PREDICTING FAILURES
Ir. Gan Chun Chet
August 2007
The Concept and Practice
• In the Meeting Room Figures Are Showing Better Outlook
• The Ability to Know Bad Results Before It Happens, Would Be Good to Know Before It Occurs
• Hence, A Scientific Method to Measure Past Records to Achieve the Required Future Targets Emerge
I have done enough.Engineer
Everything Seems to Be OK.
Plant Manager
Profit is Rising
I’m Impress Managing Director
PREDICTING FAILURES
Predicting Failures
• What is Predicting?
• The ability to know something before it happens
• What are Failures?
• Something that does not pass the required results
Predicting Failures
• Some items that are highlighted in this talk- Plant Noise- Pumps and Compressors Vibration- Machine Setup Time- Redundancy- Partial/Full Stroke Testing- Review/Check Activity
Predicting Failures
• Introduction
• Passes, Failures and Predictions
• Some Examples To Serve as A Guide
• Some Counter Measures to Overcome
• Conclusion
Introduction
• Practices in General Industry Engineering Project and Maintenance Services- Engineering Best Practices
• Oil and Gas Consultancy and Contracting Services- Requires High Safety Standards- Requires High Reliable Products
Introduction
• Some of the Issues Addressed in General Industry (Manufacturing and Processing)- Hearing Losses- Pumps and Compressors Concerns of A Breakdown- Long Machine Setup Time Which Contributed to Uneasiness Among Production Personnel (Production Planning, Production Morale, Machine Change Over, etc.)
• Some of the Practices from the Oil and Gas Industry that worth while knowing- Redundancy- Partial/Full Stroke Testing- Review Check Activities
General Industry - Engineering Project and Maintenance Services
• Improve Plant Conditions- Safe Working Areas Inhabitants in the plant are able to work in a healthy and conducive environment
• Reduce Breakdowns- Continuous Batch OperationThe production purpose is to ensure continuous supply to the market due to demand (to operate profitably)
Oil and Gas - Consultancy and Contracting Services
• Query Services- Latest DevelopmentClient would like to know whether the latest product is purchased
• Design and Engineering Services- Specify the Right Requirements- Integrating ProperlyEngineered correctly to enable the platform or plant operating within the design production output, a proper detection system, the best way to fight a fire, equipment are maintain to it best performance, etc.
What Causes Failures?
• Causes of Failures- Wear and Tear (Bath Tub Theory)- Vibration- Exhaustive Operation
• Are Failures Detectable?- Can it be Spotted and Rectified?- Are there Methods to Detect Failures?(i.e. To know before something happen)
Passes, Failures and Predictions
• 100% Passes- Is This Achievable (Take note of Process Variance)
• 0% Failures- Is this achievable (Perfection? – Good Engineering Design)
• T+1 Prediction- Based on Facts and Past Data
Passes
• National or University Examination Results- Number of Students with DistinctionIs increasing the passing rate an indication of better quality students?University in the search of glooming student that are able to meet today’s challenges
• Productivity- Operation OutputThe measurement of productivity is to achieve better result each year until it reaches its best performance. Business/Management will begin to look for other performance parameters
Passes
• Upper Range Limit- Highest Acceptable Specification Value
• Lower Range Limit- Lowest Acceptable Specification Value
• Is it possible to increase the limit, hence more will pass
• Take note of design quality• Take note of process
(machine) limit0
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LRL URL
Failures
• Bath Tube Theory- Failures Occur Beginning of Design Life.- Sporadic Failures During Normal Life Stage.- Failures Begins to Occur Towards the End of Design Life.
• Is This Actually Happening in Real Operation?
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Time
Fai
lure
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e
Infant Mortality Stage
Wear-out Stage
Normal-life Stage
Failures
• Off-Spec Rejects- Not Meeting Specification- A Known Process Variation
• Sporadic Peaks- Sudden Occurrences - Unpredictable
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Failures
• Shutdown/Detection System Fail To Operate- Not Able to Detect or Shutdown
• Valves Unable to Function- Stuck- Cannot Close
Failures
• Failure Rate = Number of Failures X 100
Total Number of Products Tested
(p776, Operations Management – Nigel Slack et al, Pitman Publishing)
• An equation to know the number of actual failure coming out of the production line
• Measurement of the percentage of product failure
Failures
• Mean Time Between Failure (MTBF) = Operating Hours Number of Failures
(p776)
The average time between failures, measured in actual operation. The number of breakdowns over the operation duration.
(To Determine Time Before a Failure, Average of Past Record)
Prediction
• Threshold Limit- Above a Set Horizontal Line Will Trigger a Warning.
