UT Testing-Add03-Q&A Mistakes

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ASNT UT Level III pre-exam preparatory course note

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slide 1:

Addendum-03 Questions Answers Collection of My Pitfalls

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Uncertain Questions 21. Which type of calibration block is used to determine the resolution of angle beam transducers per requirements of AWS and AASHTO a. An IIW block b. A DSC block c. A rompus block d. An RC block 24. Resonance or standing waves are a result of: a. mode conversion b. interference from reflected waves c. beam divergence spread d. attenuation of the sound waves

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Make mistakes now not during exam

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RC- Resolution Calibration Block

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30. On an A-scan display the dead zone refers to: a. the distance contained within the near field incorrect b. the area outside the beam spread c. the distance covered by the front surface pulse width and recovery time d. the area between the near field and the far field 40. The second critical angle is the angle of the incident beam at which: a. the angle of the refracted compression wave is 900 b. the angle of the reflected compression wave is 90 ° c. total reflection occurs d. surface waves are produced --------------------------------------------------------------------------------

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17. Surface waves are used to detect discontinuities in the test materials: a. At half the depth. b. Above the lower surface. c. On the surface where the probe is in contact. d. None of the above. 26. Which of the following probes is most commonly used for testing welded metals for laminations before angle beam inspection. a. Surface wave probe. b. Twin crystal 0 ° probe. c. Single crystal probe. d. An angle probe. 29. Artificial flaws can be produced by using: Side drilled holes Flat bottom holes EDM notches http://www.phtool.com/pages/edm.asp All of the above

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31. As the acoustic impedance ratio between two materials approaches 1 the amount of sound reflected at an interface: a. increases. b. decreases. c. is not affected. d. varies depending upon the velocity of the materials. 34. Significant errors in ultrasonic thickness measurements can occur if a. Test frequency is varying at a constant rate. b. The velocity of propagation deviates substantially from an assumed constant value for a given material. c. Water is employed as a couplant between the transducer and the part being measured. d. None of the above should cause errors.

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45. When examining thin materials for planar discontinuities oriented parallel to the part surface what testing method is most often used: a. Angle beam b. Through-transmission c. Straight beam - single crystal d. Straight beam - dual crystal 7. The ultrasonic test method in which finger damping in most effective in locating a discontinuity is: a. shear wave b. longitudinal wave c. surface wave d. compressional wave

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15. Which type of test block is used to check horizontal linearity and the dB accuracy per requirements of AWS and AASHTO a. Distance/Sensitivity block b. A DSC block c. A rompus block d. A shear wave calibration block

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Mistake Made -------------------------------------------------------------------------------- Question: Which probe will be used for critical examination in a forged component with a curved surface.: Your answer: 1 megahertz 10mm dia. Correct answer: 10 megahertz 25mm dia. Question: A general term applied to all cracks inclusions blow holes etc which cause a reflection of sonic energy is: Your answer: a refractor Correct answer: a discontinuity Question: On an A-scan display the dead zone refers to: Your answer: the distance contained within the near field Correct answer: the distance covered by the front surface pulse width and recovery time

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Mistake Made -------------------------------------------------------------------------------- Question: Dead zone size depends on: Your answer: construction of the probe. Correct answer: All of the above. Question: The second critical angle is the angle of the incident beam at which: Your answer: total reflection occurs Correct answer: surface waves are produced ---------------------------------------------------------------------------------

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Mistake Made -------------------------------------------------------------------------------- Question: When a longitudinal wave encounters an interface between two material with different accoustic impedances what occurs when the Your answer: Reflection and refraction Correct answer: Reflection Question: In an ultrasonic instrument the number of pulses produced by an instrument in a given period of time in known as the:Your answer: pulse length of the instrument Correct answer: pulse repetition rate Question: Which probe will be used for critical examination in a forged component with a curved surface.:Your answer: 10 megahertz 10mm dia.Correct answer: 10 megahertz 25mm dia.

