Levels I, II, and III
E d d y C u r r e n t / F l u x Leakage
T e s t i n g Method
Supplement to
Recommended Practice
No.
SNT-TC1A
Book E
Copyright © 1995 by the American Society for Nondestructive Testing, Inc. All rights reserved. ASNT is not
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3
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Nondestructive Testing. ASNT , Research in Nondestructive Evaluation" and RNDE* are registered trademarks of
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1
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Published by
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ISBN 0-931403-16-2
Printed in the United States of America
first printing 03/88
second printing 05/90
third printing with revisions 09/95
fourth printing 04/96
fifth printing 01/98
sixth printing 01/02
2
Table of Contents
References
5
Reference Usage List
7
Eddy Current Test Method
C
Level I
Questions
Answers
9
9
19
Level I I
Questions
Answers
21
21
33
Level I I I
Questions
Answers
35
35
45
Flux Leakage Test Method
Level I
Questions
47
47
Level I I
Questions
51
51
Level m
Questions
55
55
Level I, II, and III Answers
59
3
Recommended Training References
Eddy Current/Flux Leakage Testing Method
The following references were used in formulating the questions contained in this book.
A. *
Libby, H.L. Introduction to Electromagnetic Test Methods. Wiley-Interscience. 1971.
B. **
McClurg, G.O. "Flaw Detection by Eddy Current Methods." Nondestructive Testing, Vol. XV, No. 2 (1957):
pp. 116-119.
C*
Eddy Current Testing, Classroom Training Handbook (CT-6-5). San Diego, CA: General Dynamics/Convair
Division. 1967. (Now published by The American Society for Nondestructive Testing, Inc.)
D. *
Eddy Current Testing, Programmed Instruction Handbook, Volume 1, (PI-4-5). San Diego, CA: General
Dynamics/Convair Division. 1967. (Now published by The American Society for Nondestructive Testing,
Inc.)
E. *
Eddy Current Testing, Programmed Instruction Handbook, Volume 2, (PI-4-5). San Diego, CA: General
Dynamics/Convair Division. 1967. (Now published by The American Society for Nondestructive Testing,
Inc.)
F. *
1976 Annual Book of ASTM Standards, Part 11. Philadelphia, PA. American Society for Testing and
Materials. 1976.
G. *
McMaster, R.C., ed. Nondestructive Testing Handbook, first edition. Columbus, OH: The American Society
for Nondestructive Testing, Inc. 1959.
H. **
Libby, H.L. "Basic Principles and Techniques of Eddy Current Testing." Nondestructive Testing, Vol. XIV,
No. 6 (1956): pp. 12-27.
I . **
Allen, J.W. and R.B. Oliver. "Inspection of Small Diameter Tubing by Eddy Current Methods."
Nondestructive Testing, Vol. X V , No. 2, (1957): pp. 104-109.
J.**
Cosgrove, L.A. "Quality Control Through Nondestructive Testing with Eddy Currents." Nondestructive
Testing. Vol. X I I I , No. 5, (1955): pp. 13-15.
K.**
Hochschild, Richard. "Eddy Current Testing by Impedance Analysis." Nondestructive Testing. Vol. X I I , No.
3, (1954): pp. 35-44.
L.**
Shiraiwa, T., T. Hiroshima, T. Hirota, and T. Sakamoto. "SAM Inspection Systems for Oil Country Tubular
Goods," Materials Evaluation, Vol. 35, No. 7, (1977): pp. 52-56.
M.
Sharpe, R.S., Editor. Research Techniques in Nondestructive Testing, Volume 1. London and New York:
Academic Press. 1970.
N.
Sharpe, R.S., Editor. Research Techniques in Nondestructive Testing, Volume 2. New York: Academic
Press. 1974.
O.*
McGonnagle, W.J. Nondestructive Testing, second edition. New York: Gordon & Breach. 1969.
P.**
Forester, Dr. Friedrich. "Progress Report — The Nondestructive Inspection of Tubings for Discontinuities
and Wall Thickness Using Electromagnetic Test Methods," Materials Evaluation, Vol. 27, No. 4, (1970):
pp. 21A-31A.
Q.** Black, W.A. "Nondestructive Testing of Steel and Steel Products," Nondestructive Testing, Vol. X V I I I ,
No. 3, (1960): pp. 185-190.
