JUNE 2019 – PUMPS AND SYSTEMS
Condition monitoring helps manage over-lubrication.
Ultrasound is a guide to precision grease replenishment in motor bearings. It is also known for its versatility for leak detection, valve assessment and electrical fault detection.
Acoustic lubrication is an integral component of ultrasound programs. Fewer than 95 percent of all roller bearings reach their full engineered life span, and lubrication is the culprit in most cases. In fact, poor lubrication practices account for as much as 40 percent of all premature bearing failures. Yet, when ultrasound is used to assess lubrication needs and schedule grease replenishment intervals, that number drops below 10 percent. What would 30 percent fewer bearing related failures mean for an organization? Download our 5-STEP Acoustic Lubrication Procedure – An effective lubrication procedure to grease bearings right
To understand the role precision lubrication plays in bearing life extension, it helps to understand basics of bearings, their lubrication mechanism and how ultrasound helps.
The insides of a bearing consist of four components. The inner and outer raceways form a path for the rolling elements to glide on a thin film of lubricant. A metal cage separates the rolling elements, keeping them evenly spaced to distribute the load and stop them from crashing into one another. These components move in concert producing frictional forces from rotational inertia, surface load, misalignment, imbalance and defects. Zero friction is impossible, but optimal levels of friction are achievable with correct installation techniques and proper amounts of lubricant. Download our Induction Heating Procedure – Bearing Mounting – A simple and safe procedure for proper bearing installation
Ultrasound works on the FIT principle—it responds well to defects that produce friction, impacting and turbulence (FIT). For motor bearings, two of these phenomena apply: friction and impacting. Ultrasound detects high-frequency signals produced when two surfaces slide together or come in contact with any force. Stage 1 bearing failures happen at the micro level. Because ultrasound ignores low-frequency audible signals, it forms the perfect companion for measuring, trending and analyzing defects despite high levels of noisy interference encountered on the factory floor.
Ultrasound detectors detect friction and impacting as acoustic energy from rolling friction and defect impulses. When lubricant levels are optimum, the energy created is at its lowest. As frictional forces increase, so does the acoustic energy. Ultrasound instruments measure friction and impacting as energy using the scaled value dBµV (decibels/microvolt). The results are presented as condition indicators, and there are four of them:
- root mean square (RMS)—an indicator of friction
- maxRMS—an indicator of stability
- peak—an indicator of impacting
- crest factor—which surmises the relationship between friction and impacts
Condition indicators are most responsible for transforming ultrasound technology from a simplistic, “point the gun and pull the trigger” gadget, to being recognized as analysis and trending technology. Condition indicators add validity to trending by going beyond the single decibel. If a user currently uses an ultrasonic gun that does not have condition indicators, they should question the data. Click here to read the entire article “Use Ultrasound to Optimize Grease Replenishment”
by Diana Pereda
We’ve all read about it: leak detection should be a top priority since leaks can account for up to 30 to 40% of consumed volume… So, why is this issue still on the table? Why is it difficult to change things in the field?
In industry, one of the most common applications for ultrasonic detectors is to search for leaks to achieve greater energy savings. For both service providers and maintenance engineers, the hardest task is not so much to localize the leaks, which is child’s play if you have the appropriate tool, but to generate a report of the problems found, organize the required repairs and communicate the resulting savings to management and others within the company. A company-wide cost reduction program will be efficient only if all stakeholders are involved. When the implementation of an efficient program aiming at minimizing the energy costs related to compressed air fails, it is not due to technology, which almost never fails, but to human factors. All surveyed companies that had initiated a leak detection program that did not last over the long term had something in common: a lack of communication.
The successful implementation of an energy-saving strategy relies on good communication between all stakeholders, directly or indirectly. What you need to do is involve five different persons or groups, each having a very specific role to play in this campaign. The first person is the Ultrasound Inspector: he/she knows the network and where to find the losses. The second person is the Purchasing Officer: he/she buys the equipment required to manage the program and possibly negotiates power supplies. The third person is the Maintenance Planner: he/she will schedule the repairs to be done after inspection of the network. The fourth group is the Maintenance Supervisor and Technician(s) who will repair the defects that have been localized. The fifth person involved is the most important one: he/she is the Executive Sponsor whose role is to motivate and drive the project and communicate the savings achieved to all concerned. By highlighting these savings within the company, he/she will make the project come alive with visible and measurable results.
