Page 277 - Intro Predictive Maintenance

268 An Introduction to Predictive Maintenance

tive maintenance program must be developed with clear goals and objectives that
permit maximum utilization of the technologies. The program must be able to cross
organizational boundaries and not be limited to the maintenance function. Every func-
tion within the plant affects equipment reliability and performance, and the predictive
maintenance program must address all of these influences.

Vibration monitoring and analysis is the most common of the predictive maintenance
technologies. It is also the most underutilized of these tools. Most vibration-based
predictive maintenance programs use less than 1 percent of the power this technology
provides. The primary deficiencies of traditional predictive maintenance are:

• Technology limitations
• Limitation to maintenance issues
• Influence of process variables
• Training limitations
• Interpreting operating dynamics

13.1.1 Technology Limitations
Most predictive maintenance programs are severely restricted to a small population
of plant equipment and systems. For example, vibration-based programs are generally
restricted to simple, rotating machinery, such as fans, pumps, or compressors. Ther-
mography is typically restricted to electrical switchgear and related electrical equip-
ment. These restrictions are thought to be physical limitations of the predictive
technologies. In truth, they are not.

Predictive instrumentation has the ability to effectively acquire accurate data
from almost any manufacturing or process system. Restrictions, such as low speed,
are purely artificial. Not only can many of the vibration meters record data
at low speeds, but they can also be used to acquire most process variables, such as
temperature, pressure, or flow. Because most have the ability to convert any propor-
tional electrical signal into user-selected engineering units, they are in fact multime-
ters that can be used as part of a comprehensive process performance analysis
program.

13.1.2 Limitation to Maintenance Issues
From its inception, predictive maintenance has been perceived as a maintenance
improvement tool. Its sole purpose was, and is, to prevent catastrophic failure of plant
equipment. Although it is capable of providing the diagnostic data required to meet
this goal, limiting these technologies solely to this task will not improve overall plant
performance.

When predictive programs are limited to the traditional maintenance function, they
must ignore those issues or contributors that directly affect equipment reliability.
Outside factors, such as poor operating practices, are totally ignored.