Magnetic Particle Testing Method, Q & A

Levels I, II and IIIMagnetic Particle TestingMethod

Supplement toRecommended PracticeNo. SNT-TC-1ABook B - second edition

The American Societyfor Nondestructive Testing. Inc.

/

Supplement to Recommended Practice SNT-TC-IA(Q&A Book): Magnetic Particle Testing Method

Text Corrections

The following text corrections apply to the first printing of Supplement to Recommended PracticeSNT-TC-1A (Q&A Book): Magnetic Particle Testing Method, second edition. Subsequent printings of thedocument will incorporate the corrections into the published text.

Levell

Page 3: Question 27 should be changed as follows:27. A metal that is difficult to magnetize is said to have:

a. high permeability.b. low permeability.c. low coercive force.d. low retentivity.

Ref: CA5Answer b is correct.

Page 4: Questions 34 and 38 should be changed as follows:34. Which of the following is the most effecti ve method for the detection of near surface defects?

a. Dry residual method using DC with surge.b. Wet continuous method using half-wave rectified current.c. Wet residual method.d. Dry continuous method using half-wave rectified current with prods.

Ref: C.207Ans wer d is correct.

38. When there is absolutely no pattern or distribution of magnetic particles on the part, the possiblecause is that:a. the amperage setting is too high.b. the amperage setting is too low.c. the particle bath strength is too high.d. the part is made of steel with high retentivity.

Ref: A.64Answer 12 is correct.

Page 6: Questions 52 and 53 should be changed as follows:52. What equipment is used to determine if a part has been demagnetized?

a. a magnet on the partb. a field indicatorc. a survey meterd. careful observation for clinging magnetic particles

Ref: C.302Answer b is correct.

1 of 4

53. Which of the following is most often used for dry magnetic particle inspection?a. full cycle direct currentb. half wave rectifi~d alternating direct currentc. high voltage, low amperage currentd. direct current from electrolytic cells

Answer b is correct.

Page 11: The answers to the following Level Iquestions should be corrected as follows:

1. b2. a38. b48. d49. b66. a85. a

Level II

Ref: C.202

Page 17: Question 31 should be corrected as follows:31. Which of the following is the most common current method used for preserving and documenting

magnetic particle indications?a. hand drawn sketchb. color-tinted tapec. color-tinted lacquerd. di oital photography

Answer d is correct.

Page 19: Question 56 should be changed to read:56. The lines of force that form a path around a crack in a ring magnet are called:

a. leakage flux leaka!leb. field strengthc. magnetic linesd. longitudinal field

Answer a is correct.

Page 21: Questions 71 and 76 should be corrected as follows:71. Magnetic field strength is measured in:

a. teslab. gaussc. oerstedc.d-.webers/m2

d. aIlloereimeter

Answer Q. is correct.

2 of 4

Ref: C: 284

Ref: C.2,17

Ref: C.302

:

76. Demagnetization would most likely be required when:a. the material has low retentivity.b. the object is to be electric arc welded.c. the material has low reluctance.d. heat treatment is to be carried out after testing.


Page 23: The answers to the following Level II questions should be corrected as follows:51. a53. d62. d71. d

Page 25: Question 6 should be changed to read:6. The concentration of the solid content ef-- in a suspension of magnetic particles is measured by:

a. weighing the suspensionb. soaking the solids in benzolc. measuring the pull on a magnetd. permitting the solids to settle out of suspension

Ref. A.261-263Answer d is correct.

Page 26: Delete Question 8.

Page 29: Questions 35 and 40 should be changed to read: I35. The least important factor below that should BGt be considered when selecting a

method of magnetization to detect subsurface discontinuities is:a. available equipmentb. configuration of the partc. skill of the operator of cost of the equipmentd. type of materials the part is made from

Ref: C.233Answer c is correct.

40. The magnetic lines of flux ~ in a permanent magnet:a. in all cases produce a longitudinal fieldb. enter the south pole and leave through the north polec. flow from the north pole through the magnet to the south poled. change direction 60 times a second with the magnetizing current


3 of 4

of 4

~

Page 30: Question 47 should be changed as fOl/ows:47.

A discontinUity caused by a welding operation is:a. creep crack.b. segregation.c. machining tear.d. ~ tearing.

Answer d is Correct.

Ref: C.86

Catalog #2027second edition first printing 03107

Text CorreCtions printed 05109

tions

swersLevels I, II and IIIMagnetic Particle TestingMethod

Supplement toRecommended PracticeNo. SNT-TC-1ABook B - second edition

The American Societyfor Nondestructive Testing, Inc.

The questions in this book were originally compiled by the Magnetic Particle Supplement Committee of thePersonnel Qualification Division, Education and Qualification Council of the American Society for NondestructiveTesting. This edition was updated and edited by Charles W. Eick, Dassault Falcon Jet.

Published byThe American Society for Nondestructive Testing, Inc.1711 Arlingate LanePO Box 28518Columbus, OH 43228-0518

Copyright © 2007 by The American Society for Nondestructive Testing, Inc. ASNT is not responsible for theauthenticity or accuracy of information herein. Products or services that are advertised or mentioned do not carrythe endorsement or recommendation of ASNT.

This publication contains suggested questions and answers in the Magnetic Particle Testing Method for use in con-junction with Recommended Practice No. SNT-TC-1Afor Personnel Qualification and Certification inNondestructive Testing. Recommended Practice No. SNT-TC-1A is available from ASNT.

IRRSP, NDT Handbook, The NDT Technician and www.asnt.org are trademarks of The American Society forNondestructive Testing, Inc. ACCP, ASNT, Level III Study Guide, Materials Evaluation, Nondestructive TestingHandbook, Research in Nondestructive Evaluatioti and RNDE and arc registered trademarks of The AmericanSociety for Nondestructive Testing, Inc.

ASNT exists to create a safer world by promoting the profession and technologies of nondestructive testing.

ISBN-13: 978-1-57117-147-4

Printed in the United States of America

first printing 07/87second printing 03/88third printing 04/88fourth printing 02/89fifth printing 04/90sixth printing 05/92 ,seventh printing with revision 05/94eighth printing 10/96ninth printing 11/9810th printing 07/0311th printing 03/06

Second editionfirst printing 03/07

ii

Table of Contents

Recommended Training References v

Reference Usage List vi

Level IQuestionsAnswers

111

Level IIQuestionsAnswers

1323

Level IIIQuestionsAnswers

2533

iii

iv

Recommended Training ReferencesMagnetic Particle Testing Method

The following references were used in formulating the questions contained in this book.

A. * Betz, Carl E. Principles of Magnetic Particle Testing. Chicago, IL; Magnaflux Corporation.2004.

B. ASTM E 1444, Standard Practice for Magnetic Particle Examination, West Conshohocken,PA; ASTM International. Current edition.

C. * Schmidt, Thomas J., Kermit Skeie, tech. eds.; Paul McIntire, ed. Nondestructive TestingHandbook, second edition: Volume Six, Magnetic Particle Testing, Columbus, OR; TheAmerican Society for Nondestructive Testing, Inc. 1989.

D. McMaster, R.C., ed. Nondestructive Testing Handbook, first edition. Columbus, OR; TheAmerican Society for Nondestructive Testing, Inc. 1959.

E. * Eick, Chuck W. Levell! Study Guide: Magnetic Particle Testing Method, second edition,Columbus, OR; The American Society for Nondestructive Testing, Inc. 2003.

F.* Fenton, John D. ASNT Levellll Study Guide: Magnetic Particle Testing Method, secondedition, Columbus, OR; The American Society for Nondestructive Testing, Inc. 2006.

G. * Magnetic Particle Testing Classroom Training Book. Columbus, OR, The American Societyfor Nondestructive Testing, Inc. 2004.

Each question found in this book is followed by letter(s) and page number(s) indicating thespecific recommended reference where the answer may be found. For example:

Ref: CA5

27. A metal that is difficult to magnetize is said to have:

a. high permeability,b. low permeability.c. high reluctance.d. low retentivity.

In this example, the letter "C" refers to Reference C in the list above and "45" is the specificpage in Reference C where the answer to the question is located.

v

Reference A: Total = 65Level I (10)Level II (32)Level III (23)

Reference B: Total = 0Level I (0)Level II (0)Level III (0)

Reference C: Total = 161Level I (74)Level II (45)Level III (42)

Reference D: Total = 1Level I (0)Level II (1)Level III (0)

Reference E: Total = 7Level I (4)Level II (3)Level III (0)

Reference F: Total = 0Level I (0)Level II (0)Level III (0)

Reference G: Total = 4Level I (4)Level II (0)Level III (0)

Reference Usage List

vi

Magnetic Particle Testing Method, Level I

Level I QuestionsMagnetic Particle Testing Method

1. Magnetic particle is a nondestructive testingmethod used for:

a. locating surface and near surfacediscontinuities in aluminum.

b. locating surface and near surfacediscontinuities in steel.

c. finding and measuring material separation.d. measuring flux density.

Ref: C.2

2. Ferromagnetic material is:

a. strongly attracted by a magnet.b. not highly saturated by magnetic fields.c. a material with a 0 permeability measurement.d. not capable of being magnetized.

Ref: C.24

3. The permeability of a material describes:

a. the ease with which it can be magnetized.b. the depth of the magnetic field in the part.c. the length of time required to demagnetize it.d. the ability to retain the magnetic field.

Ref: C.26

4. The retentivity of a material describes:

a. the ease with which it can be magnetized.b. the depth of the magnetic field in the part.c. the length of time required to demagnetize it.d. the ability to retain the magnetic field.

Ref: C.24

5. Magnetic particles are available in differentcolors:

a. for color contrast with the part surface therebyenhancing detection of indications.

b. to enhance the detection of indications' byallowing background color matching.

c. to determine if an indication is surface orsubsurface.

d. to indicate different magnetic flux values.Ref: C.36

6. Which of the following can be magnetized?

a. ironb. copperc. aluminumd. magnesium

Ref: C.24

7. The magnetic field is strongest when:

a. the magnetizing voltage is flowing.b. the magnetizing current is flowing.c. the material exhibits high coercive forces.d. the magnetizing current is not flowing.

Ref: C.24

8. If a crack exists in a circular magnet, theattraction of magnetic particles to the crack iscaused by:

a. a coercive force.b. a leakage field.c. a Doppler effect.d. a high reluctance at the crack.