It’s easy to say, but in reality takes a lot of time and organization. However, since the advent of smartphones, tablets and other connected devices in the maintenance world, you can now use free assistance tools available as iOS/Android applications to measure leak-induced costs and document them with pictures. These applications can also be used to assist the various stakeholders and monitor the different steps to complete the implemented program (e.g., LEAKReporter, LeakSurvey). These tools are now able to automatically assess the costs of the defects detected over an entire year. Communication between all departments affected, directly or indirectly, by the program is now simple and natural.
In 2018, we worked with a company located in the North of Manchester, England, which, for many years, has used measuring instruments to detect leaks. However, no energy savings have been observed nor measured. As a result, the team was experiencing a loss of motivation and had given up on its cost reduction strategy. Thus, our customer’s request was simple: give a new life to their projects. The first steps consisted in clearly redefining everyone’s role. The second step was to train the team in the use of newly available tools: leak detector and mobile applications. The third step was to set up a “think tank” inviting all stakeholders to reflect on the best approach to adopt to manage and organize a leak detection campaign before, during and after our intervention (see diagram below). Finally, the fourth step was to celebrate our results with all the persons involved in the project. After two days on site, everyone precisely knew what was expected of him/her. 17 leaks were localized, representing potential yearly savings of 3,934 GBP (4,481 EUR or $5,111 US) and, after the quick repair of 7 leaks; actual savings of 1,648 GBP (1,877 EUR or $2,142 US) were quantified. As a result, the inspector has a better control of his/her network and of compressed air losses and actual needs; the purchasing officer can calculate the return on investment; the technician feels valued by the savings generated from his/her work; and finally, everyone is thankful to the sponsor for (re)establishing communication between the different departments.
Automatic savings sheet and automatic work order were generated by the SDT LEAKREPORTER mobile application.
Loss (£/year) = $249 US
We also share with you our LEAK MANAGEMENT: FIND-AND-FIX LEAKS PROCEDURE: An effective way to survey your systems and detect leaks.
Thank you Benoît Degraeve with SDT Ultrasound Solutions for sharing this case study with us!
by Diana Pereda
The SDT270 system was used to collect ultrasound data at a methane plant for start-up and commissioning of newly installed equipment to get a baseline condition on the motor’s and gear reducer’s bearings and gears. We were immediately able to pinpoint a defect in the drive end motor bearing using the SDT270 as well as collect and record a sound file (play below) and present it to the customer.
After removal and inspection of the motor bearing it was found that the motor had been stored in a basement and got water into it through the electrical conduit during a monsoon storm that flooded the facility in late summer, causing the bearings to rust and corrode. It was also found that the electrical disconnect box for the motor had water in it as well.
Pump: Progressive Cavity Seepex Pump
Motor: WEG 75HP 1775 RPM
Not only were we able to identify a bearing fault but also the “smoking gun” root cause, thereby thwarting further damage in the electrical system.
After troubleshooting the entire facility we were able to save several other motors stored in the basement that had also had water exposure through the electrical conduits.
Thank you Brian Franks with JetTech Mechanical LLC for sharing this success story with us!
by Ana Maria Delgado, CRL
As Published by Maintworld March 2018 issue
CRISTAL UNION (CU) is an agroprocessing cooperative company ranking among the top European sugar and alcohol producers.
Most of its facilities are established in France (18 sites). The BOURDON site in AULNAT (in the Puy-de-Dôme département) has a production capacity of 4,500 tons of beets per day.
The company contacted SDT Ultrasound Solutions regarding the implementation of a preventive maintenance program based on the collection and analysis of ultrasonic signals. This project dealt with about 400 rotating machines.
