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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lure

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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

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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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NUMBER OF SETUPS

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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?