Twi Ut Notes

8/19/2019 Twi Ut Notes

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Course Layout

• Duration : 9.5 Days (Mon – Fri)• Start : 8:30 am

• Coffee Break : 10:00 – 10:30 am

• Lunch : 12:30 – 1:30 pm• Tea Break : 3:00 – 3:30 pm

• Day End : 5:00 pm

• Course Objective: To train and prepare participants to obtainrequired skill and knowledge in Ultrasonic Testing and to meet theexamination schemes requirements.


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NDT

Most common NDT methods:

Penetrant Testing (PT)

Magnetic Particle Testing (MT)

Eddy Current Testing (ET)

Radiographic Testing (RT)

Ultrasonic Testing (UT)

Mainly used for

surface testing

Mainly used for

Internal Testing


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NDT

• Which method is the best ?Depends on many factors and conditions


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Basic Principles of Ultrasonic Testing

• To understand and appreciate thecapability and limitation of UT


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Basic Principles of Ultrasonic Testing

Sound is transmitted in the material to be tested

The sound reflected back to the probe is

displayed on

the Flaw Detector


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Basic Principles of Ultrasonic TestingThe presence of a Defect in the material shows up on the screen of the flaw

detector with a less distance than the bottom of the material

The BWE signal

Defect signal

Defect


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The depth of the defect can be read with reference to

the marker on the screen

0 10 20 30 40 50 60

60 mm


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Thickness / depth measurement

A

A

B

B

C

C

The THINNER the material the

less distance the sound travel

The closer the reflector to

the surface, the signal will

be more to the left of the

screen

The thickness is read from the screen

684630


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Ultrasonic Testing

Principles of Sound


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Sound• Wavelength :

The distance required to complete a cycle• Measured in Meter or mm

• Frequency :

The number of cycles per unit time

• Measured in Hertz (Hz) or Cycles per second (cps)

• Velocity :

How quick the sound travels

Distance per unit time• Measured in meter / second (m / sec)


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Properties of a sound wave

• Sound cannot travel in

vacuum• Sound energy to be

transmitted / transferredfrom one particle to

another

SOLID LIQUID GAS


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Velocity

• The velocity of sound in a particular material is CONSTANT

• It is the product of DENSITY and ELASTICITY of the material

• It will NOT change if frequency changes

• Only the wavelength changes

• Examples:

V Compression in steel : 5960 m/sV Compression in water : 1470 m/s

V Compression in air : 330 m/s

STEEL WATER AIR

5 M Hz


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Velocity

4 times

What is the velocity difference in steel compared with in water?

If the frequency remain constant, in what material does sound

has the highest velocity, steel, water, or air?

Steel

If the frequency remain constant, in what material does sound

has the shortest wavelength, steel, water, or air?

Air

Remember the formula

= v / f


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DRUM BEATLow Frequency Sound

40 Hz

Glass

High Frequency

5 K Hz

ULTRASONIC TESTING

Very High Frequency

5 M Hz


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Ultrasonic

• Sound : mechanical vibration

What is Ultrasonic?

Very High Frequency sound – above 20 KHz

20,000 cps


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coustic Spectrum

0 10 100 1K 10K 100K 1M 10M 100m

Sonic / Audible

Human

16Hz ‐ 20kHz

Ultrasonic> 20kHz = 20,000Hz

Ultrasonic Testing

0.5MHz ‐ 50MHz

Ultrasonic : Sound with frequency above 20 KHz


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Frequency

• Frequency : Number of cycles persecond

1 second

1 cycle per 1 second = 1Hertz

18 cycle per 1 second =18 Hertz

3 cycle per 1 second = 3Hertz

1 second 1 second

THE HIGHER THE FREQUENCY THE SMALLER THE WAVELENGTH


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Frequency

• 1 Hz = 1 cycle per second• 1 Kilohertz = 1 KHz = 1000Hz

• 1 Megahertz = 1 MHz = 1000 000Hz

20 KHz = 20 000 Hz

5 M Hz = 5 000 000 Hz


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Sound waves are the vibration of particles in solids, liquids or

gases.

Particles vibrate about a mean position.

One cycle

Displacement

The distance

taken to

complete one

cyclewavelength

wavelength

Wavelength

Wavelength is the distance required to complete a cycle.


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f

V

Velocity

Frequency

Wavelength


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Frequency & Wavelength

1 M Hz 5 M Hz 10 M Hz 25 M Hz

Which probe has the smallest wavelength?

