Vibration MonitoringVibration Monitoring

Maintenance MethodsMaintenance Methods

1. Breakdown Maintenance : The machine is allowed to run until complete failure forces shutdown.

Disadvantages: Untimely/ unplanned failure. Often require extensive repair. More downtime of machine. Loss of production is higher.

Maintenance MethodsMaintenance Methods2. Schedule Maintenance :

The machine is shutdown after specified period of operation & partially or completely dismantled for thorough inspection/ maintenance. This approach is having advantage of reducing the frequencies of shutdown.

Disadvantages:- Full life of machine parts can not be extracted.- Machine may be degraded by frequent disassembly.

Maintenance MethodsMaintenance Methods3. Predictive Maintenance or Condition

Based Maintenance :

Maintenance carried out in response to significant deterioration in a machine as indicated by a change in monitored parameters of the machine condition.

Maintenance MethodsMaintenance MethodsAdvantages of Condition Based Maintenance :

- Scheduled shutdown with minimum effect on production.

- Well prepared work schedule results in to reliable repair.

- Minimises unscheduled breakdowns.- Prolong machinery life.- Increase machinery / human safety

Down Time Comparison Down Time Comparison

Baseline Data Baseline data representative of an

equipment in a new and/or properly operating condition.

The baseline data is the foundation of the predictive trending analysis required to forecast equipment condition.

The baseline readings and periodic monitoring data should be taken under the same conditions (or as close as can be achieved).

Condition MonitoringCondition Monitoring

Flow Chart of Condition MonitoringFlow Chart of Condition Monitoring

1. Vibration Monitoring2. Shock Pulse Monitoring3. Temperature Monitoring4. Lubricant Wear Particle Monitoring5. Ultrasonic InspectionNon- Destructive testing: Radiography Ultrasonic testing Magnetic Particle. Dye Penetrant Hydrostatic Testing. Eddy Current Testing

Monitoring TechniquesMonitoring Techniques

1. Vibration Monitoring1. Vibration MonitoringDefination of VibrationCharacteristics of VibrationMeasurement of Vibration

– Transducers– Instrument

Analysis of Vibration

Vibration MonitoringVibration Monitoring What is vibration

– Motion of machine or machine part back & forth from its position of rest

Detect 60 to 70% of the faults

All machines vibrate Mechanical defect

generate vibration in unique way

Vibration CharacteristicsVibration CharacteristicsThree Characteristics of Vibration are

1. Amplitude

2. Frequency

3. Phase

Vibration CharacteristicsVibration Characteristics1. Amplitude

Primary indicator of machine’s condition

DisplacementMeasurement of distance an object travels from position of rest.

VelocityMeasurement of observed displacement over some specific period of time

AccelerationMeasurement of observed velocity over some specific period of time

Vibration Characteristics - AmplitudeVibration Characteristics - Amplitude

Vibration CharacteristicsVibration Characteristics2. Frequency

Measure of the number of complete cycles that occur in a specified period of time.

f=1/T Helps in identifying the probable

cause of vibration

3. Phase Position of vibration part at given

instance with reference to a fixed point.

Vibration Measurement & Vibration Measurement & AnalysisAnalysis Signal Transudation (Transducers or

Pickups) Signal Conversion Signal Analysis Signal Display Instrument

Vibration TransducersVibration Transducers

Non contact displacement transducer (eddy current probe)

Velocity pickup Accelerometer pickup

Vibration TransducersVibration Transducers

Velocity pickup

Vibration TransducersVibration Transducers

Accelerometer pickup

Vibration TransducersVibration Transducers

Non contact displacement transducer

Vibration InstrumentVibration Instrument

Vibration Instruments – FFT AnalysersVibration Instruments – FFT Analysers

Vibration SoftwareVibration Software

Machine SketchMachine Sketch

Vibration AnalysisVibration Analysis Tri Axial Measurement

Horizontal Vertical Axial

Vibration Spectrum Display of Vibration Amplitude vs. Frequency

Vibration SpectrumVibration Spectrum

Guide Line - OEMGuide Line - OEM

ISO 10816 : Mechanical vibration - evaluation of machine vibration with measurements of non rotating parts The measurement returns the RMS value of vibration velocity in mm/s or inch/s.