Ref: C.15

/Magnetic Particle Testing Method, Level I

9. The unit usually used to denote flux density is:

a. gauss.b. henry.c. farad.d. ampere.

Ref: C24

10. Which statement is true when related to magneticlines of force?

a. They are often forced to cross due to partgeometry.

b. They are most dense at the poles of a magnet.c. They seek the path of most resistance.d. They cannot be detected.

Ref: C12

11. Magnetic flux lines that are parallel to adiscontinuity produce:

a. strong indications.b. weak indications.c. no indications.d. fuzzy indications.

Ref: C.16

12. A part is adaptable to magnetic particleinspection if:

a. it is attached to an electrostatic field.b. the material is ferromagnetic.c. the material is non-ferrous.d. the material is an electric conductor.

Ref: C24

13. What rule describes the direction of current flow(+ to -) when lines of magnetic force surround aconductor?

a. left-hand ruleb. right-hand rulec. flux ruled. reluctance rule

Ref: C19

14. The magnitude of the residual magnetic field in aspecimen is dependent on:

a. the length-to-diameter ratio (LID).b. the strength of the applied magnetizing force.c. the right-hand rule.d. the left-hand rule.

Ref: C.24

15. The proper number of ampere-turns for a giventest specimen being examined by longitudinalmagnetism is determined by:

a. its length and diameter.b. the material.c. the diameter and the material.d. its diameter.

Ref: A.182

16. A circular field may be induced into a specimenby:

a. placing the part in an energized coil.b. passing current directly through the part.c. passing a magnetic field through the part.d. placing the part in a north-south orientation.

Ref: C.150

17. An electrical yoke produces:

a. a longitudinal field.b. a circular field.c. alternating fields.d. a swinging field.

Ref: C22

18. An energized coil around the part produces:

a. a circular field.b. a longitudinal field.c. an intermittent field.d. a field dependent on the type of current

applied.Ref: C152

19. In longitudinal magnetization the proper term forcalculating magnetizing force is:

a. amperes.b. ampere turns.c. watts.d. ohms.

Ref: A.182

2

20. Magnetic lines of force:

a. travel in straight lines.b. form a closed loop.c. are randomly oriented.d. overlay in highly ferromagnetic materials.

Ref: C.I2

2l. A magnetic particle buildup from a discontinuityis strongest when the discontinuity is oriented:

a. 180 degrees to the magnetic flux flow.b. 45 degrees to the magnetic flux flow.c. 90 degrees to the magnetic flux flow.d. 90 degrees to the current flow.

Ref: C.297

22. A specimen may be demagnetized by which ofthe following methods?

a. Heat treatment below the curie temperature.b. Placing the part in an alternating current coil.c. Placing the part in reversing and decreasing

direct current fields.d. Applying a direct current yoke and removing

it from the part.Ref: A.66

23. Which of the following is an advantage ofmagnetic particle testing over penetrant testing?

a. It does not require post-cleaning of the part.b. It requires direct access to the surface of the

part.c. It can detect near-surface discontinuities.d. It requires ~ shorter dwell time to produce

results.Ref: A.66

24. The amount of amperage used for magneticparticle inspection using the prod method isdetermined from the:

a. type of material.b. distance between the prods.c. diameter of the part.d. total length of the part.

Ref: C.I51


25. The flux within and surrounding a magnetizedpart or around a conductor carrying a current isknown as:

a. the saturation point.b. a magnetic field.c. the ferromagnetic field.d. the paramagnetic field.

Ref: C.I2

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

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

Ref: C.I2

27. A metal that is difficult to magnetize is said tohave:

a. high permeability.b. low permeability.c. high reluctance. L o v-!J <beT' U1 e. ~o '" e ed. low retentivity.

Ref: C.45

28. The magnetism that remains in a piece ofmagnetizable material after the magnetizing forcehas been removed is called the:

a. tramp magnetism.b. residual magnetism.c. damped magnetism.d. permanent magnetism.

Ref: C.25

29. Subsurface discontinuity indications usuallyappear:

a. sharp and distinct.b. sharp and wide.c. wide and fuzzy.d. high and loosely held.

Ref: E.35

3


30. Which residual field is most difficult todemagnetize?

a. longitudinalb. circularc. vectord. binodal

Ref: C33

31. Which magnetic particle application technique isthe most sensitive?

a. continuousb. residualc. interruptedd. counter-current

Ref: C38

32. Fluorescent magnetic particle indications shouldbe inspected under:

a. any light.b. a neon light.c. an ultraviolet light.d. a fluorescent light.

Ref: C37

33. Inspecting a part by magnetizing, removing thecurrent flow, then applying the medium is calledthe:

a. continuous method.h. wet method.c. residual method.d. dry method.

Ref: C37

34. Which of the following is the most effectivemethod for the detection of subsurface defects?

a. Dry residual method using DC with surge.b. Wet continuous method using half-wave

rectified current.c. Wet residual method.d. Dry continuous method using half-wave

rectified current with prods.Ref: C207

35. A curve is sometimes drawn to show graphicallythe relation of the magnetizing force to thestrength of the magnetic field produced in acertain material. This curve is known as the:

a. magnetic force curve.b. hysteresis curve.c. saturation curve.d. induction curve.

Ref: C24

36. What method of applying particles providesgreater sensitivity in locating subsurface welddiscontinuities?

a. continuousb. residualc. circulard. longitudinal

Ref: C.207

37. When magnetizing a weld in two directions, andif the current used in the first direction is 750 Aand the current in the second direction is 400 A,which of the following is true?

a. The part should be checked to see ifdemagnetization between operations isnecessary.

b. No precautions should be taken before thesecond operation.

c. This is not a valid technique.d. There is no need to magnetize a weld in two

directions.Ref: C30

38. When there is absolutely no pattern ordistribution of magnetic particles on the part, thepossible cause is that:

a. the amperage setting is too high.b. the amperage setting is too low.c. the particle bath strength is too high.d. the part is madetRf high retentivity steel.

Y \ Ref: A.64

\:J\-~~\

4

39. What are three causes of nonrelevant indications?

a. lack of fusion, change of section thickness,grinding cracks

b. change of section thickness, heat affectedzones, 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

Ref: C.234

40. Using the residual test method, a number of partsare magnetized and laid on a rack prior toapplication of magnetic particles. Why is itimportant that they do not rub or touch eachother?

a. There is a possible loss of the magnetic field.b. It may cause magnetic writing.c. It may damage the part.d. It makes parts hard to handle.

Ref: C.234

41. The point at which the magnetism in a materialcannot be increased even though the magnetizingforce continues to increase is known as the:

a. salient pole.b. saturation point.c. residual point.d. remnant point.

Ref: C.24

42. Which type of current produces a skin effect onthe surface of the part?

a. alternating currentb. direct currentc. half-wave rectifiedd. full-wave rectified

Ref: C.27

43. When using the wet method, why should a highvelocity flow of wet method bath over surfacesfollowing removal of the magnetizing current notbe used?

a. It may wash away a fine or weakly heldindication.

b. This is not a problem.c. It may splash particles into eyes.d. None of the above is correct.

Ref: E.23


44. Residual magnetic particle inspection may beused when:

a. parts are irregular in shape.b. parts are highly retentive.c. parts are highly stressed.d. evaluating continuous method indications.

Ref: C.37

45. Magnetic particle inspection is not a reliablemethod of detecting:

a. laps.b. deep internal cavities.c. cracks.d. seams.

Ref: C.233

46. The wet fluorescent magnetic particle inspectionmethod is the same as the visible wet magneticparticle method except that the fluorescentmagnetic particle inspection method requires:

a. an ultraviolet light.b. a higher current.c. a different machine.d. alternating current.

Ref: C.37

47. A discontinuity open to the surface produces anindication which is:

a. sharp and distinct.b. wide and indefinite.c. crisscrossed.d. high and fuzzy.

Ref: E.35

48. Which of the following will produce circularmagnetism?

a. passing current through a coilb. placing the test part in a solenoidc. yokesd. passing current through prods

Ref: G.ll

5

Magnetic Particle TestingMethod, Level I

49. When using the wet continuous method, the flowof suspension from the hose should be shut off:

a. immediately after applying the current.b. immediately before applying the current.c. while the current is flowing.d. 30 seconds before applying the current.

Ref: G.52

50. The strongest magnetic field in a coil is at the:

a. outside edge.b. inside edge.c. center.d. end.

Ref: G.17

51. To detect lengthwise discontinuities on the insidediameter of hollow parts, you should:

a. pass current through it.b. magnetize with a coil.c. pass current through a central conductor.d. increase the amperage used.

Ref: C.152

52. What equipment is used to determine if a parthas been demagnetized?

a. a magnet on the part \b. a field meter iII a.. \ C J.'\-.Q (c. a survey meterd. careful observation for clinging magnetic

particlesRef: C.302

53. Which of the following is most often used fordry magnetic particle inspection?

a. full cycle direct current ~ '\b. half-wave rectified altemati.ng current \J \ ,t,c,c. high voltage, low amperage currentd. direct current from electrolytic cells

Ref: C.202

54. An electric current through a copper wire:

a. creates a magnetic field around the wire.b. creates magnetic poles in the wire.c. magnetizes the wire.d. does not create a magnetic field.

Ref: C.l8

55. Parts should be cleaned after demagnetization:

a. to ensure that the magnetic particles areremoved.

b. to prevent false indications.c. to save the solids of the suspension.d. to prevent cracking during heat treatment.

Ref: C.30

56. In circular magnetization, the magnetizing forceis expressed in amperes. What term is used toexpress magnetizing force in longitudinalmagnetization?

a. amperesb. ampere-turnsc. consequent polesd. volts

Ref: E.18

57. A longitudinal surface crack in a circularlymagnetized part will cause:

a. the magnetic field to die out.b. a decrease in permeability.c. a magnetic leakage field.d. a current to flow.

Ref: C.18

58. In a magnetic particle test, assuming that all ofthe following are in the same relative position ina small part, which would be the hardest todetect?

a. a surface crackb. a near surface crackc. a scratchd. a seam

Ref: A.62

59. If wet magnetic particle suspension is notuniform, then:

a. the strength of an indication may vary, and theinterpretation of the indication may beerroneous.

b. the magnetic flux would not be uniform.c. greater mobility would be required.d. the part cannot be magnetized.

