METHODOS

Question 1

AE Review Questions
1. The most common range of AE is:

a. 10 to 15 kHz
b. 100 to 300 kHz
c. 500 to 750 kHz
d. 1 to 5 MHz

Answer 1

b. 100 to 300 kHz

Question 2

2. Discontinuities that are not readily detectable by AE are:

a. leaks.
b. plastic deformation.
c. growing cracks.
d. rounded inclusions.

Answer 2

d. rounded inclusions.

Question 3

3. The total energy loss of a propagating wave is called:
   a. scatter.
   b. dispersion.
   c. diffraction.
   d. attenuation.

Answer 3

d. attenuation.

Question 4

4. The Kaiser effect refers to:

a. velocity changes due to temperature changes.
b. low amplitude emissions from aluminum structures.
c. the behavior where emission from a source will not occur until the previous load is exceeded.
d. emissions from dissimilar material interfaces.

Answer 4

c. the behavior where emission from a source will not occur until the previous load is exceeded.

Question 5

5. The Felicity effect is useful in evaluating:

a. fiber-reinforced plastic components.
b. high-alloy castings.
c. large structural steel members.
d. ceramics.

Answer 5

a. fiber-reinforced plastic components.

Question 6

6. The Kaiser effect is useful in distinguishing:

a. electrical noise from mechanical noise.
b. electrical noise from growing discontinuities.
c. mechanical noise from growing discontinuities.
d. electrical noise from continuous emissions.

Answer 6

c. mechanical noise from growing discontinuities.

Question 7

7. The term “counts” refers to the:

a. number of times a signal crosses a preset threshold.
b. number of events from a source.
c. number of transducers required to perform a test.
d. duration of hold periods.

Answer 7

a. number of times a signal crosses a preset threshold.

Question 8

8. The acoustic emission signal amplitude is related to:

a. the preset threshold.
b. the intensity of the source.
c. the bandpass filters.
d. background noises.

Answer 8

b. the intensity of the source.

Question 9

9. Threshold settings are determined by the:

a. graininess of the material.
b. attenuation of the material.
c. test duration.
d. background noise level.

Answer 9

d. background noise level.

Question 10

10. Background noise can be reduced by:

a. electronic filtering.
b. using flat response amplifiers.
c. using in-line amplifiers.
d. using heavier gauge coaxial cable.

Answer 10

a. electronic filtering.

Question 11

ET Review Questions
1. Eddy currents are circulating electrical currents induced in conductive materials by:

a. continuous direct current.
b. gamma rays.
c. an alternating magnetic field.
d. a piezoelectric force.

Answer 11

c. an alternating magnetic field.

Question 12

2. The method used to generate eddy currents in a test specimen by means of a coil can most closely be compared with the action of a:

a. transformer.
b. capacitor.
c. storage battery.
d. generator.

Answer 12

a. transformer.

Question 13

3. ET relies on the principle of:

a. magnetostriction.
b. electromagnetic induction.
c. piezoelectric energy conversion.
d. magnetomotive force.

Answer 13

b. electromagnetic induction.

Question 14

4. When the electrical current in an eddy current coil reverses direction, the:

a. direction of the eddy currents in the test part remains the same.
b. eddy currents in the test part will change phase by 45°.
c. direction of the eddy currents in the test part also reverses.
d. eddy currents in the test part will change phase by 90°.

Answer 14

c. direction of the eddy currents in the test part also reverses.

Question 15

5. In order to generate measurable eddy currents in a test specimen, the specimen must be:

a. an electrical conductor.
b. an electrical insulator.
c. a ferromagnetic material.
d. a nonmagnetic material.

Answer 15

a. an electrical conductor.

Question 16

6. The magnetic field generated by eddy currents induced in a test specimen:

a. reinforces the magnetic field that induced the eddy currents.
b. cancels the magnetic field that induced the eddy currents.
c. opposes the magnetic field that induced the eddy currents.
d. has no effect on the magnetic field that induced the eddy currents.

Answer 16

c. opposes the magnetic field that induced the eddy currents.

Question 17

7. In ET, IACS is a recognized abbreviation for:

a. Induced Alternating Current System.
b. Inductively Activated Comparison System.
c. Internal Applied Current System.
d. International Annealed Copper Standard.

Answer 17

d. International Annealed Copper Standard.

Question 18

8. In ET, the specimen is coupled to the test coil by:

a. core coupling.
b. magnetic saturation.
c. the coil’s electromagnetic fields.
d. magnetic domains.

Answer 18

c. the coil’s electromagnetic fields.