After purchasing an SDT270 ultrasonic data collector and its analysis software tool, SDT and CU have defined the outline of a training program suited to the monitoring of rotating machines. The first step consisted in creating a database containing all 300 machines and then, performing the first data collection in order to determine the initial mechanical condition of each bearing. After simple on-site analysis (ultrasonic listening) and more detailed analysis (overall or static measurements and spectral or dynamic measurements), 1 800 thresholds were defined (pre-alarm, alarm and danger).
Using these background data, technicians were then able to identify, at a glance, the machines having an alarm condition.
Click here to read the full article.
by Yolanda Lopez
While we’ve been using calendars and calculators to determine grease replenishment requirements in bearings for a long time, this science is wrong. Most bearings never reach their L10 engineered life, and poor lubrication practices are attributed as the primary failure cause.
Bearings fail when they are over-greased. We lubricate them too often, and we use too much grease.
Change Your Thinking.
We lubricate bearings to manage friction, but over time, grease gets old and needs replenishment. The first sign is when friction levels increase. Ultrasound performs well at sensing and measuring changing in friction levels. It’s the perfect technology to guide lube technicians during the lubrication-replenishment task.
We want to grease bearings correctly. That means using the right grease, at the right location, following the right procedures and intervals, injecting the right amount, and receiving the right feedback when the task is done. New technologies from SDT are engineered to do just that.
The days of relying on calendars and calculators are over. Use our 5-Step Acoustic Lubrication Procedure and start greasing bearings the right way!
Download our Ultrasound Lube Technician Handbook to learn more!
by Yolanda Lopez
- Prevent metal-to-metal contact (which creates wear particles) by using condition-based lubrication through ultrasound. Ensure the proper oil viscosity and additive package is selected and that the bearing load does not exceed its design capacity through proper installation, alignment, balancing and operation.
- Use desiccant breathers.
- Adopt an aggressive fluid management program that establishes acceptable ISO cleanliness targets for new oil by machine type. Take care to use methods of adding and sampling oil that minimize contamination ingress. These include quick connect couplers and point-of-use filtration. Install an oil recirculation system to remove particles as soon as they are created and introduced.
by Yolanda Lopez
Compressed air is the fourth most commonly used source of energy in industry. Walk through any facility and see miles of pipe transporting this house-made energy source to its point of use. On this journey its fate is undecided. Will it arrive to deliver the intended value? Or is it lost along the way?
Why Do We Tolerate Leaks?
On average, 40% of compressed air goes to satisfying the false demand of leaks. Why do we tolerate this waste in an otherwise efficient economy? Lots of reasons.
- Low Safety Risk?—Compressed air Leaks are rarely considered a risk. Odorless and colorless, they don’t make a mess on the floor, and we can’t hear them over plant noise.
- Lack of Education—Many believe compressed air is free. Yet a leak costs a thousand times more than lights that are left on.
- Complacency—The reliability culture does not always extend to the compressor room. Energy efficiency must be written into an organization’s aims and objectives.
Facts and Figures Don’t Lie.
Air is free. Compressed air is not. It requires another energy source to compress it. How much energy? Here’s the cost breakdown of a typical compressor system:
- 13% CAPEX
- 12% Maintenance
- 75% Energy
A small compressed air leak can cost $2,000+/year. Consider that hundreds of leaks may exist in your facility. What are you waiting for?
Manage your leaks with ultrasound. Their turbulent flow produces sounds that generate peaks in the 35kHz to 40kHz range—exactly where SDT’s ultrasound detectors are engineered to perform. SDT pinpoints leaks at their source, regardless of background noise.
Use our Airborne Ultrasound Leak Management: Find-and-Fix Leaks, and start reducing waste plus save money!
Download our Leak Surveyors Handbook to learn more!
by Yolanda Lopez
Are you adding grease to a bearing and not hearing any changes from your ultrasound equipment? If so, start wondering where the grease is going. It is a fact that if grease gets into a bearing the ultrasound decibel will either go down on a bearing that needs grease or go up on a bearing that is already over-lubricated.
