NDT Question
NDT Question
NDT Question
(c) Most reliable for finding surface cracks in all types of material
3. Which of the following does not represent a limitation of magnetic particle testing?
4. The most effective NDT method for locating surface cracks in ferromagnetic materials
is:
(a) Ultrasonic testing
(b) Radiographic testing
(c) Magnetic particle testing
(d) Liquid penetrant testing
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6. A discontinuity which is produced during solidification of the molten metal is called:
(a) Inherent
(b) Processing
(c) Service
(a) Inherent
(b) Processing
(c) Service
(a) Inherent
(b) Processing
(c) Service
(a) Inherent
(b) Processing
(c) Service
(a) Lap
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11. Cracks which are caused by alternating stresses above a critical level are called:
12. Cracks which are caused by a combination of tensile stress and corrosion are called:
14. The reverse magnetising force necessary to remove a residual magnetic field from a
test piece after it has been magnetically saturated is called:
(a) Hysteresis
(a) Saturation
(d) Poles
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16. The ease with which a magnetic field can be established in a test piece is called:
(a) Reluctance
(b) Retentivity
(c) Permeability
(d) Electromagnetism
(a) Reluctance
(b) Retentivity
(c) Permeability
(d) Electromagnetism
18. The ability of a material to remain magnetic after the magnetising force is removed is
called:
(a) Reluctance
(b) Retentivity
(c) Permeability
(d) Electromagnetism
19. A magnetic field which is contained completely within the test piece is called a:
(a) Coil
(c) Yoke
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21. A technique used to find transverse discontinuities at the ends of longitudinally
magnetised bars by the use of transient currents is called:
22. A leakage field is strongest when a discontinuity interrupts the magnetic flux lines at
an angle of:
(b) 45 degrees
(c) 90 degrees
(d) The inside surface of a ferromagnetic tube magnetised with a central conductor
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26. An important consideration when using a direct contact method is:
28. When using prods, arc burns may be caused by which of the following?
29. The important difference between AC and DC current for magnetic particle testing
purposes is:
(a) The skin effect caused by DC adds mobility to the magnetic particles
30. The ‘skin’ effect would be most noticeable in which of the following?
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31. The most common source of DC current for magnetic particle testing is:
(b) Rectified AC
32. Fields generated in ferromagnetic material with AC current are useful for locating:
33. A common rule of thumb to use for current required in circular magnetisation:
34. The formula, NI = 45000/(L/D), is used to calculate the proper magnetising current
for:
35. The formula, NI = 45000/(L/D), gives proper magnetising current for a coil, regardless
of coil size as long as:
(a) The test piece is not larger than 1/10 the cross sectional area of the coil
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36. For direct contact magnetising methods, the magnetic field is oriented in what
direction relative to the current direction?
(a) Parallel
(b) At 45 degrees
(c) At 90 degrees
37. For direct contact magnetising methods, current should be flowing in what direction
relative to expected discontinuities?
(a) Parallel
(b) At 45 degrees
(c) At 90 degrees
38. What is the magnetic field strength at the surface of a 100 mm diameter bar as
compared to that at the surface of a 50 mm diameter bar, each carrying 1000 amps of
current?
(a) Twice
39. What is the magnetic field strength at the surface of a 25mm diameter bar as compared
to that at the surface of a 50mm diameter bar, each carrying 1000 amps of current?
(a) Twice
(a) Exponentially
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41. How is the magnetic field strength at the surface of a magnetic conductor having
permeability, µ, related to the magnetic field strength, F, at the surface of a
nonmagnetic conductor carrying the same current?
(a) F × µ
(b) Same
(c) F/µ
44. Which of the following describes the shape of particles used for dry magnetic particle
testing?
(a) Spherical
(b) Angular
(c) Elongated
(a) Wet
(b) Dry
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46. Which of the following colours is readily available for magnetic particle test powder?
(a) Red
(b) Gray
(c) Black
47. A magnetic particle testing technique in which the test piece is magnetised and
magnetic particles applied after the magnetising force has been removed is called the:
48. Which of the following characteristics would be most important in a test piece which
is to be tested using the residual method?
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51. The residual method is applicable to:
52. Highest sensitivity to fine surface cracks would be obtained by which of the following
techniques?
