Lubezine Volume 8 * NOVEMBER 2013 - JANUARY 2014 | Page 16

MAINTENANCE

FEATURE
PREDICTIVE MAINTENANCE

Lubricant oil analysis
as a Condition Based
Maintenance technique
What is
Condition Based
Maintenance
(CBM)

D

ifferent
scholars
have defined
Condition
Based Maintenance
By James Wakiru
(CBM) in different ways.
James has been
Some indicate CBM also
working in the
as predictive maintelubricants industry
nance. In general, CBM
in the areas of sales,
is a technology that
marketing and
strives to identify incipitechnical support.
ent faults before they
become critical which
enables more accurate planning of the preventive
maintenance.
The main purpose of CBM is to reduce the
cost of performing corrective maintenance
on systems and equipment by requiring
corrective/restorative maintenance actions
only when the deterioration of the system or
equipment justifies the maintenance action.
Condition Based Maintenance (CBM) bases
maintenance need on the actual condition of
the equipment or machine and not any preset
schedule. This differs from the preventive
maintenance, which is time-based and activities such as changing a lubricant which are
also based on time.
For example, most car owners change the
engine oil every 5,000kms. Here there is no
checking of the actual condition and performance capability of the oil. If the car owner
had his used oil analyzed to determine the
actual lubricant condition and properties, he
may be able to extend the oil change to more
kilometers say 10,000 kms.
This is the vital core differentiator that
predictive maintenance is used to define
needed maintenance task based on quantified equipment condition. It uses the actual
operating condition of plant equipment and
14

systems to optimize total plant operation. A
comprehensive predictive maintenance management program utilizes a combination of
the most cost-effective tools like:
i) Thermography
ii) Vibration monitoring
iii) Oil Analysis
iv) Ultrasonic technology
Central to the CBM policy is the use of condition monitoring (CM) information for planning and scheduling maintenance routines.
Condition monitoring involves observing
some component or system condition-related
variables throughout the asset’s lifetime.
Thus the degree of deterioration or degradation is determined more accurately.
CBM is the most desirable scheduling
option where asset failure has high consequence, when periodic observation is possible
and practical, and when it is the cost-effective
option.

Lubricants oil analysis
One of the basic technologies of condition
based maintenance (CBM), is lubricating oil
analysis. The reason for this is that lube oil
analysis is a very effective tool for providing
early warning of potential equipment problems. The goals of oil monitoring and analysis
are to ensure that the parts requiring lubrication are lubricated properly.
This occurs by monitoring the condition of
both the lubricant and the internal surfaces
that come in contact with the lubricant. Some
plants maintain their own oil analysis laboratories, while others send the samples to a
recognized laboratory outside their plants.
The outside laboratories normally produce a
very comprehensive independent report, in
a very short time, and at an affordable cost.
As lubricant and machine conditions
deteriorate, the physical properties, chemical
properties of the oil, wear and contaminant
levels will change. By monitoring and trending these changes in a given time, setting

limits for acceptable operation, lubricants
and equipment problems or potential failures
can Identified fast and resolved.
A vital component in understanding and
determining the exact cause of oil-related failures or problems is the ability to identify and
classify the types of wear and contaminants
present as well as knowing their suspected
source. This exercise will require an understanding of physical and chemical properties
of the lubricants being used, the type of metals
used in the internal components within the
equipment where lubricants are used, and
the various sources of contamination that
can enter the system internally or externally.
Wear and contamination can be classified
in four different categories:

System wear or contamination
System generated wear or contamination can
be a combination of ferrous and non-ferrous
particles that are generated from the parts
of the equipment like bearings, rings, seals,
and other internal components that come
in contact with the lubricant. Abrasive wear
from metal particles and other contaminants
circulating in the system, metal surface
fatigue, loss of film thickness or strength,
and other fault conditions can be detected by
analyzing the used oil.
Information regarding the amount, size,
and types of particles is required, in order to
determine what component in the system
is wearing, how severe the condition is, and
what corrective actions may be required.
Typical elements monitored to assess the

LUBEZINE MAGAZINE | November 2013-January 2014