Ref: A.261

6

60. Which of the following currents will best definesurface cracks?

a. half-wave rectified alternating currentb. direct currentc. alternating currentd. surge current

Ref: A.232

61. When a magnetic field is induced in a part withprods spaced 152 mm (6 in.) apart, the field is:

a. solenoidal.b. circular.c. longitudinal.d. distorted trapezoidal.

Ref: C.23

62. Applying the theory of the right-hand rule, alongitudinal surface defect in a round bar isdetected by "current passing in a directionparallel to the direction of expected defects"because:

a. the current direction is in line with the defect.b. the magnetic field is at right angles to the

defect.c. it makes no difference.d. the magnetic field is parallel to the defect.

Ref: C19 and 150

63. If a current is passed through an electricalconductor, what will surround the conductor?

a. eddy current fieldb. currentc. magnetic fieldd. residual field

Ref: C.18

64. With current flowing from + to - in a coil, alongitudinal field is created. Which of thefollowing may be used to establish the directionof the magnetic field?

a. left-hand ruleb. right-hand rulec. Ohm's lawd. Newton's law

Ref: C.19


65. When magnetic material is placed into a coil, themagnetic lines of flux concentrate themselves inthe material and:

a. create a longitudinal magnetic field.b. create a circular magnetic field.c. create a longitudinal circular field.d. have no effect.

Ref: C.19

66. Which form of magnetization is easiest to detectin most parts?

a. longitudinal magnetizationb. permanent magnetismc. circular magnetizationd. parallel magnetization

Ref: C293-294

67. The best type of magnetic field to use to inspecta tubular product for surface defects along itslength is a:

a. longitudinal field.b. circular field.c. swinging field.d. yoke magnetization.

Ref: C150

68. The area of maximum induced field strengthusing 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 pole pieces.

Ref: C23

69. The strength of the magnetic field induced in apart is often referred to as:

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

Ref: C.15

7


70. A major factor that determines the success ofmagnetic particle inspection is the:

a. field strength.b. voltage on magnetizing coil.c. current through the coil.d. time of magnetization.

Ref: C.15-16

71. What type of current is best suited to detectsurface discontinuities?

a. direct currentb. alternating currentc. pulsating direct currentd. half wave.

Ref: C.27

72. When preparing a magnetic particle bath, it isimportant to have the bath strength at a properlevel, as too many particles can result in:

a. lowering the test amperage.b. having to increase the magnetizing current.c. masking the indications.d. none of the above.

Ref: C.2IO

73. One advantage of using fluorescent particles is:

a. that less equipment is required.b. the high speed of inspection.c. the cost.d. that they are more readily attracted than other

particles.Ref: A.275-276

74. When using a dry magnetic particle powder, theproper way to apply it to the part is to:

a. forcibly apply it with air.b. roll the material in the container of powder.c. apply it from the bottom of the part.d. float the particles to inspection surface as

gently as possible.Ref: C.36

75. When using wet particles in water suspension,wetting agents are added to:

a. prevent freezing.b. prevent corrosion of inspection equipment.c. ensure the proper wetting of the part.d. decrease the amount of water needed.

Ref: C.208

76. When preparing an inspection bath, the amountof magnetic particles per gallon of fluid is calledits:

a. measuring scale.b. particle number.c. strength or concentration.d. usable limits.

Ref: G.lOO-lOl

77. Coercive force:

a. describes the means by which the magneticparticles are suspended in the liquid whenusing the wet method.

b. describes the magnetizing force used with thecontinuous method.

c. represents the reverse magnetizing forcenecessary to remove the residual magnetism ina material.

d. is not a term used in magnetic particle testing ..Ref: C.24

78. Demagnetization:

a. may be accomplished by heating a materialabove its curie point.

b. is always necessary.c. can be performed only with alternating

current.d. can be performed only with direct current.

Ref: C.292-293

79. Resistance to demagnetization:

a. is greater in hard materials than soft materials.b. is greater in soft materials than hard materials.c. is the same for both hard and soft materials.d. is nonexistent.

Ref: C.295

8

80. Demagnetization:

a. may be easy or difficult depending on the typeof material.

b. is easy for materials having a high coerciveforce.

c. is always most difficult in materials retaininga high residual field.

d. All of the above answers are correct.Ref: C295

81. The strength of the wet suspension should bemaintained at a given level because:

a. a low level may give weak indications.b. a high level may give heavy background.c. both A and B.d. none of the above.

Ref: C.209

82. Indications such as those at local external poles,sharp fillets or thread roots are called:

a. fake indications.b. relevant indications.c. nonrelevant indications.d. magnetic writing indications.

Ref: C234

83. Magnetic particle testing will revealdiscontinuities in which one of the followingmaterials?

a. bronzeb. carbon steelc. aluminum castingsd. austenitic stainless steel

Ref: C2

84. Magnetic particle testing is a nondestructivetesting method for detecting discontinuities inmagnetizable material. This method can detect:

a. surface discontinuities only.b. subsurface discontinuities only.c. surface and subsurface discontinuities.d. discontinuities at surface and subsurface of

any depth.Ref: C2


85. Which of the following statements is adisadvantage of magnetic particle testing?

a. It can be used only on ferrous materials.b. It can be applied only to detect surface

defects.c. It can be applied only to detect subsurface

defects.d. It can be applied to detect surface and

subsurface discontinuities in ferrous material.Ref: A.66-68, C.2

86. Which one of following magnetic particles willbe most sensitive to small surface discontinuitiessuch as fatigue cracks?

a. dry powderb. fluorescent particlec. visible particle using oil as carrier (vehicle)d. visible particle using water as carrier (vehicle)

Ref: C.211

87. Magnetic particles should have the:

a. highest possible retentivity.b. lowest possible permeability.c. highest possible permeability.d. highest possible permeability and lowest

possible retentivity.Ref: C.34

88. Nonrelevant indications can be caused by thefollowing, except:

a. excessive magnetizing current.b. inadequate magnetizing current.c. structural design of the test specimen.d. variance of permeability within the test

specimen.Ref: C293

89. A material with magnetic permeability less than1 is known as:

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

Ref: C13

9


90. A small device, generally a metal strip or disk,containing an artificial discontinuity used todetermine when the correct magnetizingcondition or magnetic field direction has beenachieved is:

a. an ohmmeter.b. a gauss meter.c. a flux indicator.d. a field indicator.

Ref: C.43

91. The direction of magnetic line of force is __degrees from the direction of current flow.

a.45b.90c. 180d.220

Ref: C.19

10

Magnetic Particle Testing Method, Levell

Level I AnswersMagnetic Particle Testing Method

-1-.~.3.4.5.6.7.8.9.

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Level II QuestionsMagnetic Particle Testing Method

1. The interpretation of magnetic particleindications may be aided by:

a. observing with a magnifying glass.b. reproducing the indication after

demagnetization.c. observing the indications after the part is

pre-cleaned.d. observing the indications after the part is

post-cleaned.Ref: C.235

2. Residual magnetism may be beneficial as an aid:

a. in demagnetization.b. in proper heat treating.c. in the deposition of weld metal.d. in interpretation and evaluation of indications.

Ref: A.397

3. An interruption in the normal physical structureor configuration of a part which produces amagnetic particle testing indication is called:

a. a defect.b. an indication.c. a deformation.d. a discontinuity.

Ref: C.43

4. Comparing parts that have been circularlymagnetized and those that have beenlongitudinally magnetized, which retain the mostobjectionable residual field if not demagnetized?

a. circularb. vectoredc. remnantd. longitudinal

Ref: A.313

5. What type of magnetization uses the formula:Ampere turns = 45 OOO/(LID)?

a. circularb. parallelc. vectoredd. longitudinal

Ref: A.182

6. Why are large soft contact pads such as lead orcopper braid used for surfaces or headstocks?

a. To increase the contact area and reduce thepossibility of burning the part.

b. Because they help heat metal, thus facilitatingmagnetic induction.

c. To increase the contact area and flux density.d. Because of their low melting points.

Ref: C.42

7. A rough forging that has received no furtherprocessing is magnetic particle tested. Anindication is observed to run in every directionand appears to extend deeply into the part andperpendicular to the surface. It is very sharp.What is the probable identity of the indication?

a. forging burstb. flakec. seamd. lap

Ref: A.85-86

13

Magnetic Particle Testing Method, Level II

8. A gear with case-hardened ground teeth and hubends is magnetic particle tested. Individualindications are detected on five teeth and one endsurface of the hub. The indications do not breakover the part edges. What is the probable identityof the indication?

a. grinding cracksb. quench cracksc. inclusionsd. porosity

Ref: A.90-91

9. If an overall pattern (sometimes circular lines)appears on the test surfaces, how should theinspector reprocess the test piece?

a. Demagnetize the piece.b. Retest at a higher amperage.c. Retest at lower amperage.d. Part is not testable.

Ref: A.383

10. A prime consideration when selecting a powderto be used as a magnetic particle medium is toselect a powder that:

a. will adhere to the surface being tested.b. provides a low contrast to the surface being

tested.c. provides a high contrast to the surface being

tested.d. requires a high demagnetization current to

remove it.Ref: C.36

11. When testing for fme shallow surface cracks, thepreferred magnetic particle test method shouldbe:

a. dry alternating current.b. dry direct current.c. wet alternating current.d. wet direct current.

Ref: C.27, 37

12. Which of the following is an advantage of thedry method over the wet method?

a. It is more sensitive to fine surface cracks.b. It is easier to use for field inspection with

portable equipment.c. It is faster than the wet method when testing a

number of small parts.d. It is more capable of providing full surface

coverage on irregularly shaped parts.Ref: C.37

13. When testing a bar with a length-to-diameterratio of 4 in a lO-turn coil, the required currentwould be:

a. 45000 A.b. 18000 A.c. 1125 A.d. Unknown, more information is needed.

Ref: A.208

14. Internal splines and holes drilled parallel to, ornear, test surfaces will cause:

a. sharp, well-defined indications directlyaligned with the part's internal contours.

b. broad, fuzzy indications directly aligned withthe part's internal contours.

c. distinct indications not aligned with anyinternal contours.

d. no indications.Ref: C.234

15. A limitation of coil magnetization techniques isthat:

a. regardless of part size, the part cannot bepainted.

b. the coil must be of maximum diameter inrelation to part.

c. the effective field is generally limited oneither side of the coil.

d. small diameter parts must be placed close tothe center of the coil.

