McqMate
Chapters
| 1. |
Magnetic particles testing is most likely to find subsurface discontinuities in: |
| A. | Soft steels with high permeability |
| B. | Soft steels with low permeability |
| C. | Hardened steels with low permeability |
| D. | Hardened steels with high permeability |
| Answer» A. Soft steels with high permeability | |
| 2. |
Which of the following is not an advantage of magnetic particles testing? |
| A. | Fast and simple to perform |
| B. | Can detect discontinuities filled with foreign material |
| C. | Most reliable for finding surface cracks in all types of material |
| D. | Works well through a thin coat of paint |
| Answer» 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? |
| A. | The type of materials which may be effectively tested |
| B. | The directionality of the magnetic field |
| C. | The need for demagnetization |
| D. | The ability to detect discontinuities filled with foreign material |
| Answer» D. The ability to detect discontinuities filled with foreign material | |
| 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 |
| Answer» C. Magnetic particle testing | |
| 5. |
Which of the following may cause magnetic particle test indications? |
| A. | A joint between two ferromagnetic materials of different permeability |
| B. | A shrink fit joint in ferromagnetic materials |
| C. | A brazed joint in ferromagnetic materials |
| D. | All of the above |
| Answer» D. All of the above | |
| 6. |
A discontinuity which is produced during solidification of the molten metal is called: |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» A. Inherent | |
| 7. |
Pipe would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» A. Inherent | |
| 8. |
A seam would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» B. Processing | |
| 9. |
A lamination in steel plate would be classified as what type of discontinuity? |
| A. | Inherent |
| B. | Processing |
| C. | Service |
| D. | None of the above |
| Answer» B. Processing | |
| 10. |
An internal rupture caused by working steel at improper temperatures is called a: |
| A. | Lap |
| B. | Cold shut |
| C. | Forging burst |
| D. | Slag inclusion |
| Answer» C. Forging burst | |
| 11. |
Cracks which are caused by alternating stresses above a critical level are called: |
| A. | Stress corrosion cracks |
| B. | Cycling cracks |
| C. | Critical cracks |
| D. | Fatigue cracks |
| Answer» D. Fatigue cracks | |
| 12. |
Cracks which are caused by a combination of tensile stress and corrosion are called: |
| A. | Stress corrosion cracks |
| B. | Cycling cracks |
| C. | Critical cracks |
| D. | Fatigue cracks |
| Answer» A. Stress corrosion cracks | |
| 13. |
Which of the following are ferromagnetic materials? |
| A. | Aluminium, iron, copper |
| B. | Iron, copper, nickel |
| C. | Copper, aluminium, silver |
| D. | Iron, cobalt, nickel |
| Answer» D. Iron, cobalt, nickel | |
| 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 |
| B. | Coercive force |
| C. | Demagnetising flux |
| D. | Reverse saturation |
| Answer» B. Coercive force | |
| 15. |
Magnetic lines of force enter and leave a magnet at: |
| A. | Saturation |
| B. | L/D ratios of greater than 4 to 1 |
| C. | Flux concentration points |
| D. | Poles |
| Answer» D. Poles | |
| 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 |
| Answer» C. Permeability | |
| 17. |
Opposition to establishment of a magnetic field is called: |
| A. | Reluctance |
| B. | Retentivity |
| C. | Permeability |
| D. | Electromagnetism |
| Answer» A. Reluctance | |
| 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 |
| Answer» B. Retentivity | |
| 19. |
A magnetic field which is contained completely within the test piece is called a: |
| A. | Confined field |
| B. | Longitudinal field |
| C. | Circular field |
| D. | Saturated field |
| Answer» C. Circular field | |
| 20. |
Which of the following produces a circular field? |
| A. | Coil |
| B. | Head shot |
| C. | Yoke |
| D. | All of the above |
| Answer» B. Head shot | |
| 21. |