Look for a blocked grease tube. Grease may be going into the windings on an electric motor. Do you see grease on the tube of the grease gun? Maybe a greaseable bearing was replaced with a sealed bearing at the motor shop after a repair. These are just some of the things you need to consider if you get no ultrasonic decibel change after injecting grease to a bearing.
Download 5-Step Acoustic Lubrication Procedure
by Yolanda Lopez
The diesel engine is the heart of heavy construction equipment and replacement costs are in the millions. Ingress of dust due to leaky air intake systems shreds components in short order. The SDT TIGHTChecker quickly and easily pinpoints leaks in the air intake system.
Dust is no friend to a diesel engine. But when the integrity of the air breather and turbo charger is compromised by leaks, microscopic grains of silica and other contaminants are sucked inside. There, they wreak havoc on the engine’s internal components costing organizations millions of dollars in premature wear and downtime.
Worse yet, you may not even realize you have dust ingress unless you are conducting regular oil analysis. These leaks are nearly impossible to ﬁnd using conventional methods. Visual inspection takes hours and is often unsuccessful. Production does not have the patience to wait. They need that asset back in the ﬁeld, leaks or not.
But what if there was a way to identify those leaks in minutes, instead of hours? SDT Ultrasound Solutions teamed up with mining giant Rio Tinto in Labrador, Newfoundland to devise a simple procedure for identifying turbo leaks in the engines of their huge loaders.
Using SDT ultrasound technology, a transmitter is placed inside the air ﬁlter basket. The high frequency sound waves are contained inside the piping unless there is a leak. Any microscopic air gap in the pipe is instantly recognized by the handheld flex ultrasound detector.
An 8 hour inspection that often ended in frustration is now a worldwide success story that continues to save Iron Ore Company of Canada $8 million per year.
by Yolanda Lopez
In some environments, reflected sounds can make it difficult to locate a leak. If you are in a confined area (a smaller room, or beneath/inside a machine), the leak can seem to be almost anywhere. A good ultrasound leak detection solution is to adjust the sensitivity downward. Ultrasonic sounds will reflect, but lose energy each time they reflect. By reducing sensitivity, the reflected sounds drop into the background, allowing you to locate the actual source of the leak.
Note that SDT inspection tools have separate adjustments for sensitivity and headphone volume, so you can manage sensitivity without affecting your ability to hear!
Download our Find-and-Fix Leaks with Airborne Ultrasound Infographic!
by Ana Maria Delgado, CRL
Question: When is it OK to over-lubricate your bearing?
Answer: NEVER!!!!, (almost) the exception is when high vibration exists.
If you attended the SDT/LUDECA Acoustic Lubrication Workshops then you now understand grease as a lubricating mechanism. You understand that the Churning Phase of the lubrication task is inevitable, and long-term, detrimental to the health of the grease. Therefore, we want to move as quickly as possible from the Churning Phase to the Bleeding Phase. This is the natural progression of precision lubrication.
Grease is not a robust grease mechanism. It is actually quite fragile compared to an oil only system. But we need grease as a lubricating mechanism in bearings because the properties of grease help to keep the lubrication in and around the warzone while sealing out contaminants.
Vibration is inherent in every machine system. Excessive vibration however, negatively impacts the ability of grease to lubricate. Some machine systems are intentionally vibrated as part of their function and process. Other equipment vibrated excessively because of a defect such as imbalance, misalignment, poor installation, or poor workmanship. For these machines, it might be best practices to over-grease their bearings.
I know that sounds counter to what we teach and know, but consider this. It is better to have thickener and oil in the warzone of the bearing, than it is to set up a bleeding mechanism and have the reservoir destroyed because of high vibration. If we let this happen we may never get any oil where it’s needed.
High vibration? Slightly over grease your bearing and allow a little thickener to exist in the warzone. It is the best compromise.
Download our 5-Step Acoustic Lubrication Procedure.
by Yolanda Lopez
There are 3 techniques that can facilitate your work in the field: the shielding technique, the covering technique and reflection management.