Ref: A. 146

14

16. Which of the following wave patterns depicts thewave form of three-phase full-wave rectifiedalternating current?

a. +

1 cycle

b. +

.•..=r==u I

\ I

-"I

\ I

-"

c. +

.•..=QJ

SU

d. +

Ref: C.2S

Mean DCVolts

Time

Time

Time

Time


17. Which of the following casting discontinuities iscaused by nonuniform cooling resulting instresses that rupture the surface of the metal?

a. hot tearsb. porosityc. drossd. shrinkage

Ref: C.77

IS. The term used to refer to the total opposition toflow of current represented by the combinedeffect of resistance, inductance and capacitanceof a circuit is:

a. inductive reactance.b. impedance.c. reluctance.d. decay.

Ref: A. 122

19. A 3500 ampere-turn coil shot is required to beperformed in a 5-turn coil after a head shot ofSOOA using the wet continuous method. In orderto properly conduct the coil shot it is necessaryto:

a. demagnetize the part between the head andfirst coil shot.

b. check the part for residual magnetism with afield indicator .

c. remove all residual wet magnetic particle fluidfrom the part using clean, dry absorbent rags.

d. place the part in the coil and continue theinspection after evaluating the head shotindications.

Ref: A.30S

20. When adding concentrate in paste form to anywet magnetic particle suspension liquid, it iscommon practice to:

a. add the paste directly to the suspension liquid.b. change the entire bath after thoroughly

cleaning the system.c. make a small, slurry-like test mixture of paste

and suspension and add directly to the bath.d. mix paste in a small container with suspension

to the required bath strength and add directlyto the bath.

Ref: A.264

15


21. A desirable property of magnetic particles usedfor either the dry or wet method is that they:

a. be toxic.b. be nonferromagnetic,c. possess high retentivity.d. possess high permeability.

Ref: C.201

22. Which of the following can cause nonrelevantmagnetic particle indications?

a. joints between dissimilar metalsb. thread cracksc. scratchesd. burrs

Ref: C.234-235

23. External poles which are too strong to permitgood inspection of a part are more likely to resultwhen using:

a. longitudinal magnetization.b. polarized magnetization.c. residual magnetization.d. circular magnetization.

Ref: A.382

24. A rough forging discontinuity has the followingcharacteristics: can occur on surface or internally,is associated with low temperature processing, isoften caused by excessive working and createscavities varying in size. How would it beidentified?

a. pipeb. burstc. shrinkaged. lamination

Ref: C.83

25. Discontinuities in plate, sheet or strip caused byinternal fissures, inclusions or blowholes in theoriginal ingot which, after rolling, are usually flatand parallel to the outside surface are called:

a. laps.b. seams.c. cracks.d. laminations.

Ref: C.81

26. Forging laps occur in what relation to the axialdirection of a part?

a. They are always found on thermal centerline.b. They are found on the surface of a part at a

90-degree angle to the long axis.c. They may occur anywhere in the part and

always run in the direction of working.d. They may occur anywhere on the surface and

may bear no relation to the axial direction ofthe part.

Ref: A.86

27. The accumulation of particles at a site on the partsurface, collected at and held to the site by themagnetic leakage field, is called:

a. a defect.b. an indication.c. a discontinuity.d. magnetic writing.

Ref: E.33

28. Where particles are attracted to a site on thesurface of a part by a magnetic leakage field thatis caused by a condition such as a crack, lap, orother condition not acceptable to the applicablestandards for the part, then we have:

a. a defect.b. an indication.c. a discontinuity.d. a nonrelevant indication.

Ref: E.33

29. Half-wave rectified alternating current is used fordetection of:

a. surface defects only.b. subsurface defects only.c. surface and subsurface defects when using dry

particles.d. surface and subsurface defects when using wet

particles.Ref: C.155

16

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30. Which of the following is an acceptabletechnique for removing a thin film of oil orgrease prior to magnetic particle testing?

a. Wash with a solvent.b. Degrease using a sand-blasting method.c. Brush the surface with power wire brush.d. Coat the surface with a thick layer of chalk

and then wipe with cloth.Ref: A.246-247

31. Which of the following is the most commonmethod used for preserving and documentingmagnetic particle indications? t .a. ~ i-\Ctv\'c\ D rCt",.vh (. t.e.. cL

b. color-tinted tapec. color-tinted lacquer \ ~ I oVto+O ~/l>I.P \.,d. it eoncisc w-gra eesefipt:i6n C I~ I 0' 1

Ref: A.407-412

32. Which of the following is not a discontinuitycommon to rolled products?

a. seamsb. cracksc. cold shutsd. laminations

Ref: D.n

33. Which one of the following is not a discontinuitythat can be produced by the forging process?

a. lapsb. burstsc. flakesd. shrinkage

Ref: C.7

34. Which of the following is a discontinuitycommonly associated with the welding process?

a. flakesb. seamsc. laminationsd. lack of penetration

Ref: C.7-8


35. Which of these cracks may appear as anirregular, checked or scattered pattern of finelines usually caused by local overheating?

a. corrosionb. crater cracksc. fatigue cracksd. grinding cracks

Ref: C.8

36. Of the following discontinuity categories, whichone is considered most detrimental to the servicelife of an item?

a. corrosionb. subsurface inclusionsc. cracks open to the surfaced. subsurface porosity and voids

Ref: A.369-370

37. If a copper conductor is placed through a ferrouscylinder and a current is passed through theconductor, then the magnetic field (flux density)in the cylinder will be:

a. less than in the conductor.b. greater than in the conductor.c. the same intensity and pattern as in the

conductor.d. the same regardless of its proximity to the

cylinder wall.Ref: A. 192

38. The length of a part being magnetized by passingan electric current from one end to the other:

a. causes the magnetic field to vary.b. affects the permeability of the part.c. changes the strength of the magnetic field.d. does not affect the strength of the magnetic

field.Ref: A.186

39. If 25 mm (1 in.) and 51 mm (2 in.) diameter barsof the same material were magnetized by passingthe same current through them, the magneticfields would be:

a. the same for both.b. stronger in the 51 mm (2 in.) diameter bar.c. weaker in the 25 mm (1 in.) diameter bar.d. stronger in the 25 mm (1 in.) diameter bar.

Ref: A.189

17


40. If a current of the same amperage is passedthrough two conductors of the same dimensions,one of which is magnetic and one of which isnonmagnetic, the magnetic field distributionsurrounding the conductors will:

a. vary with the permeability.b. be the same for both conductors.c. be stronger for the magnetic conductor.d. be stronger for the nonmagnetic conductor.

Ref: A.189

41. The most effective magnetic particle test methodfor inspection of a large casting is using:

a. a central conductor.b. direct magnetization.c. multidirectional magnetization.d. prod inspection in two directions.

Ref: A.450

42. The most common failure mechanism associatedwith in-service parts with sharp fillets, notches,undercuts and seams is:

a. shrinkage.b. crystallization.c. decarburization.d. fatigue cracking.

Ref: A.I03, 481-489

43. When it is believed that a discontinuity has beenremoved by a grinding operation, the nextoperation is to:

a. repair it.b. sign off inspection of the part.c. measure it to see if minimum thickness

remains.d. re-examine the area by magnetic particle

testing.Ref: A.398-400

44. When the most complete demagnetizationavailable is desired and demagnetization is to beaccomplished by placing the part in a coilenergized with alternating current ofprogressively decreasing amperage, the followingorientation of the long axis of the part is mostdesirable:

a. east-west.b. north-east.c. south-west.d. north-south.

Ref: A.324

45. During a magnetic particle test, nonrelevantindications due to residual local poles are notedto be interfering with the magnetic particletesting. For a successful examination one should:

a. use more amperage.b. use lower amperage.c. magnetize in another direction.d. demagnetize then remagnetize in the desired

direction.Ref: A.387

46. Cold working indications will not reappear if thepart is:

a. demagnetized then retested.b. retested after stress relieving.c. retested in the opposite direction.d. remagnetized at a higher amperage.

Ref: A.387-388

47. The unit of measure of one line of flux persquare centimeter of area is one:

a. ohm.b. gauss.c. ampere.d. oersted.

Ref: C.24

48. The ability of matter to attract other matter toitself is a phenomenon associated with:

a. magnetism.b. field strength.c. pole strength.d. coercive force.

Ref: CAS, 12-13

18

49. Materials which are strongly attracted to amagnet are called:

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

Ref: C.12-l3

50. Materials which are weakly attractedmagnetically are called:

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

Ref: C.l3

51. Materials which are repelled magnetically arecalled:

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

Ref: C.l3

52. The end of a magnet at which the lines of fluxare thought of as entering the bar is the:

a. north pole.b. south pole.c. positive pole.d. negative pole.

Ref: C.12

53. A general rule to use for determining thedetectability of surface discontinuities bymagnetic particle inspection is that:

a. the depth and width have no bearing to eachother.

b. the depth should be at a one-to-one ratio to thewidth.

c. the depth should be 20% of the materialthickness.

d. the depth should be at least five times thewidth of the opening of the discontinuity atthe surface.

Ref: A.37I


54. The general term used to refer to a break in themetallic continuity of the part being tested is:

a. discontinuity.b. crack.c. seam.d. lap.

Ref: E.33

55. The pattern of iron powder sprinkled on a paperplaced over a bar magnet is called a:

a. flux meter.b. field survey.c. magnetometer.d. magnetograph.

Ref: A.119, 169

56. The lines of force that form a path around a crackin a ring magnet are called:

• \2. el;:'-t.a. leakage flux. ......e.a- J

b. field strength.c. magnetic lines.d. longitudinal field.

Ref: C.2, 17

57. Since the magnetic lines of force within a barmagnet run the length of the bar, it is said to be:

a. randomly magnetized.b. circularly magnetized.c. permanently magnetized.d. longitudinally magnetized.

Ref: C.I5

58. Lines of flux are thought to leave a magnet atthe:

a. north pole.b. south pole.c. positive poled. negative pole.

Ref: C.12

59. A break in the magnetic uniformity of a part thatis called a magnetic discontinuity is related to asudden change in:

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

Ref: A.127

19


60. In order to detect defects in different directions ina material by magnetic particle inspection, it isbest to use:

a. only one field.b. other probe locations.c. a high frequency field.d. two or more fields in different directions.