(a) The magnetic field, as shown by a hysteresis curve, is zero when there is no
magnetising force
(b) The magnetic field, as shown by a hysteresis curve, is less when there is no
magnetising force
(c) The magnetic field, as shown by a hysteresis curve, is greater when there is no
magnetising force
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56. Which of the following is an advantage of the dry method
(b) Faster than wet method for quantities of small test pieces
57. Loss of fine particle sizes due to re-use of dry particles would probably lead to:
(a) It is the most sensitive method for detection of very fine surface cracks
60. The primary reason for using water rather than oil as a suspension medium for wet
method baths is that:
(c) Water has the capability to dissolve the needed rust inhibitors
(d) Water baths may be used at lower temperatures than oil baths
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61. A disadvantage of fluorescent magnetic particles is:
62. A common physiological effect of black light inspection on the inspector is:
63. A common physiological effect of black light inspection on the inspector is:
64. Which of the following represents ultraviolet light of wavelengths which are
potentially injurious (1 Å = 10-10m)
65. Dyes which receive light at one wavelength and re-emit light of another wavelength
are called:
(a) L.E.Ds
(b) Phosphorescent
(c) Luminescent
(d) Fluorescent
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66. Most fluorescent dyes used for magnetic particle testing fluoresce what colour?
67. The best available source of black light for inspection is:
(d) Sunlight
68. Which of the following would be likely to cause variations in the output of an
inspection black light?
69. The temperature above which steels become nonmagnetic is called the:
70. The temperature above which most soft steels become nonmagnetic is about:
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71. The most common method of demagnetising small test pieces is:
73. The type of discontinuity which magnetic particle testing most effectively locates is:
(c) Porosity
74. An indication which is formed when two pieces of magnetised steel come in contact
with each other is called:
75. Magnetic particle test indications which are due to cold work can best be removed by:
(a) Demagnetisation
(c) Re-crystallisation
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76. Which of the following might cause non-relevant indications?
77. An inspection for surface and subsurface discontinuities in ferromagnetic welds would
best be accomplished by which of the following techniques?
(a) Prods
(b) AC yoke
78. A continuous linear indication along the centre of a fillet weld would most likely be a:
(b) Overlap
79. Wet magnetic particle bath strength is checked by which of the following?
80. Which of the following describes the best technique for applying dry magnetic
particles to a test piece?
(a) Dip the test piece in a tank of dry particles while current is flowing
(d) Shake or dust the powder onto the test piece with minimum velocity
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81. An advantage of AC equipment over DC is:
(c) AC makes the magnetic particles more mobile on the test surface
82. When the orientation of likely discontinuities is unknown, what is the minimum
number of magnetising operations required to perform an adequate test?
(a) 1
(b) 2
(c) 3
(a) 100 mm
(b) 200 mm
(c) 300 mm
(d) 450 mm
(c) No indications
85. The area of maximum induced field strength using a yoke is:
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86. A minimum of external poles are produced by what type of magnetisation?
(a) Continuous
(b) Residual
(c) Circular
(d) Longitudinal
(a) DC yoke
88. The most common harmful effect of exposure to black light is:
89. Which of the following types of magnetic fields may be present without any external
evidence?
(a) Circular
(b) Longitudinal
(c) Secondary
(d) Tertiary
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91. Which of the following is a disadvantage of magnetic particle testing?
(c) Most reliable for finding surface cracks in all types of metals
1. The primary reason for using water rather than oil as a suspension medium for wet
method baths is that
(c) Water has the capability to dissolve the needed rust inhibitors
(d) Water baths may be used at a lower temperature than oil baths
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5. Highest sensitivity to fine surface cracks would be obtained by which of the following
techniques?
(a) 100 mm
(b) 200 mm
(c) 300 mm
(d) 450 mm
(a) Inherent
(b) Processing
(c) Service
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10. Cracks which are caused by a combination of tensile stress and corrosion are called:
11. The type of discontinuity potentially most harmful to the useful life of a part is:
(c) Porosity
12. Magnetic particle test indications which are due to cold work can best be removed by:
(a) Demagnetisation
14. A continuous linear indication along the edge of a new fillet weld would most likely
be a:
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15. Ferromagnetic material is:
(a) Iron
(b) Nickel
(c) Cobalt
(a) Gauss
(b) Henry
(c) Farad
(d) Ampere
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20. Which statement is true when related to magnetic lines of force?
22. The areas on a magnetised part from which the magnetic field is leaving or returning
into the part are called:
(b) Defects
(d) Nodes
23. The magnetism which remains in a piece of magnetisable material after the
magnetising force has been removed is called the:
(a) Continuous
(b) Residual
(c) Interrupted
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25. The point at which the magnetism in a material cannot be increased even though the
magnetising force continues to increase is known as the:
28. The type of current that is best suited to detect surface discontinuities is:
(a) DC
(b) AC
(c) Pulsating DC
29. Retentivity:
(b) Represents the ability of a material to resist the establishment of magnetic flux
within it
(c) Represents the ability of a material to retain a portion of the magnetic field set
up in it after the magnetising force has been removed
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30. Demagnetisation:
31. What rule describes the direction of current flow (+ to -) when lines of magnetic force
surround a conductor?