1. Shielding technique
This technique greatly reduces the influence of interfering leaks. It consists in using a piece of cardboard or foam(*)… to create a barrier between the “parasitic” leak noise and the location where you want to detect/locate a leak.
(*) Any material will work. It will reflect approximately 90% of the energy coming from the interfering leak.
Practical advice: the precision indicator tip placed on the internal or flexible sensor acts as a shield. This technique is very useful when leaks are very close to one another.
2. Covering technique
This technique also greatly reduces the influence of interfering leaks. It consists in:
Either covering an interfering leak with a rag or glove while you inspect an area.
Or covering the sensor with a rag or glove in the zone you want to inspect.
A leaking valve body can be conveniently covered with a cardboard carton too.
3. Reflection management
When searching for leaks, we sometimes get the impression that a leak is coming from a place where there is clearly no compressed air, such as a wall or a partition. This is due to the phenomenon of reflection. Ultrasounds from the leak are bouncing off the reflective surface. You will find the leak by following the angle of reflection. The angle of reflection is equal to the leak’s angle of origin relative to the reflection surface.
Download SDT Leak Surveyors Handbook to learn more!
by Yolanda Lopez
1. A Change in the Quantity of Grease Consumed
Maintenance departments track their grease consumption to monitor and control costs. A change in consumption is a sure sign that your lubrication program is on the right track.
Most organizations are guilty of over-lubricating. Expect lower grease consumption as your program matures. Bad procedures lead to bearings routinely receiving more grease than they’re designed to handle. The excess ends up being pushed into the motor casing or purged onto the floor.
Over lubrication happens when re-greasing intervals are scheduled based on time instead of condition. Control lubrication tasks with ultrasound to monitor condition and maintain optimal friction. The time between greasing intervals increases, resulting in less grease used per bearing.
2. Fewer Lube-Related Failures
Do you track failures and perform root cause analysis?
Organizations with optimized greasing programs experience fewer lube-related failures. Less fixing and fire-fighting translates to more creative time for maintenance. Use that time to bring more machines into the greasing program.
Additionally, with ultrasound you find many non-trendable defects. For example, broken or blocked grease pipes and incorrectly fitted grease paths prevent grease from reaching the bearing.
3. Optimized MRO Spares Management
Your new and improved lubrication program is delivering wins; better control of grease consumption, fewer failures, and more productivity for maintenance. Use this time to study trends and better manage your storeroom.
A decrease in bearing related failures improves spares optimization. Share your ultrasonic lubrication data with your MRO Stores manager to create a plan to reduce the number of emergency parts on hand.
Since you’re taking stock, why not shift some burden to your suppliers? Ask them to confirm your emergency parts against their own stock. If it can be supplied on the same day then it doesn’t need to be on the balance sheet.
4. Increased Number of Machines Monitored
One benefit of an effective lubrication program is time.
• Time allotted to monitoring machines instead of fixing them.
• Time allotted to correctly assessing the real needs for lubrication.
• Time to look at the big picture.
Take for instance, criticality assessment. Many lubrication programs begin with small steps. All the “A” critical machines receive priority, rightly so. But what about the rest? With more time to plan, organize, and schedule, the number of machines acoustically monitored for optimal lubrication increases.
5. Save Time. Combine Acoustic Lubrication and Condition Monitoring
You worked hard for these results. It’s time to use your data for more than just lubrication.
Acoustic lubrication is the proven method to ensure precise bearing lubrication. New technology from SDT, LUBExpert, combines the power of on-board lubrication guidance with Four Condition Indicators for bearing condition assessment.
The time savings from assessing bearing condition during the lubrication process is beyond valuable and another sign your acoustic lubrication program is on the right track.
6. Inspector Confidence at an All-Time High
Reliable machines are the product of an effective lubrication program. You have:
• Managed grease consumption
• Fewer grease related bearing failures
• Optimized MRO spares
• More machines under watch
• Increased data collection intervals
The power of adding ultrasound to your greasing program delivers win after win for reliability. Reliability breeds confidence. More confident inspectors making the right calls and infecting a positive culture throughout the organization.
by Allan Rienstra - SDT Ultrasound Solutions
Plant Engineering, celebrating its 30th anniversary of the Product of the Year award program, announced the results for the 2017 entrants. SDT’s innovative LUBExpert, an ultrasound solution designed to help grease bearings right, was awarded the GOLD medal! The award is remarkable considering the excellent company of peers in the running for Silver and Bronze.
