Efficient Plant November 2017 - 48

feature | solution focus
MAINTENANCE HISTORY

Given the wide variety
of rotating and reciprocating equipment
running in air-separation facilities, effective
PdM at these sites
translates to monthly
vibration monitoring at
hundreds of measurement points. Improved
sensors and mounting
methods are quickly
changing the nature of
this formerly time-consuming, tedious task.

surement points would be a task so time-consuming
and tedious that it would pose serious concerns about
cost-effectiveness and data accuracy.
To successfully implement the program, the analysts needed a quick-connect/disconnect mounting
method capable of providing accurate readings at
high frequencies.
In cooperation with sensor manufacturer PCB
Piezotronics (pcb.com, Depew, NY), they developed
and tested a magnet-mounting technique that met
all requirements for ease of use and accuracy at high
frequencies.

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The industrial-gases manufacturer had been actively
using predictive and proactive maintenance strategies for many years. Before implementing its new
program, the existing preventive-maintenance (PM)
program called for overhauling every major machine
at regular intervals and replacing critical components,
regardless of condition. While this approach represented an improvement over reactive maintenance,
it led to considerable expense in terms of downtime,
labor, and materials-especially if equipment was
healthy.
In addition to that particular maintenance approach, personnel at individual plants routinely
monitored the overall vibration level of major pieces
of rotating equipment using permanently installed
proximity probes. The industrial-gas manufacturer's
vibration analysts, in turn, used the data from those
probes to assess machinery health. (They typically
visited each plant two to four times a year to collect
the data.) Although this practice was seen as a step
toward PdM, it suffered from several shortcomings:
Data was acquired infrequently. The intervals between the periodic vibration surveys were too long
for good trending.
Data management was inefficient. Machine histories weren't shared among plants and the lack of
standardized measurement procedures made oneto-one comparisons difficult.
Manpower resources were not used effectively.
Highly trained vibration analysts spent more time
traveling between plants than analyzing data.
The vibration analysts decided that the most
effective way to eliminate these shortcomings was to
implement system-wide condition monitoring/PdM.
The goals were to:
Reduce costs and improve profitability by early
detection of impending problems.
Increase the interval between turnarounds.
Share information in a system-wide database that
would improve problem analysis, diagnosis, and
corrective capabilities.

HIGH-FREQUENCY DATA
An underlying principle of the new system was that
the addition of high-frequency measurements to the

NOVEMBER 2017

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Table of Contents for the Digital Edition of Efficient Plant November 2017