2. 2
Advanced Maintenance Management Level II
Presented by:-
Eng. Mohammed Hamed
Advanced Maintenance Management
Under supervision: Prof. Dr. Attia Gomaa
3. Advanced Maintenance Management 3
Content:
1. Overview on Predictive Maintenance Techniques
2. Vibration Basics and Machine Reliability
3. Spectrum Analysis & Faults Diagnosis Case Study
4. Basics of Oil Analysis
5. Oil Analysis Case Study
6. Ultrasound Technique
7. Infrared Analysis and its Usage Within the Industrial Processes
8. Introduction to RCM & FMEA
9. A Case of Reliable Improvement by Increasing Detection
7. Benefits of setting-up a PdM Program:
To detect what is out of the human sense.
To discover hidden failures.
To Detect early failures & monitor the machine
health condition.
To reduce Maintenance Costs.
As a useful tool to improve the machine reliability.
8. Most Commonly Used Techniques:
Four Tools Makes-Up 85% of any Condition Monitoring Program
10. Type of fault Vibration Temp Oil
Out of balance xxx ---- ----
Misalignment xxx x ----
Damage of bearing xxx xx x
Damage of gear box xxx x xx
Belt problems xx ---- ----
Motor problems xx x ----
Mechanical looseness xxx x x
Resonance xxx ---- ----
Why use Vibration Analysis?
11. One of the most benefits of a Condition Monitoring program is to
detect potential failures at early state.
(FailureResistance)
14. Advanced Maintenance Management 14
What is vibration?
Vibration can be defined as simply the cyclic
or oscillating motion of a machine or
machine component from its position of
rest.
Harmonics:
Frequency component at a frequency that is an integer (whole
number e.g. 2X. 3X. 4X, etc) multiple of the fundamental (reference)
frequency.
Frequency:
Is the no of cycles (vibrations) per second, measured by hertz
(HZ)
15. Vibration& reliability
Vibration analysis alone doesn’t improve reliability, root
cause analysis and acceptance testing can help.
There are two ways that we can utilize vibration to improve
reliability:
First , if we study the vibration we can often determine why the
fault condition developed in the first place; for example what
caused the crack to appear in the inner race of the bearing? If
we perform root cause failure analysis we can make chances to
our proactive so that the bearing don’t suffer the same fate in
the future.
16. Second, when we overhaul the machine, we can again use the
vibration analysis to check that the maintenance repair has been
made correctly; and that the machine is correctly aligned and
balanced, this called acceptance testing.
Vibration is still used to monitor the health of the machine,
but if we improved the reliability of the machine we will see
fewer faults conditions develop.
26. Taking readings in three directions gives more information
that helps in analysis as some defects comes with
predominant vibrations in a particular directions.
Axial is the direction parallel to the centerline of a shaft
or turning axis of a rotating part. Radial is that direction
toward the center of rotation of a shaft or rotor. The
Tangential measurement is that measurement that is
tangent or perpendicular to the radial transducer.
31. What are the faults that spectrum analysis can
tell us about?
Unbalance
Misalignment
Bent Shaft
Cocked Bearing
Foundation
Looseness
Motor Problems
Gear Problems
Mechanical
Looseness
33. Frequency
in terms of
RPM
Most likely
causes
Other possible causes and remarks
1x RPM Unbalance 1) Eccentric journals, gears or pulleys
2) Misalignment or bent shaft- if high axial
vibration
3) Resonance
4) Reciprocating forces
5) Electrical problems
2x RPM Mechanical
Looseness
1) Misalignment if high axial vibration
2) Reciprocating forces
3) Resonance
4) Bad belts if 2x RPM of belt
33
34. Frequency in terms
of
RPM
Most likely causes Other possible causes and
remarks
3x RPM Misalignment Usually a combination of
misalignment and excessive
axial clearances(looseness)
Less than
1x RPM
Oil whirl (less than ½
RPM)
1) Bad drive belts
2) Background vibration
3) Sub-harmonic resonance
Synchronous
(A.C. Line
Frequency)
Electrical
Problems
Common electrical problems
include broken rotor bars,
eccentric rotor, unbalanced
phases in poly-phase systems,
unequal air gap.
2x Synch.
Frequency
Torque pulses Rare as a problem unless
resonance is excited
34
35. Frequency in
terms of
RPM
Most likely causes Other possible causes and
remarks
High frequency
(not
harmonically
related)
Bad anti-friction
bearings
1) Bearing vibration may be
unsteady- amplitude and
frequency
2) Cavitations, recirculation and
flow turbulence cause random,
high frequency vibration.
3) Improper lubrication of journal
bearings (friction excited
vibration)
4) Rubbing
36. Frequency in
terms of
RPM
Most likely causes Other possible causes and
remarks
Many times
RPM
(harmonically
related freq.)
Bad gears
Aerodynamic forces
Hydraulic forces
Mechanical
looseness
Reciprocating forces
Gear teeth times RPM of bad gear
Number of fan blades times RPM
Number of impeller vanes times
RPM
May occur at 2,3,4 and
sometimes higher harmonics if
severe looseness
38. 1. Using Vibration Spectrum Analysis to Detect Machine Unbalance
For all types of unbalance, the FFT spectrum will show a
predominant 1. rpm frequency of vibration.
39. 39
Machine showing significant increase in vibration level at
frequency of 25hz indicating unbalance issue.
Spectrum chart
40. 2. Using Vibration Spectrum Analysis to Detect Machine Misalignment
Misalignment, just like unbalance, is a major cause of
machinery vibration. Some machines have been incorporated
with self-aligning bearings and flexible couplings that can
take quite a bit of misalignment. However, despite these, it is
not uncommon to come across high vibrations due to
misalignment. There are basically two types of misalignment:
50. Misalignment vs. bent shaft
Often, a bent shaft and dominant angular misalignment give
similar FFT spectrums. The vibrations are visible in both the
axial and radial vibration measurements. It is only with phase
analysis that these problems can be resolved further. In a
machine with a bent shaft, a phase difference will be noticed on
the two bearings of the same shaft. In the case of misalignment,
the phase difference is visible on bearings across the coupling.
51. 3. Detect Transmission Belt Fault Condition Using Spectrum Analysis
Equipment : Electric Motor
Speed : 1500RPM
Power : 10KW
V-Belts Type : SPC5300
Pulleys Diameter: 355mm
Belt Frequency = 3.142 (D/L) X (RPM/60)
Where D is the pulley diameter & L is the belt length
Belt Frequency=23.2HZ
From the tables of the v-belts specs, length is 1.2m
52. M NDE Horizontal 4.09 mm/sec
M NDE Vertical 0.57 mm/sec
M NDE Axial 01.99 mm/sec
M DE Horizontal 3.03 mm/sec
M DE Vertical 01.57 mm/sec
M DE Axial 02.12 mm/sec
52
54. When belts are worn, loose or mismatched, they may generate
harmonics of the belt frequency. Quite often, the 2× belt
frequency is dominant.
Amplitudes are normally unsteady, sometimes pulsing with
either driver or driven rpm. With timing belt drives, it is
useful to know that high amplitudes at the timing belt
frequency indicate wear or pulley misalignment.
60. It’s difficult to detect the exact reason of a bearing failure
without having the vibration test applied. The following is
a list of the common defect causes:
– Ordinary wear.
– Too high ambient temperature.
– Corrosion.
– Reduced lubrication.
– Misalignment.
– Vibrations.
– Damage due to transport.
– Bearing currents from frequency
converter drive.