A technique used to find transverse discontinuities at the ends of longitudinally magnetised bars by the use of transient currents is called: |
| A. | A coil technique |
| B. | A fast break technique |
| C. | A yoke technique |
| D. | A head shot |
| Answer» B. A fast break technique | |
| 22. |
A leakage field is strongest when a discontinuity interrupts the magnetic flux lines at an angle of: |
| A. | Zero degrees |
| B. | 45 degrees |
| C. | 90 degrees |
| D. | 180 degrees |
| Answer» C. 90 degrees | |
| 23. |
The best method of inducing a circular field in a tube is by a: |
| A. | Central conductor |
| B. | Head shot |
| C. | Coil |
| D. | Prod technique |
| Answer» A. Central conductor | |
| 24. |
Magnetic flux density is zero at: |
| A. | The inside surface of a tube magnetised with a central conductor |
| B. | The outside surface of a tube magnetised with a central conductor |
| C. | The outside surface of a bar magnetised with a head shot |
| D. | The centre of a bar magnetised with a head shot |
| Answer» D. The centre of a bar magnetised with a head shot | |
| 25. |
Magnetic flux density is highest at: |
| A. | The outside surface of a non-ferromagnetic tube magnetised with a central conductor |
| B. | The inside surface of a non-ferromagnetic tube magnetised with a central conductor |
| C. | The outside surface of a ferromagnetic tube magnetised with a central conductor |
| D. | The inside surface of a ferromagnetic tube magnetised with a central conductor |
| Answer» D. The inside surface of a ferromagnetic tube magnetised with a central conductor | |
| 26. |
An important consideration when using a direct contact method is: |
| A. | Lifting power of the yoke |
| B. | Coil diameter |
| C. | Preventing arc burns |
| D. | Field strength adjacent to the coil inside diameter |
| Answer» C. Preventing arc burns | |
| 27. |
A prod method would be most sensitive to cracks: |
| A. | Parallel to a line connecting the prod contact points |
| B. | Tangential to a radius from each prod contact point |
| C. | Perpendicular to a line connecting the prod contact points |
| D. | Perpendicular to the long axis of the coil |
| Answer» A. Parallel to a line connecting the prod contact points | |
| 28. |
When using prods, arc burns may be caused by which of the following? |
| A. | Dirty contact tips |
| B. | Inadequate pressure |
| C. | Too large a magnetic current |
| D. | All of the above |
| Answer» D. All of the above | |
| 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 |
| B. | The resulting AC magnetic fields are more difficult to demagnetize |
| C. | The DC magnetic fields are more penetrating |
| D. | The AC magnetic fields are stronger |
| Answer» C. The DC magnetic fields are more penetrating | |
| 30. |
The ‘skin’ effect would be most noticeable in which of the following? |
| A. | A magnetic conductor carrying a DC current |
| B. | A nonmagnetic conductor carrying a DC current |
| C. | A magnetic conductor carrying a 50 Hz AC current |
| D. | A nonmagnetic conductor carrying a 50 Hz AC current |
| Answer» D. A nonmagnetic conductor carrying a 50 Hz AC current | |
| 31. |
The most common source of DC current for magnetic particle testing is: |
| A. | Motor generators |
| B. | Rectified AC |
| C. | Storage batteries |
| D. | None of the above |
| Answer» B. Rectified AC | |
| 32. |
Fields generated in ferromagnetic material with AC current are useful for locating: |
| A. | All discontinuities |
| B. | Surface cracks |
| C. | Subsurface discontinuities |
| D. | Internal porosity |
| Answer» B. Surface cracks | |
| 33. |
A common rule of thumb to use for current required in circular magnetisation: |
| A. | 1000 amps/25mm of diameter |
| B. | 1000 ampere turns/25mm of diameter |
| C. | 1000 amps/25mm of prod spacing |
| D. | None of the above |
| Answer» B. 1000 ampere turns/25mm of diameter | |
| 34. |
The formula, NI = 45000/(L/D), is used to calculate the proper magnetising current for: |
| A. | Prod magnetization |
| B. | A head shot |
| C. | A central conductor |
| D. | Coil magnetisation |