SMALLESTLONGEST

Which probe has the longest wavelength?

= v / f

FF


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Wavelength is a function of frequency and velocity.

5MHz compression wave

probe in steel

mm18.1000,000,5000,900,5

Therefore:

f V V

f or or V f


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• Which of the following compressional probe has thehighest sensitivity?

• 1 MHz

• 2 MHz

• 5 MHz

• 10 MHz

10 MHz


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The Sound Beam

• Dead Zone• Near Zone or Fresnel Zone

• Far Zone or Fraunhofer Zone


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The Sound Beam

NZ FZ

Distance

Intensity

varies

Exponential Decay

MainBeam


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Main Lobe

Side Lobes

Near

Zone

Main Beam

The main beam or the centrebeam has the highest intensity of

sound energy

Any reflector hit by the main beam

will reflect the high amount of

energy

The side lobes has multi

minute main beams

Two identical defects may give

different amplitudes of signals


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Sound Beam

Near Zone

• Thicknessmeasurement

• Detection of defects

• Sizing of large defectsonly

Far Zone


• Defect detection

• Sizing of all defects

Near zone length as small as possible


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Near Zone

V

f D

f V

D

4 Near Zone

4 Near Zone

2

2


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Near Zone

• What is the near zone length of a 5MHz compressionprobe with a crystal diameter of 10mm in steel?

mm

V

f D

1.21000,920,54

000,000,510

4 Near Zone

2

2


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Near Zone

• The bigger the diameter the bigger the near zone

• The higher the frequency the bigger the near zone

• The lower the velocity the bigger the near zone

Should large diameter crystal probes have a high or

low frequency?

V

f D D

4

4

Near Zone22


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1 M Hz 5 M Hz

1 M Hz

5 M Hz

Which of the above probes has the longest Near Zone ?


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Near Zone





low frequency?

V

f D D

4

4

Near Zone22


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Beam Spread

• In the far zone sound pulses spread out as theymove away from the crystal

Df

KV

D

K

Sine or2

/2


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Beam Spread

Df

KV

D

K

Sine or2

Edge,K=1.22

20dB,K=1.08

6dB,K=0.56

Beam axis or

Main Beam


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Beam Spread

• The bigger the diameter the smaller the beamspread

• The higher the frequency the smaller the beamspread

Df

KV

D

K

Sine or2

Which has the larger beam spread, a compression or a

shear wave probe?


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Beam Spread

• What is the beam spread of a 10mm,5MHzcompression wave probe in steel?

o

Df

KV Sine

35.7 1278.0

105000

592008.12


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1 M Hz 5 M Hz

1 M Hz

5 M Hz

Which of the above probes has the Largest Beam Spread ?


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Beam Spread

• The bigger the diameter the smaller the beamspread

• The higher the frequency the smaller the beamspread

Df

KV

D

K

Sine or2

Which has the larger beam spread, a compression or a

shear wave probe?


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Testing close to side walls


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Ultrasonic Testing techniques

• Pulse Echo

• Through Transmission

• Transmission with Reflection


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Pulse Echo Technique

• Single probe sends and receives

sound• Gives an indication of defect

depth and dimensions

• Not fail safe


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Defect Position

No indication from defect A (wrong orientation)

AB

B


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Through Transmission Technique

Advantages• Less attenuation

• No probe ringing

• No dead zone• Orientation does not

matter

Disadvantages• Defect not located

• Defect can’t beidentified

• Vertical defects don’tshow

• Must be automated

• Need access to bothsurfaces


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Transmission with Reflection

RT

Also known as:

Tandem Technique or

Pitch and Catch Technique


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Pulse Length

• The longer the pulse, the more penetrating thesound

• The shorter the pulse the better the sensitivityand resolution

Short pulse, 1 or 2 cycles Long pulse 12 cycles


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Ideal Pulse Length

5 cycles for weld testing


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The Sound Beam

• Dead Zone

• Near Zone or Fresnel Zone

• Far Zone or Fraunhofer Zone


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Main Lobe

Side Lobes

NearZone

Main Beam

The main beam or the centre

beam has the highest intensity ofsound energy

Any reflector hit by the main beam

will reflect the high amount of

energy

The side lobes has multiminute main beams

Two identical defects may give

different amplitudes of signals


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Sound Beam

Near Zone


• Detection of defects

• Sizing of large defectsonly

Far Zone


• Defect detection

• Sizing of all defects

Near zone length as small as possible


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Near Zone





low frequency?