Question 19

9. The penetration of eddy currents in a conductive material is decreased when the:

a. test frequency or conductivity of the specimen is decreased.
b. test frequency is decreased or conductivity of the specimen is increased.
c. test frequency, conductivity of the specimen, or permeability of the specimen is increased.
d. permeability of the specimen is decreased.

Answer 19

c. test frequency, conductivity of the specimen, or permeability of the specimen is increased.

Question 20

10. At a fixed test frequency, in which of the following materials will the eddy current penetration be greatest?

a. Aluminum (35% IACS conductivity).
b. Brass (15% IACS conductivity).
c. Copper (95% IACS conductivity).
d. Lead (7% IACS conductivity).

Answer 20

d. Lead (7% IACS conductivity).

Question 21

11. A term used to describe the effect observed due to a change in the coupling between a test specimen and a flat probe coil when the distance of separation between them is varied is:

a. liftoff.
b. fill factor.
c. edge effect.
d. end effect.

Answer 21

a. liftoff.

Question 22

12. When testing with eddy currents, discontinuities will be most easily detected when the eddy currents are:

a. coplanar with the major dimension of the discontinuity.
b. perpendicular to the major plane of the discontinuity.
c. parallel to the major dimension of the discontinuity.
d. 90° out of phase with the current in the coil.

Answer 22

b. perpendicular to the major plane of the discontinuity.

Question 23

13. Which of the following discontinuities is easiest to detect with an electromagnetic test? (Assume that the area of the discontinuity is equal in all four choices listed.)

a. A subsurface crack which lies parallel to the direction of the eddy current.
b. A discontinuity located in the center of a 51 mm (2 in.) diameter bar.
c. A radial crack that extends to the outer surface of a 51 mm (2 in.) diameter bar.
d. A subsurface radial crack located at a depth of 13 mm (0.5 in.) in a 51 mm (2 in.) diameter bar.

Answer 23

c. A radial crack that extends to the outer surface of a 51 mm (2 in.) diameter bar.

Question 24

14. A term used to define the timing relationships involved in alternating current signals is:

a. magnitude.
b. phase.
c. impedance.
d. time-gain correction.

Answer 24

b. phase.

Question 25

15. The impedance of a test coil can be represented by the vector sum of:

a. inductive reactance and resistance.
b. capacitive reactance and resistance.
c. inductive reactance and capacitive reactance.
d. inductive reactance, capacitive reactance, and resistance.

Answer 25

a. inductive reactance and resistance.

Question 26

16. The term “fill factor” applies to:

a. a surface coil.
b. coaxial cable.
c. an encircling coil.
d. the ability to null an eddy current instrument.

Answer 26

c. an encircling coil.

Question 27

17. Which of the following materials would be more likely used as a mounting material for a probe coil?

a. Aluminum.
b. Plastic.
c. Copper.
d. Nonferromagnetic steel.

Answer 27

b. Plastic.

Question 28

18. Which of the following is a commonly used eddy current testing read-out mechanism?

a. Signal generator.
b. Oscilloscope
c. Electronic visual display.
d. Computer screen connected to eddy current system.

Answer 28

a. Signal generator.

Question 29

19. Reference standards used for ET:

a. must contain artificial discontinuities such as notches and drilled holes.
b. must contain natural discontinuities such as cracks and inclusions.
c. must be free of measurable discontinuities, but may contain artificial or natural discontinuities, or may be free of discontinuities, depending on the test system and the type of test being conducted.
d. must be constructed from the same material of the object being inspected.

Answer 29

b. must contain natural discontinuities such as cracks and inclusions.

Question 30

20. Which of the following conditions would be the most difficult to detect when testing a rod using an encircling coil?

a. A short surface crack that has a depth of 10% of the rod diameter.
b. A small inclusion in the center of the rod.
c. A 5% change in diameter.
d. A 10% change in conductivity.

Answer 30

b. A small inclusion in the center of the rod.

Question 31

21. The thickness of nonconductive coatings on a conductive base can be most simply measured by:

a. observing the liftoff effect caused by the coating.
b. testing both sides of the specimen.
c. varying the test frequency over a given range during the test.
d. using a specially shaped encircling coil.

Answer 31

a. observing the liftoff effect caused by the coating.

Question 32

22. Some of the products commonly tested using encircling coils are:

a. rods, tubes, and wire.
b. interior of hollow tubes.
c. sheets and metal foil.
d. square billets and plates.

Answer 32

a. rods, tubes, and wire.

