Chapter 9 Surface Inspection

Question 1

How should a fluorescent dye be viewed?

Answer 1

Under black light

Question 2

2. What type of developer is normally used with the solvent-removal process to spot check welds?

Answer 2

Non Aqueous

Question 3

3. “The fluorescent post-emulsified penetrant process is often recommended for high-sensitivity applications such as detection of fatigue cracks

a. True
b. False

Answer 3

a. True

Question 4

4. Does the liquid penetrant process work on stainless steel and aluminum?

Answer 4

Yes

Question 5

5. Give one way in which a change to a liquid penetrant procedure could be qualified.

Answer 5

Use a comparator block

Question 6

6. “When using liquid penetrant inspection, the surface must be ground smooth to remove all irregularities before applying the penetrant.”a. Trueb. False

Answer 6

b. False, Grinding can flow the surface and conceal defects.

Question 7

7. When using the solvent-removable method, why should the solvent not be sprayed directly on the surface to remove excess penetrant?

Answer 7

It may leach penetrant out of discontinuities.

Question 8

8. “When using post-emulsifiable penetrants, the emulsifier must remain in contact with the surface long enough to mix with the excess penetrant but not long enough to reach penetrant in the discontinuities.

a. True
b. False

Answer 8

a. True

Question 9

9. What could be the effect of spraying on too much developer?

Answer 9

It could mask indications

Question 10

10. What is the difference between a false indication and a non-relevant indication?

Answer 10

False indications are not associated with discontinuities, non-relevant indications are.

Question 11

11. What is the most likely cause of false indications?

Answer 11

Poor cleaning

Question 12

12. “If a small crack is found by LPI in an aluminum weld, it may be repaired by simply welding over it to melt out the crack.”

a. True
b. False

Answer 12

False. Retained penetrant could contaminate the repair. The metal containing the crack must be removed before repair.

Question 13

13. Is there a standard for certifying operators using the liquid penetrant inspection method?

Answer 13

Yes, CAN/CGSB 48.97

Question 14

14. The strength of the flux induced when a material is placed in a given magnetic field depends on what property of the material?

Answer 14

Permeability

Question 15

15. The level of residual magnetic flux remaining in a ferromagnetic material when an applied field is removed is known as?

a. Coercive force.
b. Saturation.
c. Retentivity.

Answer 15

c. Retentivity.

Question 16

16. What is the range of applied field (relative to saturation) normally used in magnetic particle inspection?

Answer 16

30-70%

Question 17

17. The most favorable direction for detecting a crack when using prods is when the crack lies across the weld metal.

a. True
b. False

Answer 17

a. True

Question 18

18. How are arc strikes avoided when using prods.

Answer 18

Turn the power on after the prods are in place, and turn off power before removing the prods.

Question 19

19. What would be a typical current for prods spaced 150 mm (6 in) apart?

Answer 19

About 600 amps

Question 20

20. Write down at least three changes in a material that could cause a magnetic particle indication in the absence of a discontinuity.

Answer 20

Composition, microstructure, work hardening, heat treatment

Question 21

21. Give one source of non-relevant indications not due to material changes.

Answer 21

Excessive magnetizing field, residual magnetism

Question 22

22. Give two applications when demagnetization might be specified.

Answer 22

-when the part is to be plated or painted and adhering particles would interfere-on shafts or other rotating components where adhering particles could contribute to failure-parts to be machined-when followed by welding where residual magnetism could cause arc blow-when a residual field is undesirable in service, e.g., aircraft parts-when stringent post-cleaning requires all inspection materials to be removed-when parts are to be electron beam welded (EBW)

Question 23

23. Adisadvantageof magneticparticleinspectionisthatitisimpossibleto obtainanykindof permanentrecord oftheindication. “
    a True
    b False

Answer 23

False. Photographsoradhesivetapetransferscanbe used.

Question 24

24. Is thereastandardfor the certificationofoperatorsformagneticparticleinspection?

Answer 24

Yes, CAN/CGSB 48.9712

Question 25

25. Whatisthenameofthedevicethatmeasuresthesmallelectricalpotentialcreatedatright angles toanelectriccurrent whenplacedina magneticfield?

Answer 25

Hall Detector

Question 26

26. Isthereastandardforcertifyingoperatorsfortheeddycurrentmethod?

Answer 26

Yes, CAN/CGSB 48.9712

Question 27

27. Forwhatresearchapplicationhas thepotentialdropmethodbeenused?

Answer 27

Measuring the growth of fatigued cracks

Question 28

28. Toremoveexcesspenetrantwhenusingthesolvent-removableprocessinaportablekitfor spot-checking:

a. Wipeawayexcesspenetrantwithacleancloth,thenwipethesurfacecleanwithacloth lightlymoistenedwithsolventremover.
b. Spraysurfacewithsolventremoverthenwipecleanwithacloth.
c. Apply solventremoverbydippingorsprayingand allowingtosoakforafewminutesbeforewipingclean.
d. Applyso(ventremoverbybrushingthenwipe cleanwithacloth.
e. Spraysurfacewithsolventremoverandallowdryingbynaturalevaporation.

Answer 28

a. Wipeawayexcesspenetrantwithacleancloth,thenwipethesurfacecleanwithacloth lightlymoistenedwithsolventremover.

Question 29

29. Which of the following best describes the basis of the magnetic particle inspection method?

a. The increased resistance to the flow of electric current when a discontinuity is present.
b. The attraction of magnetic particles to a flux leakage field formed when a discontinuity lies parallel to an applied magnetic field.
c. The attraction of magnetic particles to a flux leakage field formed when a discontinuity lies at a perpendicular angle to the induced magnetic field.
d The attraction of magnetic particles to the strong fields formed when a material is magnetically saturated.

Answer 29

c. The attraction of magnetic particles to a flux leakage field formed when a discontinuity lies at a perpendicular angle to the induced magnetic field.

Question 30

30. Which of the following statements is true?

a. The eddy current method is based on detecting the flux leakage around a discontinuity using a Hatt detector.
b. The eddy current method is based on detecting changes in the inductive reactance of a coil due to disturbance of the eddy current by a discontinuity and can be used on non-ferrous metals.
c. The eddy current method is based on detecting changes in the inductive reactance of a coil due to disturbance of the eddy current and can only be used on ferromagnetic metals.
d. The eddy current method is based on measuring the change in voltage across a discontinuity when an eddy current flow.
e. The eddy current method normally uses direct Current to increase depth capability.

Answer 30

b. The eddy current method is based on detecting changes in the inductive reactance of a coil due to disturbance of the eddy current by a discontinuity and can be used on non-ferrous metals.