1. LARSEN AND TOUBRO LIMITED HEAVY ENGINEERING DIVISION
NON DESTRUCTIVE EXAMINATION
ULTRASONIC TESTING
LARSEN AND TOUBRO LIMITED
HEAVY ENGINEERING DIVISION

2. ULTRASONIC SYSTEMS PULSE ECHO SYSTEM RESONANCE SYSTEM
THROUGH TRANSMISSION SYSTEM
PULSE ECHO SYSTEM
RESONANCE SYSTEM

3. ULTRASONIC SYSTEMS THROUGH TRANSMISSION SYSTEM:
1. Sound Energy is continuous or Pulsed
2. Separate transmitter / reciever
3. Soundness of test specimen based on energy lost
4. Indicates only presence of defect and not the location
Transmitter
Reciever echo
Reduced echo
Reciever
Through Trans. Testing
CRT Display - defect free area
CRT Display - defective area

4. Fundamental Resonance Frequency F = V/2T
RESONANCE SYSTEM
1. CONTINUOUS WAVES ARE NEEDED.
2. USED FOR THICNESS MEASUREMENT, LACK OF BONDING
IN CLAD & FOR DETECTING LAMINATION.
T= 1
Resonance will occur only when the specimen thickness is equal to a half wave length or an exact multiple of a half wave length.
Fundamental Resonance Frequency F = V/2T

5. PULSE ECHO SYSTEM 1. WIDELY USED FOR FLAW DETECTION
2. SOUND ENERGY IS TRANSMITTED IN PULSES
3. USED IN CONTACT AND IMMERSION METHODS
4. CRT DISPLAY -
A-SCAN : ANALOG DISPLAY - TIME VERSUS AMPLITUDE
B-SCAN : CROSS SECTIONAL VIEW
C-SCAN : PLANAR VIEW
5. MAY BE USED IN CONTACT AS WELL AS IMMERSION
TESTING OF PLATES, PIPES, FORGINGS , CASTINGS &
WELDS.

6. ULTRASONIC EXAMINATION
Basic Principles
Ultrasonic Pulse Echo equipment generates high voltage electrical pulses. These pulses are applied to the Transducer ( Probe ) which converts them into mechanical vibrations ( sound energy at high frequency i.e. Ultrasonic sound energy > 20,000 cycles per second ) that are transmitted into the material being tested. The reflected sound energy either from the back surface or from discontinuities is again converted into electrical pulses by the transducer and is displayed on the CRT ( Cathode ray tube )

7. TYPICAL A- SCAN DISPLAY
Normal Beam Scanning:
CRT Display
Transducer
A B C
Defect
Specimen
Thicknes (Time-Distance)
A- Initial Pulse
B- Defect Echo
C- Back Surface Echo

8. TYPICAL A-SCAN DISPLAY
Angle Beam scanning
CRT Display
A B
Time - Distance
A- Initial Pulse
B- Defect Echo

9. ULTRASONIC TRANSDUCERS
1. LONGITUDINAL MODE PROBES ARE USED IN GENERAL
FOR STRAIGHT BEAM EXAMINATION.
2. SHEAR WAVE PROBES ARE USED FOR ANGLE BEAM
EXAMINATION.
3. HIGHER THE FREQUENCY OF THE PROBE, HIGHER
WILL BE THE SENSITIVITY AND RESOLUTION BUT
LESSER PENETRATION.
4. LOWER THE FREQUENCY OF PROBE LESSER WILL BE
THE SENSITIVITY AND RESOLUTION BUT HIGHER WILL
BE THE PENETRATION.

10. ULTRASONIC TRANSDUCERS
1. IN GENERAL CONTACT TESTING IS CARRIED OUT USING
PROBES IN THE FREQUENCY RANGE OF 1 TO 5MHz.
2. HIGHER FREQUENCY PROBES IN RANGE OF 2.25MHz TO
25MHz ARE USED IN IMMERSION TESTING.
3. LONGITUDINAL MODE COARSE GRAIN ANGLE BEAM PROBES
FOR SPECIAL APPLICATION ARE AVAILABLE FOR TESTING
OF AUSTENITIC / NICKLE BASE WELDS.
4. TWIN CRYSTAL PROBES ARE USED FOR TESTING WELDS AND
MATERIALS FOR BETTER NEAR SURFACE RESOLUTION.

11. NDE PERSONNEL QUALIFICATIONS
NDE Personnel are qualified as per L&T’s Written Practice which is based on SNT-TC-1A of ASNT
LEVEL -I
Functions as per the written instructions from Level II/III.
LEVEL - II
Prepare Procedures , carry out testing , guide level -I , evaluate results etc.
LEVEL-III
Train & qualify Level-I & II personnel as per L&T’s Written Practice , prepare procedures, approve procedures etc.