Question 33

23. It is often possible to sort various alloys of a nonmagnetic metal by means of ET when:

a. there is a unique range of permeability values for each alloy.
b. there is a unique range of conductivity values for each alloy.
c. the direction of induced eddy currents varies for each alloy.
d. the magnetic domains for each alloy are different.

Answer 33

b. there is a unique range of conductivity values for each alloy.

Question 34

24. When conducting ET on tubing with a system that includes a frequency discriminating circuit, which of the following variables would be classified as a high frequency variable?

a. Conductivity changes.
b. Diameter changes.
c. Wall thickness variations.
d. Small discontinuities.

Answer 34

d. Small discontinuities.

Question 35

25. Tubing is generally inspected using:

a. U-shaped coils.
b. gap coils.
c. encircling coils.
d. a sliding probe.

Answer 35

c. encircling coils.

Question 36

26. An out-of-phase condition between current and voltage:

a. can exist in both the primary and secondary windings of an eddy current coil.
b. can exist only in the secondary winding of an eddy current coil.
c. can exist only in the primary winding of an eddy current coil.
d. exists only in the test specimen.

Answer 36

a. can exist in both the primary and secondary windings of an eddy current coil.

Question 37

27. For age hardenable aluminum and titanium alloys, changes in hardness are indicated by changes in:

a. retentivity.
b. permeability.
c. conductivity.
d. magnetostriction.

Answer 37

c. conductivity.

Question 38

LT Review Questions
1. Which of the following systems or components would require the most precaution and special considerations in preparation for a leak test?

a. Piping and pressure vessels.
b. Refrigeration piping.
c. Vacuum chambers.
d. Sintered material components.

Answer 38

d. Sintered material components.

Question 39

2. Pressure change leak testing is dependent on three variables. A change to any of these three will have a direct effect on at least one of the other two variables. These three variables are:

a. pressure, volume, and pumping speed.
b. pressure, volume, and temperature.
c. volume, temperature, and ambient atmospheric pressure.
d. temperature, pumping speed, and fluid viscosity.

Answer 39

b. pressure, volume, and temperature.

Question 40

3. Which of the following is a technique of LT?

a. Static.
b. Gaseous diffusion.
c. Dynamic.
d. Detector probe.

Answer 40

d. Detector probe.

Question 41

4. Which of the following LT techniques can reliably quantify a leak ≤ 10–7 atm cc/sec in a normal industrial environment?

a. Bubble leak testing.
b. Pressure change leak testing.
c. Mass spectrometer leak testing.
d. Liquid penetrant testing.

Answer 41

c. Mass spectrometer leak testing.

Question 42

5. Establishing differential pressure between the test object and the environment is an essential element in which of the following NDT methods?

a. X-ray diffraction.
b. Leak testing.
c. Neutron radiography.
d. Electromagnetic testing.

Answer 42

b. Leak testing.

Question 43

6. Which of the following best describes the type of leak test used when the interior of the test object is continuously evacuated during the test and a tracer gas is applied to the exterior, while the leak detector is connected to the evacuating system?

a. Static leak test.
b. Helium leak test.
c. Dynamic leak test.
d. Halogen leak test.

Answer 43

c. Dynamic leak test.

Question 44

7. Assuming no significant leakage, if the temperature increases during a pressure drop leak test in a constant volume system, the pressure in the system under test would:

a. increase.
b. remain the same.
c. decrease.
d. first decrease, then increase to its former level.

Answer 44

a. increase.

Question 45

8. If the sensitivity of the halogen leak detector is constant throughout a test, and the pre- and post-test calibrations of the instrument were acceptable, which of the following is true upon completion of the test?

a. No leaks smaller than a certain size have gone undetected.
b. The total leakage rate of the test object is less than a certain amount.
c. The instrument and the test procedure were capable of detecting leakage of a certain size during the test.
d. The instrument and test procedure were only capable of detecting leakage of a certain size upstream of the tracer gas during the test.

Answer 45

c. The instrument and the test procedure were capable of detecting leakage of a certain size during the test.

Question 46

9. All leak detection techniques are dependent upon:

a. barometric pressure.
b. oxygen content of the surrounding air.
c. all of the other gases in the mass spectrometer.
d. establishing a differential pressure across the test boundary.

Answer 46

d. establishing a differential pressure across the test boundary.

Question 47

10. In systems under high vacuum, sensitivity of a pressure change leak test is dependent not only on the pressure change observed, but also on the degree of outgassing. Outgassing is best defined as:

a. the release of gas from materials in a vacuum.
b. directly proportional to the temperature of the gas.
c. the viscosity of the pressurizing gas.
d. the drop in test pressure due to leakage from the vacuum manifold.