V

f D D

4

4 Near Zone

22


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1 M Hz 5 M Hz

1 M Hz

5 M Hz

Which of the above probes has the longest Near Zone ?


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Near Zone





low frequency?

V

f D D

4

4 Near Zone

22


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Beam Spread

• In the far zone sound pulses spread out as theymove away from the crystal

Df

KV

D

K

Sine or2

/2


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Beam Spread

Df

KV

D

K

Sine or2

Edge,K=1.22

20dB,K=1.08

6dB,K=0.56

Beam axis or

Main Beam


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1 M Hz 5 M Hz

1 M Hz

5 M Hz

Which of the above probes has the Largest Beam Spread ?


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Testing close to side walls


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Sound at an Interface

• Sound will be either transmitted across orreflected back

Reflected

Transmitted

InterfaceHow much is reflected andtransmitted depends upon the

relative acoustic impedance of the

2 materials


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Law of Reflection

• Angle of Incidence = Angle of Reflection

60o 60o


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Inclined incidence(not at 90

o

)

Incident

Transmitted

The sound is refracted due to differences in sound

velocity in the 2 DIFFERENT materials


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REFR CTION

• Only occurs when:

The incident angle is other than 0°

Water

Steel

Steel

Steel

Water

Steel

30°

Refracted


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REFR CTION

• Only occurs when:

The incident angle is other than 0°

Steel

Steel

Water

Steel

30°

Refracted

The Two Materials has different VELOCITIES

No Refraction

30°

30°

65°


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Snell’s Law

I

R

Material 1

Material 2

2Materialin1Material

VelinVel

RSine I Sine

Incident

Refracted

Normal


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Snell’s Law

C

Perspex

Steel

C

20

48.3

2Materialin

1Material

Vel

inVel

RSine

I Sine

5960

2730

48.3

20

Sine

Sine

4580.04580.0


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Snell’s Law

C

Perspex

Steel

C

15

34.4

2Materialin

1Material

Vel

inVel

RSine

I Sine

5960

2730

R

15

Sine

Sine

2730

596015SinSinR

565.0SinR4.34 R


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Snell’s Law

C

Perspex

Steel

C

20

S

48.3

24


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Snell’s Law

Perspex

Steel

S

C C

CC

S

When an incident beam of sound

approaches an interface of two different

materials: REFRACTION occurs

There may be more than one waveform

transmitted into the second material,example: Compression and Shear

When a waveform changes into

another waveform: MODE

CHANGE


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Snell’s Law

Perspex

Steel

C

C

S

If the angle of Incident is

increased the angle of

refraction also increases

Up to a point where the

Compression Wave is at 90°

from the Normal

90° This happens at the

FIRST CRITICAL ANGLE


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1st Critical ngle

C

27.4

S

33

C Compression wave refracted at 90

degrees


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2nd Critical ngle

C

S (Surface Wave)

90

C

Shear wave refracted at 90 degrees

57

Shear wave becomes a surface wave


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1st Critical Angle CalculationC

Perspex

Steel

C

5960

2730

90

I

Sine

Sine

59602730SinI

458.0SinI

26.27 I

S

190 Sin

27.2


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Before the 1st. Critical Angle: There are


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1st.

2nd.

33°

90°

both Compression and Shear wave inthe second material

S C

At the FIRST CRITICAL ANGLE Compression

wave refracted at 90°

Shear wave at 33 degrees in the material

Between the 1st. And 2nd.

Critical Angle: Only SHEAR

wave in the material.

Compression is reflected out of

the material.

C

At the 2nd. Critical Angle: Shear is

refracted to 90° and become

SURFACE wave

Beyond the 2nd. Critical

Angle: All waves are

reflected out of thematerial. NO wave in the

material.


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Summary• Standard angle probes between 1st and

2nd critical angles (45,60,70)

• Stated angle is refracted angle in steel• No angle probe under 35, and more

than 80: to avoid being 2 waves in the

same material.

