FMECA

Failure AnalysisBasic Concepts

Background

About FMECA

FMECA • a structured method of

determining:• equipment functions• functional failures

assessing the causes of failures and their failure effects.

Group WorkMaintenance Plans

Maintenance Plans• Break into groups of 5

• Discuss maintenance plans in:• 1960’s• 1970’s• 1980’s

The Key benefits of FMECACriticality –• Identification of critical areas of operation• Identification of critical systems within areas

FMEA - • Reduced downtime by avoiding failures• Reduced time spent on unnecessary

maintenance• Revised Preventive Maintenance schedules• Adoption of new maintenance tasks• Critical component stores listings• Revised Log Book procedures• And more …

Causes of Downtime

Equipment

Failure

Production

Related

Fit for Purpose

Equipment Failure– Quality of Parts– Effectiveness of Maintenance

Strategy– Operation of Equipment– Poor Design– Quality of Maintenance– Fast Running of Machines– Bad Operating Practices– Poor Maintenance Planning– Skills/Ability of Craftsmen

Production Related– Quality of Raw Materials– Formulation– Operating Procedures– Production Planning– Schedule Maintenance Requirements– Development Projects– Lack of Labor– Weak Management– Product Changeovers– Equipment Set-Ups– Skills of Operators

Fit for Purpose– Design Specification– Selection of Materials– Stretch the Plant/Process– Modifications– Location and Access to Equipment

Maintenance Technical Strategy

“Living Maintenance”



Relationship between a Component and Plant

Types of Maintenance

Planned or Unplanned MaintenanceCorrective Maintenance

Emergency Breakdown

Operator to Failure

Planned MaintenancePreventive Maintenance

Condition Based

Schedule Based

Failure Characteristics of PlantA thorough investigation into

the characteristics of each unit must be carried out in order to identify:

• The behaviour or performance of each unit

• The production pattern

• The unit type

MTBF

Types of Units• Single units

• A series continuous process unit

Predictive Maintenance• Human senses (sight, sound,

touch and smell)

• Monitoring with test instruments (vibration, etc)

• Performance monitoring (combustion analysis, etc)

• Quality measures

Predictive Maintenance

Determining Lead Time

Fixed Time Maintenance

Pattern of Equipment Failure

Fixed Time Maintenance

Probability of Failure vs. Predictable Failure

Teamwork

Pre-FMECA Requirements

Current PM Schedules and Tasks

Non-PM Work OrdersThe information from Non-PM WorkOrders should ideally include:

• Date

• Work Description

• Parts Usage

• Task Time

Current Downtime Data

Costs Data

Redundant Labour Costs

Maintenance Costs

Depreciation

Overheads

Drawings & Manuals

• P & IDs

• Assembly Drawings

• Installation Drawings

• Manufacturers Documentation

Spare PartsA list of spare parts may be required and should include the following:

• Local Inventory Spare Parts Number;

• Manufacturer / Supplier;• Unit Type (Each, Pair, Set, etc);• Cost per Unit;• Frequency of Usage;• Stock on Hand;• Minimum Stock on Hand.

Establishing Maintenance Plan

Defining Criticality Analysis

What is Criticality?

A criticality system provides the means of ranking equipment taking into account the plant’s operational requirements and the equipment function.

Criticality Factors

Factor for Effect on Safety or EnvironmentFactor Score Description

1 Little or no risk to the safety of the equipment or people or the environment.

2 Risk of minor injury or damage to equipment or minor levels of pollution.

3 Potential for a lost time accident, or significant damage to equipment, or discharge to atmosphere or water which requires notification to relevant authorities.

4 Severe safety consequences that could involve loss of life, major injuries and/or destruction of equipment and/or significant environmental discharges which result in a fire or removal of operating licences.

Calculation of Criticality

Factor A – Effect on Production Output

Factor Description Factor Score

No significant impact/standby equipment is available. 1

Minor impact on production. Unlikely to affect other areas of the plant.

2

Failure would have a significant impact on output and may affect other sections.

3

Major impact on the plant’s operations. Equipment failure would cause over 25% of plant production to stop.

