Category Archives: Pump efficiency

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.

 

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)