Efficient Plant March 2021 - 20

feature | lubrication solutions
around the outside of the seal can help
prevent seal degradation. For components
equipped with labyrinth seals, normal oil
levels should be maintained with the
addition of a VPCI.
While not always practical in all
situations, larger or more costly
pumps and gearboxes can and should
be protected with a dedicated oil-mist
system to ensure adequate lubrication
and prevent corrosion.

paid to possible temperature fluctuations,
which can result in a buildup of pressure
due to fluid expansion. Make sure that
port plugs, blanking plates, and other
components are rated for the possible
increased pressure, tagged with a caution, and that there is a safe means of
relieving pressure before use.

MODIFICATIONS TO
CRITICAL SPARES

GREASE-LUBRICATED MOTORS
Electric motors, equipped with greaselubricated antifriction bearings, should
be stored in a clean, dry, low-humidity
environment. Protect the shafts of motors
stored for less than 12 months with a corrosion inhibitor and rotate them monthly.
Bearings in motors stored longer than 12
months should be re-greased annually and
rotated monthly.
Shafts in vertical motors equipped with
oil-lubricated hydrodynamic bearings do
not need to be rotated but the oil should be
changed annually if stored longer than 12
months. Oil levels should be filled to the
correct operating level and the vent or fill
port protected with a desiccant breather
to maintain a low relative humidity in the
headspace.

ANTIFRICTION BEARINGS
Bearings should be stored horizontally,
away from any source of vibration. Most
bearings come with appropriate packaging
to prevent rust and corrosion and should
be left in their original packaging prior to
use. Bearings should be stored to promote
first-in-first-out (FIFO) inventory rotation.
For bearings that are going to be installed
in circulating-lube oil systems, it's a good
idea to check compatibility with the corrosion inhibitor used for storage and the
operating lubricant. Stored properly, most
bearings have a shelf life of 5 to 10 years.

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Ideally, all spares should be stored in an
environment with a relative humidity less than
60%, at a temperature between 60 F and 90 F.

Sealed-for-life bearings that use an elastomeric seal or double-shielded bearings with
no-connect metallic shields should be used
in 2 to 3 years, making FIFO practices even
more important.

HYDRAULIC COMPONENTS
Hydraulic-fluid contamination is the
leading cause of hydraulic-component
failure. When storing hydraulic components, isolate the system from particles and
moisture. Valves and other fittings should
be stored with appropriate plugs or caps to
prevent contaminant ingress. Hoses should
likewise be capped and shielded from direct
sunlight. UV rays degrade hose materials.
Similarly, hoses can also be affected by
ozone emitted by strong electromagnetic
fields.
Cylinder eyes, clevis bushings, and bearings should be protected with a thin layer of
grease to prevent rust and corrosion. Like
centrifugal pumps and gearboxes, hydraulic
pumps and motors can be stored filled with
clean, dry hydraulic fluids.
Cylinders can also be filled with clean
fluid. However, extreme caution should be

In my article " Mods Enhance Lube Practices " (p. 17, Oct. 2020), I discussed the
importance of modifying critical assets to
enable precision lubrication. Modifications
include adding visual clues such as oil-level
gauges and 3-D bullseyes; quick-connect
ports to permit filling, draining, and offline
filtration; sample ports to take proper oil
samples; and desiccant breathers to protect
the oil from particle and moisture ingression. Often, when equipment is replaced,
mechanics or millwrights who remove
the old component do not understand the
importance of upgrading the soon-to-be
installed replacement component with
these same modifications. While removing
the original modification components and
installing them on the new asset is obviously feasible, it's often simpler to ensure
that critical spares held in storage are kitted
with the requisite hardware so that it can be
added during installation.
Even with the best maintenance practices, components wear out and need periodic
replacement. The simple act of replacing
a worn component should not, in itself,
become a new failure mode. By employing
just a few common-sense steps, spare parts
can be safely and reliably stored. EP
Mark Barnes, PhD, CMRP, is Senior Vice
President at Des-Case Corp., Goodlettsville,
TN (descase.com). He has 21 years of experience in lubrication management, oil analysis,
and contamination control.

MARCH 2021

3/1/21 9:25 AM
http://www.descase.com http://www.EFFICIENTPLANTMAG.COM
Efficient Plant March 2021

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