4. Detect the Nature of Bearing Failure
61. Rough
defect
condition
in a
bearing
When a certain defect is present on a bearing element (example
of a rough defect is shown in the above figure )an increase in
the vibration levels at this frequency can be noticed, and that’s
why frequency-domain analysis of vibration reading is usually
carried out to determine the condition of motor bearings.
Frequency-domain or spectral analysis of vibration signal is the
most widely used approach for bearing defect detection.
Example
1500um
outer
race
defect
62. BPFO=Nb/2(1-Bd/PDcos α)x RPM
Formula to calculate the outer race defect frequency:
Where:
Bd=diamter of rolling element
PD=pitch diamter
α=the contact angel
Nb=no of rolling elements
RPM= the shaft rotating frequency.
Motor bearing specifications from the tables:
Shaft rotating frequency of 24Hz
Bearing having 9 balls of diameter (Bd)= 8.5mm
Pitch circle diameter (PD)= 38.5mm
Contact angle a of 0.
RPM= RPM/60
Calculations=9/2 x 24 x(1-0.22)
=84.24Hz
BPFO (Ball Pass Frequency , Outer race):
63. Outer race defect frequency 84.24Hz
Bearing Health Condition
0.68mm/s
66. Spectrum & Vibration Analysis
BPFO defect of the bearing can be measured at 84.24hz,
bearing vibration amplitude showing significant increase at
the bearing outer race frequency indicating outer race
defect.
Recommendation
It’s highly recommended to shutdown the machine to
replace the defected bearing.
69. 5. Using Vibration Spetrum Analysis to Detect Machine Looseness
If we consider any rotating machine, mechanical looseness
can occur at three locations:
1. Internal assembly looseness
2. Looseness at machine to base plate interface
3. Structure looseness.
70. A.Internal assembly looseness
This category of looseness could be between a bearing liner
in its cap, a sleeve or rolling
element bearing, or an impeller on a shaft. It is normally
caused by an improper fit
between component parts, which will produce many
harmonics in the FFT due to the nonlinear
response of the loose parts to the exciting forces from the
rotor.
71. B. Looseness between machine to base plate
This problem is
associated
with loose
pillow-block
bolts, cracks in
the frame
structure or
the bearing
pedestal
72. C. Structure looseness
This type of looseness is caused by structural looseness or
weaknesses in the machine’s feet, baseplate or
foundation.
When the soft foot condition is suspected,
an easy test to confirm for it is to loosen
each bolt, one at a time, and see if this
brings about significant changes in the
vibration. In this case, it might be necessary
to re-machine the base or install shims to
eliminate the distortion when the mounting
bolts are tightened again.
73. (Detection of Bearing Looseness)
Equipment data:
Machine Description: Centrifugal de-gasing fan
Horse Power: 350HP
Fan speed= 992RPM
Flow rate: 300,000 m3/h
No of bearing: 6 bearings
Bearing designation: 22222EK
77. Vibration Result Recommendation:
Check Bearing no. (4) for fixation problem with the
base. (Retighten bearing housing bolts & check
bearings internal clearance).
Maintenance work to be performed:
1-Retightining of bearing bolts & housing.
2-Monitor bearing condition with some other methods (use
ultrasonic)
78. How to Detect Electric Motor Faults by Vibration Spectrum Analysis?
Failure Percentage
Bearings 44%
Stator 26%
Rotor 8%
Others 22%
It’s evident that defects in the bearings represent the widest
source of failure to an induction motor, thus more focus was
needed on bearings defects in particular.
Rotor Shaft
79.
80. All gearboxes for (trucks, cars, stirrers, turbines,
industrial equipment…etc).
All engines that use oil (cars, trucks, heavy
equipment,….etc).
All hydraulic systems.
82. Terminologies
Flash Point: the point at which the oil will be turned into vapor
or begin to vaporize.
Pour Point: the lowest temperature at which the oil will flow.
TBN: is the total base number, illustrate the no of he active
additives left in the sample of oil to neutralize the acids. By
comparing the TBN of a used oil to the TBN of the same oil in
virgin condition, the user can determine how much reserve
additive the oil has left to neutralize acids. The lower the TBN
reading, the less active additive the oil has left.
83. The viscosity index is a measure of how much the oil's
viscosity changes as temperature changes. A higher viscosity
index indicates the viscosity changes less with temperature
than a lower viscosity index.
TAN: is the total acid number, present how this oil is getting
oxidized.
85. Wear particle analysis determines the mechanical
condition of machine components that are lubricated
Oil Analysis:
Sample
Survey
Results
Improvement
86. Oil Grade:
Oil Type:
Equipment Type:
Oil Specifications:
Viscosity@40degC
Viscosity@100degC
Total Base Number (TBN)
Total Acid Number (TAN)
Flash Point
87. Oil Manufacturer: Asmoil
Oil Grade : Synthetic Motor Oil SAE 5W-30
Oil type : Engine Oil
Filter type : Full Flow
Oil Analysis Report:
Example.1: Discuss the following report
88. Parameters Standard acc to
SAE for engine
grade 30
1-1-
2009
1-1-
2010
Viscosity@40C 90-110cSt 100 98
Viscoisty@100C 9.3-12.5cSt 11.5 8.6
Fuel Content % 0 0 5
Water Content % 0 0 2
TAN -------- ---------
--
----------
TBN 6-8 7 3.82
Flash Point rate for
Asmoil 5W-30 grade
375⁰F< 385 375
Rermark: cSt=Centi Stoke
89. Parameters Standard acc to
SAE for engine
grade 30
1-1-
2009
1-1-
2010
Viscosity@40C 90-110 100 98
Viscoisty@100C 9.3-12.5 11.5 8.6
Fuel Content % 0 0 5
Water Content % 0 0 2
TAN -------- ----------- ----------
TBN 6-8 7 3.82
Flash Point rate for
Asmoil 5W-30 grade
375⁰F< 385 375
Green color indicate good condition, yellow color indicate alarm
level, red color indicate that oil must be changed.
90. Recommendations based on the result:
Viscosity has been broken down at 100degC, oil should be
changed due to reduction in viscosity index number which
will reduce the friction resistivity of the oil.
Oil is contamination with fuel indicating leakage in the
piston rings.
Oil has water contents indicating failure head gasket or
worn cylinder head, check for compression ratio of your
engine.
TBN is below the oil standard, this indicate wear, oil must
be changed.
Flash point is below the oil number, oil can be vaporized
easily.
92. Sampling Methods:
The frequency of sample analysis from your equipment
depends on the machine type, machine application and
condition, operating environment and other variables. For
example, many machines that operate in harsh
environments, such as heavy equipment in mining or
construction, require short oil sampling intervals - every
100 to 300 operating hours
94. Condition Oil
program
Vibration
program
Correlation
Water in
oil
Strong Not
applicable
Water can lead to a rapid failure.
It is unlikely that a random
monthly vibration scan would
detect the abnormality.
Greased
bearings
Mixed Strong It makes economic sense to rely
on vibration monitoring for
routine greased bearing analysis.
Many lube labs do not have
enough experience with greased
bearings to provide reliable
Information.
Vibration VS Oil Analysis
95. Condition Oil
program
Vibration
program
Correlation
Greased
motors-
operated
valves
Mixed Weak Actuators are important
machinery in the nuclear
industry. Grease samples can be
readily tested, but it can be
difficult to obtain a
representative sample. It can be
hard to find these valves
operating, making it difficult to
monitor with vibration
Techniques.
Shaft
cracks
Not
applicable
Strong Vibration analysis can be very
Strong effective to monitor a
cracked
Shaft.
