Tagged: strategic tips

Lubricant Degradation / Used Oil Analysis

How can a lubricant fail?

This question has caused many sleepless nights and initiated countless discussions within the industrial and even transportation sectors. Before examining the causes for lubrication failure, one must first consider the definition of lubricant failure.

The composition of a liquid lubricant can be described as a combination of base oil and additives (Menezes, Reeves and Lovell 2013, 295). These two components work in tandem to define particular characteristics of the lubricant to perform its functions. According to Menezes, Reeves and Lovell (2013, 296) the five functions of a lubricant include;

the reduction of friction
minimization of wear
distribution of heat
removal of contaminants and
improvement of efficiency.

As such, lubrication failure can then be described as the failure of a lubricant to adequately perform any or a combination of its five functions as a result of the degradation of any of its two components; namely the base oil or additive package. Thus, it can be deduced that lubrication failure is as a result of lubricant degradation.

Now that we understand that a lubricant fails when it undergoes degradation which by extension results in the lubricant not being able to perform any of its functions properly, we need to explore further on the types of degradation that exist. Only then can we really answer the question of how a lubricant can fail.

Barnes (2003, 1536) focuses on three main mechanisms of lubricant degradation namely;

Thermal Degradation
Oxidation and
Compressive Heating (Microdieseling).

One may argue that these three types form the basis of all mechanisms of lubricant degradation.

However, Livingstone, Wooton and Thompson (2007, 36) identify six main mechanisms of degradation namely;

Oxidation
Thermal Breakdown
Microdieseling
Additive Depletion
Electrostatic Spark Discharge and
Contamination.

In this instance, the six identified mechanisms all produce varying identifiable characteristics which lend to these six forming the foundation of identification of lubricant degradation mechanisms. With these six in mind, one would need to be able to determine which degradation mechanism is at work in their facility. Afterwards, methods to treat with these mechanisms must be administered. Firstly, let’s understand each mechanism.

Oxidation

This mechanism involves the reaction of oxygen with the lubricant. According to Livingstone, Wooton and Thompson (2007, 36) oxidation can result in the formation of varnish, sludge, increase in viscosity, base oil breakdown, additive depletion and loss in antifoaming properties of the lubricant.

Barnes (2003, 1536) refers to this phenomenon as the addition of oxygen to the base oil to form:

Aldehydes
Ketones
Hydroperoxides and
Carboxylic Acids.

On the other hand, Wooton (2007, 32) explains that there are three main stages of oxidation namely initiation, propagation and termination. Fitch (2015, 41) explains that:

Initiation entails the production of a free radical via the lubricant and a catalyst.
Propagation involves the production of more free radicals via additional reactions.
Finally, termination entails either the continuation of the oxidation process after the antioxidants have been depleted or the antioxidant stopping the oxidation process.

Microdieseling

Livingstone, Wooton and Thompson (2007, 36) have characterized Microdieseling as a form of pressure induced thermal degradation. They describe it as the transition of entrained air from a low pressure to a high pressure zone which results in the adiabatic compression.

This type of compression results in localized temperatures almost on excess of 1000°C.As such, the lubricant undergoes dramatic degradation. Wright (2012, 14) explains that because of these high temperatures, the bubble interface becomes carbonized. As such, carbon by products are produced and the oil undergoes oxidation.

Electrostatic Spark Discharge

Livingstone, Wooton and Thompson (2007, 36) describe this phenomenon as the generation of static electricity at a molecular level when dry oil passes through tight clearances. It is believed that the static electricity can build up to a point whereby it produces a spark. This spark can induce localized temperatures in excess of 10,000°C which can significantly degrade the lubricant at an accelerated rate.

Van Rensselar (2016, 30) also advocates that Electrostatic Discharge contributes to the formation of free radicals in the lubricant which subsequently results in uncontrolled polymerization. This polymerization of the lubricant gives rise to the formation of varnish and sludge which may deposit on the surface of the equipment or remain in solution. Van Rensselar (2016, 32) indicates that the most common result of Electrostatic Discharge is an elevated rate of fluid degradation and the presence of insoluble materials.

Thermal Breakdown

This mechanism is largely dependent on temperature as one of its contributory factors even though dissipation of heat was highlighted above as one of the functions of a lubricant. However, during the operation of machinery particular components tend to develop increasing temperatures.

As described by Livingstone, Wooton and Thompson (2007, 36) once this temperature exceeds the thermal stability point of a lubricant, the consequences can include shearing of the molecules. This phenomenon is also called the thermal cracking of the lubricant which can result in the production of unwanted by products, polymerization and decrease in viscosity.

Subsequently, Barnes (2003, 1536) explains that thermal degradation usually occurs when the lubricant experiences temperatures in excess of 200°C. He also states that the by-products of thermal degradation differ from that of oxidation.

Wooton and Livingstone (2013) state that there are two main actions that can occur once a lubricant is thermally degraded.

Either the small molecules will become cleaved off and volatize from the lubricant. This does not leave any deposit in the lubricant.
On the other hand, there is the condensation of the remainder of the molecule in the absence of air thus dehydrogenation also occurs. Consequently, coke is formed as the final deposit with numerous types of deposits forming between the start of the condensation to its final deposit of coke.

