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Base Oil Groups

Q: How many Groups of Base oils are there?

There are 5 groups of base oils as defined by the American Petroleum Institute (API). However, between 2003-2010, the Association Technique de L’Industrie Européenne des Lubrifiants (ATIEL) (Europe) included Group VI - All polyinternalolefins (PiO).

Groups I-III are typically mineral oils while Groups IV-V are synthetic oils.

Group I: Solvent refined
Group II: Hydrocracked / Hydrotreated
Group III: Hydrocracked / Hydro-isomerized
Group IV: PAO Synthetics
Group V: All other Synthetics

Here is a table that shows the different groups.

Reference: Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro, A.A. Wessol, Chapter 2.

Group I: <90% Saturates, ≥0.03% Sulphur, Viscosity Index: 80 to 120

These were characteristically the most popular initially since they were relatively inexpensive to produce (solvent refined) and used in non-severe, non-critical applications. This Group has more double bonds (carbon) which allows for an increase in stability of the carbon chain.

Group II: ≥90% Saturates, ≤0.03% Sulphur, Viscosity Index: 80 to 120

These are hydrocracked and higher refined. However, due to hydrocracking, the double bonds are reduced greatly which decreases the stability of the carbon chain. (A lot of turbine users would have noticed this change around 2010 when most Group I base oils were replaced by Group II base stock. These users saw increased varnish as the oils did not have the level of solubility that they did before!).

Group II+: (yes, this exists!) These have VIs of 110-120 with improved low temperature and volatility Characteristics.

Group III: ≥90% Saturates, ≤0.03% Sulphur, Viscosity Index ≥ 120

There is an argument that this group should be placed in the synthetic category. However, by definition, this group is the severely hydrocracked and highly refined crude oil which can be used in semi-synthetic applications as it has similar properties to that of synthetic oil. These are also called synthesized hydrocarbons.

Group III+: These have VIs approaching (or in some cases exceeding) those of synthetic PAOs (some even go above 140). They are also very pure with almost non-existent levels of sulphur, nitrogen, aromatics and olefins. Typically, Gas to liquid base oils can be found in this group as it approaches the Group IV categorization.

Group IV: Polyalphaolefins – these are very stable, uniformed molecular chains where there is a reduction in the coefficient of friction. Most are formed through oilgomerisation.

Group V: Ester and other base stocks not included in Groups I-IV such as silicone, phosphate esters, PAGs, Polyol esters, Biolubes and Naphthenics.

References:

Chemistry and Technology of Lubricants 3^rd Edition, Chapter 1, R.M. Mortier, M.F. Fox, S.T. Orszulik)
Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro (Exxon Mobil Corporation Fairfax, Virginia), A.A. Wessol (Lubricant Consultant Manassas, Virginia). 2001.

Industrial / Strategic Tips

PAOs vs PAGs

Q: What’s the main difference between PAOs & PAGs?

Let’s start off with definitions!

PAO: Polyalphaolefin

PAG: Polyalklene Glycol

While both are synthetic oils they are classified under different Groups of Base oils. PAOs have their own Base oil Group IV while PAGs fall into the Group V (catch all).

PAOs

PAOs are actually hydrogenated oligomers of an α-olefin and there are different methods of oligomerisation. Due to this process, PAOs have very good low temperature properties and the products are wax free! Additionally, their lower volatilities also allow them to operate over a wide temperature range. Usually, they can be used in a lot of versatile applications such as gearboxes, screw compressors, fans, motors and even automotive!

However, PAOs have a low polarity which gives rise to poor solvency of polar compounds and issues with seal performance.¹

PAGs

On the other hand, PAGs can differ depending on their structure. For instance, Ethylene is water soluble while Propylene is not, however, neither are oil soluble. Both experience significant chemical reactions producing sludge like deposits when mixed with mineral oil.