C

S

C S

One Defect Two Echoes


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Snell’s Law

• Calculate the 1st critical angle for aperspex/copper interface

• V Comp perspex : 2730m/sec

• V Comp copper : 4700m/sec

5.355808.04700

2730SinI


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Sound Generation

• Hammers (Wheel tapers)

• Magnetostrictive• Lasers

• Piezo‐electric

magnetostrictive


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Piezo‐Electric Effect

• When exposed to an alternating current a crystalexpands and contracts

• Converting electrical energy into mechanical

‐ + + ‐ ‐ +

Pi El t i M t i l


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Piezo‐Electric MaterialsQUARTZ

• Resistant to wear

• Insoluble in water• Resists ageing

• Inefficient converter ofenergy

• Needs a relatively highvoltage

Very rarely used nowadays

LITHIUM SULPHATE

• Efficient receiver

• Low electrical impedance• Operates on low voltage

• Water soluble

• Low mechanical strength

• Useable only up to 30ºC

Used mainly in medical


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Polarized Crystals

• Powders heated tohigh temperatures

• Pressed into shape

• Cooled in very strong

electrical fields

Examples

• Barium titanate (Ba Ti O3)

• Lead metaniobate(Pb Nb O6)

• Lead zirconate titanate (Pb TiO3 or Pb Zr O3)

Most of the probes for conventional usage use

PZT : Lead Zirconate Titanate


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Probes

Z


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Probes• The most important part of theprobe is the crystal

• The crystal are cut to a particular

way and thickness to give theintended properties

• Most of the conventional crystalare X – cut to produce

Compression wave

X

XX

Y

Probes


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• The frequency of the probe depends on theTHICKNESS of the crystal

• Formula for frequency:

Ff = V / 2tWhere Ff = the Fundamental frequency

V = the velocity in the crystal

t = the thickness of the crystal

Fundamental frequency is the frequency of the material ( crystal ) whereat that frequency the material will vibrate.


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Probes

• The Thinner the crystal the Higher the frequency

• Which of the followings has the Thinnest crystal ?

1 MHz Compression probe

5 MHz Compression probe

10 MHz Shear probe

25 MHz Shear probe

25 MHz Shear

Probe


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Probe Design

• Compression Probe• Normal probe

• 0°

Damping

Transducer

Electrical

connectors

Housing


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Probe Design

• Shear Probe• Angle probe

Damping

Transducer

Perspex wedge

Backing medium

Probe Shoe


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Probe Design

Twin Crystal

Advantages

• Can be focused

• Measure thin plate• Near surface resolution

Disadvantages

• Difficult to use on

curved surfaces

• Sizing small defects

• Signal amplitude /focal spot length

Transmitter Receiver

Focusing

lensSeparator /

Insulator


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Sound Intensity

Comparing the intensity of 2 signals

1

0

1

0

P

P

I

I

Electrical power proportional to thesquare of the voltage produced

21

2

0

1

0

)(

)(

V

V

P

P

21

2

0

1

0

)(

)(

V

V

I

I Hence

Sound Intensity


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Sound Intensity

2

1

2

0

1

0

)(

)(

V

V

I

I Will lead to large ratios

2

1

20

10..

1

010..

)(

)(

V

V Log

I

I Log Therefore

dBV V Log

I I Log

1

010..

1

010.. 20

BELV

V Log

I

I Log

1

010..

1

010.. 2

2 signals at 20% and 40% FSH.


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1

010..20 H H LogdB

2 signals at 20% and 40% FSH.What is the difference between them in dB’s?

2..2020

4020 1010.. Log LogdB

3010.020dB

dBdB 6

2 signals at 10% and 100% FSH.


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1

010..20 H H LogdB

2 signals at 10% and 100% FSH.What is the difference between them in dB’s?

10..2010

10020 1010.. Log LogdB

120dB

dBdB 20


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mplitude ratios in decibels

• 2 : 1 = 6bB

• 4 : 1 = 12dB• 5 : 1 = 14dB

• 10 : 1 = 20dB

• 100 : 1 = 40dB

Automated Inspections


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Automated Inspections

• Pulse Echo

• Through Transmission

• Transmission with Reflection

• Contact scanning

• Gap scanning

• Immersion testing


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Gap Scanning

• Probe held a fixed distance abovethe surface (1 or 2mm)

• Couplant is fed into the gap

Immersion Testing

C t i l d i t fill d t k


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• Component is placed in a water filled tank

• Item is scanned with a probe at a fixed distanceabove the surface

Immersion Testing


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Water path

distance

Water path distance

Front surface Back surface

Defect

Ultrasonic Testing


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• Sensitivity

• Defect sizing

• Scanning procedures

Sensitivity


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• The ability of an ultrasonic system to find thesmallest specified defect at the maximum testing

range

Depends upon

• Probe and flaw detector combination

• Material properties

• Probe frequency• Signal to noise ratio

Methods of Setting Sensitivity


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• Smallest defect at maximum test range

• Back wall echo

• Disc equivalent

• Grass levels

• Notches• Side Drilled Holes, DAC Curves

rtificial / actual defect


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Example: The defect echo is set to

FSH (Full Screen Height)

Sizing Methods

6 dB Drop


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p

• For sizing large planar reflectors only

• Signal / echo reduced to half the height

• Example:100% to 50%

80% to 40%

70% to 35%

20% to 10%

Centre of probe marked representing the edge of defect.