Alex Nino of LUDECA, was on hand at the award ceremony, and looked marvelous! LUDECA is the exclusive distribution partner for SDT Ultrasound Solutions in the USA and were instrumental in architecting this recognition. Chosen from numerous submissions from around the world, Plant Engineering subscribers reviewed and voted on the finalists. LUBExpert received the most votes for this 30th anniversary Grand Award. Congratulations to LUDECA, SDT, and LUBExpert for the GOLD.
Poor greasing practices is a leading cause of bearing failure. LUBExpert is an ultrasound solution designed to precisely guide lube-techs during the lubrication replenishment process. It helps avoid over and under lubrication, while instructing the technician on which grease types, grease guns, grease quantities, and replenishment intervals to use. LUBExpert’s intelligence lends confidence to the task of grease replenishment and is a true innovation for ultrasound technology.
Winning GOLD validates our decision to work with industry leaders such as SDT,” states Ana Maria Delgado, Marketing Manager at LUDECA. “The LUBExpert compliments our full line of predictive and proactive solutions. Its clever innovation supports the leadership position of all our solutions.”
LUDECA is the premier provider of reliability solutions to USA industry. Their years of experience and wealth of knowledge make it possible to offer the very best service and support to their customers. Their commitment here strengthens their reputation as the very best in our fields. SDT is delighted to be aligned with LUDECA. Our companies share the same principles, philosophies, and values.
SDT provides ultrasound solutions that help our customers gain a better understanding about the health of their factory. We help them anticipate failures, control energy costs, and improve product quality while contributing to the overall reliability of their assets.
by Allan Rienstra - SDT Ultrasound Solutions
1. Collect the best data you can, using a high quality ultrasonic data collector.
2. Consistent sensor placement must fundamentally be observed.
3. Identifying boundaries that impact data transmission is imperative.
Ultrasound is Shy… It Keeps Boundaries
Think of ultrasound as the quiet introvert. It prefers to stay in, and rarely mixes well with ultrasounds from other places. We call this “boundary behavior” and it’s another characteristic that makes ultrasound such an attractive condition monitoring technology. Ultrasound signals remain isolated to their source, making it easy to pinpoint defects without interference from other elements of the machine.
Inspectors tempted to place their ultrasound sensor directly on the gearbox cover, should reconsider. This common mistake affects data integrity. A gasket seals the cover plate to the gearbox housing. The specific acoustic impedance of the gasket material differs greatly from the cast metal of the gearbox. The change in materials a boundary barrier through which bashful ultrasound is reluctant to is pass. A better option is to place the sensor on a bolt head, which is directly connected to the gearbox housing. The result is crystal clear ultrasound signals for listening, trending, and condition assessment. HearMore: Click here to listen to Damaged Gearbox.
Special thanks to our partner Allan Rienstra from SDT Ultrasound Solutions for sharing his great knowledge with us!
by Allan Rienstra - SDT Ultrasound Solutions
Why We Ignore Leaks
Compressed air is a misunderstood utility. As such, it tends to be misused and even abused. Leaks continue to be the biggest problem; often overlooked because they are difficult to detect, don’t smell bad, don’t make a mess on the floor, and rarely stop production.
The Real Cost of Leaks
One of your factory’s highest operating expenses is the energy consumed by your compressed air system. Only 25% of the cost of a compressed air system is capital cost and maintenance. The remaining 75% is energy, and as much as 35% of that energy is wasted satisfying leaks.
Compressed air leaks create fluctuations in system pressure, which negatively impacts product quality. Compressors work overtime to compensate, leading to early degradation of the asset. Eventually, the compressor system can’t keep up with demand. What can you do? Buy yet another compressor for more capacity? Or optimize the capacity you already have by finding and fixing leaks?
