The document discusses the basics of ultrasonic testing including: - A 9.5 day course to train participants in ultrasonic testing and prepare them for examinations. - Common NDT methods and that the best method depends on various factors and conditions. - Basic principles of ultrasonic testing including transmitting sound through materials to detect defects based on differences in signal return times. - Key concepts in ultrasonic testing like frequency, wavelength, velocity and their relationships.

1. Ultrasonic Testing Part 1 TWI

2. Ultrasonic Testing NDT Training & Certification

3. 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 obtain required skill and knowledge in Ultrasonic Testing and to meet the examination schemes requirements.

4. 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

5. NDT Which method is the best ? Depends on many factors and conditions

6. Basic Principles of Ultrasonic Testing To understand and appreciate the capability and limitation of UT

7. 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

8. Basic Principles of Ultrasonic Testing The distance the sound traveled can be displayed on the Flaw Detector The screen can be calibrated to give accurate readings of the distance Bottom / Backwall Signal from the backwall

10. Basic Principles of Ultrasonic Testing The 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 Defect The BWE signal Defect signal

11. The depth of the defect can be read with reference to the marker on the screen 60 mm 0 10 20 30 40 50 60

12. 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 68 46 30

13. Ultrasonic Testing Principles of Sound

14. 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)

15. Properties of a sound wave Sound cannot travel in vacuum Sound energy to be transmitted / transferred from one particle to another SOLID LIQUID GAS

16. 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/s V Compression in water : 1470 m/s V Compression in air : 330 m/s STEEL WATER AIR 5 M Hz

17. 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

18. DRUM BEAT Low Frequency Sound 40 Hz Glass High Frequency 5 K Hz ULTRASONIC TESTING Very High Frequency 5 M Hz

19. Ultrasonic Sound : mechanical vibration What is Ultrasonic? Very High Frequency sound – above 20 KHz 20,000 cps

20. Acoustic 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

21. Frequency Frequency : Number of cycles per second 1 second 1 cycle per 1 second = 1 Hertz 18 cycle per 1 second = 18 Hertz 3 cycle per 1 second = 3 Hertz THE HIGHER THE FREQUENCY THE SMALLER THE WAVELENGTH 1 second 1 second

22. 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

23. 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 cycle wavelength  wavelength Wavelength Wavelength is the distance required to complete a cycle.

24. Velocity Frequency Wavelength

25. Frequency & Wavelength 1 M Hz 5 M Hz 10 M Hz 25 M Hz Which probe has the smallest wavelength? SMALLEST LONGEST Which probe has the longest wavelength?  = v / f F  F 

26. Wavelength is a function of frequency and velocity. 5MHz compression wave probe in steel Therefore: or or f V   V   f V  f 

27. Which of the following compressional probe has the highest sensitivity? 1 MHz 2 MHz 5 MHz 10 MHz 10 MHz

28. Wavelength and frequency The higher the frequency the smaller the wavelength The smaller the wavelength the higher the sensitivity Sensitivity : The smallest detectable flaw by the system or technique In UT the smallest detectable flaw is ½  (half the wavelength)

29. The Sound Beam Dead Zone Near Zone or Fresnel Zone Far Zone or Fraunhofer Zone

30. The Sound Beam NZ FZ Main Beam Distance Intensity varies Exponential Decay

31. Main Lobe Side Lobes Near Zone Main Beam The main beam or the centre beam 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

32. Sound Beam Near Zone Thickness measurement Detection of defects Sizing of large defects only Far Zone Thickness measurement Defect detection Sizing of all defects Near zone length as small as possible

33. Near Zone

34. Near Zone What is the near zone length of a 5MHz compression probe with a crystal diameter of 10mm in steel?

35. 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?

36. Which of the above probes has the longest Near Zone ? 1 M Hz 5 M Hz 1 M Hz 5 M Hz

37. 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?

38. Beam Spread In the far zone sound pulses spread out as they move away from the crystal   / 2

39. Beam Spread Edge,K=1.22 20dB,K=1.08 6dB,K=0.56 Beam axis or Main Beam

40. Beam Spread The bigger the diameter the smaller the beam spread The higher the frequency the smaller the beam spread Which has the larger beam spread, a compression or a shear wave probe?

41. Beam Spread What is the beam spread of a 10mm,5MHz compression wave probe in steel?

42. Which of the above probes has the Largest Beam Spread ? 1 M Hz 5 M Hz 1 M Hz 5 M Hz

43. Beam Spread The bigger the diameter the smaller the beam spread The higher the frequency the smaller the beam spread Which has the larger beam spread, a compression or a shear wave probe?

44. Testing close to side walls