Paper360 - May/June 2017 - 37

know very well-though it is often overlooked
by operations managers. This is the concept
of how the initiating cause of a functional
failure develops.
A bearing defect caused from normal fatigue
of a race will develop over a period of time
(OAPOT); a bearing defect caused by human
error (lubrication, overload, installation, damage, etc.) will occur suddenly. Understanding
how a cause of failure develops (OAPOT or suddenly) will determine which strategy we should
employ to mitigate it. For causes that develop
OAPOT, we will look for a P-F Curve and a
usable P-F interval; but for the causes that occur
suddenly, most of the mitigations we should
employ will be policy- or procedure-based.
As an example: for the cause of failure related
to fatigue we may use vibration analysis, but for
a lubrication error we should institute training/
standardization/controls. Yet it is very common
to determine that a failure has been caused by
sudden human error and then react by implementing a strategy that is appropriate for an
OAPOT-type cause.
See if this sounds familiar: A bearing failure occurs. The maintainer reviews previous
vibration analysis, which shows no signs of
a defect. The vibration team is adamant that

their program would catch any normal OAPOT
causes of failure, so this failure must be sudden
in nature. Yet the management team increases
the interval of vibration analysis instead of
digging into what caused the sudden (human
error) failure. Now we are wasting time taking additional vibration readings that are not
needed. We degrade the confidence of the vibration team, and we will not prevent this sudden
functional failure from reoccurring.
There is one additional way a cause of functional failure can occur, and it has to do with
protective devices: I call it "this only matters
if" (TOMI). The idea is that a failure of the
protective device only matters if the protected
function fails. For example, if you have a duty/
standby pump, the standby pump only matters if the duty pump fails. Under normal circumstance, you will not know if the standby
pump works unless you need it. The same holds
true for other protective devices such as smoke
detectors, spare tires, alarms, or light curtains.
For TOMI-type functional failures, we must
understand and determine how often the duty
system is failing, how often the protective device
is failing, and how often we are willing for both
devices to be functionally failed (remember,
"never" is unattainable). With these three pieces

of information, we can calculate how often we
must check our protective devices.
So, there you have the concepts every supervisor/planner/engineer must understand for
real reliability to begin:
1. The P-F interval
2. That criticality plays no role in
inspection frequency
3. The new definition of failure:
Functional Failure
4. The different types of causes of failure:
OAPOT, uddenly, or TOMI
If you have any questions or comments about
the concepts I have outlined in this article, I
would really like to hear from you. Feel free
to contact me directly by e-mail or through
the editor.
Jay Shellogg spent the last
16 years of his career working at a large pulp and paper
mill, primarily as a senior
environmental engineer
and maintenance/reliability
superintendent. During that
time he encountered many challenges; in his own
words, "Some I overcame, and some I didn't."
Contact him at jayshellogg@strategicmaint.com.

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20171:51 PM
20/04/17

37


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Table of Contents for the Digital Edition of Paper360 - May/June 2017

Setpoint
Over the Wire
Leadership for a Changing Industry
An Ode to Small
The Graying of the Paper Industry
Suppliers Reach Out to Mill Leaders
Making a Difference: 2017 TAPPI/PIMA Awards
RISI’s Asian CEO of the Year
TAPPISAFE Offers Solid Benefits for Mills, Contractors
Reinventing Varkaus
Failure Isn’t Just an Option—It’s Unavoidable
Blower Technology Proves Its Worth
TAPPI Journal Summaries
Global Study: Most People Highly Value Paper and Print
The Changing World of OCC
TAPPI News
ASPI News
Index of Advertisers
Paper360 - May/June 2017 - intro
Paper360 - May/June 2017 - ebelly1
Paper360 - May/June 2017 - ebelly2
Paper360 - May/June 2017 - cover1
Paper360 - May/June 2017 - cover2
Paper360 - May/June 2017 - 3
Paper360 - May/June 2017 - 4
Paper360 - May/June 2017 - 5
Paper360 - May/June 2017 - Setpoint
Paper360 - May/June 2017 - 7
Paper360 - May/June 2017 - Over the Wire
Paper360 - May/June 2017 - 9
Paper360 - May/June 2017 - 10
Paper360 - May/June 2017 - 11
Paper360 - May/June 2017 - An Ode to Small
Paper360 - May/June 2017 - 13
Paper360 - May/June 2017 - 14
Paper360 - May/June 2017 - 15
Paper360 - May/June 2017 - The Graying of the Paper Industry
Paper360 - May/June 2017 - 17
Paper360 - May/June 2017 - Suppliers Reach Out to Mill Leaders
Paper360 - May/June 2017 - 19
Paper360 - May/June 2017 - Making a Difference: 2017 TAPPI/PIMA Awards
Paper360 - May/June 2017 - 21
Paper360 - May/June 2017 - 22
Paper360 - May/June 2017 - 23
Paper360 - May/June 2017 - 24
Paper360 - May/June 2017 - 25
Paper360 - May/June 2017 - 26
Paper360 - May/June 2017 - 27
Paper360 - May/June 2017 - RISI’s Asian CEO of the Year
Paper360 - May/June 2017 - 29
Paper360 - May/June 2017 - 30
Paper360 - May/June 2017 - 31
Paper360 - May/June 2017 - TAPPISAFE Offers Solid Benefits for Mills, Contractors
Paper360 - May/June 2017 - 33
Paper360 - May/June 2017 - Reinventing Varkaus
Paper360 - May/June 2017 - 35
Paper360 - May/June 2017 - Failure Isn’t Just an Option—It’s Unavoidable
Paper360 - May/June 2017 - 37
Paper360 - May/June 2017 - Blower Technology Proves Its Worth
Paper360 - May/June 2017 - 39
Paper360 - May/June 2017 - TAPPI Journal Summaries
Paper360 - May/June 2017 - 41
Paper360 - May/June 2017 - Global Study: Most People Highly Value Paper and Print
Paper360 - May/June 2017 - 43
Paper360 - May/June 2017 - 44
Paper360 - May/June 2017 - 45
Paper360 - May/June 2017 - The Changing World of OCC
Paper360 - May/June 2017 - 47
Paper360 - May/June 2017 - TAPPI News
Paper360 - May/June 2017 - ASPI News
Paper360 - May/June 2017 - Index of Advertisers
Paper360 - May/June 2017 - cover3
Paper360 - May/June 2017 - cover4
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