How do you know if you have varnish in your lube system?

Lubricant breakdown accounts for more than 50% of your machine failures.

Lubricant Breakdown

                                      

Premature failure from lubricant breakdown is the most common cause of machinery failure, because it is largely misunderstood and ignored.  Here are some clear signs for you to look for a problem without waiting on lab reports:

WARNING SIGNS:

·         Change in oil colour

·         Strong or burnt odour

·         Change in oil consistency

·         Sludge and deposits on lube tank walls and floor

·         Visible contaminants in the sample bottle

Any of these generally indicate that your oil has undergone a chemical change and will no longer perform to the standard it was designed to.  Breakdown of the oil can occur from particulate contaminant, fuel or gas entrainment, oxidation and thermal stress, but the most common cause is from water contamination. 

What is varnish?

Varnish (also known as sludge, tar and lacquer) is a soluble and insoluble contaminant made up of by-products of oil degradation.

It can appear as resinous, sticky, tacky or a gel-like substance that settles or plates out on the surfaces of the lube system.  This can cause ‘stiction’ on servos and affect clearances and tolerances in bearings and hydraulic control systems and valves.

As oil degrades, it consumes its additives packages and antioxidant properties and waste by-products are formed, creating sludge and varnish. You will have seen it in hydraulic components, inside engine rocker covers and on journal bearing surfaces or sumps.

There are many causes of varnish and sludge, but clean oil is not one of them!

Is your system susceptible?

There are a number of explanations for why lube oils suffer from high rates of varnish.  If your system ticks any of these boxes then you should ensure your lab is testing for varnish potential:

Effect of varnish on equipment

ü  Visible deposits or staining of lube circuit components

ü  Switched from Group I to Group II or blend of oils

ü  Gas turbine or hydraulic application

ü  High flow rate from a small lube reservoir

ü  High operating temps

ü  Your chosen oil brand is predisposed to varnish formation

The effect of varnish on equipment

If left unchecked, varnish can propagate at an exponential rate, creating hot spots, prematurely plugging filters or oil gallery orifices, and coating heat exchangers and rendering them thermally inefficient. Hydraulic control systems and valves can gum up or seize, causing unit trips and starting faults.  Also, hard particles canadhere to varnished components and cause premature wear.

The cost of a gas turbine or hydraulic system not starting immediately can be enormous as these are the assets that are designed to work at the press of a button to meet supply requirements.

All lubricating systems are subject to varnish potential if not maintained.  The biggest cost to industry from varnish is unscheduled downtime and lost production.  There is a yawning cost-gapfrom an unscheduled shutdown or unit trip, in comparison to condition monitoring and cost of varnish mitigation.

Effect of varnish on equipment

Varnish Detection

If you suspect that varnish could be a problem then additional laboratory analysis can identify varnish potential within your system.  Sometimes, it can be as simple as pulling filters and strainers and visibly observing the flakes and sludge indicating the oil has broken down.  Check your oil sample bottle & sheet to see if your lab can test for these:

Membrane Patch Colorimetry (MPC)

This is an excellent test to determine varnish potential.  It is very sensitive and literally assesses the colour spectrum of the oil.  MPC analyses (L) white to black, (a) red to green, and (b) yellow to blue scales providing information on not only the seriousness of varnish found but the likely cause.

High L = presence of soot, evidence of micro-dieseling, spark discharge, thermal stress.

High a = diminished EP additives, likely to produce sludge

High b = sticky, gummy deposits.

MPC Patches showing varnish potential high to low:  results are 52, 44, 32, & 21 respectively.

Remaining Useful Life Evaluation Routine (RULER)

The RULER test quantitatively measures the remaining antioxidants concentration in the oil, and as it says can determine ‘the remaining useful life of the oil’. This is a comparison test, so ideally requires the original base oil to be supplied.

Other Tests

MPC and RULER should be enough, however other methods to determine varnish potential can include ultra-centrifuge, particle contaminant levels, TAN (Acid number), moisture testing and FTIR. 

What should you do if you have varnish?