Ref: C20

61. The parts are blanks cut from rolled iron barstock and have been rough machined. Inspectionby continuous method reveals distinct but brokenlines parallel (6.35 mm to 25 mm) (0.25 in. to1 in.) with the axis on some of the pieces. Theseindications are indicative of:

a. shrinkage.b. nonmetallic inclusions.c. surface checking.d. machining tears.

Ref: C.4

62. A large forging is repaired by welding. Magneticparticle inspection of the repair weld reveals asharp irregular indication running parallel withthe weld passes. It is located near the center ofthe bead and starts and ends by turning offslightly from the axial direction. This indicationis indicative of:

a. inclusions.b. crater cracks.c. surface checking.d. weld shrinkage cracks.

Ref: A.441

63. The wattage most commonly used for mercuryvapor bulbs for portable fluorescent magneticparticle inspection is:

a. 50 wattsb. 75 wattsc. 100 wattsd. 200 watts

Ref: C.320-321

64. An example of a nonrelevant indication thatwould be classed as a magnetic discontinuityrather than an actual discontinuity could becaused by:

a. corrosion.b. a slag pocket.c. grinding cracks.d. a known abrupt change in the hardness of the

part.Ref: C234

65. The detection of deep-lying internal defects inheavy steel weldments at a depth of 6.35 mm(0.25 in.) to 51 rnm (2 in.) below surface is:

a. very improbable.b. very similar to the detection of surface cracks.c. simple if the defect's width can be

approximated.d. not difficult if the defect is attributable to fine

porosity.Ref: C233

66. In magnetic particle inspection, it is best to:

a. make sure that parts meet specified acceptancecriteria.

b. reinspect all questionable discontinuities toensure that no defective parts are accepted.

c. reinspect questionable parts utilizing anothernondestructive test method.

d. make certain that parts are better thanspecified and contain no discontinuities at all.

Ref: A.413, 416-417

67. Subjecting a magnetized object to a magneticforce that is continually reversing its directionand gradually decreasing in intensity is know as:

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

Ref: C31

68. Any of these welding processes is susceptible toa discontinuity known as slag inclusion except:

a. flux cored arc weldingb. submerged arc weldingc. gas tungsten arc weldingd. shielded metal arc welding

Ref: C.89

20

69. Which of the following induces a longitudinalmagnetic field?

a. prodb. yokec. head shotd. internal conductor

Ref: C.156

70. At the curie point, steel is temporarilytransformed from:

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

Ref: C.30

71. Magnetic field strength is measured in:

a. tesla.b. gauss.6. QSFSt@8.

C; t. webers/m-.o o.VV' P e. f't { {It ~Aer Ref: C.302

72. The following types of discontinuities can befound in an object's subsurface except:

a. pipe.b. hot tears.c. cold shut.d. segregation.

Ref: C.77

73. Which one of following materials haspermeability much greater than that of air?

a. permeability materialb. diamagnetic materialc. paramagnetic materiald. ferromagnetic material

Ref: C.13


74. As a magnet, the Earth is surrounded bymagnetic lines of force. These lines of forcemake up what is sometimes called Earth fieldand they can cause problems in both magnetizingand demagnetizing. However Earth field is weakin the order of:

a. 0.3 gaussb. 0.03 gaussc. 0.003 gaussd. 3.0 gauss

Ref: C.13

75. A hysteresis curve describes the relationbetween:

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 current generated.

Ref: A.24

'VVH?7f-L I "I....,76. Demagnetization wo~required if:

a. the material has low retentivity.b. the object is to be electric arc welded.c. the material has low reluctance.d. heat treatment is to be carried out after testing.

Ref: C.30

77. One of the disadvantages of half-wavemagnetization is, when demagnetizing:

a. the current has skin effect.b. the current does not reverse.c. the current passes very deep.d. the current passes only on the surface.

Ref: C.27-28

78. One disadvantage of using a single-phasemagnetic particle unit at current input valuesover 600 A, in comparison with a three-phaseunit is, the single-phase unit will:

a. detect only surface discontinuities.b. not detect subsurface discontinuities.c. require 1.73 times more input current.d. require 1.73 times less input current.

Ref: C.28

21


79. In longitudinal magnetization of a round bar,residual magnetism will be:

a. greatest at the center of bar.b. greatest at the ends of the bar.c. the same all over on the bar.d. the minimum at the ends.

Ref: C.293

80. Magnetic particles of varying size are used fordry powder and wet methods. Typically, particlesizes for wet method testing range from:

a. 1 to 5 micrometer.b. 1 to 25 micrometer.c. 100 to 500 micrometer.d. 100 to 1000 micrometer.

Ref: C.35

81. Yokes of solid steel have been used for manyyears to indicate transverse cracks. Alternatingcurrent yokes are assembled from laminatedtransformer sheet to reduce:

a. the size of the yoke.b. production costs.c. the weight of the yoke.d. eddy current losses.

Ref: C.162

22


Level II AnswersMagnetic Particle Testing Method

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10. c 37. b 64. d11. c 38. d 65. a12. b 39. d 66. a13. c 40. b 67. d14. b 41. c 68. c15. c 42. d 69. b16. a 43. d 70. d17. a 44. a ~. ~D18. b 45. d 72. b19. d 46. b 73. d20. c 47. b 74. a21. d 48. a 75. a22. a 49. d 76. b23. a 50. c 77. b24. b ~ ~ CA 78. c25. d 52. b 79. b26. d ~. ""

P 80. b27. b 54. a 81. d

23


24

Level illQuestionsMagnetic Particle Testing Method

1. The magnetic domains in a permanent magnetare aligned in:

a. fixed positions with directions that cancel out.b. fixed positions, predominantly in one

direction.c. the same direction as the metal's grain

structure.d. a random position and may become aligned to

attract a magnetic material.Ref: C.12

2. For which of the following would the wetfluorescent technique be preferred over the drytechnique?

a. When the parts are large and bulky.b. When increased speed and sensitivity are

desired.c. When the parts being inspected are to be field

welded.d. When it is desired to use the fluorescent

lighting provided in many plants.Ref: A.345

3. Gas, hot tears, cold shuts, shrinkage cracks andsand inclusions are examples of defects resultingfrom which of the following processes?

a. forgingb. grindingc. castingd. heat treatment

Ref: A.88

4. Which of the following statements is not a validreason for demagnetizing a part after completinga magnetic particle test?

a. Residual magnetism can disturb the weldingarc path on parts to be welded.

b. Residual magnetism may attract chips or smallparticles in-service, causing galling ormechanical wear.

c. Residual magnetism could interfere with theoperation or accuracy of instruments placed onor near the part during service.

d. If the part is to be radiographed after magneticparticle inspection, residual magnetism mayinterfere with the electromagnetic radiationspectrum.

Ref: C.30, 292-293

5. Subjecting a part to a magnetic field that isconstantly reversing in polarity and graduallydiminishing in strength accomplishes which ofthe following?

a. Magnetizes the part.b. Demagnetizes the part.c. Helps to locate deep-lying defects.d. Increases the strength of the retained magnetic

field.Ref: C.31

6. The concentration of the solid content of asuspension of magnetic particles is measured by:

a. weighing the suspension.b. soaking the solids in benzol.c. measuring the pull on a magnet.d. permitting the solids to settle out of

suspension.Ref: A.261-263

25

Magnetic Particle Testing Method, Level III

7. An important factor that must be consideredwhen selecting a method of magnetization is the:

a. part's curie point.b. the location of the inspection station.c. location of the inspection unit.d. alloy, shape and condition of the part

Ref: A.229-243, C.l54-157

8. An important factor that must be consideredwhen selecting a method of magnetization is the:

a. material's curie point.b. type of magnetizing current.c. color of the fluorescent particles.d. availability of handling equipment.

Ref: A.229-243, C.154-157

9. When a magnetic material reaches its curietemperature the material becomes:

a. magnetic.b. radioactive.c. diamagnetic.d. paramagnetic.

Ref: C.293

10. Magnetic particle inspection methods onferromagnetic materials are recognized assuperior to liquid penetrant techniques when:

a. the surface is plated.b. the parts are painted.c. the surface is anodized.d. dry particles are used for [me surface cracks.

Ref: C.389

11. A paramagnetic material:

a. is highly magnetic.b. is slightly magnetic.c. has no magnetic properties at all.d. has a demonstrated lack of electron mobility.

Ref: C.13

12. Which of the following will reduce a magneticfield?

a. Move the direct current coil closer to the part.b. Reduce the current in only one direction.c. Move the alternating current coil further away

from the part.d. Move the part toward the inner surface of the

coilRef: C.297-299

13. When an external magnetizing force is removed,some of the magnetic domains remainpreferentially oriented. The additional forcerequired to return them to their original randomorientation is commonly referred to as:

a. coercive force.b. applied field force.c. residual field force.d. direct current electric force.

