Page 117 - Intro Predictive Maintenance

108 An Introduction to Predictive Maintenance

• Equipment whose covers are interlocked without an interlock defect mech-
anism should be shut down when allowable. If safe, their control covers
should be opened and equipment restarted.

When used correctly, thermography is a valuable predictive maintenance and/or reli-
ability tool; however, the derived benefits are directly proportional to how it is used.
If it is limited to annual surveys of roofs and/or quarterly inspections of electrical
systems, the resultant benefits are limited. When used to regularly monitor all critical
process or production systems where surface temperature or temperature distribution
indicates reliability or operating condition, thermography can yield substantial bene-
fits. To gain the maximum benefits from your investment in infrared systems, you
must use its full power. Concentrate your program on those critical systems that
generate capacity in your plant.

6.3 TRIBOLOGY
Tribology is the general term that refers to design and operating dynamics of
the bearing-lubrication-rotor support structure of machinery. Two primary techniques
are being used for predictive maintenance: lubricating oil analysis and wear particle
analysis.

6.3.1 Lube Oil Analysis
Lubricating oil analysis, as the name implies, is an analysis technique that determines
the condition of lubricating oils used in mechanical and electrical equipment. It is not
a tool for determining the operating condition of machinery or detecting potential
failure modes. Too many plants are attempting to accomplish the latter and are dis-
appointed in the benefits that are derived. Simply stated, lube oil analysis should be
limited to a proactive program to conserve and extend the useful life of lubricants.
Although some forms of lubricating oil analysis may provide an accurate quantitative
breakdown of individual chemical elements—both oil additive and contaminants
contained in the oil—the technology cannot be used to identify the specific failure
mode or root-cause of incipient problems within the machines serviced by the lube
oil system.

The primary applications for lubricating oil analysis are quality control, reduction of
lubricating oil inventories, and determination of the most cost-effective interval for
oil change. Lubricating, hydraulic, and dielectric oils can be periodically analyzed
using these techniques to determine their condition. The results of this analysis can
be used to determine if the oil meets the lubricating requirements of the machine or
application. Based on the results of the analysis, lubricants can be changed or upgraded
to meet the specific operating requirements.

In addition, detailed analysis of the chemical and physical properties of different oils
used in the plant can, in some cases, allow consolidation or reduction of the number