6 dB Drop


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BWEDefect

The back wall echo reduced as some part of the

beam now striking the defect

The echo of the defect has NOT yet maximise as

the whole beam Not yet striking the defectPlan View

6 dB Drop


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Plan View

Now the whole beam is on the defect

Defect

Back wall echo is now may be reduced or

disappeared

6 dB Drop


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BWEDefect

Plan View

The probe is moved back until the echo is

reduced by half of it’s original height

At this point the probe centre beam is directly

on the edge of the defect

The probe is then removed and the centre is

marked, and repeat to size the whole defect

Sizing Method


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• Maximum Amplitude Technique

For sizing multifaceted defect – eg. crack

Not very accurate

Small probe movement

Maximum mplitude


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The whole probe beam is on the on the

defect

At this point, multipoint of the defect reflect

the sound to the probe

The echo (signal) show as a few peaks

Multifaceted defect : crack

Maximum mplitude


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Multifaceted defect : crack

The probe is moved out of the

defect, the signal disappeared

If the edge of the beam strike the

edge of the defect, a very small

echo appears

If the probe is moved into the defect,the signals height increase

At this point the MAIN BEAM is

directly at the edge of the defect

One of the peak maximised

Maximum mplitude

Remember: The peak which maximised does not

have to be the tallest or the first one


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The probe is to be moved to the other endof the defect

The signals will flactuate as the beam hits the

different faces of the defects

The probe is moved back into the defect and

to observe a peak of the signal maximises

Mark the point under thecentre of the probe

which indicates the edge

of the defect

The length of the defect is

measured

Length

Equalization Technique

BWEDefect

The equalization technique can ONLY be used if the

defect is halfway the thickness


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At this point the whole beam is on theback wall

BWE

At this point the whole beam is on

the defect

The BWE is at it maximum

The Defect echo is at it

maximum

Defect

At the edge of the defect, half of

the beam is on the defect, and

another half is on the back wall

The defect echo is at equal

height as the back wall

The point is marked as the edge of defect

20 dB Drop

Defect BWE


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Defect BWE

When the main beam is on the defect the defect signal is at it maximum

If the probe is moved and the signal is observed until it is reduced to 10%

(20dB Drop), the edge of the beam is on the edge of the defect

10%

Using the pre‐constructed Beam profile and a plotting card, the defect

maybe sized

Repeat the above at the other side of the defect

20 dB Beam profile


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Product Technology

Welding

A Weld : Definitions• A union between A ti d f t


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A union betweenpieces of metal at facesrendered plastic orliquid by heat,pressureor both.

BS 499

• A continuous defectsurrounded by parent

materialNASA

Welds• An ideal weld must give a strong bond between

materials with the interfaces disappearing


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To achieve this

• Smooth,flat or matching surfaces

• Surfaces shall be free from contaminants

• Metals shall be free from impurities

• Metals shall have identical crystalline structures

Welding• A union between pieces of metal at faces


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rendered plastic or liquid by heat,pressure or

both.

BS 499

• Ultrasonics• Electron beam

• Friction

• Electric resistance

• Electric arc

Possible energy sources

Electric Arc Welding


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Power

supply

Work piece

Electrode

Clamp(Earth)

Electric Arc Welding• Electric discharge produced between cathode and anode by

a potential difference (40 to 60 volts)


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• Discharge ionises air and produces ‐ve electrons and +ve

ions

• Electrons impact upon anode, ions upon cathode

• Impact of particles converts kinetic energy to heat (7000

o

C)and light

• Amperage controls number of ions and electrons, Voltagecontrols their velocity

Electric Arc WeldingArc Welding Processes

• Manual metal arc


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Manual metal arc

• Tungsten Inert Gas

• Metal Inert Gas

• Submerged Arc

Differences between them

• Methods of shielding the arc

• Consumable or Non-consumable electrode

• Degree of automation

Zones in Fusion Welds

F i Z


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• Fusion Zone


• F sion Zone


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• Fusion Zone

• Heat Affected Zone


• Fusion Zone


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• Fusion Zone

• Heat Affected Zone

• Parent Material or Base Metal


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Manual Metal Arc (MMA)