12. ULTRASONIC EXAMINATION
APPLICATION
Plates are usually tested for laminations using normal beam probes.
For special application such as Nuclear / Aerospace, plates are also tested with angle beam.
Forgings depending on their shape and size are tested using normal as well as angle beam probes.
Weld overlay is usually tested with twin crystal normal beam probes. In some special application angle beam scanning is also carried out.
Welds such as butt / nozzle welds are tested both with normal & angle beam probes

13. ULTRASONIC EXAMINATION
Application ( cont..)
Frequency of sound energy used in general for contact testing is up to 5 MHz, whereas in immersion testing the frequency used may be as high as 25 MHz.
Probe angles used in general in angle beam examination are 45, 60 & 70 Deg. Some other angles such as 35, 80 deg etc are also used for some special applications depending on the geometry of the specimen.
In general normal beam testing is carried out using longitudinal mode, whereas shear waves are used in case of angle beam scanning. But in some cases like angle beam examination of weld overlay, longitudinal waves are used for better penetration.

14. ULTRASONIC EXAMINATION
ADVANTAGES
Testing can be carried out with one side access.
Any thickness on higher side can be tested ( Superior penetrating power ).
Results are immediate.
Exact depth and locations of flaws can be estimated.
Compact and portable equipments are available.

15. ULTRASONIC EXAMINATION
LIMITATIONS
Highly skilled and trained personnel are required.
Coarse grain weld material like Austenitic stainless steel & Nickel based non ferrous welds are difficult to test.
Equipment cost is very high for automated testing with recording / imaging facility.

16. ULTRASONIC EXAMINATION
SPECIAL APPLICATIONS / DEVELOPMENTS
1. High Temperature Ultrasonic Examination of
welds upto 250 ° C using special purpose
RTD make probes & Silicone oil as couplant.
2. Ultrasonic Examination of Ausenitic Stainless
Steel welds using Coarse Grain Longitudinal
Mode Probes.

17. ULTRASONIC EXAMINATION
SPECIAL APPLICATIONS / DEVELOPMENTS contd...
Ultrasonic Examination of Coarse Grain Nickle Based weld overlay for detecting underbead transverse cracks at the clad interface using RTD make , longitudinal mode, twin crystal focussed probes.

18. SPECIAL APPLICATIONS / DEVELOPMENTS contd...
DC LOW SPEED MOTOR
PROBE - FIXTURE ASSEMBLY
XY - RECORDER
USM - 3S FLAW DETECTOR
REDUCTION
GEAR BOX
CLAD
TUBESHEET
PROBE
SCHEMATIC DIAGRAM
Ultrasonic Examination of Tube# Tubesheet welds in Carbamate Condenser using Auto-Immersion Technique.

19. ULTRASONIC EXAMINATION TRANSDUCERS FOR SPECIAL APPLICATIONS:
1. Panametric make Videoscan Immersion Transducer
with Mirror Reflector for Ultrsonic Examination of
Tube to Tubesheet welds.
2. High Temperature RTD make probes.
3. RTD make coarse grain angle beam probe for testing of
overlay.

20. EQUIPMENTS & ACCESSORIES
ULTRASONIC EXAMINATION
EQUIPMENTS & ACCESSORIES
ULTRSONIC FLAW DETECTORS:
1. USM 3S MAKE- KRAUTKRAMER GERMANY RANGE MM
2. USIP MAKE - KRAUTKRAMER GERMANY RANGE MM
3. USN MAKE - KRAUTKRAMER GERMANY RANGE MM
STORAGE FACILITY UPTO 30 CALIBRATIONS
DIGITAL AND ANALOG DISPLAY
4. USK -6 /7S -MAKE - KRAUTKRAMER GERMANY RANGE MM

21. EQUIPMENTS & ACCESSORIES contd...
ULTRASONIC EXAMINATION
EQUIPMENTS & ACCESSORIES contd...
ULTRASONIC TRANSDUCERS
Contact Probes : Normal, 35° ,45°,60 °,70°,80°
Frequency 1MHz to 4MHz
Krautkramer make
Immersion Type probes : Frequency 5MHz to 15 MHz
Krautkramer, Panametrics
& Ultran make
Finger Tip probes: Miniature probes , Frequency 2.25MHz - 5MHz
Make - Krautkramer.

22. VARIOUS TYPES OF WELDS AND MATERIALS EXAMINED BY UT
White metal lining examination on bearings.
Austenitic stainless steel welds on Nuclear End Shields.
Austenitic S.S to Inconel Weld joints in Steam Generators.
Weld joints on Maraging Steel M-250 materials for space application.
Monel, Inconel & Austenitic stainless steel weld overlay
Carbon Steel and Alloy Steel welds and materials
Titanium clad testing for bond and flaw detection