The lubricating oil in gas turbines and hydraulic systems is increasingly subject to the ravages of varnish. The debilitating effects of varnish are well documented and the complexities associated with detecting varnish potential render routine oil analysis ineffective in reporting varnish. However, there are a number of technologies, although seldom used, which have been successful in reporting incipient varnish potential. In this webinar you will learn what lube oil varnish is and what causes lube oil varnish in your systems. You will also learn about the proper tools to detect varnish potential and how to read varnish potential analysis test results. Sign up for the Webinar September 10, 2013 http://forms.testoil.com/acton/form/4748/0015:d-0002/0/index.htm

1. How To Outsmart Varnish and Avoid
Unexpected Downtime

2. Presentation Overview

3. What is Varnish?

4. What is Varnish?
• Varnish can be defined as:
• A thin, hard, lustrous, oil-
insoluble deposit.
• Composed primarily of organic
residue, and most readily
definable by color intensity.
• It is not easily removed by
wiping with a clean, dry, soft,
lint-free wiping material and is
resistant to saturated solvents.
• Its color may vary, but it
usually appears in gray,
brown, or amber hues.
Ref: ASTM D.02 C.01
Bath tub rings in a reservoir.

5. Turbine Oils Overview
• Turbine Oils are
formulated differently today
compared to a decade ago
• In general, they have
superior performance but
require different
maintenance strategies:
– Degradation is not linear,
requiring different
condition monitoring tests
– May be more prone to
deposits & varnish

6. Antioxidants are like an Apple’s skin

7. Antioxidants are like an Apple’s skin
When the antioxidant depletes, the lubricant fails quickly.

8. There are many ways for oils to Degrade
Varnish

9. SO WHY IS VARNISH SO
SERIOUS ANYWAY?

10. Valve Sticking in the Power Generation
Market is the highest profile problem
Varnish on bore of Gas Turbine IGV Valve
Typical Cost of a full load trip:
$20,000 - $100,000
Typical Cost of a Fail-to-Start Condition
$10,000 - $25,000
Typical Cost of a full load trip:
$20,000 - $100,000
Typical Cost of a Fail-to-Start Condition
$10,000 - $25,000

11. Other Varnish Related Problems
Premature bearing wear and
elevated temperatures on a gas
turbine.
Accelerated wear from deposits
in a load gear
Journal bearing deposits are a
common place for deposits
Deposits on heat exchangers result
in the inability to maintain low
temperatures
Premature filter life due to deposits.
Spark discharge often contributes to
deposits.

12. Testing for Varnish Potential
• Ultra Centrifuge
• Membrane Patch Colorimetry
• Particle Count Differential
• RULER

13. Ultra Centrifuge
• A portion of the oil
sample is placed in a
centrifuge tube and
spun at 17,000 rpm in
an ultra centrifuge
• Soft contaminants are
forced to the bottom
of the tube and
deposited

14. Ultra Centrifuge
The amount of material deposited in the
centrifuge tube is visually compared to a rating
scale and a numerical rating is assigned.

15. Ultra Centrifuge
Samples that are rated five or higher are
considered to show the presence of
significant amounts of contaminants.

16. Ultra Centrifuge
What factors can affect this test?
• Particle count
• Presence of water
• Fluid type

17. Membrane Patch Colorimetry
• A portion of the oil
sample is diluted with a
non-polar solvent
• The diluted sample is
passed through a .45
micron Millipore patch
• Large, polar soft
contaminants are
deposited on the patch

18. Membrane Patch Colorimetry
• These contaminants
are colored, and the
color is measured
using a
spectrophotometer
to give an indication
of the level of
contaminants
present

19. Membrane Patch Colorimetry

20. Membrane Patch Colorimetry
What factors can affect this test?
Particle count Presence of water

21. Particle Count
• Two types of particle
count testing
commonly used:
– Optical particle
count: a portion of
the sample is
passed through a
laser or light beam.
Interruptions of the
laser or light are
counted as particles

22. Particle Count
– Pore blockage: a portion of the sample is passed through
a calibrated metal mesh screen. As the pores in the mesh
become blocked with particles the flow through the screen
decreases. The instrument uses the decay in flow rate to
calculate a particle count.

23. Particle Count
• Optical particle counters will count air bubbles, water
droplets and soft contaminants as particles.
• Pore blockage will not count air bubbles, water
droplets or soft contaminants – they pass right
through the screen without decreasing the flow rate.
• Significant differences between results from the two
methods may indicate the presence of soft
contaminants.