Answer 47

a. the release of gas from materials in a vacuum.

Question 48

11. What is the essential information that must be recorded to perform a pressure change leak test?

a. Helium concentration, leak response, background.
b. Barometric pressure, start time, stop time, temperature.
c. Temperature, elapsed time, volume, pressure.
d. Mean free path of helium, fluid viscosity, pressure differential

Answer 48

c. Temperature, elapsed time, volume, pressure.

Question 49

12. What is the easiest option for increasing sensitivity in a pressure change leak test?

a. Change instrumentation.
b. Turn down the thermostat.
c. Put the test item in an environmental chamber.
d. Increase test time.

Answer 49

d. Increase test time.

Question 50

13. Performing a helium mass spectrometer hood test, what effect would a 50% versus a 100% helium concentration have on the final leak rate of the item being tested?

a. Increase it.
b. Decrease it.
c. No change.
d. Make the leak rate unusable.

Answer 50

b. Decrease it.

Question 51

14. In a pressure change rate of rise test, what test variable is not recorded?

a. Pressure.
b. Volume.
c. Temperature.
d. Elapsed time.

Answer 51

c. Temperature.

Question 52

15. In a helium mass spectrometer leak test using the hood technique, if the inspector has a final calibration 40% greater than the preliminary calibration, what would they do?

a. Nothing.
b. Retest the item.
c. Increase test time.
d. Increase the helium concentration.

Answer 52

b. Retest the item.

Question 53

PT Review Questions
1. The tendency of a liquid penetrant to enter a discontinuity is primarily related to:

a. the viscosity of the penetrant.
b. capillary action.
c. the chemical inertness of the penetrant.
d. the specific gravity of the penetrant.

Answer 53

b. capillary action.

Question 54

2. PT is a nondestructive test method that can be used for:

a. locating and evaluating all types of discontinuities in a test specimen.
b. locating and determining the length, width, and depth of discontinuities in a test specimen.
c. determining the tensile strength of a test specimen.
d. locating discontinuities open to the surface.

Answer 54

d. locating discontinuities open to the surface.

Question 55

3. Which of the following processes is best situated to detect shallow discontinuities?

a. Postemulsifiable.
b. Solvent-removable.
c. Aqueous developer.
d. Water-washable.

Answer 55

a. Postemulsifiable.

Question 56

4. The property of a dye used in penetrant materials to emit light in the range of wavelengths different from the wavelength of visible light that excites the emission is called:

a. emissivity.
b. irradiation.
c. spectrum blocking.
d. fluorescence.

Answer 56

d. fluorescence.

Question 57

5. When using a fluorescent, postemulsifier penetrant, the length of time the emulsifier is allowed to remain on the part is critical for detecting shallow discontinuities. The optimum length of time should be:

a. 10 seconds.
b. 5 seconds.
c. 2 to 3 minutes.
d. determined by experimentation.

Answer 57

d. determined by experimentation.

Question 58

6. A red penetrant indication against white background is most likely to be seen when:

a. dry developers are used.
b. visible dye penetrants are used.
c. fluorescent postemulsified penetrants are used.
d. ultraviolet light is used with visible dye penetrants.

Answer 58

b. visible dye penetrants are used.

Question 59

7. The most widely accepted technique for removing excess water-washable penetrant from the surface of a test specimen is by:

a. using a wet rag.
b. using a coarse water spray rinse.
c. washing the part directly under water running from a tap.
d. immersing the part in water.

Answer 59

b. using a coarse water spray rinse.

Question 60

8. Which of the following PT systems is generally considered the least sensitive?

a. Water-washable; visible dye.
b. Solvent-removable; visible dye.
c. Water-washable; fluorescent dye.
d. Postemulsified; visible dye.

Answer 60

a. Water-washable; visible dye.

Question 61

9. When performing PT using solvent-removable visible dye penetrant, there are several ways to remove excess penetrant from the surface of the part. Which of the techniques listed below is generally regarded as most suitable for giving accurate test results?

a. Squirting solvent over the surface with no more than 69 kPa (10 psi) pressure.
b. Wiping with a solvent-soaked cloth, then wiping with a dry cloth.
c. Wiping with a solvent-dampened cloth, then wiping with dry cloths.
d. Wiping with dry cloths, then wiping with a solvent dampened cloth, and finally wiping with a dry cloth.

Answer 61

d. Wiping with dry cloths, then wiping with a solvent dampened cloth, and finally wiping with a dry cloth.