| Answer» D. Coil magnetisation | |
| 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 |
| B. | AC current only is used |
| C. | The test piece essentially fills the coil |
| D. | The test piece is held tightly against the coil |
| Answer» A. The test piece is not larger than 1/10 the cross sectional area of the coil | |
| 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 |
| D. | At 180 degrees |
| Answer» 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 |
| D. | At 180 degrees |
| Answer» A. Parallel | |
| 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 |
| B. | One half |
| C. | One quarter |
| D. | Four times |
| Answer» B. One half | |
| 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 |
| B. | One half |
| C. | One quarter |
| D. | Four times |
| Answer» A. Twice | |
| 40. |
The magnetic field outside a conductor decreases: |
| A. | Exponentially |
| B. | In a linear manner |
| C. | Inversely with distance |
| D. | Inversely with the square of distance |
| Answer» B. In a linear manner | |
| 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 |
| D. | Not related |
| Answer» B. Same | |
| 42. |
Compared to the magnetic field strength at the outer surface, the magnetic field strength, at the centre of a hollow, nonmagnetic conductor carrying DC current is: |
| A. | I/D |
| B. | The same |
| C. | Zero |
| D. | Need more information to determine |
| Answer» C. Zero | |
| 43. |
How is the magnetic field strength, F, just outside a magnetic conductor having permeability, µ, related to that just outside a nonmagnetic conductor of the same size, carrying the same current? |
| A. | F × µ |
| B. | Same |
| C. | (F)/µ |
| D. | Not related |
| Answer» B. Same | |
| 44. |
Which of the following describes the shape of particles used for dry magnetic particle testing? |
| A. | Spherical |
| B. | Angular |
| C. | Elongated |
| D. | Mixture of elongated and globular |
| Answer» D. Mixture of elongated and globular | |
| 45. |
Which of the following particles would be most sensitive? |
| A. | Wet |
| B. | Dry |
| C. | Depends on the test piece permeability |
| D. | None of the above |
| Answer» B. Dry | |
| 46. |
Which of the following colours is readily available for magnetic particle test powder? |
| A. | Red |
| B. | Gray |
| C. | Black |
| D. | All of the above |
| Answer» D. All of the above | |
| 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: |
| A. | Magnetic method |
| B. | Continuous method |
| C. | Residual method |
| D. | Discontinuous method |
| Answer» C. Residual method | |
| 48. |
Which of the following characteristics would be most important in a test piece which is to be tested using the residual method? |
| A. | High rententivity |
| B. | High permeability |
| C. | Low reluctance |
| D. | Low permeability |
| Answer» A. High rententivity | |
| 49. |
The wet method is superior to dry particles for detecting: |
| A. | Subsurface discontinuities |
| B. | Fine surface cracks |
| C. | Open surface cracks |
| D. | None of the above |
| Answer» B. Fine surface cracks | |
| 50. |
Selection of magnetic particle colour is based on: |
| A. | Optimum performance of magnetic particle/developer |
| B. | Colour of inspection light available |
| C. | Obtaining maximum contrast with the test piece background |
| D. | Optimum colour response of the human eye |
| Answer» C. Obtaining maximum contrast with the test piece background | |
| 51. |
The residual method is applicable to: |
| A. | Surface discontinuities only |
| B. | Subsurface discontinuities only |
| C. | Either surface or subsurface discontinuities |
| D. | All but tight surface cracks |
| Answer» A. Surface discontinuities only | |
| 52. |
Highest sensitivity to fine surface cracks would be obtained by which of the following techniques? |
| A. | Residual field, wet method |
| B. | Residual field, dry method |
| C. | Continuous field, wet method |
| D. | Continuous field, dry method |
| Answer» C. Continuous field, wet method | |
| 53. |
A residual field is always less than a continuous field because? |
