Tagged: condition monitoring

Measuring the Success of an Oil Analysis Program

In a world where budgets rule the day and any additional program is shut down if merit cannot be found in it, being able to prove the success of your oil analysis program is critical. But how does one go about proving that the implementation of a program has stopped or reduced failures when there isn’t a big incident to compare it against? Simple, we start in the past to get to where we need to be in the future.

Documentation is always critical especially when we’re trying to build a case to implement some new measures. If previous failures have been documented, then the associated downtime and expenses such as additional labour, parts or expedited shipping and handling should also be taken account of. By detailing the costs associated with a failure or unplanned downtime from a lubrication issue, we can use this data to help determine the ROI of implementing the oil analysis program.

We need to then identify the times that the oil analysis program alerted the maintenance team about an upcoming issue or something that didn’t seem right which turned out to be a failing part or perhaps something that would cause some unplanned downtime. In these cases, we need to note what challenge we stopped or reduced the risk of occurring. By assigning a value to the failure that we prevented, we can then develop the ROI on the implementation of the oil analysis program.

Oil analysis can be a game changer for our maintenance teams in our fleets. It can help them to make more informed decisions allowing them to plan maintenance activities better and even reduce unwanted downtime. Oil analysis can be that hidden tool in our utility belt if we make use of it and implement it to help our fleets.

 

References

Bureau Veritas. (2020). The Basics of Oil Analysis Booklet. Retrieved from Bureau Veritas: https://oil-testing.com/wp-content/uploads/2020/08/Basics-of-Oil-Analysis-Booklet-2020V_compressed-1.pdf

Rensselar, J. V. (2016, January). Unraveling the mystery of oil analysis flagging limits. STLE TLT magazine.

Implementing Oil Analysis for a mixed fleet

Now that we understand the value that oil analysis can bring, we need to be able to implement it, especially in mixed fleets. It is critical to clearly define the objectives of this program to ensure that we can monitor the value that oil analysis brings to our operations.

Ideally, the main objective of this program is to be able to monitor the health of the assets and prevent or reduce the possibility of a major failure or unplanned downtime. While it would be great to monitor the health of all the assets, this may not be entirely necessary.

Assets can be broken down into three main categories: critical, semi-critical and non-critical. The critical assets are the pieces of equipment which if they fail, can negatively impact the business. Semi-critical assets are those which if they fail, may have some impact on the business while non-critical assets are those whose failure do not impact on the business.

Depending on the nature of the business or the operations / projects which are ongoing at any point in time, your critical assets can switch in terms of priority to become semi-critical or a non-critical asset. For instance, if there was a job which required the use of a crane, then this would be our critical asset. However, if there was a job which did not require the use of a crane, then this asset becomes non-critical.

If we were dealing with the manufacturing industry where there are stationary pieces of equipment and a standard procedure, then the criticality of assets will not change as compared to a mixed fleet operation where contractors may have different jobs and require varying pieces of equipment.

Now that we’ve identified the critical assets / pieces of equipment, the sampling frequency must be determined. For critical assets, these may require some specialty tests as we want to ensure that we are alerted at the earliest possible time about an impending failure.

(Bureau Veritas, 2020) provides some guidelines for oil sampling as per figure 4 below. However, the OEM guidelines should be adhered to once they exist. Even though the sampling intervals state 250 or 500 hours, these must be in accordance with the OEMs guidelines regarding maintenance as well.

Figure 5. Guidelines for sampling as per Bureau Veritas, 2020
Figure 5. Guidelines for sampling as per Bureau Veritas, 2020

Typically, some OEMs may require an oil change at around 500 or 1000 hours (depending on the unit). If we only take the oil sample at the end of the life of the oil, then we are monitoring and trending how the oil ages at this point in time. However, if we’re trying to extend the oil drain interval of a component, then we would need to develop shorter intervals to monitor how the health of the oil is progressing and if it can indeed last for a longer time. If we’re attempting to extend the oil drain interval, then this should be done at increments of about a quarter of the usual interval.

How to read an Oil Analysis report

While oil analysis can help our teams identify more information about the condition of the oil, we still need to ensure that they can read the oil analysis report and put measures in place to deal with the issues which may arise. In the example below, we will look through a typical diesel engine report as provided by ALS Tribology lab featured in STLE’s TLT magazine as shown in Figure 1.

Figure 1. First page of Diesel Engine oil report adapted from Rensselar, 2016
Figure 1. First page of Diesel Engine oil report adapted from Rensselar, 2016

Most labs try to make it very easy for the report readers to assess the health of the oil, at a first glance. They usually implement a traffic light system where the status of the oil is highlighted. In this case, this oil has a normal rating indicating that the oil is still in good health and there isn’t anything to be concerned about yet as shown in Figure 2.