Usually, their properties include a wide viscosity range, low pour points, good lubricity, low toxicity and non-flammable in aqueous solutions. PAGs are typically always found in fire-resistant hydraulic fluids as well as industrial gear oils, compressor lubricants, heat transfer liquids and metalworking fluids.¹

Compatibility

Both products need to be tested for compatibility with mineral oils before any mixing occurs. Additionally, most lubricant suppliers deem PAOs & PAGS as “filled for life” solutions which last for a longer time compared to mineral oils. Typically, the purchase of these products are more expensive than mineral oils, however if one looks at the cost of waste disposal and reduced downtime (due to decreased shutdowns for oil changes) the overall cost of the lubricant is by far less than that of mineral oil.

References:

Chemistry and Technology of Lubricants 3^rd Edition, Chapter 2, R.M. Mortier, M.F. Fox, S.T. Orszulik

Reliability

EasyRCA!

Recently, most of our concerns stem around getting stuff done faster but wanting the same quality result. For instance, when loading a web page, we expect it to be loaded in one second and use the next five seconds to browse the content and find what we’re looking for. Let’s take a step back and think about loading a webpage ten or fifteen years ago, using a dial up internet connection. I can guarantee you that it took a lot longer than two minutes!

Much of this, “need for speed” has been integrated into our working life where we now have apps that can take vibration measurements in a couple of seconds whereas in the past it took a couple of hours and a few technicians to get the correct reading and then analyse it. The team at Reliability Center Inc, has realized this change in dynamics and are introducing a new tool that steps up to the plate in more ways than one!

The EasyRCA tool was recently launched to allow everyone access to an RCA tool that is (as the name implies) easy to use. The tool is very intuitive and requires minimal training. If a user can click the Enter key on the keyboard or hover above the icons then they can use the tool. The only thing that is required is a stable internet connection and a device with a decent battery life.

One of the first things that stand out with the tool is the use of colour and easy to understand icons! Most tools within the industry shy away from colour but the use of colour to highlight the types of roots (Physical, Human or Systemic) and the stage (Event, Mode, Hypothesis) allows the RCA tree to be easily distinguished and more appealing to the eye.

Figure 1: Snapshot of 5 Why analysis using the EasyRCA Tool

The next interesting feature is that the user can choose the type of analysis that they require! That’s right, the user can choose from the sturdy Causal Tree, to the ever popular 5 Why or the Fishbone (utilizing the 6M method). With each of these types of RCA, the user can add more boxes, move them around the page to group them better or even delete those that they deem irrelevant. The user has full control of the software!

Figure 2: Snapshot of the Fishbone Analysis (6M) using the EasyRCA Tool

If this wasn’t enough to allow easy manoeuvrability, there is even a little “brain” that lights up orange on the screen. This is the virtual assistant and will light up whenever it “thinks” that it can offer assistance through templates from the library. The templates in the library span 50 years of experience that have been built in to allow users a guide for completing RCAs.

Figure 3: Snapshot of the Analysis Assistant using the EasyRCA Tool

What about using the tool to print out a report? Of course the team at Reliability Center Inc thought about this! When performing an RCA, we need to provide a report to all involved! The EasyRCA Tool allows users to produce a report which is downloaded into Microsoft Word. This allows the user to make even more changes if necessary. This report includes all of the pictures / pieces of evidence that were attached during the hypothesis verification process.

Figure 4: Snapshot of the Table of Contents produced by the EasyRCA Tool

Another very cool feature is that it allows teams to work in real time! For instance, if we have team members scattered across the globe (or around the table), any change that is made by a team member is reflected instantly in all open applications of that particular project in the EasyRCA Tool. When we set up a project, tasks are assigned to team members (who are alerted via email). Thus, each team member can have access to the project, once they have been assigned.

Here’s a quick snapshot of a Causal Tree in the EasyRCA software:

Figure 5: Snapshot of a Pump Failure RCA utilizing a Logic Tree in the EasyRCA software

The EasyRCA Tool is like the baby brother to the PROACT RCA software and allows analysts with little training to adapt this tool and still get results that add value! And, best of all, you can get started immediately.