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Question: Which type of screen presentation displays a profile or cross- sectional view of the test specimen Your answer: A-scan Correct answer: B-scan Question: When a longitudinal wave encounters an interface between two material with different accoustic impedances what occurs when the Your answer: Refraction Correct answer: Reflection

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Questions Answers

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Table 1.2

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Chapter 1: Physical Principles Q1-10 The acoustic energy reflected at a plexiglass-quartz interface is equal to Answer: R Z 1 -Z 2 2 / Z 1 +Z 2 2 3.2-15.2 2 / 3.2+15.2 2 42.53 Q1-11 The acoustic energy transmitted through a plexiglass-water interface is equal to Answer: R Z 1 -Z 2 2 / Z 1 +Z 2 2 3.2-1.5 2 / 3.2+1.5 2 13 T 1-R 87 Q1-12 The first critical angle at a water-plexiglass interface will be Answer: ϴ Sin-1 1483/2730 32.9 °

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Q1-13 The second critical angle at water-plexiglass interface will be Answer: ϴ Sin -1 1483/1430 Error Q1-14 The incident angle need in immersion testing to develop a 70 shear wave in plexiglass is equal to Answer: ϴ Sin -1 1483/1430 x sin70 77 °

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Q1-20 Two plate yield different back-wall reflections in pulse-echo testing 18dB with their only apparent difference being in the second material void content. The plate are both 3” thick. What is the effective change in acoustic attenuation between the first and second plate Answer: Sound path – 2 x thickness 6” Attenuation 18dB/6” 3dB/in. Comment: The answer could be confused if the pulse-echo testing 2-ways path length was not considered arriving with the incorrect answer of 6dB/in

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For evaluating material properties always remember to divide the result with the actual sweep distance if necessary It was not a one-way–trip

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Q1-15 At a water-Aluminum interface at an incident angle of 20 ° the reflected and transmitted wave are Answer: 60 transmitted and 40 reflected.

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Q1-22 The beam spread half angle I the far field of a I” diameter transducer sending 5MHz longitudinal wave into Plexiglas block is Answer: ϴ Sin-1 K λ/D Assumed K1.2 for null beam edge ϴ Sin -1 K λ/D Sin-11.2V/DF Sin -1 1.2x2730x10 3 / 25.4x5x10 6 1.478 ° Q1-23 The near field of a round 1/2 “ diameter contact L-wave transducer being used on a steel test part operating at 3MHz is Answer: Z D2/4 λ 12.7 2 3x10 6 x / 4x5900x10 3 20.5mm

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Chapter 2: Equipment Q2-5 A 5MHz 0.5” diameter flat search unit in water has a near field length of approximately Answer: Z D 2 /4 λ 12.7 2 x 5x10 6 / 4x 1480X10 3 136mm 5.36” Q2-7 A 10MHz0.5” diameter transducer placed on steel and acrylic in succession the beam spread in these 2 material is ϴ sin-1K λ/D. ϴ Fe sin-11.2x5920x10 3 /10x10 6 x12.7 3.2 ° ϴ Acrylic sin -1 1.2x2730x10 3 /10x10 6 x12.7 1.48 °

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Q2-12 An angle beam produce a 45 ° shear wave in steel what is the incident angle V s for steel0.125in/ms V L for plastid0.105in/ms Answer: Snell’s Law ϴ incident Sin -1 0.105/0.125 xSin45 36.43 ° Q2-13 Aluminum rod 6” diameter being examined in immersion technique what is the required offset to generate a 45 ° refracted shear wave Answer: First find the incident angle using Snell’s Law ϴ incident Sin -1 1.5/3.1 xSin45 20 ° Offset rSin20 3Sin20 1.026”

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Q2-14 What is the offset required if 45 refracted longitudinal wave to be generated Answer: First find the incident angle using Snell’s Law ϴ incident Sin -1 1.5/6.3 xSin45 9.69 ° Offset r.Sin9.69 ° 3.Sin9.69 ° 0.505” Q2-16 In a longitudinal wave immersion test of Titanium plate an echoes pulse from an internal defect is observed 6.56 μs following front echo. How deep is the defect below the front surface Answer: Sound path travel 6100000 x 6.56 x 10 -6 40mm The actual depth sound path / 2 20mm

