Vibration Measurements and Analyses to Enhancing Plant ...

Vibration Measurements and Analyses to

Enhancing Plant Reliability

Jyoti K. Sinha, CEng, FIMechE

Programme Director,

Reliability Engineering and Asset Management (REAM) MSc

Head, Dynamics Laboratory

Head, Structures, Health & Maintenance (SHM)

Department of Mechanical Aerospace and Civil Engineering

The University of Manchester, UK

Email – [email protected]

IncoME-V 2020, BIT Zhuhai 1

mailto:[email protected]

"Everything should be made as simple as possible, but not simpler”

“Current thinking can not solve the current problem created by current

thinking”

IncoME-V 2020, BIT ZhuhaiSource: Google Image

2

Albert Einstein


Content

• Introduction and Background

• Examples

-Design Qualifications

-Design Modification/Optimisation

-Structural Health Monitoring

-Machine Installation

- Aged Machine

• Concluding Remarks

4

Quality; Productions; Safety.

No Reactive Maintenance.

Low Maintenance Overhead.

IncoME-V 2020, BIT Zhuhai

How to achieve?

Plant objectives

Background & Introduction

Source: Google Image

Background & Introduction


Reliable Design qualifications.

Root Cause Analysis based on PHYSICS of the subject

Robust Health Monitoring (Accurate Predictive approach).

ENSURE OVERALL GOOD RELIABILITY OF EACH ASSET

(‘old age’)

(‘infant mortality’)

6IncoME-V 2020, BIT Zhuhai

Examples: Few Failures due to High Vibration

Tacoma Narrows Bridge Earthquake

Gearbox failureSource: Google images


Source: MAMJ, 30(5), 2015

7

Few Typical Industrial Examples

Source: Noise & Vibration Worldwide 37(5) 2006Source: Shock & Vibration Digest 29(2) 1997

Source: Paper No. C06,NCAM-2004, India.


Blind Men and Elephant

“Trial and Error” Method!!!


8

• Replace or repair faulty parts

• Replace by New Machine

• Machine from different

manufacturers

• Several other attempts

9

Mass (m)

Spring

m

Physical Representation Representation of a Dynamic System

Equation of Motion:

Inertia Force + Damping Force + Stiffness Force = External Force

m a(t) + c v(t) + k y(t) = F(t),

Damping

(c)k

y(t)m

AccelerationVelocity

Displacement


A Simple Vibration System Background

Design Qualification and/or Optimization.

Machine Installation

Health Monitoring - Mechanical & Civil Structures

- Machines

- Piping

Age related problem in Machines and Structures

Isolation and Control, etc.

Broader Roles of Vibration Analysis



Vibration Measurements & Analyses


+

Jyoti K. Sinha, Book cover page, CRC Press, 2014

11


Design Qualification and

Modification


Design Qualifications

Static Qualification: Static loads bearing capacity

Dynamic Qualification

Seismic Qualification

Design Optimisation to meet the design requirements


Methods

• Analysis – Limitation FE Model itself.

•

• Shake Table Testing – Availability?

• Comparison

Seismic Qualifications

14

Ideal FE Model In-situ Modal Tests

Significant Difference in Modeshapes. Stress ?

Storage TankApprox. 24m long and 4m dia.



Max deformation due to Seismic loads

Comparison of the ideal (FE model with ideal boundary conditions)

and the experimental (in-situ) cases of deflection of Tank in lateral

direction due to Design seismic loads

16


In-service loads:- Flow-induced Excitation.

- Machine induced vibration.

Methods:- Full scale Experimental model with Excitation facility.

- In-situ Tests and Analysis during Installation and

commissioning.

Dynamics Qualification

and Design Modification

17


Design Modification in Fuel Channel

of a Research Reactor

Flow Induced Vibration

Original Design Modified Design

Vibration:

Flexing

along

length

Vibration:

NO

Flexing

along

length


Structural Health

Monitoring


Contact Detection: Two Co-axial Tubes with two spacers

235MWe PHWR contains 306 Coolant Channels

Front View

Side View

Source: Nucl Eng Design 155(3), 591-596, 1995

flo

w

flow

20

Coolant Channel


Contact


Contact Detection: Two Co-axial Tubes with two spacers

Contact between inner

and outer tubes is not

acceptable for the

safety reason!

Intrusive inspection of

3 channels per day is

only possible!!

Vibration-based

contact detection

takes only 3 days to

inspect all 306

channels

Source: Nucl Eng Design 155(3), 591-596, 1995

Contact

No Contact

flo

w

Combined Spectrum

Flow Induced

Excitation

flow

21


Machine Installation

and

Aged Machine


Centrifugal Pumps: Study during installation and commissioning in Jan 1991

Pump Assembly

N

Acceptable

vibration level

Source: Noise & Vibration Worldwide 37(5) 2006

23

High vibration at casing

– Not Acceptable

Modal Tests conducted

54Hz


Resonance at 2nd mode with Pump RPM 3000RPM

causing HIGH VIBRATION at Casing.

Source: Noise & Vibration Worldwide 37(5) 2006 & JKSinha, Book, CRC Press, 2015

Pump

Stool

24

Solution:Stiffening of Stool by welding a thick plate.

Additional “U” bolts to the discharge line.

NO ANY MAJOR PROBLEM SINCE 1991

Centrifugal Pumps: Diagnosis & Solution


Centrifugal Pump: Aging effect

Pump Motor

Coupling Bearings

• 1500RPM, 23000LPM

• Commissioned in 1984.

• Frequent failure of both bearings.

• Faults always detected by Contl. condition monitoring.

• Main root cause ?

Source: Insight 48(8) 2006

25


Pump: Vibration Measurements

Source: Insight 48(8) 2006

26

Pump

Motor

Bearing

Pedestals

Modal tests conducted.

Resonating at 2x with 2nd mode.

Solution:

Supports Stiffening


Concluding Remarks


Concluding Remarks

“Early failure”

related to

Design/ Installation

“Useful Life”

related to

Random Failure

“Old Age”

related to

Frequent Failure

1st Stage

2nd Stage

Condition Monitoring 3rd Stage

3 stages in Vibration Analysis can change “Bath Tub Concept”!



Examples demonstrate the usefulness of Vibration

Measurements and Analyses in different industrial

applications to enhance Plant Reliability.

‘Magic Solution’Vibration (Ant) problem in

Structures/Machines (Elephant)


Concluding Remarks


Acknowledgements

To my teachers and Colleagues

Google Images

Prof. Fenhshu Gu and Local Committee Members

!Thank you!

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