che_october-2023 - 33

determine what the right replacement
interval should be for specific
hoses. Below are the key steps
plant managers should take to help
create a proper preventive hosemaintenance
schedule.
Identify all hoses
Before creating your plan, it is crucial
to understand what hoses are in
the plant. That means conducting a
full plant audit, tagging each hose,
and creating a log detailing the full
roster of hoses. For each one, include
information, such as the hose
type, part number, process fluid
contained inside, pressure or temperature
ratings and which vendor
supplied the hose, along with the
appropriate contact information.
This information will be handy for
not only tracking hose performance,
but also for ordering replacements.
In addition, plant managers should
log other information like the hose's
length, size, core material and construction,
reinforcement layers, end
connections, mounting, cover type,
operating conditions and cleaning
procedures. Finally, records should
be kept that indicate when a hose
was installed and when a replacement
is scheduled. If nothing else,
these steps will offer significant information
on how well a plant is operating.
If the process seems overwhelming,
a reliable hose supplier
should be able to help perform the
audit and offer recommendations
about what needs to be done.
Track the lifecycle of each hose
Schedule hose inspections at the
interval recommended by the hose
supplier. More often than not, these
inspections may be visual and do not
require system downtime.
During such routine
inspections,
employees
should examine hoses
for scrapes, cuts, corrosion,
kinks and general
deterioration, which may
provide an indication
that it is time to replace
the hose. Record all observations
in the maintenance
spreadsheet. If
it is determined that it is
FIGURE 3. Exceeding a hose's recommended bend radius can produce
undue strain and even result in premature failure
time to change the hose, the service
interval should be noted for future
reference. Over time, understanding
these intervals allows plant managers
to replace hoses before they fail.
If a hose does fail despite regular
inspections, employees should note
every detail, including the location
of failure on the hose, how severe
the break was and how the hose
was mounted. Recording such information
provides a roadmap for
determining why the hose failed and
how to prevent a similar problem in
the future.
Eliminate hose strain
Hoses can come under undue strain
during their operation due to several
common circumstances, including
the following:
* Twisting a hose or bending it on
more than one plane (Figure 2)
* Bending the hose beyond its
recommended radius (Figure 3)
* Bending too close to the hose/
fitting connection (Figure 4)
* Allowing insufficient hose length
so the hose is strained during impulses
(Figure 5)
* Failing to use elbows and adapters
to relieve hose strain on horizontal
end connections
(Figure 6)
FIGURE 2. Strain can occur when a hose is twisted or bent on
more than one plane
During regular inspections,
employees should
pay particular attention
to any unusual circumstances
that may
be putting unexpected
strain on the hose body.
If hoses are rubbing
against other equipment,
experiencing pulses, are
subject to external heat
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OCTOBER 2023
sources or are installed in straininducing
configurations, remediate
those conditions immediately. If left
unchecked, they could reduce the
lifetime of a hose or, in some cases,
cause outright failure.
Are protective covers required?
In some cases, hoses require
protective covers, including
the following:
* Thermosleeves, which protect
hoses from weld spatter and resist
deterioration from ultraviolet light
* Fire jacketing, which protects
hoses from temperature extremes
posed by internal system fluids
* Spiral guards, which protect
hoses against abrasion
* Armor guards, which keep
hoses from kinking and experiencing
abrasions
* Spring guards, which also help
to minimize kinking and abrasions
Importantly, hose covers do not
alter the technical data provided by
suppliers. Before deploying a hose
cover, it is crucial to understand the
operating temperature of each option
and what the cover does effectively.
For example, thermosleeves
may keep hoses safe from weld
splatter, but it will not protect them
from abrasion.
Inspection and replacement
As
replacement
intervals
reveal
themselves over time, a preventivemaintenance
schedule will eventually
come into focus. Though
replacement intervals may offer
good information about when a
hose may need to be replaced,
periodic inspections are still essential.
In the dynamic world of
33
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