    

Don’t ignore it…

Varnish, if present in a lube system must be managed and controlled.Predictive maintenance of your unit is far cheaper than reacting to an event, if the cues were there and were ignored the flow on effect could be significant.

Can you live with a major breakdown?

If you do no nothing, varnish will cause the machine to suffer a breakdown or component failure, at potentially huge cost.  You cannot predict when the failure will occur, but it will happen… guaranteed.   Get the problem resolved, send us your lab reports, RCA and specs and we can assist.

What solutions can be deployed?

Specialist filtration can remove varnish from a system.  No two systems are the same, so a tailored solution is needed.  Your existing oil may or may not be able to be renewed depending on the type and seriousness of the contaminants.  Specialist filtration of the lube tank oil can remove varnish plated out within the entire lube circuit.  This process will take time and may need to be a permanently installed solution.

In circumstances where the oil is heavily contaminated and the additives packs left with Elvis, then the oil will need to be replaced.  When this occurs a chemical additive,such as Boost VR or Exxon System Cleaner, can be used to sacrificially drag the varnish contaminant out with the outgoing oil.

There are several filtration methods of removing varnish in service.  A system such as VRS or ESP (Electrophysical Separation Process) are the most efficient at removing the soluble contaminants in suspension, and insoluble contaminates (the varnish and sludge that can be seen). Prior to any varnish mitigation solution being deployed, the oil will also require purification to remove any particulate, water or gas contamination. 

Summary

Varnish and sludge is like a cancer of the oil, if not treated, it spreads and further propagates, to the point of machinery seizure and failure.

Varnish detection and mitigation is far cheaper than an unplanned shutdown… as with most things prevention is cheaper than the cure. 

Don’t park the ambulance at the bottom of the cliff!

The obvious answer is ‘No’, as there are other influencing factors that impact on equipment life such as start-up wear and vibration… but equipment life when oil is clean may surprise you.

Clean Oil Really Does Matter

When you order ‘new’ oil in to stock it typically has an ISO 4406 code of 21/18/16 NAS 10, which is very dirty for close tolerance rotating machinery.  Most OEM’s specify a cleanliness code of 16/14/12 NAS 5, which is substantially cleaner than new oil, but if you can reduce that cleanliness code to 15/12/10 NAS 4, you will extend the machinery life cycle by two and a half times.   So, if your rotating asset costs $10M with a service life of 20 years, you could expect a service life cycle of 50 years, so $10M for a 50 year service life is a prudent investment compared to $25M for the same service life.

ISO 20/18/16 NAS 10 as delivered 'new'!

ISO 15/12/10 NAS 4 - Post filtration, clean

                        

The British Hydraulics Research Association (BHRA) conducted a three year field study of a range of more than 100 rotational and hydraulic machines to ascertain equipment life and the results were compelling.
What the survey found was that breakdowns diminished and the life of equipment improved greatly the cleaner the oil was kept. Nearly 20 times longer… It proved that if you want to spend less in maintenance and downtime, simply keep your oil clean.

Case Study - Aluminium Smelter

A Queensland aluminium smelter which adopted a proactive condition monitoring program, has changed its hydraulic oil overhaul schedule from annually out to 7 years, by fitting desiccant breathers, servicing the oil with vacuum dehydration and fine filtration.  Traditionally, their gearboxes gave 10 years of service life, and now the gearboxes have a service life expectancy of 25 years.  Downtime and wear rates have been greatly reduced so they are confident about moving to a synthetic lubricant.  Synthetic lubricants do not tolerate moisture or particulate contamination as well as mineral oil but do improve your equipment life when kept clean.

There are many successful examples of this proactive condition monitoring, where operational and maintenance budgets have been greatly reduced and equipment capital budgets are halved.

Take Action with Your Lubricants 

You want to see thumbs up on your Lab reports...

There are many successful examples of this proactive condition monitoring, where operational and maintenance budgets have been greatly reduced and equipment capital budgets are halved.

Fact - Keep your in-service oil clean and dry and unscheduled downtime, failures, hot spots, wear, and breakdowns will reduce.