R.
Radio Amateur's Handbook. American Radio Relay League Staff. 1977.
S.
Forester, Dr. Friedrich. (1959, January). "Principles of Eddy Current Testing." Metal Progress.
T.*
Materials Evaluation. Columbus, OH: The American Society for Nondestructive Testing, Inc.
U.*
Metals Handbook, Volume 11, Nondestructive Inspection and Quality Control. Metals Park, OH: American
Society for Metals. 1976.
Sharp, R.S., Editor, Research Techniques in Nondestructive Testing, Volume 3. New York: Academic Press.
1977.
w.
"NDT Monograph FL." Mathematics and Formulae in NDT. W.H. Houldershaw Ltd. 1978.
X.
Stumm, W. (1979, July). "Magnetic Stray Flux Techniques in NDT — Theory, Application, and New
Developments," British Journal of NDT.
Y.** Shiraiwa, T., T. Hiroshima, and S. Morishima. "An Automatic Magnetic Inspection Method Using
Magnetoresistive Elements and its Application." Materials Evaluation, Vol. 31, No. 5, (1973): pp. 90-96.
Z.** Lord, W., et al. "Residual and Active Leakage Fields Around Defects In Ferromagnetic Materials."
Materials Evaluation, Vol. 36, No. 8, (1978): pp. 47-54.
AA.**Luz, H . (1973, February). "The Nondestructive Testing of Bars and Billets for Surface Defects by Magnetic
Leakage Methods," Journal of Nondestructive Testing, Volume 6, No. 1.
BB.** Bergander, Marek J. "Computerized Magnetic Testing of Steel Ropes." ASNT Paper Summaries, National
Spring Conference, San Diego. Columbus, OH: The American Society for Nondestructive Testing, Inc.
April, 1979.
CC.
Poffenroth, Dennis N . "Flaw Detection in Mine Hoist and Elevator Transportation Systems."
Conference/Show.Niagaia Falls. May, 1979.
DD.* 1978 Annual Book ofASTM
Materials. 1978.
ASNT/CSNDT
Standards, Part 11. Philadelphia, PA. American Society for Testing and
EE.
Bergander, Marek J. (1978, May). "Principles of Magnetic Defectoscopy of Steel Ropes," Wire Journal.
FF.
Bergander, Marek J., and Julivaz Stachurski. " A New Device for Magnetic Testing of Steel Ropes," 4th
International Congress of Transportation by Rope. Vienna, Austria, June, 1976.
GG.
Egen, Richard A. "Nondestructive Testing of Wire Rope," Offshore Technology Conference. Houston,
May, 1977.
* Available from The American Society for Nondestructive Testing, Inc.
**Available in photocopy form from the ASNT Information Center (800) 222-2768 or (614) 274-6003, X247.
Each question found in this book contains letter(s) and page number(s) and sometimes chapter or section number(s) in
bold type immediately following the answers. For example,
15. When testing ferromagnetic materials, the depth to
which eddy currents are induced in the material will
be determined by the:
a.
b.
c.
d.
conductivity of the material
permeability of the material
geometrical shape of the material
all of the above
3.2.31
In this example, the first number "3" refers to Reference 3 in the list provided above. The "2" indicates the chapter
number and the " 3 1 " is the specific page in Reference 3 where the answer to the question can be found.