Consumable

electrode


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Flux coating

Core wire

Arc

Evolved gas

shield

Parent metal

Slag

Weld metal

Manual Metal Arc Welding


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• Shielding provided by

decomposition of fluxcovering

• Electrode consumable

• Manual process

Welder controls

• Arc length

• Angle of electrode

• Speed of travel

• Amperage settings

Tungsten Inert Gas (TIG)Gas nozzle


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Non‐consumable

tungsten

electrode

Arc

Parent metal

Weld metal

Gas shield

Filler wire

Metal Inert Gas (MIG)Gas nozzle Reel feed


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Consumableelectrode(filler wire)

Arc

Parent metal

Weld metal

Gas shield

Submerged Arc Reel feed


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Consumableelectrode

Flux feed

Flux

retrieval

Parent metal

Weld metal

Slag

Electroslag

Filler wire


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Molten flux

Weld metal

Water cooled

copper shoes

Welding Defects

4 Crack Types

Cracks


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yp

• Solidification cracks

• Hydrogen induced cracks

• Lamellar tearing

• Reheat cracks

Welding Defects

l ifi d b h

Cracks


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Classified by Shape

• Longitudinal• Transverse

• Branched

• Chevron

Classified by Position

• HAZ

• Centreline

• Crater

• Fusion zone

• Parent metal

Welding Defects

Cracks


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Solidification

• Occurs during weld solidification process

• Steels with high sulphur content (low ductility atelevated temperature)

• Requires high tensile stress• Occur longitudinally down centre of weld

• eg Crater cracking

Welding Defects

Hydrogen Induced

bl d h d

Cracks


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• Requires susceptible grain structure, stress and hydrogen

• Hydrogen enters via welding arc

• Hydrogen source ‐ atmosphere or contamination ofpreparation or electrode

• Moisture diffuses out into parent metal on cooling• Most likely in HAZ

Welding Defects

Lamellar Tearing

Cracks


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• Step like appearance

• Occurs in parent material or HAZ

• Only in rolled direction of the parent material

• Associated with restrained joints subjected to through

thickness stresses on corners, tees and fillets• Requires high sulphur or non‐metallic inclusions

Welding Defects

Re‐Heat Cracking

Cracks


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• Occurs mainly in HAZ of low alloy steels during post weld

heat treatment or service at elevated temperatures• Occurs in areas of high stress and existing defects

• Prevented by toe grinding, elimination of poor profilematerial selection and controlled post weld heattreatment

Welding Defects• Incomplete root penetration


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Causes

• Too large or small a root gap

• Arc too long

• Wrong polarity

• Electrode too large for joint preparation

• Incorrect electrode angle

• Too fast a speed of travel for current

Welding Defects

• Root concavity


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Causes

• Root gap too large

• Insufficient arc energy

• Excessive back purge (TIG)

Welding Defects

• Lack of fusion


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Causes• Contaminated weld preparation

• Amperage too low

• Amperage too high (welder increases speed of

travel)


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Welding Defects

• Incompletely Filled Groove


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Causes

• Insufficient weld metal deposited

• Improper welding technique

Welding Defects

• Gas pores / Porosity


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Causes

• Excessive moisture in flux or preparation

• Contaminated preparation

• Low welding current

• Arc length too long

• Damaged electrode flux

• Removal of gas shield


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Welding Defects

• Arc Strikes

Causes

• Spatter

Causes


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• Electrode straying ontoparent metal

• Electrode holder with

poor insulation

• Poor contact of earth

clamp

• Excessive arc energy• Excessive arc length

• Damp electrodes

• Arc blow

Nature and Origin of Defects


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• Inherent

• Processing

• In Service

Heat Induced Defects

• Heat treatment cracks


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• Grinding cracks

• Friction induced cracks

In Service Cracks

• Fatigue cracks

Cyclic stress

Fatique


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g

• Stress corrosion cracks

• Hydrogen induced cracks

Hydrogen

crack

Product Technology

Steel Production

Wrought ProductionCasting Welding


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Wrought Production

Extrusion

Forging

Rolling

Casting Welding

Defects Inherent

Processing

Service

Heat Treatment

Twi Ut Notes

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