 1997.

The first pump was a vertically suspended condensate pump at a refinery in California. The pump was notorious for running dry, and it had failed once or twice per year for as long as the maintenance records went back. An engineer at the refinery “found” Vespel® CR-6100 and decided to put it to the test on the condensate pump. The pump survived repeated episodes of running dry and subsequently ran for many years without failure.

Since then, over 10,000 pumps across the globe have been upgraded with Vespel® CR-6100.

Useful Links
When you are using Vespel® CR-6100 in your shop, or if you are recommending your favorite repair shop to perform the upgrade for you, the following links should prove helpful:

Standard Stock Sizes of Vespel® CR-6100

Boulden Installation Guide for Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

3MW Boiler Feed Pump Case Study

If you have any questions please contact us, or if you already know what you need? Request a quote today.

Today’s Photo

Proboscis Monkeys, Borneo

Proboscis Monkeys, Borneo

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

 

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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