6
Reference Usage List
Eddy Current/Flux Leakage Testing Method
Reference A: Total = 49
Level I (14)
Level n (15)
Level i n (20)
Reference I: Total = 0
Level I (0)
Level II (0)
Level III (0)
Reference B: Total = 0
Level I (0)
Level II (0)
Level III (0)
Reference J : Total = 1
Level I (1)
Level II (0)
Level m (0)
Reference C: Total = 105
Level I (46)
Level II (46)
Level III (13)
Reference K: Total == 0
Level I (0)
Level II (0)
Level III (0)
Reference D: Total = 14
Level I (5)
Level II (6)
Level III (3)
Reference L : Total = 3
Level I (1)
Level U (1)
Level III (1)
Reference E : Total = 15
Level I (7)
Level II (1)
Level III (7)
Reference M: Total == 0
Level I (0)
Level H (0)
Level III (0)
Reference F: Total = 2
Level I (0)
Level II (0)
Level III (2)
Reference N: Total = 3
Level 1(0)
Level I I (1)
Level III (2)
Reference G: Total = 77
Level I (24)
Level II (24)
Level HI (29)
Reference O: Total = 10
Level I (4)
Level I I (6)
Level i n (0)
Reference H: Total = 0
Level I (0)
Level II (0)
Level III (0)
Reference P: Total = 3
Level 1(0)
Level U (0)
Level i n (3)
7
Reference Q: Total = 0
Level I (0)
Level 11(0)
Level III (0)
Reference Z: Total =
Level I (2)
Level 11(0)
Level III (1)
Reference R: Total = 1
Level I (0)
Level II (0)
Level IH (1)
Reference AA: Total
Level I (1)
Level II (1)
Level i n (2)
Reference S: Total = 7
Level I (0)
Level II (6)
Level III (1)
Reference BB: Total
Level I (0)
Level II (1)
Level III (0)
Reference T: Total = 0
Level I (0)
Level II (0)
Level III (0)
Reference CC: Total
Level I (0)
Level II (0)
Level III (1)
Reference U: Total = 13
Level I (3)
Level II (6)
Level III (4)
Reference DD: Total
Level I (2)
Level II (5)
Level ffl(0)
Reference V: Total = 25
Level I (10)
Level II (10)
Level III (5)
Reference E E : Total
Level I (2)
Level H (1)
Level i n (0)
Reference W: Total = 3
Level I (0)
Level II (0)
Level IH (3)
Reference FF: Total =
Level I (0)
Level II (1)
Level IH (0)
Reference X: Total = 1
Level I (0)
Level H ( l )
Level HI (0)
Reference GG: Total
Level 1(0)
Level n(0)
Level III (2)
Reference Y: Total = 3
Level I (1)
Level II (1)
Level m ( l )
8
Level I Questions
Eddy Current Testing Method
A test specimen used as a basis for calibrating test
equipment or as a comparison when evaluating test
results is referred to as a:
a.
b.
c.
d.
6.
null-balancer
phase shifter
reference standard
high pass filter
The process of comparing the reading or output of an
instrument, device, or dial with a standard to
determine the instrument's accuracy, capacity, or
graduations is referred to as:
a.
b.
c.
d.
C.2.43; G.40.5
calibration
differentiation
integration
phase shifting
C.3.28
In an eddy current testing situation, which of the
following can provide sources of noise?
a.
b.
c.
d.
7.
instrumentation electronic circuits
nonspecific variations within the test object
electrical interference
all of the above
a. with only the reference standard in one coil
b. with the reference standard in one coil and an
acceptable test specimen in the other coil
c. with the reference standard in one coil and an
unacceptable test specimen in the other coil
d. with only the test specimen in one coil
G.40.21
A.115
The ratio of the response or amplitude from signals of
interest to the response or amplitude of indications
that contain no useful information for the test being
conducted is referred to as:
a.
b.
c.
d.
Poisson's ratio
signal-to-noise ratio
the conductivity-to-permeability ratio
the reactance-to-resistance ratio
When conducting an eddy current test using a
differential comparison coil arrangement that
compares an external reference standard with the test
specimen, the system should be nulled or balanced:
8.
The impedance of an eddy current test coil will
increase i f the:
a.
b.
c.
d.
0.366
IACS is a recognized abbreviation for:
test frequency increases
inductive reactance of the coil decreases
inductance of the coil decreases
resistance of the coil decreases
C.2.35
a.
b.
c.
d.
Induced Alternating Current System
Inductively-Activated Comparison System
Internal Applied Current System
International Annealed Copper Standard
C.2-8; G.42.11
9.
Some of the products commonly tested using
encircling coils are:
a.
b.
c.
d.
Which of the following is not a basic component of
eddy current equipment?
rods, tubes, and wire
plate when volumetrically inspected
sheets and metalized foil
all of the above
G.40.1
a.
b.
c.
d.
amplifier
coil
liquid couplant
detector
10.
Which of the following would normally be
considered the best fill factor when testing straight
tubing with an encircling or feedthrough coil?
G.36.2
a.
b.
c.
d.
0.95
1.75
0.50
0.25
(95%)
(175%)
(50%)
(25%)
G.36.17
Eddy Current Testing Method, Level I
11.