| 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 |
| D. | None of the above |
| Answer» B. The magnetic field, as shown by a hysteresis curve, is less when there is no magnetising force | |
| 54. |
Where possible, circular magnetisation is preferable to longitudinal magnetization because: |
| A. | Less current is required |
| B. | Stronger fields are obtained |
| C. | Fewer confusing secondary poles are produced |
| D. | None of the above is true |
| Answer» D. None of the above is true | |
| 55. |
Which of the following is a disadvantage of the dry method? |
| A. | Ease of application with portable equipment |
| B. | Superior sensitivity for fine surface cracks |
| C. | Good particle mobility with AC and HWDC |
| D. | Good sensitivity for subsurface discontinuities |
| Answer» B. Superior sensitivity for fine surface cracks | |
| 56. |
Which of the following is an advantage of the dry method |
| A. | Good sensitivity for subsurface discontinuities |
| B. | Faster than wet method for quantities of small test pieces |
| C. | Easily applied in an automated system |
| D. | Easy coverage of surfaces of irregularly shaped test pieces |
| Answer» A. Good sensitivity for subsurface discontinuities | |
| 57. |
Loss of fine particle sizes due to re-use of dry particles would probably lead to: |
| A. | Loss of sensitivity to larger discontinuities |
| B. | Loss of sensitivity to finer discontinuities |
| C. | Unpredictable results |
| D. | Slower inspection speeds |
| Answer» B. Loss of sensitivity to finer discontinuities | |
| 58. |
Which of the following is a disadvantage of the wet method? |
| A. | It is the most sensitive method for detection of very fine surface cracks |
| B. | Rapid testing of large quantities of small test pieces |
| C. | Readily adaptable to mechanised equipment |
| D. | Excellent detection of completely subsurface discontinuities |
| Answer» D. Excellent detection of completely subsurface discontinuities | |
| 59. |
Which of the following is an advantage of the wet method? |
| A. | Excellent detection of completely subsurface discontinuities |
| B. | Ease of bath recovery and re-use |
| C. | Low flash point ensures freedom from fire hazards |
| D. | Relatively clean and easy to work with |
| Answer» B. Ease of bath recovery and re-use | |
| 60. |
The primary reason for using water rather than oil as a suspension medium for wet method baths is that: |
| A. | Water is more chemically inert than oil |
| B. | Bath flammability hazards are eliminated |
| C. | Water has the capability to dissolve the needed rust inhibitors |
| D. | Water baths may be used at lower temperatures than oil baths |
| Answer» B. Bath flammability hazards are eliminated | |
| 61. |
A disadvantage of fluorescent magnetic particles is: |
| A. | Darkened area and black light are required |
| B. | Abnormally high sensitivity |
| C. | Only dry particles are available |
| D. | Only wet concentrate is available |
| Answer» A. Darkened area and black light are required | |
| 62. |
A common physiological effect of black light inspection on the inspector is: |
| A. | Burned retinas of the eyes |
| B. | Rejected cornea syndrome |
| C. | Eye fatigue |
| D. | Retarded iris control |
| Answer» C. Eye fatigue | |
| 63. |
A common physiological effect of black light inspection on the inspector is: |
| A. | Burned retinas of the eyes |
| B. | Rejected cornea syndrome |
| C. | Eyeball fluorescence |
| D. | Retarded iris control |
| Answer» C. Eyeball fluorescence | |
| 64. |
Which of the following represents ultraviolet light of wavelengths which are potentially injurious (1 Å = 10-10m) |
| A. | 2000 to 3200Å |
| B. | 3200 to 4000 Å |
| C. | 4000 to 4600Å |
| D. | 4600 to 5200 Å |
| Answer» A. 2000 to 3200Å | |
| 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 |
| Answer» D. Fluorescent | |
| 66. |
Most fluorescent dyes used for magnetic particle testing fluoresce what colour? |
| A. | Blue green |
| B. | Yellow green |
| C. | Blue black |
| D. | Red orange |
| Answer» B. Yellow green | |
