Maintenance Technology April 2017 - 38

ULTRASOUND

Listen Up:
Stop Lube
Related
Bearing
Failures
REGARDLESS OF INDUSTRY sector, lubrication methods are crucial to plant reliability
and maintenance efforts. Consider the fact that
lube-related failures account for 60% to 80%
of premature bearing failures. While lack of
lubrication and use of the wrong lubricant for
an application have been cited as major causes
of such failures, over- and under-lubrication are
also harmful. Preventing those last two scenarios
is one area where ultrasound technology can play
an important role.
- Jane Alexander, Managing Editor

How Ultrasound
Technology Works
Air- and structure-borne ultrasound is highfrequency sound that human ears can't hear.
These high-frequency sounds travel through the
air or by way of a solid. The ultrasound instrument senses and listens for the high-frequency
sound, and then translates it into an audible
sound that is heard through the inspector's
headset. The unit of measurement for sound is
a decibel (dB) level, which is indicated on the
display of the ultrasonic instrument.
Ultrasound can be used in conjunction with
(and is supportive of) vibration analysis and
other predictive-maintenance approaches. In
addition to mechanical inspections of rotating
equipment and associated condition-based
lubrication programs, applications for ultrasound include detection of compressed air and
gas leaks; inspection of energized electrical
equipment to detect corona, tracking, and
arcing; and inspection of steam traps.

38 |

MAINTENANCE TECHNOLOGY

Ultrasound technology can help reduce bearing and equipment failures associated
with improper lubrication procedures.

According to UE Systems (Elmsford, NY, uesystems.com), by using an ultrasound instrument to listen to a bearing while applying lubricant and then
monitor, i.e., watch, the decibel level, a technician can determine when adequate grease has been applied and, just as important, the threshold at which
over-lubrication begins.
In short, when bearings aren't lubricated properly, friction can cause damage and threaten processes. Ultrasound equipment can read the decibel levels
of over- and under-lubricated bearings and indicate to maintenance personnel
if adjustments are in order. Consistent dB levels let a technician know that the
level of lubrication is where it should be.
Experts at UE Systems describe three tiers of acceptable lubrication
practices and where ultrasound technology fits into them.
Good practice
The baseline lubrication practice is to follow the bearing manufacturer's recommendations to determine the exact amount of lubrication necessary based
on bearing size, speed, and type, and rely on runtime and operating conditions to develop a lubrication schedule. While "good" is a starting place, there
is room to improve.
Better practice
The next level uses ultrasound equipment for more exact lubrication procedures. These tools tell maintenance technicians when to stop lubricating a
bearing, rather than hoping the schedule is accurate and guessing at bearing
condition. Ultrasound can also inform technicians if there are other problems
with the bearing, unrelated to lubrication.
Best practice
A best lubrication practice is to combine a frequency schedule and ultrasound
tools with data collection and trend analysis. By examining the history of
lubrication with dB levels and other sound files, maintenance technicians can
begin to predict when bearings may be approaching failure and take preemptive action. Alarm levels can be set to alert technicians when lubrication is
approaching dangerously low levels.
The best ultrasound programs allow easy integration of data analysis with
probes, listening devices, and lubrication tools. MT

For more ultrasound information and to download a printable
infographic on "3 Ways to Incorporate Ultrasound in Lubrication
Testing," visit uesystems.com.
APRIL 2017

http://www.uesystems.com http://www.uesystems.com

Table of Contents for the Digital Edition of Maintenance Technology April 2017