When a magnetic metal part is placed in an eddy
current test coil, the impedance of the coil will be
changed by which of the following properties of the
part?
a.
b.
c.
d.
15.
When testing ferromagnetic materials, the depth to
which eddy currents are induced in the material will
be determined by the:
a.
b.
c.
d.
conductivity
dimensions
permeability
all of the above
conductivity of the material
permeability of the material
geometrical shape of the material
all of the above
C.2-31
G.36.2
16.
12.
An eddy current is a circulating electrical current
induced in a conducting article by:
a.
b.
c.
d.
gamma rays
an alternating magnetic field
a piezoelectric force
any of the above
When testing plate with a probe coil, it is noted that
the eddy current output indication varies as the
distance from the coil to the surface of the test part
varies. The term used to describe this action is:
a.
b.
c.
d.
C.2-5
fill factor
lift-off
phase differentiation
edge effect
C.2-24
13.
The conductivity of a material can be changed by
changing the:
a.
b.
c.
d.
17.
alloy of the specimen
heat treatment of the specimen
temperature of the specimen
all of the above
The main purpose for spring-loaded eddy current
probe coils is to:
a.
b.
c.
d.
C.2-9 to 2-12
minimize lift-off variations
minimize wear on the probe
reduce operator fatigue
eliminate edge effect
C.2-24
18.
Figure 1
B
Lift-off is utilized in:
a. measuring permeability changes
b. measuring conductivity changes
c. measuring the thickness of non-conductive
coatings
d. determining proper test frequency
A
C.2-25
19.
In eddy current test systems where encircling coils
are used, coupling efficiency is referred to as:
a.
b.
c.
d.
lift-off
edge effect
fill factor
phase differentiation
G.36.17
20.
B
14.
Figure 1 is an illustration of a material's:
a.
b.
c.
d.
When inspecting products with a uniform cross
section, an eddy current signal is produced when the
leading end or trailing end of the product approaches
the test coil. This phenomenon is referred to as:
a.
b.
c.
d.
phase analysis loop
sine wave
hysteresis loop
none of the above
lift-off
end effect
fill factor
phase discrimination
C.2-27
C.2-19
10
Eddy Current Testing Method, Level I
21.
Which of the following conditions would be the most
difficult to detect when eddy current testing rod with
an encircling coil?
27.
a. a deep surface crack that has a depth of 30% of the
rod diameter
b. a small inclusion in the center of the rod
c. a 5% change in diameter
d. a 10% change in conductivity
C.2-29
22.
a.
b.
c.
d.
When testing tubing with an inside diameter coil,
most of the eddy currents:
28.
100 Hz
10 kHz
1 MHz
10 MHz
30.
A n eddy current test coil's opposition to the flow of
alternating current is called:
steel
aluminum
copper
brass
C.3-9
31.
An increase i n the impedance of an eddy current test
coil will:
The single absolute coil arrangement can be used in:
a.
b.
c.
d.
encircling coils only
probe coils only
probe and encircling coils only
probe, encircling, and inside diameter coils
C.3-9
32.
The primary purpose(s) of the secondary winding in
an eddy current coil is to:
a. induce eddy currents in the test specimen
b. detect changes in the eddy current flow
c. induce eddy currents in the test specimen and to
detect changes in the eddy current flow
d. provide dc saturation
C.3-10
Which of the following will affect the impedance of
an encircling eddy current test probe?
a.
b.
c.
d.
Direct current saturation coils would most likely be
used when testing:
a.
b.
c.
d.
resistance
inductive reactance
impedance
capacitive reactance
a. cause an increase in the current flow through the
test coil
b. cause a decrease in the current flow through the
test coil
c. not affect current flow i n the test coil
d. decrease the voltage applied to the coil
C.2-34
26.
slow changes in dimensions
gradual changes in conductivity
variation in heat treatment
small surface defects
C.3-8
C.2-33
25.
Eddy current test coils, which are wound to form a
narrow coil, would normally be used to detect:
a.
b.
c.
d.
C.2-31
a.
b.
c.
d.
pitting
small inclusions
changes in conductivity
porosity
C.3-8
29.
24.
Eddy current test coils which are wound to form a
wide coil would normally be used to detect:
a.
b.
c.
d.