The Cost Benefit Analysis

As an added benefit, the expenditure for implementing proactive condition monitoring and lubrication filtration servicing is insignificant, compared to the savings in capital and operational up-time.  One unscheduled stoppage in a plant could pay for years of lubrication maintenance and service.
What are you wanting to see on your lab tests?

Summing Up

It may be naïve to suggest close tolerance machinery can last forever, but you can increase its service life cycle by multiples saving you money and maintenance headaches, all by simply keeping your lube oil clean.

So yes, your close tolerance machinery can nearly last forever, if your lube oil is well serviced.

If you would like further information on this article or others, please let me know or visit our website.

James McAllister
james@biokem.com.au
Ph 0466 625 225
www.biokem.com.au

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Why You Must Eradicate Contaminants from Your Lube Oil

Regardless of contaminant type, any lube system will be compromised if contaminated.  The effect can then compound as some contaminants have a catalyst effect, causing further problems.  The types of contaminants are quite varied including hard particles, soft particles, moisture and free water, gas and varnish.

Over the next few articles we will cover the range of issues that you should consider when managing your lubrication oil for close tolerance machines, hydraulics and gearboxes.

What you cannot see is doing the damage

Silica & Bright Metal at 100x
Let’s start with the types of contaminants:

1. Hard particles, such as Iron, Chrome and other metals, Silica and sand
2. Soft Particles, such as Copper, Tin and other soft metals, fibres
3. Soluble contaminants, varnish, incompatible top up lubes or additive packages
4. Gases and Aeration, process gases and aeration from ingression or inadequate system design
5. Water and liquid contaminants that can change lube viscosity

Hard particles will score and wear away lubricated surfaces, producing other contaminants in the lube oil, creating a snowball effect of increased wear rates. Wear particles and contaminants that oxidise, will deplete the antioxidants in additive packages, leading to varnish potential.

Soft contaminants have the potential to damage lubricated surfaces and increase wear rates, as well as depleting antioxidants, plugging filtration systems and galleries.

Varnish is a by-product of contaminants or depleted antioxidants, and a real concern in any lube system as the damage caused by varnish includes sticky and gummed valves and actuators, decreased tolerances which restricts lubrication to the wearing components causing higher operating temperatures.  Varnish can also plate out on bearing surfaces, causing hot spots and journal deformation. There are costs associated with varnish removal, but the real costs are downtime and loss of production.

Gas - In processing industries, where gas is present, such as gas compression facilities, lube oil can become entrained with gas, becoming aerated and not supplying the correct oil film or strength to the lubricated surfaces, as well as reacting with other contaminants in the oil to cause varnish potential. Aeration in hydraulic equipment also causes cavitation, prematurely wearing pumps, controls and work accessories.  Aeration and cavitation in lubricating oil destroys components and pumps, and reduces operating efficiency.

Moisture in oil is a common contaminant, as our climate can be humid with a wide temperature range.  In close tolerance rotational equipment, moisture levels below 200 ppm are acceptable but some OEM specifications allow for much higher.
                                                     
Free Water has a devastating effect on bearing surfaces, as the water droplet compresses and becomes super-heated into steam, exploding and 'etching' the bearing surface, rendering it unserviceable.

Magnified Samples (60x & 100x)

The following slides are all pictures taken by BioKem Oil Services in the last year.  They show a range of contaminants in 100ml samples of lube oil from gas compressors, turbines, steam feed pumps and gearbox lube oil tanks. For reference the black line shown is 44µm in width.

RUST – The presence of water speeds oxidation and additive breakdown of the oil and is considered a serious problem.  Particle size varies from 10 - 120 micron range

FIBRES - Typically introduced by improper cleaning and maintenance practices.

ASPHALTENES - particles are generally in the 0.5 - 2.0 µm range and they agglomerate into an oily sludge. This problem is made worse when free water is present.

SILICA & SAND – range of debris on this slide typically found airborne in Australia.

BRIGHT METAL PARTICLES - Typically comes from component wear. These particles are abrasive and, as a result, can lead to further wear and tear of the system bearings.

SOOT & SILT (<5µM), SILICA AND DUST PARTICLES - This is typically airborne contamination or part of sludge from the bottom of tanks.  Very hard and extremely abrasive against delicate components in boundary layer systems.

