F.M.E.A

1. The
Renoir
Group
FMEA

2. The
Renoir
Group
What is FMEA?
 Failure Modes and Effects Analysis (FMEA) is a disciplined procedure to facilitate
process/system improvement
 FMEAs be used for multiple reasons
 To anticipate problems so that steps can be taken to counteract them and
reduce or eliminate risks involved in implementation
 To improve processes/systems to give improved functionality and reliability
which results in reduced day-to-day operation problems (Reliability projects)

3. The
Renoir
Group
FMEA
FMEA facilitates improvement by asking
fundamental questions
How likely is the
occurrence of failure?
What are the causes
of the failure?
How easy is it
to detect the cause?
How can the design
/process/system/
service fail?
What is the effect &
how serious
is the effect?
How can we minimise
the risk of failures?
Can we prevent
this cause of failure?

4. The
Renoir
Group
When is an FMEA started?
 When new systems, products and processes are being designed
 When existing designs or processes are being changed
 When carry over designs/processes will be used in new applications, or
new environments
 After completing a problem solving study (to prevent recurrence of a
problem)

5. The
Renoir
Group
Steps in an FMEA
Step 1: Write the functional statement for the system/process
Step 2: Evaluate ways in which the system/process can fail to fulfill its functions
Step 3: Determine and analyze failure modes and effects
Step 4: Complete the FMEA
Step 5: Draw up an action plan for recommended actions
Step 6: Update the FMEA periodically

6. The
Renoir
Group Record the functions and the performance
standards of the critical equipment
 Determine what the users want the equipment to do
 Primary Functions
 Secondary Functions
 Determine the performance standards that the users expect it to deliver
 Qualitative
 Quantitative
 Specification limits
 Ensure that it is capable of doing what its users want

7. The
Renoir
Group
Some of the common secondary function indicators..
 Environmental integrity
 Safety and structural integrity
 Control/ containment/ comfort
 Appearance
 Protection to users
 Economy/ Efficiency
 Superfluous functions

8. The
Renoir
Group
Some sample function statements..
 A pump – To pump from tank A to tank B not less that 800 liters /min
 A chemical reactor – To heat up to 500 kg of product X from ambient
temperature to boiling point ( 125 deg C) in one hour
 A motor car – to transport up to 5 people along made roads at speeds up
to 100 km/hr with a mileage of not less that 15 km/lit
 Grinding machine – To finish grind main bearing journals in a cycle time of
3.00 +/- 0.03 min to a diameter of 75 +/- 0.1 mm with surface finish of
Grade 2
A function statement should consist of a verb, an object and a desired
standard of performance. The essence of a good function statement is to
include an exhaustive list of primary and secondary functions.

9. The
Renoir
Group A detailed functional statement example …
( Exhaust System of a gas turbine)
1. To channel all the hot turbine exhaust gas without restriction to a fixed point 10
meters above the turbine wall
2. To reduce exhaust noise levels to ISO Noise Rating 30 at 150 meters
3. To ensure the surface temperature of ducting inside the turbine hall does not
exceed 60 deg C
4. To transmit a warning signal to the turbine control system if the exhaust gas
temperature exceeds 475 deg C and a shutdown signal if it exceeds 500 deg C at
a point of 4 meters from the turbine
5. To allow free movement of the ducting in response to temperature changes

10. The
Renoir
Group
A detailed functional statement example …
( 4 MW DG Set)
 To generate 82560 units per day with
 fuel efficiency of 4.03 units per liter,
 lube oil consumption of 0.8 gm/unit
 maintenance cost of Rs. 0.7/unit,
 without crossing decibel level of 98 db,
 exhaust temperature not exceeding 300 deg C,
 CO emission not exceeding ,
 NOX emission not exceeding .

11. The
Renoir
Group
A detailed functional statement example …
( VRM)
 To produce fine coal at 71 TPH with fineness of 18 on a 90micron sieve and 2.5
on a 212 micron sieve at power consumption of 24 KwH/T of material with
outlet temp of 70 deg C and stack emission of 60 mg/nm3
 Vibration of gear box below 0.5 mm/s
 Filter DP below 90 mmWg
 Grinding Pressure 115 bar
 Mill inlet temp not to exceed 370 deg C

12. The
Renoir
Group Evaluate the ways in which it can fail to fulfill its
functions
 Partial failure and total Failure
 Upper and lower specification limits
 Gauges and indicators
 The operating context
‘A functional failure’ is defined as the inability of any asset to fulfill a
function to a standard of performance which is acceptable to the user

13. The
Renoir
Group
Some examples
 A pump
 Fails to pump any water at all
 Pumps water at less than 800 lit per minute
 Grinding machine
 Completely unable to grind work piece
 Grinds work piece in a cycle time of longer than 3.03 minutes
 Diameter exceeds 75.1 mm
 Diameter less than 74.9 mm
 Surface finish too rough