However, one of the main premises of oil analysis is the ability to spot trends over time and from this report, we can see that the oil may not have always been in a good condition as shown in figure 3. Each column represents an oil sample from a different date, so at a quick glance we can see that for two of the results, the oil was not in a good state whereas for the other results they remained in the normal region.

Figure 3: Changing condition of the oil
Figure 3: Changing condition of the oil
Figure 2: Current condition of the oil
Figure 2: Current condition of the oil

One question that often gets asked is, “What is the normal region?”. Most oil analysis labs have collected data from OEMs which explicitly state the alarm limits for their pieces of equipment. As such, for each component, a lab should have matching data for alarm limits for the oil in that component. If none exists, then the lab may use a general industry guideline for these limits.

Therefore, if the actual value of the oil either exceeds or is below the limit, then this value will be flagged and the user notified. As seen in the report, there are basic sections into which these values are broken up, namely; metals, contaminants, additives and physical tests. Depending on the OEM, there will be different limits for these values.

However, our teams need to be able to identify what the presence or absence of the elements mean for different components.(Bureau Veritas, 2020) compiled a listing to help report readers understand this better as seen below.

fig4-et
fig5-et
fig6-et
Figure 4. Identify what the presence or absence of the elements mean for different components (Bureau Veritas, 2020)
Figure 4. Identify what the presence or absence of the elements mean for different components (Bureau Veritas, 2020)

Armed with this information, our teams can make more informed decisions. If they start seeing the quantity of Chromium increasing in their engines then this could be a sign of wear on the Liners and rings, shafts, valve train, bearings, shafts and gears, seals. Therefore, some investigations can begin on these components and possible wear can be addressed before the component gets damaged to the point that it can no longer function. Similarly, if they notice particular additives decrease over time such as zinc, then this could indicate that the antiwear additive is being depleted at a faster rate. These tables can guide report readers on what is actually occurring in their oils allowing them to properly plan for maintenance activities.

What is Oil Analysis?

When we think about the various tools available to our maintenance team, we often think about physical tools such as a screwdriver, wrench or possibly even a hammer (if used in the right circumstances!). However, we don’t think about some of the methods we could employ which can make our maintenance teams more efficient or our equipment more reliable.

One such method is oil analysis and while it may not be at the forefront of our minds when thinking about increasing the reliability of the fleet, its impacts can be very significant once utilized properly. In this article, we will talk about the implementation of oil analysis for a mixed fleet of equipment, the impact of this program and the ways that the success of this method can be measured.

What Is Oil Analysis?

If you’ve ever drained the oil from the sump of a diesel engine, then you would know that it’s a messy process. Typically, when this oil is drained, the mechanic can tell you a few things about what happened on the inside of the engine without going to a lab.

For instance, some mechanics may place a magnet in a sealed bag and drop this into the drained oil. When they remove the bag, if there are metal filings stuck to the outside of the bag with the magnet, then that means there is some significant wear occurring on the inside of the engine. Similarly, if there is a tinge of a rainbow colour on the surface of the drained oil, that could mean that fuel is getting into the oil system and there may be an issue with one of the fuel injectors.

While these methods may not be able to precisely tell us how much fuel or wear (or what type of wear metal was present), they do provide some indications of what’s happening on the inside of the equipment. This is where oil analysis can be the game changer for our mechanics and our teams leading the reliability initiative.

With oil analysis, we can accurately and quantitatively trend the presence or absence of certain characteristics of the oil and what it contains. In this instance, we are able to correctly identify the wear metals present in the oil and trend whether these values increase or decrease over time. This can help our mechanics to figure out exactly where the wear is coming from as they would be able to identify the parts of the engine which are associated with the increase in the particular wear metal from the report.

Additionally, they can become more aware of other important parameters such as viscosity or TBN (Total Base Number) which they would not have been able to quantify without oil analysis. They can also get information on the decreases in additives or increases in contaminants which can allow them to identify or troubleshoot these issues in advance.

Is Oil analysis still relevant today?

With the many advancements in Artificial Intelligence, Machine Learning and the advent of countless different sensors on the market, the question arises, “Is Oil Analysis still relevant today?”. Granted that these advancements have significantly transformed the industry, we need to recognize that they are here to help evolve what we already do and not necessary replace it.

These advancements build upon the foundations of the techniques of oil analysis. With artificial intelligence and machine learning, we can train models to interpret oil analysis data and trigger alerts accordingly but there should always be a human present to overview these. In the real world, not every situation has occurred or been recorded yet hence the models do not have that particular data to learn from nor can they make decisions about it since it simply doesn’t exist in their “brain”.