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Q2-17 A change in echo amplitude from 20 of FSH to 40 of FSH is a change of how many dB Answer: ΔdB 20log20/40 6dB drop or -6dB. Q2-20 What is the lens radius of curvature is needed in order to have a 20mm diameter 5MHz transducer focus in water at a distance of 40mm drom the lens face Answer: RFn-1/n n V Lens /V water n 2.67/1.49 1.792. R400.792/1.792 17.7mm

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Q2-18 In Fig.29 what is the rate of attenuation in dB/in of 5MHz transducer in Far Field the horizontal scale is 0.5” per division and the vertical scale is linear. Answer: ΔI 20log1.25/2 D2” Attenuation 2.04dB/in or ΔI 20log1.25/2 D1.85” Attenuation 2.21dB/in or ΔI 20log1.075/2.2 D3” Attenuation 2.07dB/in

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Q2-19 What is the rate of attenuation for 2.25MHz transducer Answer: Δ I 20log0.9/2.2 D2.5” Attenuation 3.11dB/in

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Q2-21 Two signals were compared to each other. The second was found to be 14dB less than the first. This change could be represented by a change of Answer: ΔI 20LogI/I o -14dB 20LogI/I o I/I o 0.2 2 answers could be confused: 70 FSH to 14 FSH a drop of 80 20 FSH to 100 FSH an increase of 80

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Q2-11 A change in 16dB on the attenuator correspond to an amplitude ration of: Answer: ΔI 20LogI/Io 16dB 20LogI/Io I/Io 6.3

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Charter 3: Common Practices Q3-6 In Fig. 3.7 the respond from 3.23mm FBH at a depth of 25mm is above that detected from 1mm FBH by Answer: ΔdB 20Log2.1/0.6 10.88

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Q3-7 The half angle beam spread of the reflected wave front from 8 FBH in an aluminum “A” block being immersion tested using 25MHz transducer is Answer: Focal size 8/64 x 25.4 3.175mm diameter. The beam spread is in aluminum block the wave velocity VL6300 m/s The half angle beam spread ϴ Sin -1 K λ/D ϴ Sin -1 1.2x6300x10 3 /3.175x 25 x 10 6 5.47 ° Comment: Be careful with the unit used my mistake is: ϴ Sin -1 1.2x6300x10 3 /3.175x 10 -3 x 25 x 106

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Always Check the units correctly Only Donkey made such mistake

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Monkey made mistake too

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Smart Engineer do not made mistake with UNIT USED so do you

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Smart Himba Girl do not made mistake with UNIT USED too so do you http://cn.bing.com/images/searchqhimba+womengoE68F90E4 BAA4E69FA5E8AFA2E58685E5AEB9qsbsf ormQBIR

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Smart Himba Girl do not made mistake with UNIT USED too so do you http://cn.bing.com/images/searchqhimba+womengoE68F90E4BAA4E69FA5E8AFA2E58685E5AEB9qsbsformQBIR

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Smart Himba Girl do not made mistake with UNIT USED too so do you http://cn.bing.com/images/searchqhimba+womengoE68F90E4BAA4E69FA5E8AFA2E58685E5AEB9qsbsformQBIR

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Smart Papua New Guianese do not made mistake with UNIT USED too so do you http://www.tennenaturephotography.com/gallery/papua/Native_Dancer_Facefull1

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Q3-8 Answer: The next SDH used will be 5/4T first SDH after backwall echo. The node is 5/4x2 5/8 node

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Q3-11 When using a focued straight beam search unit for lamination scanning in an immersion test of steel plate a change in water path of 0.2” will result in the focal point moving in the steel a distance of Answer: The change in water path0.2” correspond to 0.2 x 1483/5900 0.05” Q3-12 A search unit with a foal length in water of 4” is used. A steel plate 8” thick velocity 0.230”/ms is place at a water depth of 2” from the search unit At what depth is the focal point in steel Answer: Focal depth in steel 2 x V water / V steel 2x1480/5900 0.5”

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Q3-13 During examination an indication of 25 FSH is detected and maximized. Foe better analysis the gain is increase by 12bB and the indication increase to 88 FSH. What value should be reached and what is the apparent problem Answer: 12dB 20LogI/25 I/25 3.98 I100