Which of the following test frequencies would
produce eddy currents with the largest depth of
penetration?
a.
b.
c.
d.
absolute winding
secondary winding
phase winding
none of the above
C.3-3
a. flow in a longitudinal direction down the tubing
b. flow radially in the tube
c. flow around only the outside diameter of the
tubing
d. flow around the inside diameter of the tubing
C.2-30
23.
When a test coil consists of a double winding
arrangement, and one winding is referred to as a
primary winding, the other winding is referred to as
the:
conductivity of a test specimen in the coil
permeability of a test specimen in the coil
fill factor
all of the above
C.2-34,2-35
11
Eddy Current Testing Method, Level I
33. Which of the following eddy current test coil
arrangements uses one area of the test specimen as a
reference standard against which another area on the
same specimen is simultaneously compared?
a.
b.
c.
d.
a.
b.
c.
d.
single absolute coil
double absolute coil
dc saturation coil
differential coil
an encircling coil
a probe coil
a secondary winding
none of the above
E.l-4
C.3-11
34. The readout mechanism used when testing by the
ellipse method is a:
a.
b.
c.
d.
39. The entire circumference of a test part is evaluated at
one time when using:
40. When attempting to determine the exact point
location of a discontinuity, the test system should
include:
a.
b.
c.
d.
meter
strip-chart recorder
cathode ray tube
any of the above
a phase shifter
a probe coil
an attenuator
a penetrameter
E.l-7
C.3-16
35. Reference standards used for eddy current testing:
41. It is often possible to sort various nonmagnetic alloys
of a metal by means of an eddy current test when:
a. there is a unique range of permeability values for
each alloy
b. there is a unique range of conductivity values for
each alloy
c. the direction of induced eddy currents varies for
each alloy
d. the magnetic domains for each alloy are different
E.3-10
a. must contain artificial discontinuities such as
notches and drilled holes
b. must contain natural discontinuities such as cracks
and inclusions
c. must be free of measurable discontinuities
d. may contain artificial or natural discontinuities or
be free of discontinuities depending on the test
system and the type of test being conducted
C.3-27
36. A reference standard used to ensure that the amplitude
and phase characteristics of an eddy current system do
not drift during continuous testing is called a:
a.
b.
c.
d.
42. Which of the following products would be most
applicable to a test using an inside coil?
a.
b.
c.
d.
DGS standard
calibration standard
reference block
none of the above
sheet
rod
bolt hole
coating thicknesses
E.3-33
C.3-28
37. Which of the following could not be tested by the
eddy current testing method?
43. When eddy current testing rod for discontinuities,
which of the following conditions could produce
extraneous indications?
a. improper adjustment of the hold-down rollers used
to center the rod in the coil
b. rod is fed through the coil at varying speeds
c. changes in dimension
d. all of the above
e. none of the above
E.3-33
a. a 102 mm (4 in.) thick plate to be tested for small
discontinuities throughout the plate
b. tubing to be tested for surface cracks
c. rod to be tested for laps and seams
d. tubing to be tested for variations in outside
diameter
C.4-36
38. Which of the following is not applicable to eddy
current testing?
44. One method of reducing nonrelevant indications
when eddy current testing ferromagnetic materials is
to:
a. decrease the pressure on the hold-down rollers
b. use a direct current saturation coil to magnetically
saturate the test specimen
c. readjust the gain control
d. increase the rate of feed through the coil
E.3-34
a. can be used for high-speed testing
b. can accurately measure conductivity
c. can be set up to provide high sensitivity to small
discontinuities
d. can penetrate up to 152 mm (6 in.) in a test part
C.4-36
12
Eddy Current Testing Method, Level I
45.
Eddy currents are circulating currents induced in a
conducting material by a:
a.
b.
c.
d.
51.
varying piezoelectric field
standing wave front
direct current
varying magnetic field
Which of the following is not a read-out system used
to present eddy current test information?
a.
b.
c.
d.
calibrated and uncalibrated meters
litmus paper
cathode ray tube
strip-chart recorders
C.2-5
46.
E.2-18,76
52.