Humans can “think outside the box” and formulate patterns or trends which may not be triggered by the models simply because these models have not been taught these patterns. Hence it is important to always have a human in the loop and not rely solely on these models especially when million-dollar decisions can be negatively initiated with the wrong interpretations.

Lately, sensors have gained more traction and a wider adoption as they can be integrated into warning systems to alert users to potential deviation from known characteristics of the oil. However, as noted above, sensors rely on data sets to compare the information and on some form of capacitance which must be converted into a signal before it can be interpreted.

With lab equipment performing the actual tests, there is a higher rate of accuracy plus the added advantage of having humans review the results for discrepancies before sending off the report. While sensors can be the first warning system for some users, lab equipment should be utilized for those more precise tests which require a higher level of accuracy.

In essence, oil analysis remains very relevant today. However, it has significantly evolved over the last few decades. Today, oil analysis can achieve a higher efficiency level with the integration of the advancements in technology (AI, machine learning and sensors) and other available monitoring technologies. Together, these should all be used to create a greater impact on improving the reliability of the machines.

 

Find the full article here on Engineering Maintenance Solutions Magazine.

Oil analysis vs Other technologies

Just as oil analysis is similar to blood testing, we can think of our bodies as a critical machine with various components which need to be monitored. If we get a fractured bone, a blood test will not help us to assess if the bone is broken or can be repaired. In this case, we may need an x-ray. Similarly, with machines, there are various types of tests to determine different aspects to be monitored.

Typically, oil analysis can provide the operator with insight into whether there has been any internal damage to the equipment in the form of wear particles which can be quantified. As with most condition monitoring methods, being able to trend the patterns over time helps the operators to identify if wear is occurring at an increased rate or whether the oil is degrading.

On the other hand, other technologies such as vibration analysis or ultrasound analysis or even thermography are not able to detect the presence of molecules. These other types of analyses focus on alignment, or other mechanical issues as they occur and can trend them over time. However, oil analysis can accurately detect the presence or absence of contaminants or additive packages which could affect the health of the oil and by extension that of the machine.

Oil analysis should not be used as the only technology in your condition monitoring artillery. Other technologies can be used alongside oil analysis to provide the user with a more comprehensive overview of the health of the asset. For instance, if the oil analysis discovered high wear, the next step would be to identify where the wear was coming from. Perhaps in this case, one of the other technologies could identify a misalignment or other mechanical issue which could be the source of this wear. Thus, these technologies should be used to work together to achieve better reliability for their asset owners.

Find the full article here on Engineering Maintenance Solutions Magazine.

Why oil analysis?

The P-F curve is one that is used throughout reliability to demonstrate the point at which a component is expected to have a functional failure. There are many variations of the PF curve, and different monitoring technologies can be placed in specific orders accordingly. However, it remains dominant that oil analysis is among the top three techniques used for early detection of failure.

Oil analysis can be used to detect the presence of contaminants, metals and other molecules at a microscopic level and quantify these appropriately. Most OEMs (Original Equipment Manufacturers) publish their acceptable standards for various tests (usually standardized tests by some accredited body such as ASTM) and have these available to laboratories around the world. When an oil analysis test is performed (as per the stipulated standards), the lab will compare the actual values to the expected values (from the OEM) and then provide some guidance to the user on possible steps forward.

Every lab will have a specific format for reporting the results of your oil analysis (similar to the labs for reporting on blood samples). Typically, the actual value is shown and then there may be an expected range for the various characteristics or just an indication of whether the actual value falls outside of the range (on the higher or lower end of the scale).

Bureau Veritas, 2017, gives an example of a report and all of the variables involved here:

BV_Understanding-An-Oil-Analysis-Report_FINAL_11_8_2017

 

While this is their reporting standard, other labs will have a different format, but the tests will all conform to the same internationally recognized standard. As such, if oil is tested in the United States (as per a particular standard) and then tested in Italy (as per the same standard) then there can be some comparisons of these results. However, one must also be aware of the types of instruments being used and their calibration as this can account for slight differences in test results.  As such, oil analysis provides a global standard for which equipment performance can be compared across regions.

Find the full article here on Engineering Maintenance Solutions Magazine.

What is oil analysis?

For those not familiar with oil analysis, it can be likened to performing blood tests for the human body. Oil in our machines is often compared to the blood in our bodies. Blood circulates throughout the body taking important blood cells with food and oxygen in it to the various organs, similarly oils follow this behaviour. However, oils transport additives which provide varying functions including reducing wear or friction or even preventing corrosion or oxidation to name a few.

When performing a blood test, we can test for a few things; the overall condition of the organs or we can test for specific things such as the presence of bad cholesterol. With oils, we do a very similar practice where we can test for the overall health of the machine or pinpoint exact components and look for distinct changes which are reflected in the characteristics of the oil.