With so much at stake, why are compressed air leaks managed so poorly, and why doesn’t every organization have an air leak management program?
Where to Look for Leaks
Every component has the potential to leak, but we can hasten our search by focusing on common failure points. Usual problem areas are branch line connections, automatic drain traps, desiccant filters, regulators, coalescent filter assemblies, quick couplers, valves, hoses, fittings, pneumatic cylinders and thread sealants. Most leaks occur at points of use, so begin your search there.
How to Find Leaks
Locating air leaks in a loud factory floor is next to impossible with a human ear. The best, and easiest, way to find air leaks is with an ultrasound leak detector. Ultrasound detectors allow you to hear the minute hissing noise produced by leaks, despite the roaring noise of a production area. Ultrasound detectors are portable, easy to use and require little training to get started.
How to Manage Leaks
It’s not enough to just find leaks. Fixing and documenting savings is a necessary part of the program. One way to justify the labor costs and capital expense is to track them with SDT’s LEAKReporter, a mobile smartphone App available for iOS and Android. LEAKReporter is focused, simple and free. It saves inspectors time and money by documenting leaks in pictures, estimating their cost impact and creating fast comprehensive leak reports.
Being competitive has never been more important than it is today. Energy costs directly impact your bottom line. There is no easier way to reduce energy waste than to tackle the “low hanging fruit” in your compressed air system.
by Tristan Rienstra
Using ultrasound to locate compressed gas leaks is relatively easy, but it occasionally it can present some challenges. The reason ultrasound is so successful is that it is a high frequency, short wavelength signal that does not like to penetrate 2nd mediums. While performing compressed gas leak inspections, keep in mind that strong ultrasonic signals can bounce off most materials leading to false indications.
To overcome this challenge, turn your ultrasonic detector 180° and see if the signal is stronger coming from that direction.
Download Find-and-Fix Leaks Procedure
by Paul Klimuc CRL - SDT Ultrasound Solutions
Simon is a condition monitoring specialist from a local oil refinery. He contacted my office for advice about predicting flexible coupling failures. Currently, they perform basic vibration analysis on their pumps and motors using an overall meter. They have some success predicting bearing failures but the same cannot be said for couplings. Several unexpected failures shut them down this year.
Within the facility they identified 58 pump systems considered “A Critical”, meaning if they go down, the plant goes down. I suggested ultrasound as a fast, safe, and affordable solution. Specifically, the SDT270DU offered him best value. Not only could Simon use it to monitor couplings with ultrasound; it also takes vibration measurements, thus eliminating the need for Simon to carry two data collectors.
By placing an airborne sensor near to the coupling Simon can quickly trend an evolving defect. The SDT270DU gives Simon the choice to either spot check for defects – good – or integrate all 58 couplings into his established bearing routes – best.
I explained to Simon how several clients already trend couplings using the Flexible Wand. The SDT270 collects a STATIC ultrasound measurement that gives four indicators of condition. The first two – Overall RMS and Max RMS – indicate the level of friction produced by the defect. When these indicators rise, maintenance may consider corrective alignment during a planned shutdown. The second two – Peak and Crest Factor – identify the emergence of impacting. Together, all four indicators establish a life cycle trend for each coupling.
Once impacting appears, the Peak indicator increases in step with Overall RMS. Crest Factor (CF) is a comparative ratio between Overall RMS and Peak. As CF trends higher it warns that the window for simple maintenance has narrowed. Inspectors may choose to collect a DYNAMIC measurement when CF alarms are triggered. The DYNAMIC measurement provides a visual representation of friction and impacting severity. For both STATIC and DYNAMIC measurements it’s important to define the signal acquisition time.
User defined signal acquisition time, available exclusively on SDT instruments, is a luxury that lends ultrasound technicians the highest level of precision. Without the ability to set the sample time, inspectors must guess when to pull the measurement trigger, and question the validity of their data. Simon explained that all 58 pumps turn at speeds above 1800 RPM. Accordingly, he should set his SDT270’s signal acquisition time to between one and three seconds. One to three seconds at 1800 RPM samples the coupling for 30-90 revolutions.