In order to generate measurable eddy currents in a
test specimen, the specimen must be:
a.
b.
c.
d.
a. the frequency must equal the f/f ratio to give an
accurate test
b. the frequency must be within ± 3 % of the f/f ratio
to give an accurate test
c. there is a range of suitable frequencies centered
around the optimum frequency
d. the frequency should be within ±25% of the
characteristic frequency
V.84
a conductor
an insulator
either a conductor or insulator
a ferromagnetic material
c
C.2-8
47.
A l l ferromagnetic materials that have been
magnetically saturated to suppress permeability
variations may retain a certain amount of the
magnetization called the:
53.
a.
b.
c.
d.
coercive force
residual magnetism
hysteresis loop
hysteresis loss
An ac current flowing in a conductor will set up:
a. an alternating current field around the conductor
b. a periodically changing voltage tangent to the
conductor
c. an alternating magnetic field around the conductor
d. none of the above
D.l-4
49.
Which of the following is not a method that may be
used to improve the signal-to-noise ratio?
a. change to a test frequency that will decrease the
noise
b. increase the amplification of the test instrument
c. improve the fill factor
d. add filter circuits to the instrument
A.16,35-36
C. 2-17,2-18
48.
Which of the following statements best describes the
selection of eddy current test frequency?
54.
When conducting an eddy current test on tubing, the
magnitude of the indication caused by a discontinuity
is dependent on:
a.
b.
c.
d.
The characteristics of the alternating magnetic field in
the vicinity of the ac coil are affected by:
the depth of the discontinuity
the width of the discontinuity
the length of the discontinuity
all of the above
G.37.11
a.
b.
c.
d.
50.
the coil parameters
the magnitude of the applied ac current
the frequency of the applied ac current
all of the above
C.2-32 to 2-35
55.
A coil's magnetic field may be viewed as a
distribution of lines of flux around the coil. The
number of lines in a unit area is defined as:
a.
b.
c.
d.
When using an encircling coil with both primary and
secondary windings, the excitation alternating current
is applied to:
magnetic density
flux density
magnetic coupling
hysteresis density
C.2-19
a. the secondary winding
b. the primary winding
c. either the primary or secondary winding depending
on the setting of an instrument control
d. both the primary and secondary coils
D. l-21,1-23
13
Eddy Current Testing Method, Level I
56.
Which of the following discontinuities would be
easiest to detect with an eddy current test?
a. a crack that lies parallel to the direction of the eddy
current flow
b. a discontinuity located in the center of a 51 mm
(2 in.) thick diameter rod
c. a radial crack that extends to the outer surface of a
rod
d. a subsurface radial crack located at a depth of
13 mm (0.5 in.) in a 51 mm (2 in.) diameter rod
C.2-29; V.80
57.
62.
a.
b.
c.
d.
63.
measure coating thickness
measure cladding thickness
gauge the thickness of sheet
all of the above
eliminate overloading
detect the possible existence of a third alloy
make proper balancing possible
phase the readings correctly
G.41.6; V.98
Eddy currents cannot be induced in:
64.
a.
b.
c.
d.
aluminum
latex paint
steel
copper
A term used to define a condition of balance in a
device or system which results in zero output is:
a.
b.
c.
d.
D.l-9
59.
When sorting a known mix of two alloys with a
comparator having a quantitative readout device, it is
desirable to hold all indications within the bounds of
the readout device in order to:
a.
b.
c.
d.
J.145
58.
start to increase
start to decrease
show no significant change
suddenly drop to zero
C.2-21
Eddy current test techniques can be used to:
a.
b.
c.
d.
For the purposes of eddy current testing, saturation of
ferromagnetic material is reached when the current is
at such a value that for any further increase in current,
the signal-to-noise ratio will:
high frequency standardization
integration
null-balance
differentiation
A.202
Which of the following characteristics do not apply to
magnetic materials?
65.
a.
b.
c.
d.
high permeability value
no hysteresis loop
definite saturation point on hysteresis loop
appreciable residual magnetism
A term used to define a unit of flux density is:
a.
b.
c.
d.
D.4-51
a maxwell
a gauss
an ohm
a mho
G.33.12
60.
Which of the following is not an eddy current testing
method?
a.
b.
c.
d.
66.
pulse-echo testing
impedance testing
phase analysis testing
modulation analysis testing
a.
b.
c.
d.
D.5-115
61.