96. Condition Oil program Vibration
program
Correlation
Lubricant
condition
monitoring
Strong Not
applicable
The lubricant can be a
significant cause of failure.
Resonace Not
applicable
Strong Vibration program can
detect a resonance
condition. Lube analysis will
eventually see the effect.
Root Cause
Failure
Analysis
Strong Strong Best when both programs
work together.
97. Condition Oil
program
Vibration
program
Correlation
Gear wears Strong Strong Vibration techniques can link a
defect to a particular gear.
Lube
analysis can predict the type of
failure mode.
Alignment Not
applicable
Strong Vibration program can detect a
misalignment condition. Lube
analysis will eventually see the
effect of increased/improper
bearing load.
98. Advanced Maintenance Management 98
RCM Reliability Centered Maintenance
The RCM philosophy employs Preventive Maintenance (PM), Predictive Testing
and Inspection, Repair (also called reactive maintenance) and Proactive
Maintenance techniques in an integrated manner to increase the probability
that a machine or component will function in the required manner over its
design life cycle with a minimum of maintenance. The goal of the philosophy is
to provide the stated function of the facility, with the required reliability and
availability at the lowest cost. RCM requires that maintenance decisions be
based on maintenance requirements supported by sound technical and
economic justification.
99. A rigorous RCM analysis is based on a detailed Failure Modes and
Effects Analysis (FMEA) and includes probabilities of failure and
system reliability calculations. The analysis is used to determine
appropriate maintenance tasks to address each of the identified
failure modes and their consequence
As with any philosophy, there are many paths, or processes, that lead
to a final goal. This is especially true for RCM where the
consequences of failure can vary dramatically. Rigorous RCM
analysis has been used extensively by the aircraft, space, defense,
and nuclear industries where functional failures have the potential
to result in large losses of life, national security implications, and/or
extreme environmental impact.
Advanced Maintenance Management 99
Equipment or Maintenance Reliability Definition:
The instantaneous likelihoods of failure for a specific piece of equipment
during a specific time period.
100. RCM Analysis
The RCM analysis carefully considers the following questions:
• What does the system or equipment do; what is its function?
• What functional failures are likely to occur?
• What are the likely consequences of these functional failures?
• What can be done to reduce the probability of the failure, identify the onset of failure, or reduce the
consequences of the failure
• To ensure realization of the inherent safety and reliability levels of the equipment.
• To restore the equipment to these inherent levels when deterioration occurs.
• To obtain the information necessary for design improvement of those items where their inherent
reliability proves to be inadequate.
• To accomplish these goals at a minimum total cost, including maintenance costs, support costs, and
economic consequences of operational failures.
RCM Goals
Advanced Maintenance Management 100
101. Indentify System &
Boundary
Indentify Sub System
and Components
Examine Function
Identify Consequence of
Failure
Define Failure & Failure
Mode
------------------------
•System Input
•System Output
•Resources
•Constraints
To what level?
•Inconsequential
•Primary or Support
•Continuous or
Intermittent
•Active or Passive
Failures:
•Hidden Failures
•Potential Failures
Environmental, Health & Safety
Operational/Mission
•Availability
•Quantity
•Quality
Cost
------------------------
------------------------
------------------------
-----------------------
Reliability Analysis
Advanced Maintenance Management 101
102. Will the failure have a direct
effect on environment health
or safety
Is there an effective PdM
technology or approach?
Develop & schedule PdM task
to measure condition
Develop Condition Based Task
Will the failure have a direct
& adverse effect on mission
quantity or quality?
Will the failure result in other
economic losses (high cost
damage to equipment or
system)
No
Candidate For
Run to Failure
Is there an
effective Interval
Based Task
Develop &
schedule Interval
Based Task
Re design system
or accept the
failure risk
No
Yes
Yes
Yes
No
No
Yes
Yes
Maintenance Analysis
No
Advanced Maintenance Management 102
103. Will the failure of the system or equipment
item have a direct & adverse effect on safety or
critical mission function
Is this item
expendable
Can redesign solve the problem
effectively and cost effective
Accept Risk
Is there a PdM technology that will monitor condition
and give sufficient warning of an impending failure
Redesign
Is PdM cost and priority
justified
Define PdM task
and schedule
Is there an effective PM task that
will minimize functional failure
Define PM task
and schedule
Is installed redundant cost and priority justified
Install
Redundant Unit
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No Yes
Abbreviated decision
tree used to identify
the maintenance
approach
Advanced Maintenance Management 103
105. Asfour Training Session 105
TPM RCM
The main target is basically restoring the equipment
to the basic condition
Identify the failure modes and quantify the failures
as a cost.
Minimize the risk of failure and likelihood of failure
for critical/safety hazard components
and optimize the maintenance performance
Promote the use of planned or preventive
maintenance
Promote the use of predictive maintenance
Involve using autonomous maintenance to reduce
the maintenance resources usages and costs.
TPM includes eight pillars including safety,
education, quality, PM, autonomous maintenance,
support systems, focused improvement, and initial
phase management.
Involve using a special analysis process to determine
the best maintenance approach to use based on the
cost analysis. Then some tools can be used to
minimize the risk of failures for high safety,
production, cost components such as FMEA and
RCFA.
Increase the overall productivity of the process or
machine by enhancing maintenance, reducing
unscheduled downtime, increasing
production capacity, and quality (example OEE)
Improve the reliability and life time of the product or
machine. This can be done through improving the
maintenance, the manufacturing process, and the
design process by applying some total quality
management tools.
Invented by JIPM Invented by aerospace & aircraft industries
107. KPI Description
MTBF Mean Time Between Failure
No of failures addressed by root cause analysis >75%
Ratio of PM work orders to CM work orders generated by PdM inspection
OEE (Overall Equipment Effectiveness) Availability x Reliability x
Quality (85%)
Percent of Faults Found in Predictive maintenance Survey (Vib, IR, UT,
OA)
No of faults found/ No of
devices checked (target <3%
Percent of equipment covered by condition monitoring Target= 100%
Reliability of critical equipment 99%
Facility Availability >98%
Availability of critical equipment >98%
Percent emergency maintenance <5%
Percent planned maintenance 90%
Reliability KPIs
Advanced Maintenance Management 107
108. A proactive tool to minimize the risk of failures
Advanced Maintenance Management 108
109. Advanced Maintenance Management 109
FMEA can provide the answer to many problems:
•How can we prevent this problem from occurring again int he future?
•How can we minimize the risk of this potential failure?
•How can we produce an error-free product?
•How can we reduce the warranty costs?
•How can we improve the safety condition in the workplace?
110. What is Failure Mode Effect Analysis FMEA?
An FMEA is a systematic method for identifying and preventing product and process
problems before they occur. FMEAs are focused on preventing defects, enhancing safety
and increasing customer satisfaction.
FMEAs are conducted in the product design or process development stages, although
conducting an FMEA on existing products and processes can also yield substantial
benefits.
What is the purpose of a FMEA?
Preventing the process and product problems before they occur is the purpose of
Failure Mode Effect Analysis. Used in both the design and manufacturing process, they
substantially reduce costs by identifying product and process improvement early in the
develop process when changes are relativity easy and inexpensive to make.
Advanced Maintenance Management 110
111. FMEA as a part of a Comprehensive Quality System
Can FMEA be used a lone? While FMEAs can be effectively used a lone, a company
won’t get maximum benefit without systems to support conducting FMEAs.
Two things are necessary needed:
1. A reliable product or process data. Without this data, FMEA becomes a guessing
game based on opinions rather than actual facts. Without data the team may
focus on the wrong failure modes or missing significant opportunities to improve
the failure modes that are the biggest problems.