Basically, oil analysis can help you to determine the condition of your oil (if it is degrading or if the additives have depleted such that it no longer protects the equipment) and the health of your asset as the oil can reflect if there is wear occurring in the components. As such, it can provide very useful information to help operators and maintenance personnel to plan effectively for any type of maintenance to be done on the components.

 

Find the full article here on Engineering Maintenance Solutions Magazine.

Can Lube Oil Varnish be Eliminated? 

Varnish can be likened to cholesterol in the human body. It can build up in our arteries and eventually clog those, causing restrictions in blood flow to our heart which may lead to a heart attack.

Humans cannot simply change their blood to remove the cholesterol build-up. However, cholesterol is controlled through proper diet, exercise, and with some condition monitoring in the form of blood tests to help gauge the presence of it in the bloodstream. Similarly, a couple of approaches can be used to reduce the varnish build-up or eliminate it.

As per Livingstone et al. (2011), the lifecycle of varnish is critical. Particular attention should be paid to the double arrows between the stages of Solubility to Varnish formation in the figure below.

This means that even after varnish has been deposited, it can be solubilized back into the oil. This can only occur if conditions are met per Hansen’s Solubility principles where the solvent and degradation products meet using the three parameters of Polarity, Hydrogen Bonding, and Dispersive Forces as discussed in “The Hansen Solubility Principles and Its Relation to Varnish” (2022).

mechanisms-oil-varnish-formation

The Varnish Lifecycle as per Livingstone et al. (2011)

Varnish exists in various forms and can consist of differing compositions. Hence, it is essential to understand the characteristics of the varnish being formed in a system before attempting to eliminate it.

There are certain technologies, such as solubility enhancers or specifically engineered filtration media, which can be effective at removing lube oil varnish. However, this technology is heavily reliant on the type of varnish being formed and can be customized as per the system accordingly.

Solubility enhancers can solubilize the varnish back into the oil solution. When these deposits are reintroduced into the oil, they can be removed using resin-based filtration. In this method, the media is specifically designed to allow for the adsorption and removal of the varnish which presently exists in the oil.

When these methods are used together, they can prove quite effective and prevent manufacturing plants from experiencing unwanted downtime.

To summarize, it is of utmost importance to first understand the characteristics of the varnish being produced in your equipment before attempting to remove it from your system.

There is no cookie-cutter method to eliminate varnish from a system as it is a complex deposit. Similar to practices we observe with our bodies in the instances of cholesterol build-up, we can employ methods of dissolving the varnish and removing it while monitoring for possible recurrences in the future.

 

Want to read the entire article? Find it here on Precision Lubrication Magazine!

 

References:

Livingstone, Ameye, & Wooton. (2015.). Antioxidant Monitoring as Part of Lubricant Diagnostics – A Luxury or a Necessity? OilDoc, Rosenheim, Germany.

Livingstone, Overgaag, & Ameye. (2011). Advanced removal Techniques for Turbine oil Degradation Products. Powergen Milan.

Mathura, S. (2020). Lubrication Degradation Mechanisms (CRC Press Focus Shortform Book Program) (1st ed.). CRC Press.

The Hansen Solubility Principles and its Relation to Varnish. (2022, July 31). Fluitec International. https://www.fluitec.com/the-hansen-solubility-principles-and-its-relation-to-varnish/

Is Oil Analysis the Only Method of Varnish Detection?

Varnish will deposit in layers and adhere to the metal surfaces inside the equipment. As it continues to deposit, the layers will eventually accumulate until it reaches a point whereby it can cause significant changes to the clearances of the components.

There have been instances where shafts in rotating pieces of equipment have been moved due to the build-up varnish. This is where vibration analysis can be instrumental.

When the vibration analysis method is used, it can detect any small changes in the alignment of the shaft in rotating equipment. As varnish continues to build on the inside of the component, vibration analysts can detect if the shaft observes some misalignment over a period.

This may be easy to miss as sometimes the varnish which has built up can be wiped away, causing the shaft to resume its proper alignment. Thus, these technologies should be used in tandem before conclusions are made about the presence of varnish.

Another detection method that can be employed is the monitoring of temperature fluctuations. As stated earlier, varnish can form an insulating layer trapping heat. There have been case studies that demonstrate that bearings experiencing varnish tend to display temperature increases.

Typically, these temperature patterns assume a saw-tooth pattern where temperatures rise continuously as the varnish builds up. The varnish becomes wiped away, and the temperature is reduced drastically.

This saw tooth pattern of temperature variation is characteristic of varnish formation. In some cases, the formation of localized deposits on bearing surfaces may cause temperature escalations without a corresponding MPC increase. In this case, the bulk oil may not show any degradation, yet temperature excursions may be experienced at the bearing surface.

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