Non Magnified Samples

Sludge – This is a filter housing showing a buildup of oil additives after exposure to moisture (no magnification)

Varnish – Flakes of varnish plated out onto a filter and the varnish washed out onto an an absorbent towel (no magnification)

Examples of Damage

The next few articles will focus on how the different contaminants are caused, and the types of resolutions that can be performed.
If you would like further information on this article or others, please let me know or visit our website.

Has your Lubricating Oil got Gas?

Entrained gas can reduce your oil lubrication effectiveness by up to 80%

Entrained gas reduces the efficiency of your lube oil, which can have negative consequences on the machinery it is supposed to be lubricating. This can range from minor consequences up to devastating effects.  The longer it’s left, the worse the consequences.

But first, here is a description of the problem - this is about fluid aeration, it happens at high temperature and compression rates, when the lubricating oil in your equipment comes into contact with gas, bubbles form in the lube oil. When oil is aerated, it won’t give a full film, leaving sensitive components unlubricated, causing extremely premature wear rates or catastrophic failure. 

Electrophysical Separation Process

Before you open a bottle of Coke or beer there are no visible bubbles, this is dissolved gas.  When you open the bottle you see tiny bubbles in suspension - this is entrained gas.  The same as in your oil.

There are several situations when this can occur even in closed loop systems.

Return lines where oil ‘plunges’ into the tank under gravity or pressure.

Hydraulic systems under suction resistance.

When process gas comes into contact with your oil.

Sudden pressure drops.

What are the effects? Machinery operating with entrained gas in its lube oil has the same effect as oil starvation as your lube oil is just not lubricating all of the area it was designed to.  When gases in oil are compressed (eg. rolling element bearings, gear teeth and hydraulics) oil temperatures rise causing other issues and concerns.  If left unchecked, the result is increased wear in sensitive and expensive components. The lubricating oil will suffer a marked degradation in quality, enabling catalysts to deplete antioxidants and other additive packages, raising varnish potential which, in turn, can decrease tolerances and cause sticking valves (the list goes on!).  Entrained gas will also dilute the viscosity of the oil, falling outside of its design specification for the given application. Entrained gas also creates cavitation. This is caused when the pressure of the dissolved gas is higher than the fluid.  When this happens the bubbles can collapse, which degrades the quality of the oil.  It is also often the source of increased high-frequency vibrations and noise… plus it can cause direct damage to equipment. Finally, entrained gas in lube oil can reduce thermal conductivity, increase erosion, and decrease the efficiency of pumps. Your solution to restore your lubricating oil: Simple bubble removers can be effective on highly aerated systems and work like mini centrifuges to spin the gas and bubbles into the middle of the vortex and then remove them.  However, to remove 100% of entrained gas and 90% of dissolved gas you need vacuum dehydration. Vacuum dehydration or VDOPS is ideally a six stage process with the added benefit of removing moisture and dirt as well as the gas.  The oil is passed through a vacuum chamber at an elevated temperature, above 66˚C is ideal for most oils for moisture or gas removal to separate the oil from water vapour and process gas.  The resulting lube oil is almost completely free from gas and ready for service. Oil purification systems Australia Bulk Particle Removal – The first stage of the process, where large particles are removed by a 10µm or greater filtration element. (Element selection differs with viscosity). Temperature and Viscosity Adjustment- The oil is heated to above 66˚C, which lowers the viscosity for higher flow and processing rates, and allows for vacuum dehydration to occur. Vacuum Chamber - is where the heated oil is exposed to vacuum, where gas is removed, and water evaporated. Fine Filtration – Using absolute β1000 pleated microglass filtration media, particles as small as 2 micron can be removed (dirt, scale, rust, wear metal, silica, etc). Multi pass procedure - Used to maximise the results, five passes are often used to achieve the targets of 100 percent entrained gas removal, and 90 percent dissolved gas removal. Additive blending – If available, this is an optional restorative process which returns the lube oil to an as-new, or higher specification, as required. If you would like further information on this article or others, please let me know or visit our website.