4

This factor considers the impact of the equipment failure on the process of the plant.

Factor B - Utilisation


Equipment is used on an occasional basis. 1

Equipment is required to function independently for up to 50% of available time.

2

Equipment is part of a continuous process, required to function for a proportion of the planned production time.

3

Equipment is required to function for all of the planned time.

4

This factor measures the importance of the equipment in terms of the required utilisation within its operating environment.

Factor C - Quality


No effect on product quality. 1

Minor effect on Product quality. 2

Critical effect on product quality and can result in major losses.

3

This factor measures the effect on product quality.

Factor D – Effect on Safety or Environment


Little or no risk to the safety of people, equipment or the environment.

1

Minor risk to people, equipment or the environment. 2

Major risk to people resulting in a lost time accident, significant damage to equipment or the environment, which requires notification to relevant authorities.

3

Catastrophic resulting in loss of life, or destruction of equipment and/or significant environmental discharges which result in the removal or operating licences.

4

This factor is concerned with assessing the effects of an equipment failure in terms of the risk of injury to people, damage to equipment and environment, implications for the company if equipment fails in service.

Getting the Criticality Score

Step 1 – Criticality ScoreCriticality Score = (Factors) A x B x C x D

Factor E – Frequency of Failure This factor requires assessment of failure rate. The information should be obtained from equipment history records or best estimates.

Description Factor Score

Failures are rare, less than once per year. 1

Occasional failure between 3 and 12 months. 2

Failure likely between 1 and 3 months. 3

Frequent failures at least once per month. 4

Frequent failures at least once per week. 5

Factor F – Average Downtime/Repair Time

Downtime Downtime Duration

Factor Score

Minor 0 - 30 Mins 1

Significant 30 - 120 Mins 2

Major 2 - 8 hrs 3

Severe >8 hrs 4

Factor G – Potential for Waste Reduction

Factor Description Quantity Factor Score

No waste is generated under normal operating conditions.

0% 1

Small amounts of waste are produced by a failure.

5% 2

Waste is produced during production that is significant.

15% 3

Quantities of waste are significant and warrant immediate attention.

+ 15% 4


Step 2 – Equipment ScoreEquipment Score = (Factors) E x F x G


Step 3 – Overall ScoreOverall Score = (Critic. Score) x (Equip. Score)

Equipment Classification and Criteria

CriticalityScore

EquipmentCategory

80 - 32024 - 791 - 23

(A)(B)(C)


Criticality Example

Local No.

Description FlowSheetNo. Output Util’n Quality

Safety& Env

Equip.Score(ES)

Freq. ofFailure

AveD’time

WasteRdn

PriorityScore(PS)

TotalScore

EC ReactorReactor CondenserReactor CondenserAbsorber Tower Hydrogen DryerAbsorber Tower Hydrogen DryerIntercooler for D202/1 and 2Steam Heater for D202/1 & 2Blower for Hydrogen DryersDust afterfilter for Hydrogen DryerH2 Drying Hydr/water SeparatorRe-run ColumnRe-run ReboilerSlops DrumHC1 Drying Column (Top & Bottom SectionsEC Vent Gas ScrubberVent Gas HeaterReactor Mixing NozzlePolymer Knock Out DrumGear Box for HC1 Recycle Comp K251Recycle Compressor Gland EjectorHC1 Recycle CompressorNon Condensing Geared Turbine for K251Lube Oil Pump Recycle comp. GearboxLube Oil Pump Recycle CompressorLube Oil Pump Recycle CompressorRecycle Compressor Gland Ejector TankVent Relief StackFlame Trap VesselCatalyst Screw ConveyorGear Box for Catalyst Screw FeederUnloading HopperCatalyst HopperCatalyst Dissolving PotIrrigation FilterHC1 Demister VesselSump Pump £Durco)Inter/Aftercooler for K201/1Inter/Aftercooler for K201/2Gearbox for HC1 Compressor K201/1Gearbox for HC1 Compressor K201/2HC1 Comp Gland ejectorsHC1 Comp Gland EjectorsHC1 CompressorHC1 CompressorInter/Aftercooler FanInter/Aftercooler Fan

R251E252/1E252/2D202/1D202/2E205E206K205S203V205C254E258V255C201C256E253J251V254G251J255K251M251P256/1P256/2P256/3T255GB201X251B251G252V251V252V253S202S205P253/2E204/1E204/2G201/1G201/2J203/1J203/2K201/1K201/2K204/1K204/2

FMECAWorkSheetNo.