14. The
Renoir
Group
Some cautionary points
 An issue which needs consideration when defining the functional failures is the
user. These are not to be set by the maintenance people working on their on their
own
 The performance standards used to define the functional failure defines the
proactive maintenance needed to avoid that failure
 Performance standards can very useful if established before the occurrence
of a failure
 The standards must be set by the Production and maintenance people
together along with anyone who can add value to determine how an asset
should behave

15. The
Renoir
Group Sample information sheet… ( Exhaust System of a gas
turbine)
FUNCTIONS FUNCTIONAL FAILURE
Unable to channel gas at all
Gas flow restricted
Fails to contain the gas
Fails to convey the gas to a
point 10 mm above the roof
To reduce exhaust noise levels to ISO Noise Rating
30 at 150 meters
Noise level exceeds ISO Noise
Rating 30 at 150 meters
To ensure the surface temperature of ducting inside
the turbine hall does not exceed 60 deg C
Duct Surface temperature
exceeds 60 deg C
Incapable of sending a warning
signal if the exhaust temperatur
exceeds 475 deg C
Incapable of sending a
shutdown signal if exhaust
temperature exceeds 500deg C
To allow free movement of the ducting in response to
temperature changes
Does not allow free movement
of the ducting
To channel all the hot turbine exhaust gas without
restriction to a fixed point 10 meters above the
turbine wall
To transmit a warning signal to the turbine control
system if the exhaust gas temperature exceeds 475
deg C and a shutdown signal if it exceeds 500 deg C
at a point of 4 meters from the turbine

16. The
Renoir
Group Sample information sheet…
( 4 MW DG set)
FUNCTIONS FUNCTIONAL FAILURE
Unable to generate at all
Generation less than 82560 units
Fuel efficiency of 4.03 units/ltr Efficiency less than 4.03 units/ltr
Lub oil consumption of 0.8 gm/unit Lub oil consumption > 0.8 gm/unit
Maintenance cost not exceeding Rs.
0.7/unit
Maintenance cost exceeding Rs. 0.7/unit
Decibel level < 98 dB Decibel level > 98 dB
Exhaust temperature <300 deg C Exhaust temperature >300 deg C
CO < ppm CO > ppm
NOX emission < ppm NOX emission > ppm
To generate 82560 units per day

17. The
Renoir
Group
Determine Failure Modes
 A single equipment can fail for a dozen of reasons. Systems can fail due to
hundreds of reasons
 Maintenance is actually managed at the ‘failure mode level’
 Work orders or job requests are raised to cover specific failure modes
 Day to day planning is basically to deal with specific failure modes
 Most of tech history recording systems record individual failure modes
 Most maintenance and production meetings are spent discussing failure
modes
A failure mode is any event which causes a functional failure.

18. The
Renoir
Group
Sample Sheet
FUNCTIONS FUNCTIONAL FAILURE FAILURE MODE
Bearing seizes
Impeller comes adrift
Impeller jammed by
foreign object
Coupling hub shears due
to fatigue
Motor burns out
Inlet valve jams closed
… etc
Transfers less than 800 lit/min
Unable to transfer water at all
To transfer water
from tank A to tank B
at not less than 800
lit/min

19. The
Renoir
Group
Sample Sheet ( 4 MW DG set)
FUNCTIONS FUNCTIONAL FAILURE FAILURE MODES
Engine breakdown
Alternator breakdown
Electrical panel failure
Air circuit problem
Governor problem
Exhaust Temp high
Improper cooling
Quality of fuel
Improper air fuel ratio
Fuel pump malfunctioning
Frequent tripping of system
Leakages of fuel oil in system
Operation underloaded
Leakage of lub oil
Oil purifier malfunctioning
Worn out piston rings
Frequent and unexpected failures
High cost of spares
Lack of in house skills
Fuel quality poor
Breakdown of silencer
Poor acoustics of DG house
Exhaust Valve leakage
Improper fuel quality
Inadequate ventilation
Exhaust temperature >300 deg C
Exhaust temperature <300 deg C
Maintenance cost exceeding Rs. 0.7/unit
Maintenance cost not exceeding Rs.
0.7/unit
Decibel level > 98 dB
Decibel level < 98 dB
Unable to generate at all
Generation less than 82560 units
To generate 82560 units per day
Efficiency less than 4.03 units/ltr
Fuel efficiency of 4.03 units/ltr
Lub oil consumption > 0.8 gm/unit
Lub oil consumption of 0.8 gm/unit
Fishbone analysis

20. The
Renoir
Group
Categories of failure modes
 Falling capability
 Deterioration
 Lubrication failures
 Dirt
 Disassembly
 Human errors
 Increase in desired performance ( or increase in applied stress)
 Sustained, deliberate overloading
 Sustained unintentional overloading
 Sudden, unintentional overloading
 Incorrect process parameters
 Initial incapability

21. The
Renoir
Group
Failure effects
 Contains from an internal and/or external customer point of view the effect of
the failure mode on the process/system/equipment’s function
 While documenting Effects the following should be recorded
 What evidence ( if any) that the failure has occurred
 In what ways ( if any ) it poses a threat to safety and environment
 In what ways ( if any) it affects production or operations
 What physical damage ( if any) is caused by the failure
 What must be done for the repair
 What are the cost implications( if any )?
 What are the inter linkages with other systems which can fail due to this
failure?

