Lubezine Volume 8 * NOVEMBER 2013 - JANUARY 2014 | Page 17

See also

Automated/Centralized
Lubrication Systems P.26
through breathers, fill/vent plugs, access
covers, and other entry pathways.
Typical parameters monitored to assess the
amount of external contamination present
include Fourier transform – infrared spectroscopy, and elemental levels of silicon, sodium,
boron, and potassium.

Water

Source:Wearcheck

amount of system or internal wear present
include: iron, copper, tin lead, aluminum,
chromium, silver nickel, titanium, and antimony.
Particles generated from system wear contamination pose the following dangers:
• The particles are mostly abrasive to the
metal surfaces they come in contact with.
• They may also chemically interact with
the oil itself, causing the formation of
sludges and gums. These will corrode
metal surfaces, deplete additives, and
accelerate the chemical breakdown of the
lubricant.
• Smaller particles pass through the bearing
clearances and contact areas, cutting away
at the metal surfaces they come in contact
with. This results in the damage to the
metal surfaces, fatigue, and the generation
of new particles that will be introduced
into the system.
• In some cases these particles may also
imbed themselves in the metal surfaces.
This creates a surface anomaly that acts as
a cutting tool against the opposing bearing
surface.

Contamination from external
sources
Contamination from airborne particulates
(dirt, coal dust, organics), process fluids
(Freon, acids), and other external processes
are another source of contamination that
can affect lubricant and machine condition.
These contaminants typically enter lubrication systems from the outside environment

One of most common and damaging sources
of contamination is water/moisture. Even at
low levels, the presence of water will corrode
metal surfaces (rusting), increase oxidation,
and reduce the oil film strength which leads
to increased wear. There are a variety of
sources where water can come from cooler
leaks, seal leaks, condensation and pathways
into the lube oil system through breathers,
access covers, vents, and other opening.
Water may exist in three different states;
1) Free water, 2) Emulsified water and 3) Dissolved water.
It is important to understand the source of
water ingression, so that adequate corrective
actions can be taken to eliminate the problem.
Water is one of the most harmful contaminants that can affect lubrication systems
since it degrades both lubricant and machine
condition.
Water poses the following dangers to the
system:
• Water will increase the rate of oxidation,
and deplete additives through the process
of hydrolysis.
• Insoluble acids are created that cause corrosion of the metal surfaces, pitting, bearing fatigue, and the generation of abrasive
rust particles.
• The rust particles accelerate machine wear
as they act like catalysts.
• The acids also breakdown the chemical
properties of the lubricant. This leads to
the formation of sludge and varnish.
• Large amounts of water can lower viscosity and reduce film thickness, to the point
where metal-to-metal contact may occur.
The end result is inadequate lubrication
and reduced bearing life.

Products from degradation of lubricants
Lubricants are formulated and manufactured
with high quality base stocks and additive
packages. The additive package causes the
lubricant to withstand chemical degradation
or breakdown during normal operation. As
the lubricants are used, they age and due

November 2013-January 2014 | LUBEZINE MAGAZINE

to the presence of heat and oxygen, they
also undergo oxidation, additive levels are
depleted and eventually insoluble acids and
oxides are formed. As insoluble acids accumulate, the viscosity of the lubricant will
increase, causing greater fluid friction and
an increase in operating temperatures. These
high temperatures will increase the rate of
oxidation and the chemical breakdown of
the lubricant.
This process is accelerated under abnormal
conditions such as high operating temperatures, water contamination, air entrainment,
and excessive machine wear. The oxidation
deposits may harden and adhere to the
surfaces causing lacquering. In hydraulic
systems where the lubricant is utilized as a
medium, the sludge may block the system as
well as cause erratic operation of the system.
Typical parameters that are monitored to
evaluate the chemical breakdown of lubricants and oxidation include:
• Fourier transform (infrared spectroscopy).
• Total acid number (TAN).
• Elemental levels of zinc, phosphorous,
barium, calcium, magnesium, and molybdenum in parts per million (ppm).
Lubricant oil analysis plays a vital part
in evaluating contamination levels and
managing the condition of the lubricant
and machine components. Setting threshold
limits for lubricant properties, contamination, wear metals and measuring actual
equipment performance against these limits,
abnormal conditions can be quickly identified and resolved before internal equipment
or component damage occurs.
Two areas key in machinery lubrication
are the condition of the lubricant and the
condition of the surface lubricated. These two
issues can be found from the lubricant samples extracted from the lubrication system.
This yields important information about the
internal machine condition.

Conclusion
With lubricant oil analysis as part of the
CBM policy in any plant, equipment availability can be enhanced, unplanned repairs
avoided, scheduled downtimes incorporated
and better asset management attained in the
whole life cycle of the asset. These eventually
leads to longer useful life of the equipment,
better returns and lower operating and maintenance costs which directly improved the
plant economics.

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