Page 80 - An Introduction To Predictive Maintenance

70 An Introduction to Predictive Maintenance

or component within a typical plant. For example, time-domain vibration can be used
to quantify the response characteristics of valves, cylinders, linear-motion machines,
and complex systems, such as oscillators on continuous casters. In effect, this type of
predictive maintenance can be used on any machine where timing is critical.

The same is true for thermography. In addition to its traditional use as a tool to survey
roofs and building structures for leaks or heat loss, this tool can be used for a variety
of reliability-related applications. It is ideal for any system where surface temperature
indicates the system’s operating condition. The applications are almost endless, but
few plants even attempt to use infrared as a reliability tool.

4.1.4 The Difference
Other than the mission or intent of how predictive maintenance is used in your plant,
the real difference between the limited benefits of a traditional predictive maintenance
program and the maximum benefits that these technologies could provide is the diag-
nostic logic that is used. In traditional predictive maintenance applications, analysts
typically receive between 5 and 15 days of formal instruction. This training is always
limited to the particular technique (e.g., vibration, thermography) and excludes all
other knowledge that might help them understand the true operating condition of the
machine, equipment, or system they are attempting to analyze.

The obvious fallacy in this is that none of the predictive technologies can be used as
stand-alone tools to accurately evaluate the operating condition of critical production
systems. Therefore, analysts must use a variety of technologies to achieve anything
more than simple prevention of catastrophic failures. At a minimum, analysts should
have a practical knowledge of machine design, operating dynamics, and the use of
at least the three major predictive technologies (i.e., vibration, thermography, and
tribology). Without this minimum knowledge, they cannot be expected to provide
accurate evaluations or cost-effective corrective actions.

In summary, there are two fundamental requirements of a truly successful predictive
maintenance program: (1) a mission that focuses the program on total-plant opti-
mization and (2) proper training for technicians and analysts. The mission or scope
of the program must be driven by life-cycle cost, maximum reliability, and best prac-
tices from all functional organizations within the plant. If the program is properly
structured, the second requirement is to give the personnel responsible for the program
the tools and skills required for proper execution.

4.1.5 Benefits of a Total-Plant Predictive Program

A survey of 500 plants that have implemented predictive maintenance methods indi-
cates substantial improvements in reliability, availability, and operating costs. The
successful programs included in the survey include a cross-section of industries
and provide an overview of the types of improvements that can be expected. Based