part 1: general of guidelines part 2: Land-based steam turbines and generators in

excess of 50 MW with normal operating speeds of 1500 r/min, 1800 r/min, 3000 r/min and 3600 r/min

part 3: Industrial machines with nominally power above 15 KW of and nominally speeds between 120 r/min and 15000 r/min when measured in situ

part 4: Gas turbine sets driven excluding aircraft of derivative

part 5: Machine sets in hydraulic power generating and pumping plants

Part 6: Reciprocating machines with power ratings above 100 kW

Vibration Identification ChartVibration Identification Chart

Vibration Case StudyVibration Case Study

Limits of Vibration

Rough Very rough

Disp. µm,H 100-200 >200

Vel.(pk) mm/s 8.0-12.0 >16.0

Date 02-Dec-98 02-Dec-98After

BalancingPos Dir Units Ampl. Ampl.

1 A µm,H 134.0 11.0A mm/s 11.0 1.6H µm,H 100.0 16.0H mm/s 9.0 2.3V µm,H 48.0 6.0V mm/s 5.0 1.2

2 A µm,H 132.0 11.0A mm/s 11.0 1.6H µm,H 178.0 20.0H mm/s 15.0 2.7V µm,H 135.0 9.0V mm/s 12.0 1.9

3 A µm,H 80.0 18.0A mm/s 7.2 2.3H µm,H 195.0 30.0H mm/s 18.0 4.0V µm,H 52.0 11.0V mm/s 6.3 1.7

Vibration ReportMachine : F Station C.T.I.D.Fan 3D

Motor

Sketch321

Gear Box & Fan

Vibration Case StudyVibration Case Study

Limits of Vibration as per BHEL

Rough Very rough

Disp. µm,H 120-240 >240

Vel.(pk) mm/s 6.4-12.7 >12.7

Date 14-Jul-01 17-Aug-01 18-Aug-01Ampere 69 69 71

Vane 65 65 75Pos Dir Units Ampl. Ampl. Ampl.

1 A µm,H 8.6 19.1 12.0A mm/s 1.1 3.4 1.2H µm,H 13.9 38.5 13.1H mm/s 1.8 6.6 1.4V µm,H 12.9 37.7 12.5V mm/s 1.6 6.0 1.5

2 A µm,H 18.5 33.0 21.9A mm/s 1.2 5.7 1.4H µm,H 28.5 33.7 30.4H mm/s 2.0 5.6 2.2V µm,H 15.6 27.4 22.6V mm/s 1.8 2.4 1.4

3 A µm,H 13.9 213.7 73.4A mm/s 2.7 24.0 5.2H µm,H 11.3 124.6 38.8H mm/s 1.0 10.2 2.6V µm,H 7.6 60.4 23.0V mm/s 1.0 4.7 1.7

4 A µm,H 59.6 88.9 90.2A mm/s 5.1 11.0 9.8H µm,H 15.4 17.1 17.0H mm/s 1.7 3.7 1.7V µm,H 7.4 18.3 15.3V mm/s 1.0 2.6 1.6

Vibration ReportMachine : C1 Station I.D.Fan B

Motor

Sketch

Fan

321 4

Vibration Spectrum (before & after attending)Vibration Spectrum (before & after attending)

D stn PA Fan AD stn PA Fan A

Vibration higher on foundation bolt than bearings

Recommended to check foundation bolt looseness

Limits of VibrationRough Very rough

Disp. µm,H 80-160 >160Vel. mm/s 6.4-12.7 >12.7

10/05/05 07/07/05Pos. Brg. Dir Units Ampl. Ampl.