Ref: C.24

14. When a cylinder is magnetized by a centralconductor, the field is most intense:

a. at the ends of the cylinder.b. at the outer surface of the cylinder.c. at the inside surface of the cylinder.d. halfway through the thickness of the cylinder

wall.Ref: C.19, 152

15. When is the magnetic field strongest in an objectbeing inspected by the magnetic particle method?

a. While the magnetizing current is applied.b. Just after the magnetizing current is shut off.c. When the magnetic particle powder is applied.d. Just prior to current reversal when using

alternating current.Ref: C.24, 152

16. Which of the demagnetization methods listedbelow is most effective?

a. full-wave rectifiedb. half-wave rectified alternating currentc. direct current with reversing and step-down

controld. variable voltage alternating current with

step-down controlRef: C.300

26

17. When using the longitudinal magnetizationmethod to inspect a bar 152 mm (6 in.) long and51 mm (2 in.) in diameter with a 5-turn coil,which of the following amperage values shouldbe used?

a. 1200Ab.3000Ac. 12 000 Ad. 2000 amp-turns

Ref: A.181-182

18. To examine a part 127 mm (5 in.) long and 51mm (2 in.) in diameter using a 5-tum coil andhead stock magnetic particle machine, whatamperage should be used for longitudinalmagnetization?

a.3000Ab.3600Ac.4500Ad. 10000 ampere-turns

Ref: C.181-182

19. To examine a bar 381 mm (15 in.) long and51 mm (2 in). in diameter using a 7-tum coil andhead-stock magnetic particle machine, whatamperage should be used for circularmagnetization?

a.750Ab. 1800Ac. 1800 ampere-turnsd. 49 000 ampere-turns

Ref: A.208

20. If the same amperage is passed through a 25 mmand 51 mm (1 in. and a 2 in.) diameter bar of thesame length and material, the strength of themagnetic field at the surface:

a. will be the same for both bars.b. of the 25 mm (1 in.) bar will be one-half that

of the 51 mm (2 in.) bar.c. of the 25 mm (1 in.) bar will be approximately

twice that of the 51 mm (2 in.) bar.d. of the 51 mm (2 in.) bar will be approximately

four times that of the 25 mm (1 in.) bar.Ref: A.186


21. If the same amperage is passed through a 25 mm(1 in.) diameter bar and a 51 mm (2 in.) diameterbar of the same length and material, the strengthof the magnetic field at the center of:

a. both bars will be O.b. the 25 mm (1 in.) bar will be one-half that of

the 51 mm (2 in.) bar.c. the 51 mm (2 in.) bar will be one-half that of

the 25 mm (1 in.) bar.d. the 25 mm (1 in.) bar will be approximately

one-fourth that of the 51 mm (2 in.) bar.Ref: A.186-187

22. When a magnetic field is induced in a part withprods spaced 152 mm (6 in.) apart, the field is a:

a. circular field.b. residual field.c. solenoid field.d. longitudinal field.

Ref: C.22-23, 150-151

23. When circular magnetization is used to detectsubsurface discontinuities, direct current is usedinstead of alternating current because:

a. particle mobility is no longer a factor.b. there is no logical reason to use direct current

instead of alternating current.c. direct current saturates the magnetic particles

better than alternating current.d. the skin effect of alternating current reduces

the maximum depth at which discontinuitiescan be found.

Ref: C.27, 154-157

24. An inspection method in which an initialmagnetizing force is applied to a part and thenreduced to a lower continuous value is called:

a. the surge method.b. the residual method.c. the multi vector method.d. the continuous method.

Ref: A.155-156

27


25. When deciding to inspect a part by the residualmethod of applying the particles, what factoraffects the residual magnetic field strength of thepart?

a. the retentivity of the partb. the part's magnetic field saturation pointc. the direction of the magnetic field in the partd. the type of field indicator used to measure the

residual fieldRef: A.237-240, C.37-38

26. Factors that must be considered wheninterpreting an indication are:

a. the direction of the magnetic field and locationof the magnetic particle unit.

h. the location of the magnetic particle unit andthe nondestructive testing level of theinspector.

c. the orientation and shape of the indication andthe direction of the magnetic field.

d. the strength of the leakage field at theindication and the type of demagnetizationmethod.

Ref: A.379, C.233-23S

27. A 7-tum coil at 1000 A is used to inspect a roundsolid part 381 mm (IS in.) long and 64 mm(2.5 in.) in diameter. The length-to-diameter ratiois:

a. 2.14.b.6.0.c. 7000 amp-turns.d. 45 000 amp-turns.

Ref: A181-182

28. Which of the following, when used as the lastmagnetizing method, will best render a partsuitable for relatively easy measurement of theexternal magnetic field using a field indicator?

a. probe magnetizationb. circular magnetizationc. longitudinal magnetizationd. central bar conductor magnetization

Ref: C.32-33

29. When using direct current an indication isdetected. What is the next logical step todetermine if the indication results from a surfaceor subsurface condition?

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

Ref: A.397

30. Which of the statements below is mostappropriate concerning materials I and IIrepresented by the hysteresis curves shown inFigure I?

a. Material I is not a good subject for magneticparticle inspection.

b. Material I could be used for dry powdermagnetic particles.

c. Material IIcould be used for dry powdermagnetic particles.

d. Material IIis paramagnetic.Ref: A.217

Figure 1

Material I B+ (Flux Density)

----B

E

H---------~--------~----~~------(- MagnetizingForce)

Material II

---------------r-+~-----------------H+. (+ MagnetizingForce)

B- (Flux Density of OppositePolarity to B+)

28

31. Considering the curves shown in Figure 1,material II in comparison to material I indicatesthat the material:

a. has a high retentivity.b. has a high permeability.c. has a high coercive force.d. would make an excellent permanent magnet.

Ref: A217

32. Point B on the hysteresis curve for material Ishown in Figure 1:

a. is the limit of coercive force.b. is the material's magnetic saturation point.c. represents the mid-point of the rectified

alternating current applied.d. represents the point at which the residual

magnetic value will remain when themagnetizing current is removed.

Ref: A.116-117

33. Which point on the hysteresis curve shown inFigure 1 represents the residual field value?

a. Ab. Bc. Cd. E

Ref: A116-1117

34. When withdrawing a part from the field around acoil and without changing the direction ofcurrent, which of the following has the leasteffect on demagnetizing the part?

a. direct currentb. alternating currentc. full-wave rectified currentd. half-wave rectified alternating current

Ref: C.297-299hU\'J1-

35. T~portant factor below that should~ beconsidered when selecting a method ofmagnetization to detect subsurface discontinuitiesis:

a. available equipment.b. configuration of the part.c. ~l sf Hie 9fletmei" of the equipment. CO tvt-d. type of material the part is made from.

Ref: C.233


36. Which of the following discontinuities occur as aresult of the rolling process?

a. fissuresb. laminationsc. lack of penetrationd. blowholes and pipe

Ref: C.5

37. Which of the following discontinuities occur as aresult of the forging process?

a. pipeb. lapsc. laminationsd. lack of penetration.

Ref: C.7

38. If an indication is formed when using theresidual method as well as the continuousmethod, it is most likely:

a. very deep and tightb. a relevant indication.c. a nonrelevant indication.d. very shallow and open to the surface.

Ref: A397

39. Plated parts can be reliably tested for fine surfacecracks using the magnetic particle method if theplating is less than:

a. 0.762 mm (0.03 in.) thick.b. 1.016 mm (0.04 in.) thick.c. 0.127 mm (0.005 in.) thick.d. 0.2032 mm (0.008 in.) thick.

Ref: A.247

40. The magnetic lines of flux erfttrx in a permanentmagnet:

a. in all cases produce a longitudinal field.b. enter the south pole and leave the north pole.c. flow from the north pole through the magnet

to the south pole.d. change direction 60 times a second with the

magnetizing current.Ref: C.12

29


41. Which of the following magnetization techniquesis not recommended for magnetic particletesting?

a. vector magnetizationb. parallel magnetizationc. circular magnetizationd. longitudinal magnetization

Ref: A.139, C.159

42. When attempting to demagnetize a partcontaining a circular residual field:

a. use a swinging cyclic field.b. consideration of the material's hysteresis is

most important.c. establish a longitudinal field and then proceed

with demagnetization.d. using half-wave current with a head shot setup

and step-down magnetization will ensurecomplete removal of the residual field.

Ref: C.33, 294

43. Small parts requiring demagnetization should be:

a. loaded in baskets and passed through analternating current coil.

b. loaded in a steel basket for better fielddistribution.

c. processed through a demagnetization cycleone at a time.

d. demagnetized after assembly to ensurecomplete demagnetization of the entireassembly.

Ref: A.314

44. The best shape for magnetic particles used in thedry powder method is:

a. globular.b. elongated.c. long and slender.d. a mixture of elongated and globular.

Ref: C.36

45. The best method for testing ball bearings is:

a. along one axis using a coil.b. two head shots along the X and Y axis.c. two shots using a coil at the X and Y axis.d. induced current shots along X, Y, and Z axis,

rotating 360 degrees during each shot.Ref: A.349-350

46. When a magnetized ferromagnetic object isexposed to a subsequent heating operation abovethe curie point:

a. the marten site structure will occur.b. the magnetic domains become random.c. there is no change from its previous state.d. the magnetic domains are reversed from their

previous stateRef: C.30

47. A discontinuity caused by a welding operation is:

a. creep crack.b. segregation.c. machining tear.d. 1"ammtJ. tearing.

~Il#er\LCl1Yl e,l! 0>r

Ref: C.86

48. The most effective current to be used with drymagnetic particle is:

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

three-phase bridge circuitry.d. full-wave rectified alternating current with

single-phase bridge circuitry.Ref; C.155

49. The following properties should be considered inchoosing a vehicle for the wet method, except:

a. capillarity.b. corrosivity.c. wetting ability.d. foaming ability.

Ref: C.208

50. The amount of light reflected by one surfacecompared to that reflected by another adjacentsurface is:

a. length-to-diameter ratio.b. BIH ratio.c. color contrast.d. brightness contrast.

Ref.C.229

30

51. Given a certain continuous magnetization currentin a material, which type of current would givethe deepest penetration?

a. direct currentb. alternating currentc. direct current surged. half-wave direct current

Ref: C.I57

52. Given a certain continuous magnetization currentin a material, which type of current would givethe shallowest penetration?

a. direct currentb. alternating currentc. direct current surged. half-wave direct current

Ref: C.I57

53. Which type of radiation can most damage humantissue?

a. UV-Ab. UV-Bc. white lightd. visible light

Ref: C.322

54. Compared with magnetic particle testing, liquidpenetrant testing is not reliable after paintremoval from weld because:

a. liquid penetrant testing can be applied only tosmall parts.

b. liquid penetrant testing can be applied only infield conditions.

c. magnetic particle testing will detect subsurfacediscontinuities.

d. partial smearing of weld surface metal acrossthe discontinuity opening can occur.

Ref: C.389

55. Prod spacing less than 76.2 mm (3 in.) is usuallynot practical because:

a. the possibility of sparking will increase.b. more time will be consumed for inspection.c. it requires more media than a 152 mm (6 in.)

prod distance.d. particles tend to bend around the prod making

interpretation difficult.Ref: C.151


56. One of most important facts that must beremembered while establishing magnetic particleprocedure.

a. The magnetic field follows the path of greatestreluctance.

b. Coil shot, wet method provides only surfacediscontinuities.

c. The head shot wet method is better fordetecting subsurface discontinuities.

d. In most cases the continuous method is moresensitive than is the residual method.