Question 62

10. A problem with retesting a specimen that has been previously tested using PT is that the:

a. penetrant residue left in discontinuities may not readily dissolve, and the retest may be misleading.
b. penetrant may form beads on the surface.
c. penetrant will lose a great deal of its color brilliance.
d. added penetrant will intensify the penetrant residue, making indications larger than normal.

Answer 62

a. penetrant residue left in discontinuities may not readily dissolve, and the retest may be misleading.

Question 63

11. A commonly used method of checking the overall performance of a liquid penetrant material system is to:

a. determine the viscosity of the penetrant.
b. measure the wettability of the penetrant.
c. compare two sections of artificially cracked specimens.
d. check the penetrant contaminant levels.

Answer 63

c. compare two sections of artificially cracked specimens.

Question 64

12. The function of emulsifier in the postemulsified penetrant process is to:

a. influence the rate of penetration into deep, tight cracks.
b. react with the surface penetrant to make the penetrant water washable.
c. add fluorescent dye or pigment to the penetrant.
d. emulsify surface oils and greases to facilitate their removal.

Answer 64

b. react with the surface penetrant to make the penetrant water washable.

Question 65

13. Which of the following statements most applies to developers used during PT?

a. Developers are normally highly fluorescent.
b. Some developers furnish a fluctuating background during inspection.
c. Developers absorb or blot the penetrant that remains in discontinuities after the excess penetrant has been removed.
d. Nonaqueous developers are better suited for very humid environments.

Answer 65

c. Developers absorb or blot the penetrant that remains in discontinuities after the excess penetrant has been removed.

Question 66

14. The penetrant indication for a cold shut on the surface of a casting will normally be:

a. a dotted line.
b. a large bulbous indication.
c. a smooth continuous line.
d. undetectable since cold shuts are closed over on the surface.

Answer 66

c. a smooth continuous line.

Question 67

15. A crack-type discontinuity will generally appear as:

a. a rounded indication.
b. a continuous line, either straight or jagged.
c. a broad, fuzzy indication.
d. random round or elongated holes.

Answer 67

b. a continuous line, either straight or jagged.

Question 68

16. In PT, scattered round indications on the surface of a part could be indicative of:

a. fatigue cracks.
b. porosity.
c. weld laps.
d. hot tears.

Answer 68

b. porosity.

Question 69

17. Which of the following are typical nonrelevant indications found in PT?

a. Indications due to part geometry or part design configurations.
b. Nonmagnetic indications.
c. Indications due to contact with another test object.
d. Indications on low-stressed areas of the part.

Answer 69

a. Indications due to part geometry or part design configurations.

Question 70

18. Which of the statements below best states the effects of sandblasting for the cleaning of surfaces to be tested with PT?

a. Surface discontinuities may be closed.
b. Oil contaminants might be sealed in the discontinuities.
c. The sand used in the sandblasting operation may be forced into the discontinuity.
d. The sandblasting operation may introduce discontinuities into the part.

Answer 70

a. Surface discontinuities may be closed.

Question 71

19. The penetrant indication of a forging lap will normally be a:

a. round or nearly round indication.
b. cluster of indications.
c. thin continuous line.
d. dotted line.

Answer 71

c. thin continuous line.

Question 72

20. Aluminum alloy test specimens that have been tested with PT should be thoroughly cleaned after testing because:

a. acid in the penetrant may cause severe corrosion.
b. the oily residue from the test will severely inhibit the application of paint on aluminum alloys.
c. a chemical reaction between the penetrant and aluminum could cause a fire.
d. the alkalines in wet developers and most emulsifiers could cause surface pitting, particularly in moist atmospheres.

Answer 72

d. the alkalines in wet developers and most emulsifiers could cause surface pitting, particularly in moist atmospheres.

Question 73

21. Which of the following is a discontinuity that might be found in rolled bar stock?

a. Blow holes.
b. Shrinkage laps.
c. Stringers or seams.
d. Insufficient penetration.

Answer 73

c. Stringers or seams.

Question 74

22. Anodized surfaces are usually considered poor candidates for high-sensitivity PT because the anodizing process produces a conversion layer that:

a. is extremely smooth and slick.
b. has a multitude of extremely small pores.
c. may have alkaline residue that “quenches” the penetrant.
d. cannot be cleaned by ordinary processes.

Answer 74

b. has a multitude of extremely small pores.

Question 75

23. Which of the following PT techniques is best suited for performing inspections without a source of electricity?

a. Water-washable fluorescent penetrant.
b. Postemulsified fluorescent penetrant.
c. Visible dye penetrant.
d. Hydrophilic fluorescent penetrant.