2. Documentation of procedures. In the absence of documents and procedures,
people working in the process could be introducing significant variation in to it by
operating it slightly different each time the process is run.
Advanced Maintenance Management 111
112. Advanced Maintenance Management 112
FMEA is one of the ISO 9001:2000 requirements as you must
have a system capable of controlling process that determine the
acceptability of your product or services.
113. Benefits of Failure Modes Effect Analysis “FMEA”
The object of an FMEA is to look for all of the ways a process or product can fail. A
product failure occurs when the product does not function as it should or when it
malfunction in some way.
•Contribute to improve design for product & process.
-Higher reliability
-Better Quality
-Increase Safety
•Contribute to cost saving.
-Decrease development time & redesign cost
-Decrease warranty costs.
-Decrease wastes
•Contribute to continuous improvement.
Advanced Maintenance Management 113
114. Advanced Maintenance Management 114
• System FMEA focuses on global system functions.
• Design FMEA focuses on components and subsystems.
• Process FMEA focuses on manufacturing and assembly processes.
• Service FMEA focuses on service functions.
Apply to: System, Process, Design, Service
Service engineers use FMEA to improve the lifecycle of the product and
lower its service costs by developing a proper maintenance program.
FMEA helps manufacturing engineers control the process and eliminate
errors during production, thus decreasing warranty costs and wastes.
115. Potential Applications:
•Equipment components & parts.
•Component proving process.
•Outsourcing/resourcing of product.
•Develop suppliers to achieve quality.
•Major process/ Equipment / Technology.
•Changes.
•Cost Reductions.
•New Product/ Design Analysis
•Assist in analysis in a flat Pareto chart.
Advanced Maintenance Management 115
116. Failure Modes:
•Any event which causes a functional failure.
Example failure modes:
•Bearing Seized
•Motor burned out
•Coupling broken
•Impeller jammed
Compressors Failure Modes :
•Discharge pressure low
-Air leakage
-leaking valves
-Defect gauge
Engines Failures Mode:
•Knocking
-Pistons hitting the head
-Crankshaft plays
-Oil pump not function
Advanced Maintenance Management 116
•Ways in which product or process can fail are called failure modes. The FMEA is a
way to identify the failures, effects, and risks within a process or product, and then
eliminate or reduce them.
117. Even the simple products have many opportunities for failure. For example, a drip coffee
maker. A relativity simple household appliance-could have several things fail that would
render the coffeemaker inoperable. Here are some ways the coffee make can fail:
• The heating element doesn’t heat water to sufficient temperature to brew coffee.
• The pump doesn’t pump water into the filter basket.
• The coffee maker doesn’t turn on automatically by the clock
• The clock stops working or running too fast or too slow.
• There is a short in the electrical cord.
• There is either not enough or too much coffee used.
Advanced Maintenance Management 117
119. Advanced Maintenance Management 119
Failures are not limited to problems with the product. Because
failures also can occur when the user makes a mistake. Those
types of failures should be included in the FMEA. Anything can
be done to ensure the product works correctly, regardless of how
the user operates it, will move the product closer to 100 percent
total customer satisfaction. The use of mistake-proofing
techniques, also known by its Japanese term poka-yoke, can be a
good tool for preventing failures related to user mistakes.
The goal is
120. The failure effect as it applies to the item under
analysis.
Ex. Water pump stop
The failure effect as it applies at the next higher
indenture level.
Ex. Water system pressure drop down.
The failure effect at the highest indenture level or total system.
Ex. System stop.
Local Effect
Next Higher Effect
End-Effect
Failure Effects Description
Advanced Maintenance Management 120
121. The team size should be between 4 to 6 persons. But the number
of people is dedicated by the number of areas affected by the FMEA
for example (manufacturing, maintenance, design, engineering,
material, technical service…etc). The customer add another unique
perspective and should be considered for team membership.
Team Leader:
The team leader is responsible for coordinating the FMEA process as
follow:
1. Setting up and facilitate meeting.
2. Ensuring the team has the necessary resources available.
Advanced Maintenance Management 121
122. Advanced Maintenance Management 122
3. Making sure the team is progressing toward the completion of
the FMEA process.
4. The team leader role is more like of a facilitator rather than
decision maker.
124. Advanced Maintenance Management 124
Select a high-risk process, then follow these steps.
1. Review the process: this step usually involves a carefully selected team that includes
people with various job responsibilities and levels of experiences. The purpose of an
FMEA team is to bring a variety of perspectives and experiences to the project.
2. Breakdown the system into components and sub-components.
3. Brainstorm potential failure modes.
4. List potential effects of each failure mode.
5. Assign a severity ranking for each effect.
6. Assign an occurrence ranking for each failure mode.
7. Assign a detection ranking for each failure mode.
8. Calculate the risk priority number (RPN) for each effect.
9. Prioritize the failure modes for action using RPN.
10. Take action to eliminate or reduce the high-risk failure modes.
11. Calculate the Resulting RPN as the failure modes are reduced or eliminated.
Steps of FMEA Process :
125. Advanced Maintenance Management 125
FMEA Working Sheet
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
Component/Item Name:
Function :
126. Step.1 Review the Process or Product
Advanced Maintenance Management 126
If the team is considering a product, they should review the
engineering drawing of the product.
If the team considering a process, they should review the operation
flowchart.
This is to ensue that everyone has the same understanding about the
process or product.
For a product, they should physically see the product and operate it.
For a process, they should physically walk through the process
exactly as the process flows.
127. Advanced Maintenance Management 127
Step.2 Breakdown the system into components and sub-components
If the system is a large system, like a water system that supplies an industrial process,
the pump can be a critical component inside the system. A motor pump is a critical
subcomponent because its failure can break down the entire process. The motor pump
should be broken down into more subcomponents that are likely to fail and will affect
the system, such as the motor’s bearings and the rotor shaft. The FMEA will be used to
prevent the probability of failure for each component or subcomponent.
128. Step.3 Brain Storm Potential Failure Modes
Advanced Maintenance Management 128
Once everyone in the team has an understanding about the
product or the process, team members should begin thinking
about the potential failure modes that could affect the
manufacturing process or the product quality.
Focusing should be on the different elements
(people, material, equipment, method,…etc).
Once the brainstorming is completed, the ideas
should be organized by grouping them into like categories. There
are many ways to group failure modes, they can be grouped by
type of failure (electrical, mechanical, user created). Where on the
product or process the failure occurs.
129. Advanced Maintenance Management 129
Main Rules of Brainstorm:
1. Do not comment on, judge or
critique ideas at the time they are
offered.
2. Encourage creative and offbeat
ideas.
3. The goal is to end up with a large
number of ideas; and evaluate ideas
later.
4. Each idea should be listed and
numbered exactly as offered, on a
flip chart.
5. Expect to generate at least 50 to 60
concepts in a 30-minute
brainstorming session.
130. Failure Mode & Effect Analysis FMEA
-How can this sub system fail to perform its function?
-The Way the failure occurred
-What will the operator see?
Advanced Maintenance Management 130
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
131. Step.4 List Potential Effects for Each Failure Mode
Advanced Maintenance Management 131
For some of the failure modes, there may be one effect, while for
other modes, there may be several effects.
This information must be through because it will feed into the
assignment of the risk ranking for each of the failure.
Tips:
1. One failure mode could have several effects. For example, an electrical cutoff in the home
could stop the refrigerator and damage food or prevent you from doing work on the
computer.
2. Several failure modes could have one effect. A dead car battery or tire failure has the same
effect on your vehicle – it will be difficult to make it to work on time with such a failure early
in the morning.