32. The proper number of ampere-turns for a given test specimen is determined by:
34. In longitudinal magnetisation the proper term for calculating magnetising force is:
(a) Amperes
(b) Ampere-turns
(c) Watts
(d) Ohms
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35. The amount of amperage used for magnetic particle inspection using the prod method
is determined from the:
36. Which of the following is the most effective method for the detection of extremely
deep-lying defects:
(d) Dry continuous method using half wave rectified current with prods
(a) Continuous
(b) Residual
(c) Circular
(d) Longitudinal
(a) AC
(b) DC
39. When using the wet continuous method, the flow of suspension from the hose should
be shut off:
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40. The area of maximum induced field strength using a yoke is:
(c) Centre
(d) End
(b) DC
(c) AC
44. Applying the theory of the ‘Right Hand Rule’, a longitudinal surface defect in a round
bar is detected by ‘current passing in a direction parallel to the direction of expected
defects’ because:
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45. Why are magnetic particles available in different colours?
(d) Different colours are used with different magnetic flux values
46. A magnetic particle build-up from a discontinuity is strongest when the discontinuity
is oriented:
(b) Interfaces will create leakage fields which may confuse the inspection
49. Why should one avoid using a high velocity flow of a wet testing media over the test
area
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50. What are the three causes of non-relevant indications?
(b) Change of section thickness, very high amperage, drilled hole near surface
(c) Very high amperage, drilled hole near surface, blow holes
(d) Drilled hole near surface, very high amperage, lack of fusion
(a) Laps
(c) Cracks
(d) Seams
(c) Criss-cross
54. When preparing a bath it is important to have the bath strength at a proper level, as too
many particles can result in:
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55. Magnetic particle is a non-destructive examination method used for:
58. If a crack exists in a circular magnet, the attraction of magnetic particles to the crack is
caused by:
59. The flux within and surrounding a magnetised part or around a conductor carrying a
current is known as:
(c) Ferromagnetic
(d) Paramagnetic
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60. A metal that is difficult to magnetise is said to have:
(a) Longitudinal
(b) Circular
(c) Vector
(d) Binodal
(a) AC
(b) DC
(c) Pulsed DC
63. To detect lengthwise defects on the inside diameter of hollow parts, you should:
64. Which of the following is most often used for dry magnetic particle inspection:
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65. When a magnetic field is induced in a part with prods spaced 150mm apart, the field
is:
(a) Solenoidal
(b) Circular
(c) Longitudinal
66. With current flowing from + to - in a coil, a longitudinal field is created. Which of the
following may be used to establish the direction of the magnetic field?
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70. The space within and surrounding a magnetized part of a conductor carrying a current
is known as:
(a) Saturation point
(b) Magnetic field
(c) Ferromagnetic
(d) Paramagnetic
71. Subjecting the part to a magnetic field that is constantly reversing in polarity and
gradually diminishing in strength accomplishes which of the following:
(a) Magnetises the part
(b) Removes residual field from the part
(c) Soaks in the flux density
73. Which of the following is NOT a liquid vehicle in which particles are suspended in
magnetic particle testing:
(a) Water treated with a wetting agent
(b) Kerosene
(c) Gasoline
(d) Water treated with antifoam
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76. Paramagnetic materials:
(a) Are commonly inspected using magnetic particle testing
(b) Are affected by magnetic fields
(c) Cannot be magnetized
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82. Which technique is the most sensitive?
(a) Residual
(b) Continuous
(c) Permanent
(d) Interrupted
84. What rule describes the direction of current flow (+ to -) when lines of magnetic force
surround a conductor?
85. The areas on a magnetised part from which the magnetic field is leaving or returning
into the part are called:
(b) Defects
(d) Nodes
86. The opposition that a ferromagnetic material shows to the establishment of a magnetic
field is called:
(a) Retentivity
(b) Reluctance
(d) Permeability
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87. The magnetism which remains in a piece of magnetisable material after the
magnetising force has been removed is called the:
89. The correct number of ampere-turns for a given test specimen is determined by:
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2.1.3 Magnetic Particle Testing Level 1 (MT-1) Answers to Questions
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