Answer 75

c. Visible dye penetrant.

Question 76

24. Which of the following statements is true concerning PT of welds with rough surfaces?

a. The postemulsified process offers advantages over the water-washable process.
b. If the solvent removal process is used, the best developer would be an aqueous suspension.
c. Welds with rough surfaces cannot be successfully tested by any PT technique.
d. Welds with rough surfaces may need to be ground smooth prior to PT.

Answer 76

d. Welds with rough surfaces may need to be ground smooth prior to PT.

Question 77

25. A penetrant must:

a. change viscosity in order to spread over the surface of the part.
b. spread easily over the surface of the material.
c. have a low flash point.
d. be able to change color in order to fluoresce.

Answer 77

b. spread easily over the surface of the material.

Question 78

26. Which of the following discontinuities could be classified as an in-service related discontinuity?

a. Grinding cracks.
b. Porosity.
c. Stress-corrosion crack.
d. Cold lap.

Answer 78

c. Stress-corrosion crack.

Question 79

27. Penetrant materials are tested and qualified to what specification?

a. AMS 2642
b. AMS 2644
c. AMS 2646
d. AMS 2648

Answer 79

b. AMS 2644

Question 80

28. Which of the following penetrants is able to be removed with water?

a. Method A penetrant.
b. Method B penetrant.
c. Method C penetrant.
d. Method D penetrant.

Answer 80

a. Method A penetrant.

Question 81

29. Fluorescent dye penetrant is typically which color?

a. Red.
b. Yellow-green.
c. Orange.
d. Blue.

Answer 81

b. Yellow-green.

Question 82

MFL Review Questions
1. In MFL inspection for discontinuities using an active field, the part being inspected should be magnetized:

a. beyond saturation.
b. to saturation or near saturation.
c. well below saturation.
d. near the point of maximum permeability.

Answer 82

a. beyond saturation.

Question 83

2. An advantage that MFL has in comparison with ET is that MFL is:

a. less sensitive to interferences caused by surface roughness.
b. useful on products at temperatures above the curie point.
c. useful on austenitic steels.
d. easier to use on ferromagnetic materials.

Answer 83

d. easier to use on ferromagnetic materials.

Question 84

3. What type of discontinuity would not typically be indicated by MFL techniques?

a. Laps.
b. Pitting with cracking.
c. Deep-surface discontinuities.
d. Longitudinal seams.

Answer 84

c. Deep-surface discontinuities.

Question 85

4. The strength of the magnetic field in the interior of a coil is determined by the:

a. number of turns in the coil only.
b. strength of applied current only.
c. number of turns in the coil and the strength of the applied current.
d. direction of applied current in the coil.

Answer 85

c. number of turns in the coil and the strength of the applied current.

Question 86

5. The current used for magnetization when performing MFL must be a:

a. steady nonfluctuating current.
b. current that reverses direction at an inconsistent rate.
c. current that fluctuates on and off at a consistent rate.
d. current that varies based on the thickness of the material.

Answer 86

a. steady nonfluctuating current.

Question 87

6. As a general rule, hard (high-strength) ferromagnetic materials have:

a. high coercive force and are easily demagnetized.
b. high coercive force and are not easily demagnetized.
c. low coercive force and are easily demagnetized.
d. low coercive force and are not easily demagnetized.

Answer 87

b. high coercive force and are not easily demagnetized.

Question 88

7. In MFL, the greatest tube wall thickness for which maximum sensitivity can be maintained is:

a. 0.08 mm (0.003 in.)
b. 0.8 mm (0.03 in.)
c. 8 mm (0.318 in.)
d. 76 mm (3 in.)

Answer 88

c. 8 mm (0.318 in.)

Question 89

8. In the examination of aboveground storage tanks where the flux sensor is on the top surface:

a. only top surface discontinuities are detected.
b. only bottom surface discontinuities are detected.
c. both top and bottom surface discontinuities can be detected and can generally be distinguished from each other.
d. both top and bottom surface discontinuities can be detected but generally cannot be distinguished from each other.

Answer 89

d. both top and bottom surface discontinuities can be detected but generally cannot be distinguished from each other.

Question 90

9. Materials that are weakly repelled magnetically are called:

a. diamagnetic.
b. nonmagnetic.
c. paramagnetic.
d. ferromagnetic.

Answer 90

a. diamagnetic.

Question 91

10. A break in the magnetic uniformity of a part that is called a magnetic discontinuity is related to a sudden change in:

a. resistivity.
b. inductance.
c. permeability.
d. capacitance.