| 67. |
The best available source of black light for inspection is: |
| A. | The mercury vapour lamp |
| B. | The fluorescent tube |
| C. | The incandescent bulb |
| D. | Sunlight |
| Answer» A. The mercury vapour lamp | |
| 68. |
Which of the following would be likely to cause variations in the output of an inspection black light? |
| A. | Voltage fluctuations |
| B. | Aged bulb |
| C. | Dirty filter |
| D. | All of the above |
| Answer» D. All of the above | |
| 69. |
The temperature above which steels become nonmagnetic is called the: |
| A. | Zero retentivity |
| B. | Curie point |
| C. | Demagnetisation temperature |
| D. | Random polar point |
| Answer» B. Curie point | |
| 70. |
The temperature above which most soft steels become nonmagnetic is about: |
| A. | 440ºC(770oF) |
| B. | 523ºC (975ºF) |
| C. | 626ºC (1160ºF) |
| D. | 754ºC (1390ºF) |
| Answer» D. 754ºC (1390ºF) | |
| 71. |
The most common method of demagnetising small test pieces is: |
| A. | Heat treatment |
| B. | Shot peening |
| C. | Passing through an AC coil |
| D. | Direct contact with AC current |
| Answer» C. Passing through an AC coil | |
| 72. |
Demagnetisation with reversing DC is more effective than AC because: |
| A. | DC is more penetrating |
| B. | Demagnetisation is assisted by the skin effect |
| C. | DC is more direct |
| D. | Not true - AC is more effective |
| Answer» A. DC is more penetrating | |
| 73. |
The type of discontinuity which magnetic particle testing most effectively locates is: |
| A. | Slag inclusions |
| B. | Magnetic writing |
| C. | Porosity |
| D. | Surface cracks |
| Answer» D. Surface cracks | |
| 74. |
An indication which is formed when two pieces of magnetised steel come in contact with each other is called: |
| A. | A metallurgical discontinuity |
| B. | Magnetic writing |
| C. | Magnetic transfer |
| D. | A ferromagnetic notch |
| Answer» B. Magnetic writing | |
| 75. |
Magnetic particle test indications which are due to cold work can best be removed by: |
| A. | Demagnetisation |
| B. | Using a lower current |
| C. | Re-crystallisation |
| D. | Heat treating |
| Answer» D. Heat treating | |
| 76. |
Which of the following might cause non-relevant indications? |
| A. | Over magnetisation |
| B. | Indications at the edges of a braze joint |
| C. | A joint between hard and soft steels |
| D. | All of the above |
| Answer» D. All of the above | |
| 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 |
| C. | Half wave DC yoke |
| D. | None of the above |
| Answer» A. Prods | |
| 78. |
A continuous linear indication along the centre of a fillet weld would most likely be a: |
| A. | Crater crack |
| B. | Overlap |
| C. | Root indication |
| D. | None of the above |
| Answer» C. Root indication | |
| 79. |
Wet magnetic particle bath strength is checked by which of the following? |
| A. | Specific gravity |
| B. | Optical density |
| C. | Settling test |
| D. | None of the above |
| Answer» C. Settling test | |
| 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 |
| B. | Apply with an electrostatic spray gun at approximately 30 PSIG |
| C. | Gently pour the powder onto the test piece |
| D. | Shake or dust the powder onto the test piece with minimum velocity |
| Answer» D. Shake or dust the powder onto the test piece with minimum velocity | |
| 81. |
An advantage of AC equipment over DC is: |
| A. | AC is more penetrating |
| B. | AC is less hazardous |
| C. | AC makes the magnetic particles more mobile on the test surface |
| D. | AC equipment is heavier than DC |
| Answer» 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 |
| D. | None of the above |
| Answer» B. 2 | |
| 83. |
Maximum practical prod spacing is about: |
| A. | 100 mm |
| B. | 200 mm |
| C. | 300 mm |
| D. | 450 mm |
| Answer» B. 200 mm | |
| 84. |
Magnetic lines of flux which are parallel to a discontinuity produce: |
| A. | Strong indications |
| B. | Weak indications |
| C. | No indications |
| D. | Fuzzy indications |
| Answer» C. No indications | |
| 85. |