Feel free to book a demo of the EasyRCA tool and check out the family of tools as they keep expanding to help better serve the industry!

Storage and Handling / Strategic Tips

Expired grease?

Are there any signs that my grease has expired?

There are a lot of signs to tell if grease has expired!

Some of the signs include:

Separation of the oil from the thickener
Change in the consistency of the NLGI grade.

Ideally, we should check the expiration date on the packaging and contact the lubricant manufacturer.

We must note that if the packaging has been removed or opened in some way, the expiration date may not be valid.

The expiration date on the product is the approximate shelf life of the product should the packaging remain intact and if stored in the recommended environment.

If these are compromised then the validity of the expiration date has also been compromised.

Storage and Handling / Strategic Tips

Outdoor Storage

I have no room in the warehouse, can I store the oils outside until I get room?

It is never ideal to store lubricants outside exposed to the elements. However, there may be situations where this cannot be helped.

For instance, transformer oils are very sensitive to light and water.

If there is an option of at least storing one type of oil away from the elements, then this type of oil is at the top of the list.

If it has to be stored outside, then there are some measures that can be taken to ensure it is not compromised.

We can place a tarp over the product to ensure that the rain does not settle on the drums and they remain fairly dry.

They can also be stacked on pallets, so that they are not directly touching the ground. This way, water cannot enter the product.

Additionally, they can be stored such that the bungs are at a 9 or 3 o’clock position. In this position, if water falls on the top of the drum, it cannot accumulate by the bungs and seep into the product.

Once the packaging has been opened, the product can be considered open to contamination and anything that gets into the product will eventually get into the equipment.

Ideally, opened products should be stored in enclosed areas or have dedicated decanting systems.

Industrial / Strategic Tips

ISO 4406 rating

Is the ISO 4406 rating important?

Yes, it is very important!

The ISO 4406 rating tells us the cleanliness level of our lubricant. It tells us the number of particles that can pass through a 4, 6 and 14 micron rating.

However, the value on the ISO rating does not represent the number of particles. On the contrary, it represents the range in which the number of particles can lie.

One key point to remember is that the rating will always change from the time that the sample was taken to the date that the results were processed.

Therefore, it is a good idea to use the sample result as a guide as estimate a bit higher for the real value of your lubricant.

Check out our article which goes into more detail about ISO 4406.

Matt Spurlock CLS, CMRP, MLE explains further about redefining the ISO code in his article entitled; "A Twist on Particle Evaluation: Redefining the ISO Cleanliness Code".

Industrial / Strategic Tips

Filter rating

Is the filter rating important?

Yes! It is very important.

Usually, the OEM of the equipment specifies the filter rating (and even the filter material in some cases). These ratings help us to keep out particles of larger sizes that may cause damage to the equipment either through wear or clogging of fine clearances.

Some filters allow us to monitor the differential pressure. This is the pressure between the outside of the filters and inside and as this approaches the warning limits, we know that a filter change is needed in the near future.

However, there are times when there is no warning and the filter goes into bypass. When a filter goes into bypass, this means that the filter is no longer keeping back the larger particles. This can be catastrophic for the equipment as a higher concentration of contaminants can now enter the system and damage it.

It is common practice to change the oil filter when the oil is being changed. In some instance, (especially depending on the environment), OEMs recommend changing the oil filters twice or more before the actual oil change.

Always consult with your owner’s manual about the maintenance practices before adopting your own.

Industrial / Strategic Tips

Synthetic vs Mineral

Should I use a synthetic oil in my equipment or just stick to mineral?

Check with your OEM first.

There are some OEMs that require a synthetic to be used but others that prefer mineral oils.

Typically, a synthetic oil (in industrial applications) tends to have longer operating hours compared to that of a mineral oil.

As such, lots of companies prefer to use synthetic oils as it leads to cost savings in the long term.