• Review of past data shows that a limit has to be set. Anything above this set limit must need to be attended.
• E.g. Noise (Hearing) Level
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Threshold Limit
Warning
Prediction
• Analysis- Frequency Spectrum
• An analysis of the pump or compressor vibration behaviour. Because the pump and compressor rotate at fixed angular rotation, the frequency of the pump or compressor can be calculated.The spectrum shows the frequency of the pump or compressor, etc.
Frequency
Amplitude
f 2f 3f
Prediction• Trend Line
- A Straight Line Can Be Drawn on The Collected Data.- The Straight Line Can be Extended to Know the Next Value.
E.g. A Linear Relationship Between X and Y and be Concluded, Case of reduction in setup time.
Line of Regression
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Prediction
• Moving Average- Average of Past Data and Moving Forward
• The moving average line of 2 past data is the average of 2 past data.
• The moving average line of 2 past data is more reactive than 5 past data.
• Moving average is the record of past historical data. With this type of trend line, the future up or down trend can be know, provided all factors remain unchange.(E.g. Monitoring Setup time) 0
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5 past data
2 past data
Real Examples
• Threshold Shift (Noise Study) – (Factories and Machinery, Noise Exposure) Regulations, 1989(A Real Noise Reduction Project)
• Noise Level Collected and Recorded at 500, 1000, 2000, 3000 & 4000Hz
• Sampled of Production Workers at Floor Level
Real Examples
• Less than 10 years service
• 2 Clusters• Results
- Below 20 dB (Cluster 1)- Below 30 dB (Cluster 2)
Real Examples
• More than 10 years service
• 1 Cluster• Results
- Below 30 dB
Counter Measures• Hearing Conservation Program
- Engineering Control(To Install Enclosure At Rotating Equipment, To Reduce Device Noise e.g. Control Valve & Relief Valve, To Prevent Noise From Traveling Into The Control Room)
Enclosure
Machine
Limit noise out of the enclosure
Control Room
Limit noise to the control room
Counter Measures
• - Administrative Control(To Move Workers In And Out Of Noisy Area (take note of threshold shift, very dangerous, so act mentioned to limit daily exposure to noise by control of work schedule, very difficult to practice), Constant Monitoring, Do Not Allow People To Enter Noisy Areas, Sign Board of High Noise Areas, etc.)
HIGH NOISE AREA
- WEAR EAR MUFFLE
Counter Measures
• Required by law that the Permissible Exposure Limit is - 85 dB(A) for 16 hours duration per day,- 90 dB(A) for 8 hours duration per day, etc per schedule- Nobody shall be exposured to noise level exceeding 115 dB (A) at any time
Factories And Machinery (Noise Exposure) Regulations, 1989
• Employees need to check for a baseline reading (required by law)
• Take note of Threshold Shift! DO NOT play with this! • Reduce Noise Level (Engineering Measures)• Consult Noise Consultant or Ear Specialist!
Counter Measures
• Some Examples (Also Consult Doctors or Specialist! Hearing Problem Must not be Taken Lightly)
• E.g. The Sum of Hearing Threshold Levels Shows an Increase of 30 dB Compared to Preceding Level. Very Serious Shift! (Case Study : Less than 10 yrs employment, 1st cluster 20 dB and below. 2nd cluster 30 dB and below.
: More than 10yrs employment, cluster 30 dB and below)
• International Standard Organisation (ISO)
Real Examples
• Vibration AnalysisPumps or Compressors
• Pump fails• Compressor showing high
vibration (fitters showing concern of the compressor vibration)
Frequency
Amplitude
f 2f 3f
After correction
Counter Measures
• Condition Monitoring Program- Compressors and Pumps Characteristics
• Principle Of Vibration Is Caused By Rotation of Shaft and Components Connected to the Shaft Inside The Compressors Or Pumps, A Sinusoidal Behaviour
Time
Amplitude Y Direction
X Direction
Vibration in X and Y Direction
Shaft
Rotation Direction
f = 1/T
f = frequency
T
Counter Measures
• Identify Equipment to Measure, Critical Pumps or Compressors (e.g. Screw Compressor)
• Collection of Data at Specified Points, e.g. X-Direction or Y-Direction
• Storage of Data• Analyse and Compare Spectrum• Corrective and Rectification Actions, Take Your
Time to Decide
• Spot the Rise• DO NOT Exceed the Limit
Counter Measures
• Engage a Vibration ConsultantCollection Spot
Frequency
Amplitude
f 2f 3f
Analyse Data
Collect Data
Corrective Action
Invoice
Pump Blade
1 Qty
…………….Received ByExecutive
Axial Compressor
√
Counter Measures
• Compressor was overhaul, monitored and shows low vibration.