3. The team must determine the end-effect each failure mode has on the system or the process.
This means examining how each failure affects the entire system, the facility or the other
connected processes.
132. Failure Mode & Effect Analysis FMEA
-What happen when failure mode occurs?
-Immediate consequences of a failure on operation, function or
functionality, or status of some item.
Advanced Maintenance Management 132
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
133. Steps 5-7 Assign Severity, Occurrence, and Detection Rankings
Advanced Maintenance Management 133
Each of these three rankings is based on 10-point scale, with 1 being
the lowest ranking, and 10 the highest.
134. Failure Mode & Effect Analysis FMEA
Effect of failure is determined by the worst case outcome with
respect to safety and environment impact, production
availability and direct economic cost and all that in numerical
measure which are identified from ranking criteria
Advanced Maintenance Management 134
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
135. Failure Mode & Effect Analysis FMEA
Safety and Environment severity degree
Impact degree on availability of Production
Impact degree on Cost
Advanced Maintenance Management 135
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
136. Description of Failure Effect Effect Ranking
No reason to expect failure to have any effect on Safety, Health, Environment or Mission. None 1
Minor disruption of production. Repair of failure can be accomplished during trouble call. Very Low 2
Minor disruption of production. Repair of failure may be longer than trouble call but does
not delay Mission.
Low 3
Moderate disruption of production. Some portion too of the production process may be
delayed.
Low to
Moderate
4
Moderate disruption of production. The production process will be delayed. Moderate 5
Moderate disruption of production. Some portion of production function is lost.
Moderate delay in to High restoring function.
Moderate to
High
6
High disruption of production. Some portion of production function is lost. Significant
delay in restoring function.
High 7
High disruption of production. All of production function is lost. Significant delay in
restoring High function.
Very High 8
Potential Safety, Health or Environmental issue. Failure will occur with warning. Hazard 9
Potential Safety, Health or Environmental issue. Failure will occur without warning. Hazard 10
Severity Ranking Criteria
Advanced Maintenance Management 136
137. Advanced Maintenance Management 137
Step.6 Assign an occurrence ranking for each failure mode
The best method for determining the occurrence ranking is to use
actual data from the process. This may be in the form of failure logs.
When actual failure data are not available, the team must estimate
how often a failure mode may occur, The team can make better
estimate on how likely a failure mode is to occur and at what
frequency by knowing the potential cause of failure. Once the
potential causes have been identified for all of the failure modes, an
occurrence ranking can be assigned even if the failure data are not
exist.
138. Failure Mode & Effect Analysis FMEA
For each failure mode there may be several failure causes. Assign a Cause for each
failure mode.
Select only potential failure to get failure causes.
Use Why Why Technique to get the root causes.
Identifying the failure cause can be the second option to determine the occurrence if
no data is available in the form of failure logs.
Advanced Maintenance Management 138
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
139. Failure Mode & Effect Analysis FMEA
The probability of failure Occurrence during the expected life of the
system “potential occurrence”
Advanced Maintenance Management 139
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
140. Rank Freq Description
1 1/10,000 Remote probability of occurrence; unreasonable to expect failure to occur
2 1/5,000 Low failure rate; similar to past design that has, in the past, had low failure rates for given volume or load
3 1/2,000 Low failure rate; similar to past design that has, in the past, had low failure rates for given volume or load
4 1/1000 Occasional failure rate; similar to past design that has, in the past, had similar failure rates for given volume or
load
5 1/500 Moderate failure rate; similar to past design that has, in the past, had moderate failure rates for given volume or
load
6 1/200 Moderate failure rate; similar to past design that has, in the past, had moderate failure rates for given volume or
load
7 1/100 High failure rate; similar to past design that has, in the past, had high failure rates that have caused problems
8 1/50 High failure rate; similar to past design that has, in the past, had high failure rates that have caused problems
9 1/20 Very High failure rate; almost certain to cause Problems
10 1/10 Very High failure rate; almost certain to cause Problems
Occurrence Ranking Criteria
Operating hours based on the automotive industry benchmark.
Ranking can be determined based on historical data or similar system
benchmarking
Advanced Maintenance Management 140
141. Advanced Maintenance Management 141
Step.7 Assign a detection ranking for each failure mode and/or
effect
First, the current control should be listed for all of the failure
modes, or effects , and then the detection rankings assigned.
*If one failure mode or effect has several causes, detection
and occurrence rankings should be assigned based on these
causes. When potential causes are eliminated, the risk of
failure is lowered.
142. Current control/fault detection methods applied to detect this failure. This will help
assign the detection ranking. Each detection method should be assigned for each failure
mode or effect.
Advanced Maintenance Management 142
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
143. Failure Mode & Effect Analysis FMEA
Probability that a failure of mode will be Detected using the control
methods that are in place.
Advanced Maintenance Management 143
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
144. Rank Description
1-2 Very high probability of detection
3-4 High probability of detection
5-7 Moderate probability of detection
8-9 Low probability of detection
10 Very low probability of detection
Detection Ranking Criteria
Advanced Maintenance Management 144
145. Step.8 Calculate the Risk Priority Number RPN
Advanced Maintenance Management 145
Risk Priority number= Severity x Occurrence x Detection
This number alone is meaningless because each FMEA has a
different number of failure modes and effects. However, it can
serve as a gauge to compare the revised RPN once the
recommended actions has been instituted.
146. Failure Mode & Effect Analysis FMEA
Risk Priority Number Calculation
Occurrence
X
Severity
X
Detection
RPN= O x S x D
Advanced Maintenance Management 146
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
147. RPN Calculation Benefits:
•Contribute in Risk Assessment.
•Compare components to determine priority for corrective action.
What is RPN?
The Risk Priority Number (RPN) methodology is a technique for
analyzing the risk associated with potential problems identified
during a Failure Mode and Effects Analysis (FMEA)
Advanced Maintenance Management 147
148. Assessing the risk priority number.
Each potential failure mode or effect is rated in each of these three
factors on a scale ranging from 1 to 10. By multiplying the ranking a
risk priority number RPN can be determined for each potential
failure mode and effect.
The RPN will range from 1 to 1000 for each failure mode. It is used to
rank the need for corrective action. Those failure modes with the
highest RPN number should be attended first. Although the special
attention should be given when the severity ranking is high from (9
to 10) regardless of the RPN.
Once a corrective action is takes, a new RPN is determined . This
new RPN is called the resulting RPN.
Advanced Maintenance Management 148
149. Step.9 Prioritize the Failure Modes for Action
Advanced Maintenance Management 149
Failure modes should be prioritized by ranking them in order, from
the highest risk priority number to the lowest. Chances are that you
will find that the rule 80/20 rule applied with the RPNs.
The team must now decided which item to work for. Usually it helps
to set a cutoff RPN (cutoff point), where any failure modes with an
RPN above that point are attended to. Those below the cutoff are left
alone for the time being.
Tip:
High-risk numbers should be given attention first; then you can pay attention to the
severity rankings. Thus, if several failure modes have the same risk priority number, that
failure mode with the highest severity should be given more priority.
150. Failure Mode & Effect Analysis FMEA
Appropriate maintenance action, appropriate maintenance task
Corrective actions may include: reduce the severity of occurrence ,or increase
the detection probability
Advanced Maintenance Management 150
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
151. Step.10 Take Actions to eliminate or Reduce the High-Risk
Failure Modes
Advanced Maintenance Management 151
This is organized using the problems-solving approaches and
implement actions to reduce or eliminate the high risk failure
modes.