Ref: C.37

57. Which one of the following magnetic particletesting techniques is logically acceptable fortesting a large flat area?

a. prodb. rod shotc. coil shotd. head shot

Ref: C.158

58. Permeability of a material can be numericallywritten as:

a. RIB.b. B/H.c. Hc/Hb.d. ampere turns/number of turns.

Ref: C.26

59. One disadvantage for using undyed wet magneticparticles is:

a. it is more costly.b. it is suitable for the fluorescent method only.c. it is suitable for surface discontinuity detection

only.d. the lack of contrasting color makes them

difficult to see.Ref: C.35

31


60. One of most desirable characteristics of themedia for magnetic particle testing is:

a. the ability to show clearly against anybackground.

b. the insensitiveness to concentration in water asvehicle.

c. no need for agitation when used with liquidvehicle.

d. the highest possible permeability and lowestretentivity.

Ref: C.34

32


Level III AnswersMagnetic Particle Testing Method

I. b 2I. a 4I. b2. b 22. a 42. c3. c 23. d 43. c4. d 24. a 44. d5. b 25. a 45. d6. d 26. c 46. b7. d 27. b 47. d8. b 28. c 48. b9. d 29. a 49. a

10. b 30. c 50. dII. b 3I. b 51. d12. c 32. b 52. b13. a 33. c 53. b14. c 34. a 54. d15. a 35. c 55. d16. c 36. b 56. d17. b 37. b 57. a18. b 38. b 58. b19. b 39. c 59. d20. c 40. b 60. d

33


34

Sample SpecificationWet Magnetic Particle Testing Method

1.0 Scope1.1 Magnetic particle testing is a

nondestructive testing method used todetect surface and near surfacediscontinuities in ferromagnetic materials.

2.0 General2.1 The Magnetic Particle Testing Method

consists of magnetizing the area to beinspected, and then applying magneticparticles to the surface of the test area.Magnetic field leakages caused by cracksand other discontinuities will attract themagnetic particles, and the resultingpattern will be characteristic of the type ofdiscontinuity present. Sensitivity of theMagnetic Particle Testing Method isgreatest at the surface and diminishesrapidly with increasing depth.

2.2 Drawings and purchase orders shouldspecify the extent of magnetic particleinspection required for each item and theacceptance standards to be met.

2.3 Documents referenced, as modifiedherein, shall be considered part of thisstandard procedure.

2.4 All persons performing magnetic particleinspection shall have received trainingand be certified in accordance with awritten program developed perrecommended guidelines of SNT-TC-1A(1980 Edition).2.4.1 A Level I certified technician shall

perform work under the directionof a Level II, except that finalinterpretation shall be performed bya Level II or Level III. All reportsand technique sheets shall beprepared by a Level II, and thetechnique sheet approved by aLevel III.

2.5 A minimum of two separate examinationsshall be conducted on each area inspected,with the lines of flux of one examinationapproximately perpendicular to the linesof flux of the other. A different method ofmagnetization may be used for the secondexamination (i.e., longitudinal magneticfield technique and circular magnetic fieldtechnique).

2.6 An ammeter shall be used on the magneticparticle inspection unit to ensure that theproper amperage is being applied.

2.7 In the absence of requirements to thecontrary, magnetizing currents shall bedetermined by experiment, and recordedon a magnetic particle technique sheet andapproved by a Level III.2.7.1 The behavior of the magnetic

particles on the surface of a testpart while it is being magnetized isan excellent indication of theamount of magnetizing currentbeing used, or the strength of themagnetic field. Complete lack ofparticle activity indicates that thefield is too weak; excessive particleaccumulation with lack of particlemobility indicates that the field istoo strong. Some slight indicationof pattern around ends, edges, andprotuberances indicates sufficientfield strength. A special carbonsteel/copper plate field indicatormay be used to determinecomparative field strength. Ifclearly defined lines of particlesappear on the copper side of thefield indicator, the magnetic field isof sufficient strength.

2.7.2 When particle activity indicateseither insufficient or excessive fieldstrength, even though all testparameters have been met, achange in current value shall berecorded on the magnetic particletechnique sheet.

2.8 Continuous exposure to the wet particlebath can cause subcutaneous fats and oilsof the skin to be dissolved. The resultantdrying and cracking encourages secondaryinfection. Persons suffering rashes andskin irritation from exposure to the wetparticle bath should report this conditionto the supervisor.2.8.1 Good working habits which prevent

the unnecessary wetting of handsand clothing should be developed.

2.8.2 The use of a hand protectivepreparation is recommended when

35

Sample Specification

working for extended periods withthe wet particle bath.

2.8.3 A polyvinyl apron shall be worn.2.8.4 After working with the wet particle

bath, hands and arms should bewashed with warm water and mildsoap.

2.9 Care and maintenance of magneticparticle test equipment shall be performedin accordance with instructions providedin procedure M-2.

3.0 ReferencedDocuments3.1 ASME Section V Nondestructive

examination ASTM E-125 Referencephotographs for magnetic particleinspectionASTM E-138 Wet magnetic particleinspection ASTM E-269 Terms relating tomagnetic inspectionPROC. M -1 Calibration of magneticparticle test method equipmentPROC. M-2 Care and maintenance ofequipmentPROC. M-4 Mixing and checkingmagnetic particle bath3.1.1 All documents referenced in this

section shall be maintained to thelatest revision, and work requests,technique sheets, and test reportswill cite the proper revision for thework performed.

4.0 Identification4.l Identification methods shall be established

which will enable the test report, thecomponent, and the area tested to beidentified with respect to each other at anytime.

4.2 A suitable method shall be used to ensurecorrect part identification. Whereidentification is removed or obliterated, anidentity tag shall be used until theidentification can be reapplied. If positiveidentification cannot be determined, thena nonconformance report shall be issued.

5.0 Surface Condition5.1 With most magnetic particle test methods,

satisfactory results may generally beobtained when the surface to be inspectedis in the as-welded, as-rolled, as-cast, oras-forged condition. However, in somecases, surface conditioning may berequired to prevent the masking ofdefects.5.1.1 Surfaces to be inspected shall be

clean and free from oil, grease,

sand, loose rust or scale, whichmay interfere with satisfactoryinspection.5.1.1.1 Surfaces to be inspected

shall be cleaned prior tosubmission to NDT. Whenthe surface condition is notsuitable for inspection, thepart shall be returned toproduction untested, orNDT will condition thesurface, whichever ismutually agreeable.

5.1.2 Small openings and holes whichlead to areas from which it wouldbe difficult to remove magneticsubstances shall be plugged beforethe part is inspected.

5.2 Unless otherwise specified in the drawing,final magnetic particle inspection shall beperformed on any part in the finishedsurface condition, and final heat treatedcondition.

6.0 Equipment6.1 The wet magnetic particle inspection unit

is a horizontal stationary unitmanufactured by Company,Model No. ,2000 DC amps,equipped with head-tail stocks and a5-turn coil.

6.2 The demagnetizing unit is a 60-cycle,single phase AC, coil-type with timer,manufactured by Company, Model No.

6.3 The field indicator is a dial readout,pocket size magnetometer used tomeasure comparative magnetic fieldstrength.

7.0 Examination Medium7.1 The examination medium shall consist of

finely divided ferromagnetic particleswhich have high permeability and lowretentivity characteristics.! They shall beof suitable size and shape to readilyproduce magnetic particle indications.7.1.1 Fluorescent magnetic particles shall

be used.

8.0 Methods of Examination8.1 The methods of "wet" magnetic particle

examination used shall consist of thelongitudinal magnetic field technique andthe circular magnetic field technique.

8.2 Using the longitudinal magnetic fieldtechnique, magnetization is accomplished

1 Suspended in base oil "C" as described in Proc. No. MT-4.2 The pan to be inspected is placed within the coil assembly or flexible

leads are coiled through large complex pans.

36

by passing current through a multi-turncoil.?This technique produces a longitudinalmagnetic field parallel to the axis of thecoil.8.2.1 Direct or rectified AC shall be

used. The magnetizing current isdetermined by dividing 45 000 bythe length-over-diameter ratio ofthe part to be inspected, and thendividing this value by the numberof turns in the coil.

8.345 000

Ampere-turns = ---LID

Am Ampere-turnsperes =

No. coil turns

Using the circular magnetic fieldtechnique, magnetization is accomplishedby passing current through the part to beinspected. This technique produces acircular magnetic field throughout the partperpendicular to the current flow.8.3.1 Direct or rectified AC shall be

used. The magnetizing current isdetermined by multiplying the partdiameter by an amperage-per-inchdiameter value.

8.3.2 The magnetizing current shall be asshown in the table.

Part Diameter0-250 rom (0-10 in.)

Over 250 rom (10 in.)Amperes per Inch of Part Diameter

500-800 A

9.0 Examination9.1 A pre-inspection visual examination shall

be made of the test part to determinesurface condition, equipmentrequirements, and also that all testparameters can be met.9.1.1 When any material or part cannot

be fully inspected as required bydrawing, due to design, test facilityrestrictions, or other reasons, anonconformance report shall beissued. The nonconformance reportshall state the reasons why the partcannot be fully inspected, andrecommended appropriate action.The magnetic particle test reportshall state the test limitations.


9.2 Unless otherwise specified by drawing,magnetic particle inspection shall beperformed by the continuous method. Thisis accomplished by keeping themagnetizing current on while theexamination medium is being applied (byflowing it over the part).

9.3 The sequence of "shots" shall bedetermined by ascending order of current.That is, the "shot" requiring the lowestamperage shall be first, and the "shot"requiring the greatest amperage valueshall be the product of the amperagemultiplied by the number of turns in thecoil.9.3.1 When exceptions to 9.3 are

necessary, this shall be indicated bythe order of listing for each shot onthe technique sketch.

9.4 Examinations shall be performed withsufficient overlap to ensure 100%coverage of the area or part underinspection at the established field strength.9.4.1 When using the longitudinal

magnetic field technique, no lengthgreater than 229 rom (9 in.) of testpart extending from each side ofthe coil shall be inspected witheach "shot." Therefore, if a part islonger than 460 rom (18 in.), twoor more "shots" along its lengthwill be necessary.

9.4.2 When using the circular magneticfield technique, no length greaterthan 310 rom (12 in.) shall beviewed during anyone "shot."Therefore, if a part is longer than310 rom (12 in.), two or more shotswill be necessary.