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Q3-23 A air filled 3 FBH 0.5” into the bottom of 4.5” aluminum block will return to the 0.75” diameter sending immersion transducer ans echo signal equal to Of the initial pulse. Assume no attenuation to beam divergence or other causes. Answer: The size of reflector 3/64” 0.046875”. For a small reflector used inverse square law Echo1/Echo2 Area 2 / Area 1 100/x 0.046875 2 / 0.75 2 x 0.39

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Q3-15 In contact testing the back surface signal from a 2” plate was set at full screen height. Passing over a coarse grained area the back surface signal dropped to 10 FSH. What is the change in attenuation in this area Answer: ΔI20Log10/100 the drop in dB 20dB. The sweep distance 4” The attenuation is 20/4 5dB/in. Comment: Remember that the attenuation is cause by the sound path traversing thru the sweep distance.

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Q4-12 Answer: First calculate the principle offset d ϴ Sin-11483/3250 xSin4518.8 ° dR.Sin18.8 0.323 Assume R1. Wobbling ±10 d’0.355 0.290 d’0.355 ϴ Sin-10.35520.8 ° giving inspection Φ Sin-13250/1483xSin20.851 13.3 above 45 ° d’0.290 ϴ Sin-10.29016.9 ° giving inspection Φ Sin-13250/1483xSin16.939.6 12 below 45 °

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Q4-13 Answer: PRR number of pulse per second N/s Length generated by pulse per second PRR x D For effective inspection Vp ≤ PRR x D Q4-14 Answer: Effective inspection Length generated by the PRR x Width 600in/s For a defect to be detected 3 time consecutively the travel speed V p 600/3 200in/s

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Q4-15 Answer: Offset T.tan70 x Number of ½ skip. Offset 3x 1.5 tan70 Comment: 1 skip 2 legs Q4-16 Answer:

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Q4-16

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Q4-17 Answer: Total length of axial 8x12x0.0254m L2.438m Sweep distance for a complete return loop 2 x L 4.876m For PRR 2000 Distance travel by each pulse L p 5920/2000 m L p 2.96m Since L p is less than the 4.876 the next pulse was found to be generated before the previous echo has returned to the receiver thus reduce the PRR is required. Set PRR1000 yield L p 5.92m L4.876m Will resolve the problem.

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Q4-17 Illustrations Length of axial 8’ or 2.438m Complete loop4.876m 2 nd pulse generating The previous pulse return position when 2 nd next pulse start to send Incoming returning wave meet ₵ 0.522m 0.958m 0.958m

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Q4-18 Answer:

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8. When testing a 30 mm diameter 500 mm long shaft from the flat end of the shaft using longitudinal waves from a 20 mm diameter 2 MHz probe numerous signals are seen on the screen after 500 mm. These are: a ghost images b side wall echoes c internal thread indications d none of the above

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Break mms://a588.l3944020587.c39440.g.lm.akamaistream. net/D/588/39440/v0001/reflector:20587BBC- UIDe5203c9d59fef1a79c12d8c601e839f58db16f7d5 d6448f55674c540f1856834ampSSO2-UID

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Q5-20 Answer: None of above

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Q5-22 Answer: Class C

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Q5-22 Table B-1

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5. At a solid to free boundary an obliquely incident longitudinal wave from the solid can result in at most: a a reflected longitudinal wave only b a reflected longitudinal and reflected shear wave c a refracted longitudinal long wave d a reflected longitudinal and reflected shear and refracted longitudinal wave 6. Geometric-optic treatment of ultrasonic waves fails to account for: a reflection b refraction c diffraction d normal incidence 34.The most useful range of incident longitudinal wave angles for ultrasonic testing is: a Normal incidence to the first critical angle b First critical angle to the second critical angle c Second critical angle to the third critical angle d Above the third critical angle

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38. The angle of a refracted shear wave generated as a sound wave passes at an angle through an acoustic interface is dependant on: a The acoustic impedances of the materials of each side of the interface b The frequency of the incident sound wave c The wavelength of the incident sound wave d The hardness of the materials on each side of the interface 22. The three most common modes of sound vibration are: a Longitudinal compressional and transverse waves b Longitudinal transverse and rayleigh waves c Transverse longitudinal and shear waves d Transverse shear waves and rayleigh waves