Often the easiest way to make an improvement to the product or
process is to increase the detectability of the failure, thus lowering
the detection rate.
Increase the detection rate can be done though assigning a schedule
PM action, use a proper condition monitoring program or consider a
mistake proofing method in the design. For example, ac computer
software will automatically warn incase of low disk space.
152. Advanced Maintenance Management 152
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
Appropriate actions taken to reduce the risk of failure
153. Advanced Maintenance Management 153
Step.11 Calculate the Risk Priority Number RPN as the High
Risk is Removed
Once actions have been taken to reduce the risk priority number, a
new ranking for the severity, occurrence, and detection should be
calculated. And a resulting RPN is calculated.
Expectation is at least 50 percentage reduction in RPN with the
FMEA approach.
There will always be a potential for failure modes to occur. The
question the company must ask is how much relative risk the team
is willing to take. That answer might depend o the industry and the
seriousness of the failure. For example, in the nuclear industry, there
is a little margin for errors,; they can’t risk a disaster occurring. In
other industries, it may be acceptable to take the high risk.
154. Advanced Maintenance Management 154
Item Function
Failure
Mode
Failure
effect
Severity
Failure
Cause
occurrence
Current
Controls
Detection
RPN
Recommendation
Take
action
Resulted
S O D
RPN
NEW RPN based on the new Severity, Occurrence, and Detection rankings
155. Advanced Maintenance Management 155
Failure mode Failure Effect Failure Effect
(System)
Failure Effect (End) Failure cause
Level 1
Root cause
Fan operate
with high
vibration
level
Equipment
damage/breakdown
Unexpected plant
shutdown
Major production
losses
Bearing fails Poor Maint
Equipment
damage/breakdown
Unexpected plant
shutdown
Major production
losses
Housing wear Poor Maint
Equipment
damage/breakdown
Unexpected plant
shutdown
Major production
losses
Unbalance fan
blade
Poor Maint
Equipment
damage/breakdown
Unexpected plant
shutdown
Major production
losses
Looseness in
foundation
Poor Maint
Equipment
damage/breakdown
Unexpected plant
shutdown
Major production
losses
Shaft wear Poor Maint
156. Item name Failure mode Failure
Effect (local)
Failure
Effect
(System)
Failure
cause
Failure
Cause
Root cause
Oil
1.Short circuit
in transformer
Functional
stop
Production
losses
Particles in
the oil
Overheated
Bad
Maintenance
Functional
stop
Production
losses
Water in the
oil
Overheated
Bad
Maintenance
Aging
Tap
Changes
2-Can’t change
voltage level
Functional
stop
Production
losses
Mechanical
damage Wear
Life time/
maintenance
Ex.2 Transformer
Advanced Maintenance Management 156
157. Ex.3 Water System
Function Functional failure/failure modes Causes
Provide water to the industrial
process
Total loss of pressure, volume &
flow
Pump failed
Motor failed
Valve out of position
Electric Motor
Function Functional failure/failure modes Causes
Drive the water pump Burn out
Circuit Breaker tripped
Bearing seized
Insulation Rotor
Insulation Stator
Failure mode Failure Cause Sources of failure/causes Causes
Bearing seized,
this include
bearing, seals,
lubrication
Lubrication
Contamination
Supply dirty
Sealing failed
Wrong type
Procedure wrong
Supply information wrong
Tool little
Human error
Procedure error
Too much
Human error
Procedure error
Motor Bearing
Advanced Maintenance Management 157
158. Failure effect Severity Causes Root
Cause
Occurrence
Current
fault
detection
methods
Detection
RPN Actions
Local sys end S A C
Seal failed
Seal
failed
Motor
shutdown
System
shutdown
TPL
Procedure
wrong
Lack of
trainingHuman error
Human error
Final Table
Advanced Maintenance Management 158
159. Consequence or Severity
Probability
or frequency (1)
Low
(2)
Medium
(3)
High
(1)
Low
(2)
Medium
(3)
High
1
L
2
L
3
M
6
H
4
M
2
L
9
H
6
H
3
M
It’s important to design your own matrix
Risk=Probability x Severity
Advanced Maintenance Management 159
162. Electric Distribution Transformer
Equipment Information
Equipment Type : Distribution Transformer
Technical Specs : 11KV, 2.5KV
Function : Transform electric voltage from 11KV to 400V
System : Electric station- Supply Glass Furnaces
Availability of standby system: Generators
Working intervals : 1-2 seconds
Effectiveness : Avoid furnace damage, but medium productivity
Advanced Maintenance Management 162
163. Advanced Maintenance Management 163
The electric transformer is considered critical because a failure
causes high production losses – $5,000 an hour. A standby
generator could keep the furnace running if the transformer failed.
The standby was sufficient to avoid damaging the furnace but did
not supply enough electricity to continue production.
166. Advanced Maintenance Management 166
Current Control/Prevention methods
PM type Component/Item PM Level
Visual inspection
Oil level Monthly
Silica gel Monthly
Cooling fans Monthly
Temp & gauges Monthly
Cleaning
External body of the
transformer
Monthly
Tightening Cables Monthly
Measurements
Voltage Semi annual
Ampere Semi annual
Sampling Oil Annually
167. Advanced Maintenance Management 167
Failure type Frequency per year
Oil heated 3
Short circuit 2
Volt regulation function error (tap
changers fault)
3
Working condition= 24 hours
Failure Log History
168. Component Name & Function: Bushing, supply high voltage
Failure
Mode
Failure
Effect
Severity
Failure
Causes
Failure Cause Failure Causes
Failure
Cause
Occurrence
Current
control
detection/pr
evention
methods
Detection
RPN
Short
circuit
Equipmentshutdown
4
Fault in
insulation
material Water
penetration
or dirt
Inelastic gasket Aging
1
Visual
inspection
and cleaning
6 24
Lack of
maintenance 1 6 24
Damage
bushing
Sabotage
stone, crash
or
Careless
handling
1 4 16
Analysis
Advanced Maintenance Management 168
Recommendation Take actions
Result
S O D RPN
Increase inspection & detectability
Use infrared camera & ultrasound for
high detection ability
4 1 2 8
4 1 2 8
169. The function of the bushings is to
isolate electrical between tank and
windings and to connect the windings
to the power system outside the
transformer
Advanced Maintenance Management 169
170. Component Name & Function: Tank , enclose oil, protect active parts
Failure
Mode
Failure
Effect
Severity
Failure
cause
Failure
Cause
Failure
Cause
Failure Cause
Occurrence
Current
controls
Detection
RPM
Leakage
Equipmentshutdown
4
Tank
Damage
(Rupture)
Material/
method
Inelastic
gasket or
corrosion
Aging 1
Visual
inspection
5 20
Insufficient
maintenance 1 5 20
Mechanica
l damage
High
pressure
due to gas
generation
Arcing 1
None
10 40
Careless
handling
1 1 4
Advanced Maintenance Management 170
Recommendation Take actions
Result
S O D RPN
Increase inspection & detectability
Use ultrasound for detection of
arcing phenomena
4 1 1 4
4 1 1 4
4 1 1 4
171. The tank is primarily the container of
the oil and a physical protection for the
active part of the transformer. It also
serves as support structure for
accessories and control equipment. The
tank has to withstand environmental
stresses, such as corrosive atmosphere,
high humidity and sun radiation. The
tank should be inspected for oil leaks,
excessive corrosion, dents, and other
signs of rough handling.