22. The
Renoir
Group
Sample information sheet
FUNCTIONS FUNCTIONAL FAILURE FAILURE MODE FAILURE EFFECT
Unable to channel gas at all
Silencer mountings are
corroded
Silencer assembly collapses and fails to bottom of stack. Back
Pressure causes the turbine to surge violently and shut down on
high exhaust gas temperature. Downtime to replace silencer up to
four weeks.
Gas flow restricted
Part of the silencer falls due to
fatigue
Depending on nature of bloackage, exhaust temperature may rise
to where it shuts down the turbine. Debris could damage parts of
the turbine . Downtime to repair silencer 4 weeks
Fexible joint holed by corrosion
Gasket in ducting improperly
fitted
Gas escaped into the turbine hall and ambient temperature rises.
Hall ventilation system would expel gases through louvres to
atmosphere, so concentration of gases is unlikely to reach
noxious levels. A small leak at this point may be audible. Down time
t
Upper belows holed by corrosion
The upper belows are outside turbine hall, so a leak here
discharges to atmosphere. Ambient noise levels may rise.
Downtime to repair up to 1 week
Exhaust stack mounting bolts
shear due to rust
Exhaust stack blown over by
gale
Fails to contain the gas
Fails to convey the gas to a
point 10 mm above the roof
To channel all the hot turbine
exhaust gas without restriction
to a fixed point 10 meters above
the turbine wall

23. The
Renoir
Group
Completing the FMEA - Severity
 Assesses the seriousness of the potential failure mode to the component,
subsystem, system or process, if it should occur
 The estimation is done on a 1 to 10 ranking scale
 The team agrees to a specific evaluation criteria for each ranking value
 Example evaluation criteria is given on the next slide. Decide evaluation criteria
for your system/process

24. The
Renoir
Group
Severity ranking table
Effect Ranking Criteria: Severity of effect (Example) Criteria: Severity of effect (for a cement plant)
Hazardous -
without
warning
10 May endanger machine or operator. Failure will occur
without warning, Very high severity ranking when the
failure mode affects safe operation and/or involves
noncompliance with statutory requirements
Hazardous -
with warning
9 May endanger machine or operator. Failure will occur
with warning, Very high severity ranking when the
failure mode affects safe operation and/or involves
noncompliance with statutory requirements
Very High 8 Major disruption of production. 100% of the product
may not pass quality standards. Loss of primary
function. Customer very dissatisfied
High 7 Minor disruption of production. A portion of the
product may not pass quality standards. Machine
operable but at a lower performance level. Customer
dissatisfied
Moderate 6 Minor disruption of production. A portion of the
product may not pass quality standards. Machine
operable but some item(s) inoperable. Customer
experience discomfort
Low 5 Minor disruption of production. Some equipment full
operability lost. Customer experiences some
dissatisfaction
Very Low 4 Minor disruption of production. For some equipment,
part operability lost
Minor 3 Minor disruption of production
Very minor 2 Very minor disruption of production
None 1 No effect

25. The
Renoir
Group
Cause of failure
 Describes how failure could occur in terms of a correctable or controllable
item
 As descriptive as possible to describe all root causes of failure
 Includes causes such as human error, failure mechanisms like fatigue, wear
and corrosion, improper operation
 Analysis done earlier can be directly keyed into format of the FMEA
 Detailed list of failure modes will be available form the 5 Why analysis data
 Fish bones can help in generating data of past history and also anticipatory
failure modes.
 While 5 Why analysis is like a FIR , fishbone provides detailed data for the
FMEA
Fishbones have to be constantly updated to include
new failure modes…

26. The
Renoir
Group
 Estimates the frequency of occurrence without consideration to failure
detecting measures
 Consideration to statistical data from previous experience, historical data, or
similar systems/processes improves the accuracy of ranking values
 Probability
 Failures which have occurred before
 Failure modes which are already the subject of proactive maintenance
 Un-occurred failure modes but which are real possibilities
 Example of criteria and ranking are given in the next slide
 Alternative subjective assessments use descriptive words to describe rankings
Occurrence