Comments

EC ReactorReactor CondenserReactor CondenserDryer PackageDryer PackageDryer PackageDryer PackageDryer PackageDryer PackageDryer PackageRerun ColumnRerun ColumnSlopsDryer 1EC Vent ScrubberEC Vent ScrubberEthylene SystemPolymer 5RecycleRecycleRecycleRecycleRecycleRecycleRecycleRecycleStackStackCatalyst SystemCatalyst SystemCatalyst SystemCatalyst SystemCatalyst SystemDryer 6Dryer 7EC SumpHCL CompressionHCP CompressionHCL CompressionHCL CompressionHCL CompressionHCL CompressionHCL CompressionHCL CompressionHCL CompressionHCL Compression

PRS No

PRS251PRS252PRS252PRS201PRS201PRS201PRS201

PRS201

PRS253PRS253PRS251PRS202PRS252PRS252

PRS251

PRS252

PRS251

PRS251PRS251PRS251PRS202PRS202

PRS202PRS202

PRS202PRS202

Overall Priority Factors

A B C D AxBxCxD E F G ExFxG (ESxPS)

J93-1126/P1J93-1128/P1

J93-1116J93-1116J93-1116J93-1116J93-1116

J93-1116J94-1115/P1J94-1115/P1J94-1083/P1J93-1122J93-1130/P1J93-1130/P1

J93-1126/P1J93-1128J93-1128J93-1128/P1J93-1128/P1J93-1128/P1J93-1128/P1J93-1128/P1J93-1128J93-1131J93-1131J93-1125/P2J93-1140J93-1125/P2J93-1125/P2J93-1125/P2J93=1122J93-1122J93=1134J93=1123J93=1124J93=1124J93=1123J93-1124J93-1124J93-1124J93-1123J93-1124J93-1123

4444444444444444443333333344444444442222222222

4444444444444444444444444444444444444444444444

3332222222221111111111111111111111111111111111

4332222222224333334444444433222222224444444444

19214414464646464646464646464484848484848484848484848484848323232323232323232323232323232323232

1112222222221111212222222211333332124444444444

4444444444444444244444444444444444434444444444

4441111111111111111112222222211111111111111111

161616888888888444444161616161616161644121212121284616161616161616161616

307223042304512512512512512512512512512256192192192192192768768768768768768768768192192384384384384384256128192512512512512512512512512512512

EC0014EC0013EC0013EC0001EC0001EC0001EC0001EC0001EC09001EC0001EC0011EC0011EC0012EC0002EC0016EC0016EC0017EC0018))))EC0010))))EC0019EC0019

EC0007EC0008

)))))))))EC0009)


Low HighCriticality Score

Typical Distribution of Scores

Nu

mb

er

of

Ite

ms

C B A

EquipmentCategory

MaintenanceCriteria

SelectionTechniques

A Maximum availability and reliability. Target zero failures

Use RCM/FMECA

B Minimise failures, maximise availability to meet production demand

Use FMECA

C Minimise maintenance costs

Based on manufacturers recommendations and experience.


Simplified Version of Criticality

Category Criticality Situation

A (1) Vital Main process equipment whose outage results in immediate production loss and penalty cost.Safety equipment whose outage creates danger or damage to equipment, or loss of life or injury.

B (2) Essential Process and auxiliary equipment, usually spared, whose outage does not normally cause immediate loss of production but whose continued outage (more than 24 hours) could lead to production loss and penalty cost.All safety equipment not already classified vital.Life support equipment whose outage of more than 24 hours could cause health problems or produce disagreeable operating or environment conditions.