Answer 91

c. permeability.

Question 92

11. A hysteresis curve describes the relation between:

a. magnetizing force and flux density.
b. magnetizing force and applied current.
c. strength of magnetism and alignment of domains within material.
d. magnetic flux density and the current generated.

Answer 92

a. magnetizing force and flux density.

Question 93

12. When inspecting wire rope, a magnetic flux loop is used to monitor:

a. broken external wires.
b. broken internal wires.
c. changes in inspection speed.
d. reductions in cross-sectional area.

Answer 93

d. reductions in cross-sectional area.

Question 94

13. A hall effect probe measures:

a. permeability.
b. conductivity.
c. flux density perpendicular to the probe surface.
d. tangential field strength.

Answer 94

c. flux density perpendicular to the probe surface.

Question 95

14. The direction of magnetic lines of force are generally considered to be _____ from the direction of current flow.

a. 45°
b. 90°
c. 180°
d. 270°

Answer 95

b. 90°

Question 96

15. If the sensor bounces along the surface of aboveground storage tanks, it may:

a. make it difficult to estimate the severity of an indication.
b. generate noise in the signal.
c. decrease the speed of the inspection.
d. distort the magnetizing system.

Answer 96

b. generate noise in the signal.

Question 97

16. In an MFL examination of aboveground storage tanks, the factor(s) that must be considered when interpreting an indication is/are:

a. signal amplitude only.
b. signal width only.
c. visual and ultrasonic evaluation.
d. signal amplitude and width.

Answer 97

c. visual and ultrasonic evaluation.

Question 98

17. In the application of pipe body inspection, longitudinal magnetization is best for detection of:

a. longitudinal discontinuities.
b. transverse discontinuities.
c. internal surface discontinuities.
d. subsurface discontinuities.

Answer 98

b. transverse discontinuities.

Question 99

18. Residual magnetization is the:

a. magnetizing force remaining after flux density has decreased.
b. residual magnetizing force beyond the curie point.
c. flux density after removal of magnetizing force.
d. flux density beyond the level of saturation.

Answer 99

c. flux density after removal of magnetizing force.

Question 100

MT Review Questions
1. Which of the following materials is considered nonferrous?

a. Copper alloys.
b. High alloy steels.
c. Tool steels.
d. Ferritic stainless steels.

Answer 100

a. Copper alloys.

Question 101

2. Materials that are strongly attracted to a magnet are called:

a. magnetized.
b. nonmagnetic.
c. ferromagnetic.
d. magnetic.

Answer 101

c. ferromagnetic.

Question 102

3. Magnetic lines of force (magnetic fields) are oriented in what direction in relation to the direction of the magnetizing current?

a. Parallel.
b. At right angles.
c. At a 45° angle.
d. At random angles.

Answer 102

b. At right angles.

Question 103

4. “Magnetizing flux” is a term that relates to:

a. the direction of current flow in an electromagnet.
b. the manner by which magnetism flows through space.
c. the lines of force associated with a magnetic field.
d. permanent magnets only.

Answer 103

c. the lines of force associated with a magnetic field.

Question 104

5. Subjecting a part to a magnetic field that is constantly reversing in polarity and gradually diminishing in strength accomplishes which of the following?

a. Demagnetizes the part.
b. Magnetizes the part.
c. Increases the residual magnetism.
d. Locates deep-lying discontinuities.

Answer 104

a. Demagnetizes the part.

Question 105

6. Circular magnetization is useful in the detection of:

a. circumferential cracks.
b. longitudinal cracks.
c. cracks in cylindrical parts at right angles to the long axis of the part.
d. deep-lying discontinuities.

Answer 105

b. longitudinal cracks.

Question 106

7. In which magnetizing method is the current passed directly through the part, thereby setting up a magnetic field at right angles to the current flow?

a. Longitudinal magnetization.
b. Coil magnetization.
c. Central conductor magnetization.
d. Circular magnetization.

Answer 106

d. Circular magnetization.

Question 107

8. Which of the following is a major disadvantage of using prods?

a. The magnetic field may be applied in the wrong direction.
b. The inspection surface may be arc burned.
c. Magnetic saturation may occur.
d. Control of the amperage.

Answer 107

b. The inspection surface may be arc burned.

Question 108

9. Inspecting a part by applying the wet magnetic particle suspension while the current is flowing is called the:

a. continuous method.
b. dry method.
c. residual method.
d. demagnetization method.

Answer 108

a. continuous method.