27. The
Renoir
Group
Occurrence ranking scale
Probability of failure Possible failure rates Ranking
>= 1 in 2 10
1 in 3 9
1 in 8 8
1 in 20 7
1 in 80 6
1 in 400 5
1 in 2000 4
Low: Isolated failures associated with
similar processes/systems
1 in 15,000 3
Very low: Only isolated failures
associated with almost identical
processes/systems
1 in 150,000 2
Remote: Failure is unlikely. No failures
ever associated with almost identical
processes/systems
<= 1 in 1,500,000 1
Moderate: Generally associated with
processes/systems similar to previous
processes/systems which have
experienced occassional failures
High: Generally associated with
processes/systems similar to previous
processes/systems that have failed
Very high: failure is almost inevitable

28. The
Renoir
Group
Current process controls
 Describes controls that can prevent failure mode from occurring or detect
occurrence of the failure mode
 Includes control methods like SPC and Poka Yoke(mistake proofing) at the
equipment/system/ process or subsequent operations
 Preferred method of control is prevention or reduction in the frequency
of the cause/mechanism or the failure mode/effect
 Next preferred method is detection of the cause/mechanism which leads
to corrective actions
 Least preferred method is detection of the failure mode

29. The
Renoir
Group
Detection
 Assesses the ability of current controls to detect a potential
cause/mechanism from process weakness or the subsequent failure
mode before the product leaves the manufacturing operation
 Ranking values consider the probability of detection when failure occurs
 Sample detection criteria are given on the next slide

30. The
Renoir
Group
Sample detection criteria
Detection Criteria: Likelihood that the existence of a defect
will be detected by process controls before next
or subsequent process, or before the product
leaves the process/system
Criteria (for a cement plant): Ranking
Almost impossible No known control(s) available to detect failure mode
known
10
Very remote Very remote likelihood that current control(s) will
detect failure mode
9
Remote Remote likelihood that current control(s) will detect
failure mode
8
Very Low Very low likelihood that current control(s) will detect
failure mode
7
Low Low likelihood that current control(s) will detect failure
mode
6
Moderate Moderate likelihood that current control(s) will detect
failure mode
5
Moderately high Moderately high likelihood that current control(s) will
detect failure mode
4
High High likelihood that current control(s) will detect
failure mode
3
Very high Very High likelihood that current control(s) will detect
failure mode
2
Almost certain Current control(s) almost certain to detect the failure
mode. Reliable detection controls are known with
similar processes/systems
1

31. The
Renoir
Group
Putting it all together – the FMEA format
Project Name/Description Date: Review No:
Prepared by: Review Date:
Team:
Function Functional
Failure
Failure
Mode
Failure
Effect
Sev
(S)
Cause of
Failure
Occ
(O)
Current
controls
Det
(D)
RPN =
S*O*D
Recommended
Action
Resp Target
Date
Action
Taken
S O D RPN
FMEA FMEA REVIEW

32. The
Renoir
Group
Drawing up a course of action – Risk Priority Number
 Risk Priority Number (RPN) – the product of severity, occurrence and detection
 The RPN helps prioritize concerns and action plan is developed based on higher
RPN
 However, issues with a low RPN also deserve special attention if the severity
ranking is high
 To achieve this, sort the FMEA by descending order of RPN and then by
descending order of severity

33. The
Renoir
Group
Recommended action
 Actions are instituted that lower occurrence, severity and/or detection of the
highest RPN failure modes
 Example actions include control charts to improve the focus of defect
prevention/continuous improvement activities
 Focus is on activities that lead to the prevention of defects (i.e. occurrence
ranking reduction) rather than improvement of detection methodologies (i.e.
detection ranking reduction)
 Special attention should be paid for corrective action towards severity reduction
by instituting changes in process or design
 “None” indicates that there are no recommended actions
 Action plans are made with responsibilities and target dates set for completing all
recommended actions

34. The
Renoir
Group
Updating the RPN in the FMEA
 A periodic review of the RPN rating has to be done to unearth new failure modes and
also to understand how we have dealt with the case where high RPN was identified at
a earlier stage
 No change in the RPN rating also reflects our inability to solve a critical problem and
also gives problems to focus on
 Ideally the severity rating may not change for a failure mode, but the ability to detect
and the frequency of failure should have been under control – That is where the RPN
rating goes down
 The team needs to evaluate the periodicity of these reviews

35. The
Renoir
Group
Key take ways from the FMEA
 FMEA like a fish bone diagram has to be constantly updated when new
failure modes are identified
 The RPN number as to be reviewed at regular intervals
 Take conscious steps to decrease the frequency and increase the chance of
detection
 The severity of the problem may not reduce but the frequency of failure and
the chance of detection scores has to come down
 If the RPN does not reduce, then review all the preventive actions that you
have done