Advanced Maintenance Management 171
172. Component Name & Function: Core, carry magnetic flux
Failure Mode Failure Effect
Severity
Failure Cause Failure Cause
Occurrence
Current Control
Detection
RPN
Loss of
efficiency
(reduction of
transformer
efficiency)
Lower voltage,
production
disturbance
4
Mechanical
failure
DC magnetization
1
Basic
measurements
4 16
Displacement of the
core steal during
construction
(construction fault)
1 4 16
RPN=S x O x D=16
Advanced Maintenance Management 172
No Recommendation or actions will be taken here.
174. Failure
Mode
Failure
Effect
Severity
Failure cause Failure Cause Failure Cause
Occurrence
Current
Controls
Detection
RPN
Short
circuit
Equipmentshutdown
4
Fault
insulation
Generation of
copper sulfide 1 8 32
Hot spot Low oil quality
1
Oil sampling
1 4
Mechanical
damage
Movement of
transformer
Ageing of
cellulose 1
None
5 20
Transient
overvoltage
Short circuit in
the net
1 5 20
Connection of
transformer
1 5 20
Lightning 1 5 20
Construction
fault 1 5 20
Component Name & Function: Winding, carry current
Advanced Maintenance Management 174
175. Advanced Maintenance Management 175
Recommendation Take actions
Result
S O D RPN
Increase inspection & detectability
Use ultrasound for detection of
winding problems
4 1 2 8
4 1 2 8
4 1 2 8
4 1 2 8
4 1 2 8
4 1 2 8
176. The windings belong to the active part of a transformer, and their
function is to carry current. The windings are arranged as cylindrical
shells around the core limb, where each strand is wrapped with
insulation paper. Copper is today the primary choice as winding material.
In addition to dielectric stresses and thermal requirements the windings
have to withstand mechanical forces that may cause windings
replacement. Such forces can appear during short circuits, lightnings,
short circuits in the net or during a movement of the transformer
Advanced Maintenance Management 176
177. Failure
Mode
Failure
Effect
Severity
Failure cause
Failure
Case
Failure Cause Failure Case
Occurrence
Current
Controls
Detection
RPN
Oil
Equipmentshutdown
4
Short circuit in
transformer
Particles
in the oil
Overheated
Pump failure,
Dirty
particles in
the oil
2
Visual
monitoring of
gauges and oil
sampling
4 32
Water in
the oil
Overheated
or aging
Overheated
Oil is not
cooled
Oil,
circulation
out of
function,
or
Air/Water
cooling is out
of function
Fan/Pump
failure 2 4 32
Component Name & function: Oil, the oil serves as both cooling medium and
part of the insulation system
Advanced Maintenance Management 177
178. Advanced Maintenance Management 178
Recommendation Take actions
Result
S O D RPN
Increase oil sampling frequency
1. Sample oil every 6 months
2. Increase detectability with
infrared camera inspection
4 1 2 8
4 1 2 8
179. The transformer oil is a highly refined product from
mineral crude oil and consists of hydrocarbon
composition of which the most common are paraffin,
naphthenic, and aromatic oils. The oil serves as both
cooling medium and part of the insulation system. The
quality of the oil greatly affects the insulation and cooling
properties of the transformer. The major causes of oil
deterioration are due to moisture and oxygen coupled
with heat. Another function of the oil is to impregnate the
cellulose and isolate between the different parts in the
transformer.
Advanced Maintenance Management 179
182. The function of a on-load tap-changer
(OLTC) is to regulate the voltage level
by adding or subtracting turns from the
transformer windings
Advanced Maintenance Management 182
183. Component Name & Function: Solid Isolation, is cellulose based products such as
press board and paper. Its function is to provide dielectric and mechanical
isolation to the windings.
Failure
Mode
Failure
Effect
Severity
Failure cause Sources of failure Failure Cause
Occurrence
Current
Controls
Detection
RPN
Can’t
supply
insulation
EquipmentShutdown
4
Mechanical
damage
Short circuit,
Ageing of cellulose 1
None
10 40
Movement of transformer
fault in
insulation
material
Ageing of cellulose 1 10 40
Hot spot
Low oil quality, or
Overload 1 1 4
Generation of copper sulfide
1 10 40
Advanced Maintenance Management
183
184. Advanced Maintenance Management 184
Recommendation Take actions
Result
S O D RPN
Increase inspection & detectability
Use ultrasound for detection of
winding problems
4 1 2 8
4 1 2 8
4 1 2 8
185. The solid insulation in a transformer is
cellulose based products such as press
board and paper. Its function is to
provide dielectric and mechanical
isolation to the windings.
Advanced Maintenance Management 185
186. Part/Item RPN
Bushing
16
16
16
Tank
20
20
40
4
Core
16
16
Winding
4
4
20
RPN Analysis for Transformer Components
Advanced Maintenance Management 186
Part/Item RPN
Winding
20
20
20
Oil
32
32
Tap Changers 36
Solid Insulation
40
40
4
40
Total 492
A cutoff point of RPN 16 can be set because over 50% of the
failure modes are above this number.
187. Total Risk Priority Number= 492
Recommendations
1. Increase the detection probability for the following failures:
-Winding insulation
-Tap changers
-Oil condition
-Insulation breakage
-Bushing insulation failure
-Tank corrosion/leakage
2. Fit more generators to avoid production losses upon transformer
failure (we will need more specially if the whole furnaces are
working).
Corrective Actions (stage 1):
1. Usage of thermal camera to monitor the winding, tap changers, oil temp,
insulation, bushing and tank corrosion.
2. Increase visual inspection capability for the tank.
Advanced Maintenance Management 187
190. Expected Total Risk Priority Number after applying the corrective actions
Corrective Actions (stage 2):
Use the Ultrasound detection to detect winding problems & isolation.
Expected Total Risk Priority Number after applying the corrective actions
(stage 1 &2): Supportive for early detection
RPN Reduction %=R initial – R revised/
=492-184/492
=62%
R initial
Increase inspection reduce the risk of failure
Thermal
Camera
Advanced Maintenance Management 190
191. Advanced Maintenance Management 191
The improvements that yielded success included using ultrasound to detect
issues, increasing the frequency of oil sampling and using infrared analysis
to detect mechanical damage.
193. Remember FMEA is a Team Work Job! Team Members for FMEA:
•Process Engineer
•Operators
•Quality
•Safety
•Maintenance
•Product engineer
•Customer
•Supplier
Advanced Maintenance Management 193
194. Design of FMEA Sheet
Advanced Maintenance Management 194
196. Advanced Maintenance Management 196
An FMEA process can trigger a number of such actions to improve a product’s service or
maintenance processes. They include, but are not limited to:
Increase the detection rate of high-risk failures using a proper technique to monitor
conditions.
Increase the inspection rate for a specific component or part.
Modify the routine maintenance program.
Increase the frequency of replacing a specific spare part.
Modify the preventive maintenance schedule.
Change a spare part supplier.
Redesign a specific part in the system – or redesign the whole system.
Use different types of materials or spare parts.
198. Advanced Maintenance Management 198
Failure mode and effects analysis can maximize a product’s reliability. But don’t mistake
it as a standalone tool. For example, to determine occurrence ratings, FMEAs rely on the
failure log history, and the documentation process also is important. Problem-solving
techniques like “five whys,” brainstorming, fault-tree analysis and Pareto analysis must
be engaged. These techniques will help determine potential failure modes; assign the
severity, occurrence and detection rankings; and provide solutions or actions to
eliminate those failures.