Question 109

10. How is the inside diameter of a cylinder best magnetized?

a. By a head shot.
b. By using prods at either end.
c. With a central conductor placed between contact heads.
d. With the cylinder placed crosswise in a solenoid.

Answer 109

c. With a central conductor placed between contact heads.

Question 110

11. The amount of amperage used for MT using prods is based on the distance between the prods and the:

a. thickness of the part.
b. length of the prods.
c. diameter of the prods.
d. total length of the part.

Answer 110

a. thickness of the part.

Question 111

12. Demagnetization of a part is usually necessary if the part is:

a. made of stainless steel.
b. is a nonferromagnetic steel.
c. high-carbon steel to be welded after inspection.
d. to be hardened by heat treatment after inspection.

Answer 111

d. to be hardened by heat treatment after inspection.

Question 112

13. Which of the following is an advantage of the dry technique over the wet technique?

a. It is more sensitive for detecting fine surface cracks.
b. It is more capable of providing full surface coverage on irregularly shaped parts.
c. It is easier to use for field inspection with portable equipment.
d. It is faster when testing many small parts.

Answer 112

c. It is easier to use for field inspection with portable equipment.

Question 113

14. Fluorescent magnetic particles are used in preference over visible magnetic particles:

a. when parts are big and bulky.
b. when working in the field.
c. if parts are for railroad applications.
d. to increase the speed and reliability of detecting very small discontinuities.

Answer 113

d. to increase the speed and reliability of detecting very small discontinuities.

Question 114

15. What causes a leakage field in a steel bar?

a. Paint on the bar surface.
b. A longitudinal crack.
c. Reversal of the magnetic field.
d. Hysteresis.

Answer 114

b. A longitudinal crack.

Question 115

16. MT techniques are recognized as superior to liquid penetrant testing techniques when the:

a. surfaces of the test object are corroded.
b. surface is anodized.
c. parts are painted.
d. part is made from austenitic steel.

Answer 115

c. parts are painted.

Question 116

17. When using direct current, an indication is detected. What is the next logical step to determine if the indication results from a surface or subsurface condition?

a. Reinspect using the surge method.
b. Demagnetize and apply powder.
c. Reinspect at higher amperage.
d. Reinspect using alternating current.

Answer 116

d. Reinspect using alternating current.

Question 117

18. A requirement to use MT on a part should also include:

a. a fabrication and service manual.
b. a statement on the drawing that requires MT.
c. the procedure to be used and acceptance criteria.
d. the method of test and service conditions.

Answer 117

c. the procedure to be used and acceptance criteria.

Question 118

19. The reverse magnetizing force necessary to remove a residual magnetic field from a test piece after it has been magnetically saturated is called:

a. coercive force.
b. demagnetizing flux.
c. reverse saturation.
d. direct force.

Answer 118

a. coercive force.

Question 119

20. The best type of magnetizing current for inspection of fatigue cracks is:

a. direct current.
b. alternating current.
c. half-wave rectified alternating current.
d. full-wave current.

Answer 119

b. alternating current.

Question 120

21. A star-shaped indication is seen on the cover pass of a weld. What type of discontinuity is indicated?

a. Crater crack.
b. Cooling crack.
c. Slag inclusion.
d. Arc burn.

Answer 120

a. Crater crack.

Question 121

22. For maximum sensitivity in MT of rough welds:

a. the weld should be wire brushed to remove slag and scale.
b. standard test weldments should be used for comparison.
c. the weld bead should be coated with lacquer.
d. the weld bead should be ground to remove surface irregularities.

Answer 121

d. the weld bead should be ground to remove surface irregularities.

Question 122

23. Ferromagnetic materials are made up of small, polarized regions known as:

a. photons.
b. quarks.
c. electrons.
d. domains.

Answer 122

d. domains.

Question 123

24. The reapplication of magnetic particle suspension after current has already been applied to a part is known as the:

a. residual method.
b. continuous method.
c. magnetization method.
d. demagnetization method.

Answer 123

a. residual method.

Question 124

25. Subsurface indications will have the appearance of:

a. well-defined lines.
b. fuzzy-looking lines.
c. bright, solid lines.
d. intermittent lines.

Answer 124

b. fuzzy-looking lines

Question 125

26. The areas on a magnetized part from which the magnetic field is leaving or returning into the part are called:

a. defects.
b. salient points.
c. magnetic poles.
d. nodes.

Answer 125

c. magnetic poles.

Question 126

27. The strength of a magnetic field induced in a part is often referred to as:

a. retentivity.
b. current density.
c. voltage.
d. flux density.

Answer 126

d. flux density.