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13. An oscilloscope display in which the screen base line is adjusted to represent the one way distance in a test piece is called a: a A scan display b B scan display c C scan display d D scan display 12. Which of the following test frequencies would generally provide the best penetration in a 12 inch thick specimen of coarse-grained steel a 1.0 MHz b 2.25 MHz c 5.0 MHz d 10 MHz Incorrect – silly mistake

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48. A more highly damped transducer crystal results in: a Better resolution b Better sensitivity mistake c Lower sensitivity d Poorer resolution 6. The portion of a test piece which is represented by the CRT screen area from zero to the rightmost edge of the initial pulse is called: a The dead zone mistake b The near field c The near zone d The far zone

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17. Transducer focal lengths are normally specified as: a Distance in steel b Distance in aluminium c Distance in air d Distance in water mistake 21. An advantage of using a ceramic transducer in search units is that: a It is one of the most efficient generators of ultrasonic energy b It is one of the most efficient receivers of ultrasonic energy c It has a very low mechanical impedance d It can withstand temperatures as high as 700 o C

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47. When a vertical indication has reached the maximum signal height which can be displayed or viewed on the CRT of an ultrasonic instrument the indication is said to have reached its: a Distance-amplitude height mistake b Absorption level c Vertical level d Limit of resolution

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53. An ultrasonic instrument control which is used to adjust the sharpness of the CRT screen display is called: a Astigmatism or focus b Pulse repetition rate c Pulse energy d Gain

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63. The purpose of the couplant is to: a Match impedances between the transducer and test piece b Absorb stray reflectors c Clean the test piece so a more efficient test may be continued d Lock the ultrasonic scanner into place prior to testing Note: by exclude the air between the 2 interfaces.

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72. When conducting an immersion test the water path distance must be controlled so that: a Spurious signals are not created by surface waves on the test piece b The water path distance/diameter ratio does not result in asymmetric standing waves c The test piece discontinuity indications appear between the first front and first back surface echoes d The second front surface echo does not appear on the CRT screen between the first front and first back surface echoes

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Immersion Testing Method

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Standards Answer: C

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Standards Answer: B

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Standards Answer: A

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Standards Answer: A or C

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Standards Answer: A

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Standards Answer: C

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Standards Answer: B

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Standards Answer: C

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Standards Answer: C

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Standards Answer: A

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Arrows shown standard correct answers: Level I QA

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Arrows shown standard correct answers: Level I QA

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Study Blueeeeeeee… 28 th July 2014 17:34

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Arrows shown standard correct answers:

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mms://a588.l3944020587.c39440.g.lm.akamaistre am.net/D/588/39440/v0001/reflector:20587BBC- UIDe5203c9d59fef1a79c12d8c601e839f58db16f7 d5d6448f55674c540f1856834ampSSO2-UID

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Arrows shown standard correct answers: Level II QA http://www.mtv123.com/mp3/45297/326534.shtml

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Arrows shown standard correct answers:

slide 90:

Arrows shown standard correct answers: R↑∝F ↑

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Arrows shown standard correct answers:

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Arrows shown standard correct answers:

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Arrows shown standard correct answers: 3-Screen Height Linearity The ultrasonic testing instrument shall provide linear vertical presentation within ±5 According to ASME Sec.V Article 5 T-532 of the full screen height for 20 to 80 of the calibrated screen height. The procedure for evaluating screen height linearity is provided in appendix 1 of article 5 ASME code Sec.V and shall be performed at the beginning of each period of extended use or every 3 months which ever is less. http://www.inspection-for-industry.com/ultrasonic-testing.html

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Take a break mms://a588.l3944020587.c39440.g.lm.akamaistream.net/D/588/394 40/v0001/reflector:20587BBC- UIDe5203c9d59fef1a79c12d8c601e839f58db16f7d5d6448f55674c5 40f1856834ampSSO2-UID

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Calculation: Incident angle 7 ° Refracted longitudinal wave 29.11 ° Refracted shear wave 15.49 °

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Arrows shown standard correct answers:

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Arrows shown standard correct answers: Q2. During ultrasonic inspection of a weld having a thickness of 28 mm angle beam search units are to be used. The recommended angle of search unit Is: a. 70º b. 60º c. 45º d. any one

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