However, there are times when mineral oils are more cost effective.

For instance, if the component has to undergo maintenance (where the oil has to be drained) every 500 hours then it would not make sense to have a more expensive oil that lasts for 2000hours.

Before choosing whether mineral or synthetic, we need to do a cost benefit analysis of using both and then make an informed decision. If we can see savings by switching to a synthetic (such as energy, fuel or manpower savings) then this is definitely the way to go.

Industrial / Strategic Tips

Mixing viscosities

Can I mix different viscosities of oils to get the viscosity that I want?

It can be done but this is not an ideal situation.

There are times when the only available viscosity is an ISO 46 (on a rig) but the equipment requires an ISO 68 and the new stock will not be delivered in time to avoid shutdown. Can the ISO 46 be used instead?

An ISO 46 oil is lighter in viscosity than an ISO 68 however, for most oils, there is a chart that depicts the viscosity of the oil at operating temperature. In these cases, one can consult this chart and determine if the viscosity at operating temperature will still fall within operating limits.

If we mix an ISO 46 with an ISO 68 oil we cannot be certain of where the new viscosity will fall especially if we do not know the ratios that are being used. There is a viscosity calculator that can help guide this decision available at: https://www.widman.biz/English/Calculators/Mixtures.html

This can be used as a guide and the actual values of the oil should be verified via oil analysis.

While this situation is not ideal, we need to remember that compatibility is also key.

As such, we should stick with the same line of lubricants that we being used. Typically, lubricant suppliers have the same formulation but change the viscosities for lubricants of the same line.

Industrial / Strategic Tips

Stop production?

I can’t shut down the equipment but I know the oil has degraded significantly. What can I do?

Tough decisions!!!

There are times when production cannot be stopped such as when an order has to be fulfilled in a manufacturing facility. Before a decision is made, we need to understand the risks of not stopping production.

Can prolonged production cause a reduction in the overall quality of the final product or will it damage the equipment from working outside of its stipulated hours?

If we absolutely cannot shut down the equipment but the quality of oil has degraded, we need to firstly understand why the oil is degrading (especially if this is outside of its regular working hours).

Next, we need to identify which property of the oil has degraded, is it that the viscosity has increased / decreased, or the antioxidant levels have depleted significantly? By identifying the property that has degraded, we can choose the best way of replenishing this property.

Methods

There are a few methods that can be employed when trying to get the lubricant back to a healthy state however, as indicated above it is dependent on the property that has been degraded.

Cleanliness – if the ISO 4406 value has been increasing significantly this can hamper the performance of the lubricant. The clearances that the lubricant has to pass through can become blocked or the surfaces can experience an increased rate of wear.

One simple method of improving the cleanliness is through a kidney loop filtration system. This is an external system where the oil can be filtered through a filter cart and returned to the system.

Usually, this is a very effective method but one should investigate why the cleanliness values have become so high. Is it that the lubricant is being contaminated by the system, a process within the system or external factors?

Antioxidant levels – usually in turbines, this value decreases quickly especially if there is the presence of oxidation. Some users try to add antioxidants to their lubricant to increase the values. This is NOT recommended!!!

The composition of most turbine oils is 1% additive, 99% base oil. By adding any additive directly to the lubricant, we will be throwing the lubricant off balance and may induce other issues such as coagulation (clogged clearances) if the additive did not react well to the initial additives in the lubricant.

One of the easier ways of increasing the antioxidant levels without shutting down the machine is referred to as sweetening.

This process involves removing a percentage of the used oil (lubricant in the system) and then refilling the sump with new lubricant. The ratios can vary depending on the desired change in the antioxidant levels. It is important to note that the same lubricant should be used to ensure compatibility of the lubricants during the sweetening process.

Additionally, lab tests should be done frequently to monitor the changes in the antioxidant levels. The frequency of lab tests is highly dependent on the result turnaround time and budget available.

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