9.5 Repaired areas on the test part shall bereinspected in accordance with theoriginal test procedures.

10.0 Evaluation of Indications10.1 Evaluation of indications shall be to

acceptance standards shown on drawingsor purchase orders.

10.2 The inspection area shall be provided withadequate lighting to facilitate examinationof the test part for indications.10.2.1 The examination shall be conducted

in a darkened area under ultravioletlight illumination.

10.2.2 The ultraviolet light shall emitnear-ultraviolet radiation in the330-390 nm (3300-3900 A)wavelength range.

37


10.2.3 The ultraviolet light shall have, as aminimum, an intensity of800 !!W/cm2 at the inspectionsurface, as measured by XYZCompany light meter (or equal),with a lOX multiplier disk.

10.3 The ultraviolet light shall have aminimum warm-up time of 5 minutesprior to its use in examination.

10.4 Relevant indications are indications thatresult from discontinuities within the testpart.

10.5 Nonrelevant indications are indicationsthat result from excessive magnetizingcurrent, structural design, or permeabilityvariances within the test part. They haveno bearing on the suitability of the testpart for service.10.5.1 Any indication believed to be

nonrelevant shall be regarded asrelevant and shall be reexamined todetermine whether an actual defectexists. Surface conditioning mayprecede the reexamination.

10.5.2 If test part quality cannot beensured by magnetic particleinspection upon re-examination,then other methods ofnondestructive testing may be used.Decisions concerning nonrelevancyrequire Level ill approval.

10.6 Linear indications shall be considered asthose having a length more than threetimes the width.

10.7 Rounded indications shall be consideredas those having a length less than threetimes the width.

10.8 Aligned indications shall be considered asa group of three or more indicationswhich touch an imaginary straight lineconnecting any two of the group.

11.0 Demagnetization11.1 Demagnetization shall be required

following final magnetic particleinspection, where residual magnetism willinterfere with subsequent processes orusage.

11.2 Only the demagnetizing unit shall be usedfor demagnetization. Do not use the coilon the wet magnetic particle inspectionunit for demagnetization.

11.3 Energize the demagnetizing coil byoperating the timer switch. This timerlimits the operating periods from a fewseconds to one minute, as selected. Thered light will glow and a strong pull willbe felt on a piece of ferromagneticmaterial held near the coil.

38

11.3.1 CAUTION: Due to high currents,operation should be intermittent.That is, each operating periodshould be followed by an equalperiod of rest, to allow for cooling.The maximum "on" period shouldseldom be longer than 30 seconds.

11.4 To demagnetize a part, turn on the currentand pass the part completely through thedemagnetizer. The part shall be placedinside the coil and then slowly withdrawnfrom the magnetic field in a straight line,a distance of at least 1.2 m (4 ft).11.4.1 CAUTION: Do not allow the

current to turn off while the part isin the magnetic field, as incompletedemagnetization may result. Repeatthe demagnetization process if thisoccurs.

11.4.2 Small parts, much smaller incross-section than the demagnetizercoil cross-section, should be passedthrough the coil close to one wallor corner and not through thecenter of the coil.

11.5 For parts too large to pass through thedemagnetizer coil, satisfactorydemagnetization can often beaccomplished by bringing the part as closeas possible to the coil, turning it to bringall sides into the field, and thenwithdrawing it slowly before the currentturns off.

11.6 Striking the part with a mallet while thepart is in the magnetic field and beingwithdrawn will often improve results onparts difficult to demagnetize.

11.7 Demagnetization may often be improvedby the "Transient Current Method." Thepart to be demagnetized is placed in thedemagnetizer coil, the current turned onand off several times, and then while thecurrent is on, the part is withdrawn fromthe magnetic field as described in 11.4.

11.8 The demagnetizer should be positioned sothat an imaginary line drawn through thecenter of the coil runs in the east-westdirection.

11.9 A field indicator shall be used todetermine the amount of residualmagnetism remaining in the part.

11.10 Cleaning should occur prior to completedrying of residual bath.11.10.1 The test part shall be cleaned by

wiping it with a cloth soaked inbase oil "C." After the test parthas dried, a light coat of mineraloil shall be applied as a rustpreventative.


12.0 Records12.1 A magnetic particle inspection technique

sheet shall be submitted with the finalinspection records.

12.2 A magnetic particle inspection report shallbe submitted with the final inspectionrecords.

12.3 A maintenance/calibration record shall bekept (current) on the wet magnetic particleinspection unit.

12.4 A wet magnetic particle inspection userecord shall be kept (current) on the wetmagnetic particle test unit.

12.5 All records of inspection, original, repair,and final, shall be retained for a minimumperiod of seven (7) years.

/

39


40

Sample Specification Questions

Sample Specification QuestionsWet Magnetic Particle Testing Method

Using the sample specification located on pages 35-39, answer the remaining questions. (References listedpertain to paragraphs in the sample specification.)

5. Part position is varied in the coil when the partis:

1. The magnetic particles suspended in the bathshall have:

a. over 46 em (18 in.) in lengthb. over 31 ern (12 in.) in lengthc. squared. round

Para. 9.4.1a. high red iron oxide contentb. low retentivity and low permeabilityc. low retentivity and high permeabilityd. high permeability and low coerciveness

Para. 7.1

6. Inspected parts requiring repair must be:

a. determine the polarity of magnetizationb. determine the amperage being usedc. ensure that the part has been demagnetizedd. measure amp-turns

a. reinspected using a sampling planb. reinspected following repairc. inspected with another NDT methodd. made to follow the original fabrication plan

after defect removal is checked and reworkedPara. 9.5

2. The ammeter is used to:

7. Ultraviolet light intensity requirements specify:Para. 2.6

a. magnetic polarity and amperageb. the comparative strength of field and if

demagnetization is effectivec. retentivity and magnetic permeabilityd. both a and b

a. a minimum of five minute warm-upb. that a darkened room be usedc. a minimum of 800 /-lW/cm2 at the inspection

surfaced. all of the above

3. The field meter is used to determine:

Para. 10.2

Para. 6.3; 11.98. The ammeter shall be checked against a

calibration shunt meter:

a. as soon as the part has been cleanedb. prior to magnetic particle inspectionc. for all parts which are inspectedd. where residual magnetism will interfere with

subsequent processes or usage

a. prior to each useb. at the start of the shiftc. per Procedure M-Id. per Procedure M-4

4. Demagnetization is required:

Para. 3.1

Para. 11.1

41


9. Parts will be demagnetized by:

a. banging with a hammerb. placing within a demagnetizing coil for 30

secondsc. holding within the demagnetizing coil while

the stepdown transformer moves through itsdescending order of amperage shots

d. setting the demagnetizing current at anamperage higher than the original magnetizingcurrent and slowly passing the part throughthe coil

Para. 11.4

10. When magnetizing a part, 31 cm (12 in.) long by64 mm (2.5 in.) diameter, by placing it withinthe head stocks and passing an electric currentthrough it, the ammeter should be set at:

a.900Ab.1750Ac. 1875 Ad.2200A

Para. 8.3.2

11. For demagnetization, the maximum "on" periodshould seldom be more than:

a. 5 secondsb. 30 secondsc. 120 secondsd. 240 seconds

Para. 11.3.1

12. If a part cannot be fully inspected as required bythe drawing:

a. a drawing revision must be issuedb. the part must be scrappedc. a nonconformance report must be issuedd. the part must be marked with red paint

pending dispositionPara. 9.1.1

13. The sequence of "shots" shall be determined by:

a. accessibility of areasb. descending order of currentc. ascending order of currentd. this is not an important consideration

Para. 9.3

14. Unless otherwise specified, magnetic particleinspection shall be performed by:

a. the residual methodb. the continuous methodc. both a and bd. none of the above

Para. 9.2

15. Unless otherwise specified, the fmal magneticparticle inspection shall be performed on parts:

a. prior to final machining but after final heattreatment

b. after final machining but before final heattreatment

c. after fmal machining and heat treatmentd. any time prior to final heat treatment

Para. 5.2

16. The extent of magnetic particle inspection shouldbe specified:

a. in the procedureb. in the drawings and in the purchase orderc. in the acceptance standardd. by normal shop practice

Para. 2.2

17. The technique sheet shall be approved by:

a. a Level IIb. a Level illc. no one; techniques used do not need to be

approvedd. a Level II and the client

Para. 2.7

18. If the magnetizing current is not specified, themagnetizing current should be determined by:

a. experimentation and then recorded on thetechnique sheet

b. the cognizant engineerc. the clientd. the technician's experience

Para. 2.7

42

19. Nonrelevant indications:

a. have no bearing on the suitability of the partfor service

b. shall be reexamined to determine whether anactual defect exists

c. must be completely removedd. both a and b must be considered

Para. 10.5, 10.5.1

20. The intensity of the ultraviolet light shall bemeasured using a:

a. light meter with a lOX multiplier discb. light meter with an amber field filterc. light meter set at 343 nm (3425 A)d. light meter with an M2 rating

Para. 10.2.8

21. A part being demagnetized should be slowlyremoved from the magnetic field in a straightline for a distance of:

a. 31 em (l ft)b. 61 em (2 ft)c. 122 em (4 ft)d. the distance is not important

Para. 11.4

22. Records of inspection shall be maintained:

a. for the life of the partb. for 40 yearsc. for 7 yearsd. until the client accepts the part

Para. 12.5

23. A field indicator shall be used to determine the:

a. amount of residual magnetism remaining in apart

b. orientation of the magnetic fieldc. overall vector component of the magnetic fieldd. outer limit of magnetic field

Para. 11.9


24. The part shall be post-cleaned:

a. by rinsing it with acetoneb. by wiping it with a dry clothc. by wiping it with a cloth soaked in base oil

"e"d. this is not a provision of the procedure

Para. 11.10.11

25. Demagnetization may often be improved by theuse of:

a. the DC surge techniqueb. insulated paramagnetic railsc. the "Transient Current Method"d. a booster-type demagnetizer

Para. 11.7

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Sample Specification AnswersWet Magnetic Particle Testing Method

l. c2. b3. b4. d5. a6. b7. c8. c9. d

10. dII. b12. c13. c14. b15. c16. b17. b18. a19. d20. a2l. c22. c23.24.25.

acc

44

45

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Magnetic Particle Testing Method, Q & A

Documents

answer d

d page

magnetic particles ref

ca5 answer b

book b

answer c

magnetic particle indications

magnetizing current