24. Particle Count
• What factors can affect these results?
– Procedures for testing water contaminated oil
with an optical particle counter call for the
addition of solvents to make the water dissolve
in the oil. The addition of these solvents may
also cause soft contaminants to be dissolved,
and therefore not counted by the optical
counter.

25. RULER
• Tests for the presence of antioxidants in the
oil using linear sweep voltammetry.

26. RULER
• Levels of antioxidants present in in-use oil
are compared to the levels in a virgin sample
of that specific oil type.

27. RULER
• Each antioxidant
produces a peak on
the graph
• The area under each
peak is calculated
• The areas for the in-
use oil are compared
to the areas for the
new oil to generate
percent remaining
values

28. RULER
• Antioxidants protect oil from oxidation – varnish
can be comprised of by-products of oxidized oil.
Low levels of remaining antioxidants mean less
protection from oxidation and higher risk of
varnish.
• Varnish can also be comprised of degraded
antioxidants. Low levels of remaining active
antioxidants mean higher levels of spent
antioxidants and a greater potential for varnish
formation.

29. RULER
• What factors can affect RULER analysis?
– Lubricant identification. Each oil type has different
types and amounts of antioxidants. It is important
to compare in-use oil to the same type of virgin oil
to obtain accurate percent remaining values.

30. RULER
– Variations in formulations. Whenever possible,
use a retain sample from the original fill of the
turbine as the baseline.

31. RULER
– Mixed oils. If the oil in use is a mixture, accurate percent
remaining values will not be obtainable. However, this test
can still produce valuable trend data if the same virgin
sample is used for each analysis. Test results will also give
a general picture of the amount of antioxidants present.

32. SOLVING VARNISH
Understanding Fluid Parameters

33. Factors to Consider When Selecting Technologies

34. Chemistry of Deposits

35. The fluid temperature determines solubility
25o
C 50o
C

36. SOLVING VARNISH
What Technology to Use, When

37. Varnish Removal Technologies
Technologies that can remove soft contaminants under the right conditions.

38. Depth Media Filtration
Pros Cons
1. Simple and
economical to
operate
2. High dirt holding
capacity and
efficiently filters to as
low as 3mm.
3. Adsorbs soft
contaminants
4. Adsorbs moisture
1. Only removes
soluble soft
contaminants that
are in suspension.
For varnish removal,
ideally suited for
reservoirs operating
<40C.
Source: CC Jensen,

39. Electrostatic Oil Cleaning
Pros Cons
1. Efficiently removes
all suspended
contaminants down
to 0.01mm in size.
2. Successfully
removes inorganic,
insoluble
degradation products
(i.e. depleted
ZnDDP)
3. Removes soot-type
carbonaceous
particles
1. Only removes
soluble soft
contaminants that
are in suspension.
For varnish removal,
ideally suited for
reservoirs operating
<40C.
2. Sensitive to water
and other conductive
contaminants/fluids
3. Complex controls
can be sensitive
Source: Kleentek

40. Charged Agglomeration
Pros Cons
1. Efficiently removes
all suspended
contaminants
including sub-micron
particles
2. Product does not
“trip off” in the
presence of moisture
3. Through
agglomeration,
allows conventional
micro-fiberglass
filters to remove soft
contaminants
1. Only removes
soluble soft
contaminants that
are in suspension.
For varnish removal,
ideally suited for
reservoirs operating
<40C.
2. Does not work in
conductive or moist
fluids
Source: ISOPur

41. Chemical Filtration Media
Pros Cons
1. Removes soft
contaminants that
are both in
suspension and in
solution
2. Has a wide range of
temperature
effectiveness from
10o
C – 70o
C.
3. Simple design allows
for easy operation
1. Only removes
organic soft
contaminants. Has
no impact on other
hard contaminants or
inorganic soft
contaminants.
Source: Livingstone, Wooton

42. Will Varnish Technologies Clean a System?
• It is often claimed that varnish mitigation technologies
will clean the fluid, allowing the fluid to be a cleaner and
to remove sludge and varnish deposits through the
system. True or False?
• Dependent upon the
chemistry, location and age
of the deposit
• Sometimes, the system
becomes cleaner as a
result of these technologies,
other times there is no
deposit removal

43. Avoiding Varnish requires a holistic perspective

44. www.testoil.com
216-251-2510
kwilliams@testoil.com