Maintworld 2/2018

ASSET MANAGEMENT
Insignificant Minor Moderate Major Extreme Likelihood Detectability
0.5
Equipment
(EQR)
Minimal damage
to equipment. No
effect on other
equipment. Spare
held on site.
Moderate damage to
equipment. Minimal
damage to other
equipment. Spare held
in region.
Major damage to
equipment. Damage
to other equipment.
Spare available in
1 day.
Destruction
of equipment.
Destruction of other
equipment. Spare not
available in state.
Rare < 1%
Will only occur
in exceptional circumstances
in the
next 12 months
Confident > 90%
Frequent testing with
Condition Monitoring
and are confident that
faults will be detected
9
1
People (HSR)
Minor first aid.
No medical
treatment. Low
level short term
inconvenience or
symptoms.
Restricted work injury
(RWI), occupational
illness (OI) or medical
treatment injury
(MTI). Objective but
reversible disability/
impairment.
Loss time injury
(LTI). Moderate
irreversible
disability or
impairment to one
or more persons.
Single or multiple serious
injury. Severe irreversible
disability or impairment.
Single or multiple
fatality.
Unlikely 1-10%
Possible, but not
expected to occur
in the next 12
months
Likely 51-90%
CM in place, but not
extremely confident
that fault will be
detected
1
0.9
0.8
1
Environment
(EVR)
Production
(PPR)
Product
Quality /
Safety
Negligible spillage
or emissions
(technical ENCR)
Negligible plant
downtime. Output
targets affected
but not missed.
Net cost of issue
$0.5m ≤ $2m USD
Moderate product
quality issue or mildly
harmful food safety
issue.
Discharge to the
environment
outside of consent
conditions (external
ENCR rating Minor),
prosecution not
likely.
Plant downtime >
1 ≤ 2 days. Critical
output target
missed.
Net cost of issue
>$2m ≤ $5m USD
Significant product
quality issue or
harmful food safety
issue with potential
consumer illness or
discomfort.
Discharge to the
environment outside
of consent conditions
(external ENCR rating
Moderate). Infringement
fine likely, prosecution
possible.
Plant downtime > 2 ≤
5 days. Several critical
output targets missed.
Net cost of issue
> $5m ≤ $10m USD
Highly harmful product
safety issue with
potential single consumer
death or widespread
illness.
Major event,
pollution of air or
river, fish kill, public
outcry, prosecution
certain (external
ENCR Major).
Plant downtime
> 5 days. Several
critical output targets
missed by significant
margin.
Net cost of issue
>$10m USD
Highly harmful food
safety issue with
potential multiple
consumer deaths or
widespread serious
illness.
Possible 10-50%
Could possibly
occur in the next
12 months
Likely 51-90%
Will probably
occur in the next
12 months
Certain > 90%
Will almost
inevitably occur
int he next 12
months
Possible 10-50%
Some CM, but due to
test frequency and/
or technology, not
confident
Unlikely 1-10%
No CM, but local
operators and
inspectors may detect
signs of failure
No Warning < 1%
No condition
monitoring and no
local operators and
therefore no warning
6
21
1
Criticality ranking incorporating the consequence weighting and the assessment of likelihood and
detectability on each consequence of failure
FINAL CONSEQUENCE
38
Component criticality ranking
Although it has not been clearly stated,
thus far we have considered the asset as
a combination of components: for example,
a motor coupled to a gearbox which
drives a pump. Now it is time to take the
assets with the highest criticality ranking
and split them up into individual components.
It is quite likely that we will find
that the motor has a much lower criticality
ranking than the gearbox (assuming
that it is expensive and will have a longer
lead time), which may have a lower
criticality ranking than the pump (if the
failure of the pump could cause an explosion
and harm to the environment).
With this information we can better
determine which spares to hold, how to
prioritize maintenance, where to employ
condition monitoring, and much more.
RCM and FMECA
Once we divide our analysis into individual
components, we will identify
the components that pose the greatest
risk to the organization (and to the employees
and customers). Now it is time
to perform more detailed analysis of
each individual failure mode, the consequence
of each individual failure mode,
10 maintworld 2/2018
and the likelihood of each failure mode.
This is traditional reliability centered
maintenance (or failure modes, effects,
and criticality analysis), but at least we
have performed that analysis only where
it is warranted.
Back to the criticality
spectrum
And thus, we have our criticality spectrum,
with very basic system criticality
analysis at one end, and RCM/FMECA at
the other. Taking such an approach will
ensure that the critical components are
given the attention they require without
having to perform detailed analysis on
each and every component within the
facility.
Conclusion
While the above sequence has described
the transition process from a very basic
criticality analysis to a highly detailed
analysis based on criticality, when time is
available, we can circle back and review
the ranking provided to the least critical
assets, just to make sure we did not miss
anything. This is part of the continuous
improvement process. We should review
the criticality assigned to all assets as improvements
are made to reliability, our
ability to detect the onset of failure, and
the perceived consequences of failure.
The key is to determine the criticality
with as much detail as possible and then
use that information to prioritize and
justify everything from the reliability improvement
process to the maintenance
work that is performed on a daily basis.
The complete
criticality spectrum.