The area of maximum induced field strength using a yoke is: |
| A. | At the north pole of the yoke |
| B. | At the south pole of the yoke |
| C. | The area directly between the poles |
| D. | On the outside of the pole pieces |
| Answer» C. The area directly between the poles | |
| 86. |
A minimum of external poles are produced by what type of magnetisation? |
| A. | Continuous |
| B. | Residual |
| C. | Circular |
| D. | Longitudinal |
| Answer» C. Circular | |
| 87. |
A split coil would most likely be used with a: |
| A. | DC yoke |
| B. | Split phase AC yoke |
| C. | Stationary magnetic particle unit |
| D. | Portable magnetic particle unit |
| Answer» D. Portable magnetic particle unit | |
| 88. |
The most common harmful effect of exposure to black light is: |
| A. | Eyeball fluorescence |
| B. | Burned retinas |
| C. | Skin burns |
| D. | None of the above |
| Answer» A. Eyeball fluorescence | |
| 89. |
Which of the following types of magnetic fields may be present without any external evidence? |
| A. | Circular |
| B. | Longitudinal |
| C. | Secondary |
| D. | Tertiary |
| Answer» A. Circular | |
| 90. |
The primary reason for using water rather than oil as a suspension medium for wet method baths is that |
| A. | Water is more chemically inert than oil |
| B. | Bath flammability hazards are eliminated |
| C. | Water has the capability to dissolve the needed rust inhibitors |
| D. | Water baths may be used at a lower temperature than oil baths |
| Answer» B. Bath flammability hazards are eliminated | |
| 91. |
Wet magnetic particle strength is checked by which of the following? |
| A. | Specific gravity |
| B. | Optical density |
| C. | Settling test |
| D. | None of the above |
| Answer» C. Settling test | |
| 92. |
A residual circular field may be objectionable because: |
| A. | Grinding may produce heat cracks |
| B. | Machining may create external poles |
| C. | Heat treating may lead to tight surface cracks\ |
| D. | All of the above |
| Answer» B. Machining may create external poles | |
| 93. |
A prod method would be most sensitive to cracks: |
| A. | Parallel to a line connecting the prod contract points |
| B. | Tangential to a radius from each prod contact point |
| C. | Perpendicular to a line connecting the prod contact points |
| D. | Perpendicular to the long axis |
| Answer» A. Parallel to a line connecting the prod contract points | |
| 94. |
Maximum practical prod spacing for a 2000 amp unit is about: |
| A. | 100 mm |
| B. | 200 mm |
| C. | 300 mm |
| D. | 450 mm |
| Answer» B. 200 mm | |
| 95. |
Demagnetisation with reversing DC is more effective than AC because: |
| A. | DC is more penetrating |
| B. | Demagnetisation is assisted by the skin effect |
| C. | DC is more direct |
| D. | Not true-AC is more effective |
| Answer» A. DC is more penetrating | |
| 96. |
Fluorescent magnetic particle indications should be inspected under |
| A. | Fluorescent light |
| B. | Any light |
| C. | Black light |
| D. | Red light |
| Answer» C. Black light | |
| 97. |
Cracks which are caused by a combination of tensile stress and corrosion are called: |
| A. | Intergranular stress corrosion cracking |
| B. | Cycling cracks |
| C. | Stress corrosion cracking |
| D. | Fatigue cracks |
| Answer» C. Stress corrosion cracking | |
| 98. |
The type of discontinuity potentially most harmful to the useful life of a part is: |
| A. | Slag inclusions |
| B. | Magnetic writing |
| C. | Porosity |
| D. | Surface cracks |
| Answer» D. Surface cracks | |
| 99. |
Magnetic particle test indications which are due to cold work can best be removed by: |
| A. | Demagnetisation |
| B. | Using a lower current |
| C. | Using penetrant testing |
| D. | Re-heat treating |
| Answer» D. Re-heat treating | |
| 100. |
Which of the following might cause non relevant indications? |
| A. | Magnetic writing |
| B. | Indications at the edges of a braze joint |
| C. | A joint between hard and soft steels |
| D. | All of the above |
| Answer» D. All of the above | |
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