C (3) Support All other process equipment and that life support equipment whose outage of more than 72 hours would affect operating conditions.Commodity articles which directly support process equipment or processes. Examples are general purpose bearings, seals, lubricants, gases, chart paper.


D (4) Operational All non-industrial equipment and life support equipment not already classified.All commodity articles not already classified.

Criticality Scoresheet

Criticality Classification

Criticality Sorting

Criticality Assessment

Defining FMECA

Failure Characteristics

Definitions and Examples

• Failure Mode Describes how the system or component fails

• Failure Effect Describes the effect of the failure, e.g. noise, lost performance

• Failure Cause Describes the principle cause of failure

Definitions and Examples

Modes Causes Effects/Symptoms

CollapsedSeized

FracturedBurnt

`Failed’Ruptured

Decay

OverloadWear

ErosionCorrosionFoulingDecay

PerishingContamination

DeformationTemperature

ChangesFlow Rates

Lost EfficiencySpillagesVibration

Lost PerformanceTolerances

NoisePressure

Levels

Failure Modes

1. Cracked/fracture2. Distorted3. Fails to open4. Fails to close5. Fails open6. Fails closed7. Internal leakage8. External leakage9. Fails to stop10.Fails to start

1. Corroded2. Contaminated3. Open circuit4. Short circuit5. Out of tolerance

(drifted)6. Scored7. Noisy8. Arcing9. Unstable10.Chafed

1. Binding/jamming2. Loose3. Incorrect

adjustment4. Seized5. Worn6. Sticking7. Overheated8. Delayed

operation9. Burned10.Collapsed11. Overloaded

Failure Effects and Causes

Failure Cause

Deterioration Characteristics & MTBF

Risk Priority Number – Occurrence Ratings

Criteria Rating Possible Failure Occurrence Rate

(Weeks)REMOTE probability of occurrence. It would be unreasonable to expect failure to occur.

1 0

LOW probability of occurrence. Generally associated with equipment or components similar to above with a relatively low number of failures per unit.

23

1: 1001: 50

MODERATE probability of occurrence. Generally associated with equipment or components that have shown up occasional failures, but not in major proportions.

456

1: 261: 131: 8

HIGH probability of occurrence. Generally associated with equipment or components similar to ones that have traditionally caused problems.

78

1: 41: 2

VERY HIGH probability of occurrence. Near certainty that major failures will occur.

910

1: 1Less than 1

week

Possible failure occurrence rates are meant as a guideline only.

Risk Priority Number – Severity Ratings

Criteria RatingMINOR SEVERITY - A very minor failure which would have no noticeable effect on the system performance. Operator would probably not notice the failure.

1

LOW SEVERITY - A minor failure causing only slight system annoyance. Operator would not notice any deterioration of system performance.

23

MODERATE SEVERITY - A failure which would cause some system dissatisfaction, discomfort or annoyance, or would cause noticeable deterioration in system performance.

456

HIGH SEVERITY - A failure which would engender a high degree of system dissatisfaction (e.g. inoperative control). Does not affect safety or ability to meet regulations.

78

VERY HIGH SEVERITY - A failure which would affect safety or ability to meet regulations.

9

CATASTROPHIC - A failure which may cause damage to property, serious injury or death.

10

FMECA Form Completion1. Equipment Enter the equipment name and plant

item number

2. Function Describe the component’s function

3. Failure Mode For each item describe the most likely reason for failure

4. Effect Describe the effect of each failure, e.g. pressure drop or visible leaks. The effect should relate specifically to the item under consideration and to the total equipment.

5. Cause Describe the principle cause of failure, e.g. normal wear.

6. Risk Priority

7. Number (RPN) Calculate the RPN for each failure mode, e.g.

FMECA Form Completion

8. Failure Characteristic Decide if the failure is random, increasing, predictable or age related.

9. Type Is the failure Evident (E) or Hidden (H).

10. Mean Time Between Failure MTBF Enter the known or estimated time between failures for each item.

11. Maintenance Approach The applicable maintenance approaches are determined using a maintenance strategy decision diagram

FMECA Form Completion

Why why analysisCase studyMore videos

Elements

Documents

FMECA