Other Quality Tools and FMEA
199. Advanced Maintenance Management 199
Eng. Mohammed Hamed Ahmed Soliman
The American University in Cairo
Email: mhamed206@yahoo.com
m.h.ahmed@ess.aucegypt.edu
Tel: +201001309903
https://eg.linkedin.com/in/mohammedhamed
References:
Raymond J. Mikulak, Robin McDermott. (2008). The Basics of FMEA. Productivity Press; 2
edition
Robert T. Amsden and Davida M. Amsdenand. (1998). SPC Simpliefied: Practical steps to
quality. Productivity Press; 2 edition
200.
201. What is ultrasonic?
Ultrasound is cyclic sound pressure with a frequency greater
than the upper limit of human hearing, excess of 20,000 cycles
(hertz) per second (20KHZ).
Ultrasonic is a predictive maintenance technique and one of the non-
destructive testing tools that used in the field of industry to detect early &
hidden equipment failures.
So by definition, ultrasound is totally undetectable by human ears unless
aided by instruments capable of translating ultrasound to audible sound.
In the marketplace, these instruments are commonly known as ultrasonic
detectors and have been used for various maintenance related functions
for over 25 years.
Audible
Ultrasound
202. What is the difference between Ultrasonic &
Vibration??
Vibration is a low frequency method that can detect
bearing failures and the reason of this failure.
Ultrasonic is a high frequency vibration method
(ultrasonic vibration) that can detect the degrees of
bearing failures & wears, it can also detect the lubrication
problems of the bearing.
One of the most advantages of using ultrasonic over
vibration, is that ultrasonic can reveal the lubrication
problems and provide a very early warning of bearing
faults.
203. Overview of the Instrument
Lightweight and portable, ultrasonic translators are often
used to inspect a wide variety of equipment. Some helpful
accessories are supplied with the instrument too.
Transducer
Long range
module
Rubber
focusing probe
Stethoscope
module
Headphones Scanning
module
217. CORONA
TRACKING
ARCING
GOOD FOR MEDIUM and HIGH VOLTAGE
26.8
24.4
*>28.4°F
*<23.0°F
23.0
24.0
25.0
26.0
27.0
28.0
UE SYSTEMS INC. All Rights Reserved
222. 1. Ultrasound emissions are directional.
2. Ultrasound tends to be highly localized.
3. Ultrasound provides early warning of impending mechanical
failure
4. The instruments can be used in loud, noisy environments
5. They support and enhance other PDM technologies or can
stand on their own in a maintenance program
6. Test hazard equipments from long distances.
7. Discover early failures without stopping the equipments.
Advantages of Ultrasonic
223. 1. Surface to be tested must be ground smooth and clean
2. Skilled and trained operator is required.
3.Quite expensive method.
Disadvantages of Ultrasonic
224. This equipment can usually store the measurements to an
onboard memory chip and transmit the data to PC software.
225. Treatment and measurements of signal
Ultrasonic or acoustic vibration is energy created by the
friction between moving components (bearings, couplings,
gear mesh, etc…). This energy is really an AC voltage or
current that is at best, highly unstable and erratic. To provide
useful data for acoustic vibration monitoring this energy must
be made linear for repeatability purposes. A quality ultrasonic
detector uses True RMS conversion techniques to accomplish
this. RMS means “Root Mean Squared.” It’s a way of measuring
an AC voltage by means of taking the root of mean squared
samples. Basically, True RMS measurement is a technique that
provides consistent theoretically valid measurements of
electrical signals derived from mechanical phenomena such as
strain, stress, vibration, shock, expansion, bearing noise, and
acoustic vibration.
226. The electrical signals produced by these mechanical actions
are often noisy, non-periodic, non-sinusoidal, superimposed
on DC levels, and require True RMS for, valid, accurate, and
repeatable measurements
227.
228. Infrared monitoring and analysis has the widest range of
application (from high- to low-speed equipment), and it can
be effective for spotting both mechanical and electrical
failures. It also requires minimum skills for analysis.
Everything on this planet contains thermal energy and therefore
has a specific temperature. This thermal energy is emitted from
the surface of the material. This energy is called is infrared (IR)
radiation. The amount of IR radiation emitted at a certain
wavelength, from the surface of an object, is a function of the
object's temperature. This is a very important concept, since it
implies that one can calculate the temperature of an object by
measuring the infrared radiation emitted from it.
229. Detectors in the infrared camera convert this incoming
infrared energy from the infrared spectrum to the visual
spectrum so we can see the infrared energy
Infrared Thermography is the technique for producing a visible
image of invisible (to our eyes) infrared energy emitted by
objects
232. Measurements are:
Non-contact.
Obtained without disturbing production.
Applies to all type of equipment.
Reliable data
Quickly identifies specific location
Apply to most all conditions
233. Average downtime cost:
Lost Revenues
Industry Sector Revenue/Hour
Chemicals $704,101
Construction & Engineering $389,601
Electronics $477,366
Energy $2,817,846
Food & Beverage $804,192
Manufacturing $1,610,654
Metals/natural resources $580,588
Pharmaceuticals $1,082,252
Utilities 643,250
237. Electromechanical & Mechanical Systems
Commonly inspected components
• Pumps
• Fans
• Heat Exchangers
• Gearboxes
• Bearings
• Drive belts
• Motors
Typical reasons for temperature hotspots or deviations
• Bearing problems - lubrication, wear, etc.
• Bad alignment
• Bad cooling- due to reduced airflow
• Friction due to wear, misalignment or inadequate
lubrication
264. •IR can identify leaking
bypass lines and improper
operation (must monitor).
•One must know the trap
cycle of operation.
•Comparison between like
equipment that is operating
the same often confirms
problems.
•Use Ultrasonic Acoustics to
confirm problems
118.6°F
361.0°F
150
200
250
300
350
SP01
80.2°F
103.2°F
85
90
95
100
SP01
Steam trap stuck open.
Steam
trap
working
normally
.
Steam
trap by-
pass
leaking.
Steam Traps
283. Missing insulation in a
residential dwelling wall
costs the occupants
hundreds of dollars each
year in heating and
cooling.
House Insulation
Inspection
289. Aircraft Inspections
Composite aircraft
materials are extremely
sturdy and lightweight.
These materials are vital
to aircraft performance
and airworthiness.
However, the honeycomb
structure of this material
presents a potentially
dangerous problem:
water ingress
292. It shows a visual picture so temperatures over a large area
can be compared.
It is capable of catching moving targets in real time.
It is able to find deteriorating, i.e., higher temperature
components prior to their failure.
It can be used to measure or observe in areas inaccessible
or hazardous for other methods.
It is a non-destructive test method.
It can be used to find defects in shafts, pipes, and other
metal or plastic parts.
It can be used to detect objects in dark area.
Advantages of Thermography
293. Due to the low volume of thermal cameras, quality cameras
often have a high price range (often US$6,000 or more)
Images can be difficult to interpret accurately when based
upon certain
objects, specifically objects with erratic temperatures,
although this problem is reduced in active thermal imaging
Accurate temperature measurements are conflicted by
differing emissivity and reflections from other surfaces
Most cameras have ±2% accuracy or worse and are not as
accurate as contact methods.
Only able to directly detect surface temperatures.
Limitation of the Thermography:
294. Books:
Machinery Vibration Analysis & Predictive Maintenance.
Institutes:
Mobius Institute www.Mobiusinstitute.com
Vibration Institute www.vibration.org
Infraspection Institute www.infraspection.com
295. Prepared by Eng.Mohammed Hamed
Industrial Engineering Consultant & Lecturer
Email: mhamed206@yahoo.com
: m.h.ahmed@ess.aucegypt.edu
Tel : +201001309903
LinkedIn: eg.linkedin.com/in/mohammedhamed/