The main contributing factor for thermal degradation can therefore be linked to dramatic increases in temperature or constant high temperatures.

Additive Depletion

Wooton and Livingstone (2013) indicate that additive depletion can result in either organic or inorganic deposits. The nature of the deposit is dependent on the type of additive that has been depleted and its reaction with other components in the oil.

For instance, if the rust and oxidation additives drop out of the oil, they typically react to form primary antioxidant species thus producing organic deposits. However, as Wooton and Livingstone (2013) explain, inorganic deposits can also be formed from additives that have dropped out of the oil but did not react with anything. This unresponsive reaction is typical of ZDDP (Zinc dithiophosphate) which is an additive that assists with reducing wear in the lubricant.

In cases of additive depletion, the FTIR test seeks to identify spectra relating to the reacted or unreacted additive packages for the lubricant in use (Wooton and Livingstone, 2013).

Contamination

This mechanism of degradation can include foreign material entering the lubricant and being used as catalysts for degradation mechanisms listed above. Contaminants can include a variety of foreign material, however Livingstone, Wooton and Thompson (2007, 36) have narrowed the list to metals, water and air. These main contaminants can significantly contribute to the degradation of the lubricant by oxidation, thermal degradation or compressive heating.

From the above, we can summarize these lubricant degradation mechanisms into the following table:

From this summary, we can now assess the methods in which a lubricant can fail. While this article may serve as a guide in determining various lubricant degradation mechanisms, each mechanism must be treated differently depending on the conditions (environmental and operational) that exist during the lubricant failure. A proper root cause analysis should always be done when investigating any type of failure.

References

1 Livingstone, Greg, Dave Wooton, and Brian Thompson. 2007. “Finding the Root Causes of Oil Degradation.” Practicing Oil Analysis, Jan – Feb.

2 Barnes, M. 2003. “The Lowdown on Oil Breakdown.” Practicing Oil Analysis Magazine, May-June.

3 Livingstone, Greg and David Oakton. 2010. “The Emerging Problem of Lubricant Varnish.” Maintenance & Asset Management, Jul/Aug.

4 Wooton, Dave and Greg Livingstone. 2013. “Lubricant Deposit Characterization.” Paper presented at OilDoc Conference and Exhibition Lubricants Maintenance Tribology, OilDoc Academy, Brannenburg, Rosenheim, Germany, United Kingdom, January 22-24, 2013.

5 Van Rensselar, Jeanna. 2016. “The unvarnished truth about varnish”. Tribology & Lubrication Technology, November 11.

Book Reviews / Reliability

5 Habits of an Extraordinary Reliability Engineer – My review

Peter Horsburgh has essentially captured the 5 Habits of an Extraordinary Reliability Engineer in his book! His style of writing appeals to engineers as he keeps the content directly on point and provides case studies to each of his chapters. Most engineers aren’t big readers (except for manuals and when absolutely necessary) but the conversational tone in which Peter explains some of his revelations about the industry ideally captures the attention of reader. I couldn’t put the book down once I started reading it!

What I really love about this book is that it was holistically designed for engineers. The book is small allowing persons to carry it around anywhere and it isn’t too thick to daunt the reader into thinking that they need to allocate a couple of days to reading it. Peter has kept the chapters short, driving the various points home and has even provided summaries for each section of the book. This makes it super easy when trying to relate to an issue that he has discussed. Peter has also done an excellent job with the illustrations in the book to keep the reader’s attention and provide for some light amusement to keep the book as a guide that engineers want to return to time and time again

Additionally, an extra step was taken to ensure that the book has some durability built into it. The pages aren’t the ordinary soft paper, rather the pages have a bit of a card stock finish. This was my first light bulb moment after opening the book (there were tonnes more light bulb moments while reading it!). Obviously the pages had to be durable! This book was meant to be in the workshop with the engineers becoming part of their manuals! I can clearly see engineers rushing back to this book during the course of the day to get back to a particular chapter or case study that can assist them in some issue of the day.

I definitely enjoyed this book! Peter first introduces the reader to the 5 Don’ts of Reliability Engineering. I hadn’t realized until then that the “Don’ts” that were covered form critical parts of any Reliability Engineers’ day! The manner in which he introduces these stood out for me, as he brought in case studies to demonstrate instances where he dealt with some of these “Don’ts” or even performed them himself. It is with these case studies that I appreciated that some of the situations that I face daily may receive a “Don’t” when it shouldn’t. With Peter’s story telling ability, he was able to truly relate to the readers the practical examples of things that should and shouldn’t be done. Unlike other books, he demonstrates the impacts (and throws some financials in there as well, which helps us to actually quantify what we’re looking at) of particular “Don’ts”.

Right after the “Don’ts” section, he launches into the “5 Habits” which are each covered in their own Chapters. While he explains the habits in this section, he then further dedicates each Habit to a Section (not just a Chapter) where he mixes in his real life experiences as his Case Studies while providing introductory information on the habits and their impacts on the plant and its reliability. Quite skilfully, afterwards he dedicates a Section to “Applying the habits”. This is in keeping with the conciseness of the book!