• Pump Performance before and after shows the peak has reduced.
• To Avoid Failures Which Will Cause Process Interruption. If NO Breakdown, Smooth Operation
Real Examples
• Reducing Machine Set Up Time – An Improvement in Production Output- Trending
• The Set Up Time was Recorded, From Start Time to Finish Time
Real ExamplesSETUP TIME
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
NUMBER OF SETUPS
TIM
E
Target
Actual Time
Linear Trend Line
Moving Average (of Past 5 Setup)
Real Examples
• To Reduce Setup Time, Is To Identify Time Consuming Tasks
• After Identifying The Time Consuming Tasks, Actions Have to be Taken To Reduce These Tasks, e.g. By Quick Fit, Work Continuously Along Critical Activities (take note of resource exhaustion), Adjust Machine Parts Before Set Up Activities (not directly connected to the machine), Re-design same activities, etc.
• Monitor Time To Avoid Slippage, Inform Everybody• Plan Actions
Counter Measures
• Time Motion Study- Determine Tasks to Monitor Progress- Concurrent Activities (Resource, Sequence)- Engineering Measures- Team Approach
Maintenance Time
Set Up Time
Operation Time
Total Time
Reduced
Counter Measures
• The Total Time- Identify Tasks
• Number of Resources- Spot the Critical Activities (Including Bottle Neck)
Task 1
Task 2
1 Man
1 Man Task 3
Finish
Start
1Man
2 Men
1 ManStart Finish
Total Time
Real Examples• Setup Time to be Reduced to Achieved
Shorter Setup Time
• More Production Flexibility In Some Application
Product A
Setup
Product B
Setup
Product A, …
Known Knowledge
• That There Will be Failures Due to Failure Rate.
• Bath Tube Theory, Wear and Tear, Electronic Failure, etc.
• Field Detectors Faults• Valve fail to Close • Drawing Representation/Specification Errors
Counter Measures
• Redundancy- 1 Out Of 2 Voting (Logic) In The Field (In Some Application – 2 out of 3)
Counter Measures
• Redundancy In The Field
• A Third Detector In Some Projects To Detect The Shadow (triple!)
• Same like pumps, one operating and one spare
FD 1
FD 2
V1Shadow Area if FD1 fail
FD 3 to detect hidden area
Counter Measures
• Redundancy Throughout, i.e. From the Field Up to the Input/Output Card and Process
Input
Input
Detector
Detector
OutputProcessor
Processor Output
Counter Measures
• Partial Stroke Test- Able to Detect 70% of Valve Failures
• Full Stroke Test- Remaining 30% of Valve Failures
(p5, Partial-Stroke Testing of Block Valves,Angela E. Summers, Control Engineering, Nov
2000)
Flow Direction
open
Partial close
Flow Direction
open
close
Counter Measures
• Review / Check- Try to Spot The Error
• By keep checking for error, there is a high possibility of reducing the errors.
• Check technical contents, specified correctly, etc.
• Quality guru will say that quality is driven to a certain extent only. After which it is worth it.
• Also do not spent too much time checking, otherwise, waste of time, not efficient, non productive, etc.
Start Review / Check
IDC
Review / Check
IFR
Review / Check
AFC Finish (or As-Built)
IDC Interdisciplinary Check
AFC Approved For Construction
IFR Issued For Review
Conclusion
• Identify The Failure(s)• Take Time to Study/Investigate (Collect Data,
Analyse, Trending, etc.)• Ask Around for Available Practices/Advise• Take Action(s) after that, do not do it by yourself,
make sure company management know about it.
• Make Use of the Prediction Concepts and Proven Practices to Avoid Failures in Plant or Oil and Gas Facilities.
Conclusion
• Areas that were looked into:- Plant Noise- Pumps and Compressors Vibration- Machine Setup Time- Redundancy- Partial/Full Stroke Testing- Review/Check Activity
Predicting Failures
• Prediction is Possible to Resolved Failures
• Prediction Requires Past Data
• It is Scientific Based, i.e. Measurable
Built Trend/Threshold Limit/Moving Average/Analysis, to Predict a Better Future.
• Spot the Change (Before and After)
Predicting Failures
Counter Measures
Identify Failure Study/Investigate Corrective Action
Collect Data/ Records Threshold/Analyse/Trend/Moving Average
P R E D I C T I O N
Failure Rate
Stages In Predicting Failure
Speaker Contact
• Current Employer : Technip Geoproduction (M) Sdn. Bhd.
• Position : Instrument Engineer
Any queries?
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