3 Fan DE H µm,H 14.5 16.9H mm/s 1.3 1.7

V µm,H 42.2 62.8V mm/s 3.0 4.4A µm,H 66.4 93.0A mm/s 4.0 6.1

4 Fan NDE H µm,H 43.3 48.4H mm/s 2.6 3.4V µm,H 19.8 29.2V mm/s 1.7 2.2

A µm,H 62.4 85.8A mm/s 4.0 5.7

Remarks

CMC

Loosness was suspected. Vib.at Base of fan stool on DE side (Estn. Side) were

up to 108 micron.

TORRENT POWER AEC LIMITEDSabarmati Thermal Power Station

1 2 3 4

Motor Fan

D stn PA Fan AD stn PA Fan A

Tightening of the bolts carried out immediately by BMS

Potential loss of equipment breakdown & Generation loss of 50 MW for 8 hrs (0.4 MU , Rs 7.2 lacs) could be avoided

Limits of VibrationRough Very rough

Disp. µm,H 80-160 >160Vel. mm/s 6.4-12.7 >12.7

10/05/05 07/07/05 07/07/05Pos. Brg. Dir Units Ampl. Ampl. Ampl.

3 Fan DE H µm,H 14.5 16.9 16.8H mm/s 1.3 1.7 1.4

V µm,H 42.2 62.8 17.6V mm/s 3.0 4.4 1.3A µm,H 66.4 93.0 34.2A mm/s 4.0 6.1 2.3

4 Fan NDE H µm,H 43.3 48.4 26.0H mm/s 2.6 3.4 1.8V µm,H 19.8 29.2 20.6V mm/s 1.7 2.2 1.5

A µm,H 62.4 85.8 31.7A mm/s 4.0 5.7 2.1

Remarks vib. at base of fan stool

upto 6 microns

CMC

Loosness was suspected. Vib.at Base of fan stool on DE side (Estn. Side) were

up to 108 microns

TORRENT POWER AEC LIMITEDSabarmati Thermal Power Station

Thank youThank you

Shock Pulse MonitoringShock Pulse Monitoring

Antifriction Bearing’s life influenced byo Installationo Lubricationo Maintenance

The technique is based on monitoring the mechanical impacts caused by bearing damage & operating condition problems is known as Shock Pulse Method (SPM)

Shock Pulse Measuring InstrumentShock Pulse Measuring Instrument

Modes of MeasurementModes of Measurement

Data Input prior to measurement SPM Type no. (1-8) Norm no., (10-58)

o Last three digits of Brg.’s ISO number

o RPM Manual Mode

Input data for bearing to be assessed

Note down the readings

Modes of MeasurementModes of Measurement

Data Logging Mode For setup of

measuring points Software is used

Measured readings are Stored in Instrument

Stored data reported back to software

Measurement of Shock Pulse Measurement of Shock Pulse ReadingsReadings

Evaluation of Shock Pulse ReadingsEvaluation of Shock Pulse Readings

LR & HR CODE LUB No. COND No.

SPM Measurement DataSPM Measurement Data

Machine : D Stn. CEP 1C

Measuring Point Date Time LatestReadingsD-115-02 LR: 60C.E.Pump C 28-10-1997, 08:25 HR: 52Motor DE brg. Lub. : -Brg. No.: NU 322 Code : DSpeed :1480 Cond : 38

44

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Principle of Shock Pulse MethodPrinciple of Shock Pulse Method

Monitoring of Shock PulsesMonitoring of Shock Pulses

Initial Shock Pulse is affected by Bearing Geometry Rolling Velocity

LR and HRLR and HR

CODECODE

Lubrication No.Lubrication No.

COND NumberCOND Number

< 30 Minor Damage

30 - 40 Increasing Damage

> 40 Severe Damage

Relationship of Output DataRelationship of Output Data

Brg. No. 6230, RPM 990

LR :41, HR 37,

Code A, Lub No.2

Brg. No. NU230, RPM 990

LR :52, HR 48,

Code A, Lub No.5

52

53