I would highly recommend that all Reliability Engineers add this book to their library! It’s a book that gets all the lightbulbs blinking in your head from the moment that you begin reading it. However, it is not a book to be read just once, it needs to form part of your routine (either weekly or monthly). After reading this book, I can almost guarantee that the week that you spend in work afterwards will be nothing short of interesting as you may find yourself thinking… “Peter covered this in his book…let me just look back and verify if this can be dealt with in another way”. That being said, I believe that any engineer will make it part of their “consultation” guide especially during brainstorming sessions. It was indeed a pleasure reading this book!

Check out his website for more info on getting this amazing book! https://www.reliabilityextranet.com/

Book Reviews / Reliability

PROACT Review

Root Cause Analysis has always been dear to my heart. The procedure involved in finding the root causes and addressing them have intrigued me greatly as it involves using all your data gathering and cognitive skills. In the past, it was a bit difficult to properly perform RCAs since it usually meant jumping around different types of software. For instance, depending on the type of analysis that I wanted carry out, I would either use a Fish Bone Diagram or Cause and Effect Logic Tree. Depending on the type that I needed to use, I would have to switch programs just to get these generated. Then, there’s the issue of writing the final report and utilizing my expert copy and paste skills with Microsoft word while toggling excel worksheets to determine the costs attached to the failure.

Needless to say, I was very impressed when introduced to the PROACT software. It has an extremely friendly user interface (in some cases, I can even use drag and drop options!) which is very easy to navigate even for a beginner like me at the time. What I really love about the software is that it bridges the gaps and guides users (both for beginners and experts) on the RCA process. By allowing users to follow a step a by step process it ensures that users don’t forget vital pieces of information that are absolutely critical to the RCA.

If you are familiar with RCA, you will be aware that the basis of any RCA is properly establishing the Severity of the failures. As such, the first step when the user enters the software, is the assigning of the Severity of the failure with the Severity Calculator. This calculator can even be customized for varying applications! Afterwards, the profile of the failure is then defined. This profile allows the user to identify elements that may have been forgotten if the RCA was being done from scratch. The Severity Calculator also allows users to determine the type of analysis that is fit for the severity index. Depending on the severity, the user can be guided to use either; 5 Whys, Fish Bone Diagrams or Cause and Effect Logic Trees. This is definitely one key advantage since it allows for different forms of analysis based on the severity.

Next the Critical Success Factors are inserted. The strategic placement for the input of these factors at this point in the analysis is purely genius! It forces the user to determine which factors directly impact them and these are usually placed on the final report. These CSFs start shaping the pending RCA into the mould that we need. Once these CSFs are established, then the objectives need to be defined. These help the analyst in guiding their RCA and ensuring that it is kept focused. It is easy to become distracted when performing these types of analyses since users are presented with an abundance of information. The definition of these aspects help the analyst to keep on track.

As with any RCA, there must be a team involved. The PROACT software allows users to delegate different tasks to different team members! It can even track the status of these events. Instead of sending long reminder emails (which tend to choke one’s inbox and can be easily missed), it is essentially easier to view the status of the assigned tasks using the PROACT software. This is a definite advantage of the software!

Now to the core of the software, the development of the RCA! Users are allowed to define the event that lead to the failure. Here’s where the software gets very interesting!!! Users can pull from existing templates dependent on the type of failure! This is the highlight of the PROACT software for a user like myself! It is very interesting to view templates (there are over 300 templates) of common failures and compare these to what the user has actually experienced. It allows the user to be able to access years of experience of a consultant at their fingertips! The team at Reliability Center Inc have definitely put a lot of work into developing these templates and have drawn upon their actual field experience for the past30+ years! This is the absolute game changer for the software!

During the building (or growing) of the Cause and Effect Tree, the user is allowed to authenticate their hypotheses and can attach pictures from the failure as verification for ruling out or accepting that mode as one of the root causes. These pictures can then be input into the final report without the need for cropping, cutting and pasting and all the exciting formatting issues that tend to occur when trying to include pictures in the final report.

PROACT also allows for users to input financial data. Another game changer for me! Users can define the costs associated with the downtime for particular failures, repair costs or even manpower costs. These all help to put a financial value on the cost of the failure being investigated. This neat trick is crucial for the review by upper management! Additionally, the final steps in any of the RCAs is to determine recommendations for the latent causes that were determined. These will be the courses of action to be taken to prevent failures of this nature from occurring in the future.

Overall, the PROACT software is indeed a time saver, keeps excellent track of the findings and collections of the investigation at hand and produces a very succinct, detailed report that anyone from upper management to the engineers can clearly understand. I love working with this software and my clients are always very impressed that this type of software actually exists and is so easy to use! I would highly recommend any user (novice or expert) in the reliability field to use the software in their everyday tasks and realize the impact that it has on increasing the efficiency of RCAs and their ROIs to their organizations.

More information can be found at www.reliability.com