Non Destructive Ultrasonic Testing Presentation

L&T Heavy Engineering
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HED-HZW-HRD-S-009 & Revision No: 1
Dec 14, 2024
• Introduction to Ultrasonic Testing
• Ultrasonic wave modes
• Transducers
• Couplant
• Data presentations
• Advantages and disadvantages of ultrasonic testing.
• Operator Qualifications
• Calibration blocks, Qualification blocks & their purpose
• UT equipment
• Surface preparation required for UT
• UT hands on training
• Acceptance standards
• References
Ultrasonic Testing (UT)

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Ultrasonic Testing (UT)
• In 1912 Following the Great Disaster of Giant Ship TITANIC , It was suggested
after research That Ultrasound can be used for detection of iceberg in the
ocean , later it was used in World War-1 for detecting submarines in the sea.
After that journey continues......
Sound – Mechanical vibrations transmitted by an elastic medium.
Infrasound – Whales, elephants, hippopotamuses, rhinoceros, giraffes & alligators
Ultrasound – Bats , dolphins
Types of Sound Wave

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ULTRASONIC INSPECTION involves the detection of echoes produced when an
ultrasonic pulse is reflected from a discontinuity or an interface of a test piece.
Short bursts of ultrasonic energy are introduced into a test piece at regular
intervals of time.
Nature of Sound Waves, when entering
the Materials

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How it Generates ?
Crystals :- A three-dimensional array or atoms having a certain regularity in its
arrangement primarily made of :- Quartz, Lithium Sulphate, Barium Titanate, Lead
Zirconium titanate (PZT).
Piezoelectric Effect :
Piezo Electric
Pressure (Mechanical Energy) Electric (Electrical Energy) & Vice-Versa
The conversion of electrical pulses to mechanical vibrations and the conversion of
returned mechanical vibrations back into electrical energy is the basis for
ultrasonic testing.
Wavelength (  ) : The distance needed for a wave to go through a complete
cycle.
Frequency ( f ) : The number of waves that pass a given point in a specified unit of
time.
Velocity ( v ) : Distance traveled per unit time.
Wavelength : Velocity / Frequency

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Types of Ultrasonic Waves
On the basis of particle displacement in the medium ultrasonic waves are
classified. Velocity remains the same in the given medium but differs when the
method of vibration changes.
1. Longitudinal or Compressional Wave
Longitudinal waves have particle vibration in a back and forth motion in the
direction of wave propagation. These waves are readily propagated in the liquids,
gases and elastic solids.
These waves mostly used in the inspection of materials. The velocity of
longitudinal waves is about 6000 m/sec in steel,1500 m/sec in water and 330
m/sec in air.

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2. Transverse or Shear Wave
These wave have particle vibration perpendicular to the direction of wave
motion. These waves will not travel through liquid, gases because force of
attraction between molecules are too small . the velocity of these waves is about
50% the longitudinal waves for the same medium.

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3. Surface or Rayleigh Wave
These waves travel along the flat or curved surface of relatively thick solid parts. The
velocity of these waves are 90% of the transverse waves in the same material. Surface
waves are useful for detecting surface cracks. Vibration of particle follow an elliptical path.
4. Plate or Lamb Wave
These waves also another type of ultrasonic waves used to detect surface defect
and penetrates only up to half of wave length. These waves propagate in plate
only.

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Ultrasonic Transducers
•The active element is the heart of the transducer as it converts the electrical
energy to acoustic energy, and vice versa.
•Normal Beam, Angle beam, TR, Immersion, focused are few types of UT probes.
Types of Probe

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Couplant
A couplant is a material (usually liquid or semi liquid) that facilitates the
transmission of ultrasonic energy from the transducer into the test specimen.
The couplant displaces the air and makes it possible to get more sound energy
into the test specimen so that a usable ultrasonic signal can be obtained.
Couplant

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Ultrasonic Testing Systems
A typical UT inspection system consists of several functional units, such as the
pulsar/receiver, transducer, and display devices.
A pulsar/receiver is an electronic device that can produce high voltage electrical
pulse. Driven by the pulsar, the transducer generates high frequency ultrasonic
energy. The sound energy is introduced and propagates through the materials in
the form of waves. When there is a discontinuity (such as a crack) in the wave
path, part of the energy will be reflected back from the flaw surface.
0 2 4 6 8 10
Initial
pulse
Lamination
Echo
Back Surface
Echo
Plate
Lamination

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Probe Placement for Various Joint Configuration

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Data Presentation
A Scan
Display amplitude on y
axis ,distance between two
reflector on X - axis
B scan – Cross sectional View of the
material
C Scan
Top View of the material

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Advantages of UT
It is sensitive to both surface and subsurface discontinuities.
The depth of penetration for flaw detection or measurement is superior to
other NDT methods.
Only single-sided access is needed when the pulse-echo technique is used.
It is high accuracy in determining reflector position and estimating size and
shape.
Minimal part preparation required.
Electronic equipment provides instantaneous results.
Detailed images can be produced with automated systems.
It has other uses such as thickness measurements, in addition to flaw detection.

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Disadvantages of UT
Surface must be accessible to transmit ultrasound.
Skill and training is more extensive than with some other methods.
It normally requires a coupling medium to promote transfer of sound
energy into test specimen.
Materials that are rough, irregular in shape, very small, exceptionally thin or
not homogeneous are difficult to inspect.
Cast iron and other coarse grained materials are difficult to inspect due to
low sound transmission and high signal noise.
Linear defects oriented parallel to the sound beam may go undetected.

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Operator Qualifications
• The personnel employed for conducting the examination shall be trained,
examined and qualified for ultrasonic testing Level II or III (UT) as per L & T
Written Practice No. NDT-WP -01.
• Written practice for certification/re-certification of NDE personnel shall be
prepared in consultation with HOD-Quality by Level III.
• Recommendations of SNT-TC-1A, 2006 edition are fully incorporated in the
written practice

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Calibration blocks
• They are blocks prepared with standard defects in the form of side drilled
holes, notches or flat bottom holes . These defects are intended to
replicate the defects which could arise in the material.
• DAC curves are plotted with the help of calibration blocks

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Surface preparation for UT
• Surface preparation is very important in contact UT as the probe needs to
have a proper contact with the surface to transfer the ultrasound energy
into the material.
• Surface roughness also causes additional noise and false indications which
needs to be avoided for reliable ultrasonic test results.
• Minor surface roughness may be compensated by the application of
viscous couplant.

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Reference Code Section & Acceptance Standard
• ASME Section V, 2011a addenda
• Subsection – A
• ARTICLE 4 - Ultrasonic Examination Methods for Welds
• ARTICLE 5 - Ultrasonic Examination Methods for Materials
• Subsection – B
• ARTICLE 23 – 13 Sub Articles
• Acceptance Criteria
– ASME Sec. VIII Div. I & II

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THANK YOU

Non Destructive Ultrasonic Testing Presentation

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Non Destructive Ultrasonic Testing Presentation