Shaft couplings are guarded for safety. Any ultrasound inspector working around rotating equipment must be required to demonstrate an understanding of company safety policies. Safety considerations are engineered into SDT sensors. The Flexible Wand’s 10mm diameter sensor is designed to access the coupling with the safety guard in place (see figure 2). The 21” long sensor sports a comfortable, ergonomic grip that allows an inspector to collect danger-free data.
Simon seemed convinced but wanted to Hear More. Since this solution was already working well at a nearby paper mill, I introduced Simon to the plant manager, Sunil, and invited them both to lunch. Sunil and Simon connected on so many common reliability issues that afternoon. He confirmed the affordability of this solution based on coupling failures alone but went on to explain how their mill was rolling out ultrasound for acoustic lubrication, steam trap monitoring, electrical inspection, and air leak management. Simon and Sunil continued their conversation well into the afternoon. They agreed that ultrasound, with its 8 primary applications for reliability, represented a fast, safe, and affordable technology with the potential to revolutionize reliability culture. I sat back, happily watching two impassioned specialists strategize about reliability culture. I love my job!
by Allan Rienstra - SDT Ultrasound Solutions
Condition Monitoring Expert Tip #5 by Mobius Institute
Now this is a tricky question to answer… We have a few contenders: high frequency vibration analysis, regular vibration analysis, ultrasound, oil analysis, wear particle analysis, and infrared analysis. Let’s start by ruling a few of them out.
Infrared analysis is used to detect heat in a bearing, which is a late stage fault condition, so that’s not your best option. Regular oil analysis can detect the presence of the wear metals within the bearing, but wear particle analysis is a better tool for that. Regular vibration analysis (i.e. velocity spectra) provide very clear indications of bearing faults, however the high-frequency detection techniques provide an earlier warning. That leaves high-frequency vibration analysis, ultrasound, and wear particle analysis.
Ultrasound is easiest to use. Push the probe against the bearing and listen carefully and you will hear if the bearing is in distress. (You can also record and analyze a waveform, but now you may as well be performing vibration analysis). Many would argue that high-frequency vibration analysis (such as enveloping, PeakVue, shock pulse, and others) provide a clearer indication of the nature and the severity of the fault. But it does require more training and potentially a more expensive system to perform the collection and analysis.
And that leaves wear particle analysis. Let’s just say that if you own critical gearboxes, you absolutely must perform wear particle analysis. Performed correctly, you will detect the first signs of wear, and complex gearboxes provide a greater challenge for the vibration analyst and the ultrasound tools.
Although I haven’t really answered the question, I am hoping to have put you in a position to make the right decision for your situation.
Thank you Mobius Institute for this valuable tip!
by Yolanda Lopez
Condition Monitoring Expert Tip #4 by Mobius Institute
This tip is sponsored by IMVAC (International Machine Vibration Analysis Conference)
There is no doubt that technologies such as vibration analysis, oil analysis, ultrasound and infrared are very powerful. They can tell you a great deal about fault conditions in rotating machinery, electrical systems, and more. But if the criticality warrants it, you will be in a much stronger position if you have multiple technologies indicating that a fault condition exists rather than relying on just one.
For example, if vibration analysis indicates there is a problem in a gearbox, oil analysis can confirm the fault with the presence of wear particles. In the case of vibration analysis, you can utilize high frequency analysis, spectrum analysis, time waveform analysis, and phase analysis to enable you to validate your diagnosis.
There can be a great deal at stake when you make a diagnostic call on a piece of equipment. More so if it is critical equipment. At the very least, a false diagnosis may lead to equipment failure (if you miss the fault condition) or it can lead to unnecessary work and downtime. What’s more, your reputation is at stake. Sadly, people often forget when you make the right call, but it can take years for people to forget when you make the wrong call.
Thanks Mobius Institute for sharing such valuable information with us!
by Ana Maria Delgado, CRL