Changes in the hardness of age hardenable aluminum
and titanium alloys will normally be accompanied by
changes in:
retentivity
permeability
magnetostriction
conductivity
V.78
Eddy currents always travel:
a.
b.
c.
d.
in nonconductive materials
radially when testing rod with an encircling coil
in closed paths
in a gas
C.2-5
67.
A term used to describe holes, grooves, notches, etc.,
that are introduced into a reference standard to
provide accurately reproducible quality levels is:
a.
b.
c.
d.
a natural discontinuity
an artificial discontinuity
an ellipse
none of the above
V.88
14
Eddy Current Testing Method, Level I
68.
A term used to define one or more turns or loops of a
conductor wound in such a manner as to produce an
axial magnetic field when current passes through the
conductor is:
a.
b.
c.
d.
74.
a. the coil would otherwise be out of balance
b. parts of the material furthest away from the coil,
radially, may receive a less sensitive inspection
c. the flow of eddy currents around the product will
be disturbed, resulting in improper penetration
d. lack of proper centering may change the phase
adjustment of the instrument
C.2-25
a coil
a resistor
a capacitor
an oscillator
V.76
69.
Nondestructive tests are commonly conducted to:
75.
a. determine the quality of finished products
b. locate defective material before excessive
fabrication is performed on the material
c. monitor production techniques
d. all of the above
The region around a magnet that attracts other pieces
of iron or steel is called:
a.
b.
c.
d.
76.
a maxwell
the magnetic field
retentivity
alternating current
An eddy current coil arrangement that does not make a
comparison with either two sections of the test
specimen or one section of the test part and a reference
standard is called:
a.
b.
c.
d.
72.
73.
77.
an absolute coil arrangement
a self-comparison differential coil arrangement
an external reference differential coil arrangement
none of the above
A.69
size or shape
grade or chemistry of the material
the way in which the material has been processed
all of the above
0.346
A length of tubing containing a notch running from
end to end and having uniform width and depth, when
tested with an encircling self-reference differential
coil system, will produce:
a.
b.
c.
d.
Which of the following are common applications for
eddy current testing?
a. measurement of conductivity or a combination of
conductivity and permeability
b. measurement of the thickness of thin metal
sections, cladding, or coating
c. detection of surface and subsurface discontinuities
d. all of the above
G.36.2
An eddy current system (60-cycle comparator type)
will measure variations caused by differences in:
a.
b.
c.
d.
G.30.2
71.
When you determine that a flaw detection instrument
has been set up incorrectly, or is defective, all
material:
a. should be retested since the time correct set-up or
proper operation was last verified
b. accepted should be retested
c. rejected should be retested
d. none of the above
C.4-31
A.7-8
70.
Material must be reasonably centered in the test coil
of a flaw detection system because:
erratic signals
a continuous, sustained signal
no signal
excessive signals
G.3-11
78.
In eddy current testing, optimum sensitivity to a
known defect placed at random on the surface of a
nonferrous length of tubing is obtained by:
a.
b.
c.
d.
proper choice of frequency
centering the tubing in the coil
proper adjustment of phase
all of the above
.
V.79, 81, 83
Which of the following is not a primary purpose for
using an eddy current standard?
79.
a. determine i f the eddy current test system is capable
of performing the test properly
b. determine i f a discontinuity is cause for rejection
c. determine the instrument control settings needed to
pass the highest percentage of test specimens run
d. determine if the sensitivity of a test system has
drifted with time
A.295
Spinning probe-type eddy current instruments are
most useful in the detection of: •
a.
b.
c.
d.
-
surface and subsurface inclusions
the smallest surface blemishes
internal piping or burst
all of the above
V.90
15
Eddy Current Testing Method, Level I
80. One principal advantage of spinning probe eddy
current instruments is:
86. What causes phase shift in an eddy current test coil?
a. a change in the ratio of inductive reactance (X ) to
resistance (R)
b. a change in the sensitivity setting of the instrument
c. use of modulation analysis
d. none of the above
A.31; G.36.3
L
a. the ability to locate the circumferential position of
defects
b. relative insensitivity to vibration
c. the variety of internal and surface defects that may
be detected
d. all of the above
C.3-5
81. A t any given instant, a spinning probe eddy current
instrument should be inspecting:
a.
b.
c.
d.
a. to check the phase selectivity
b. to ensure proper centering of the material in the
test coil
c. to select the modulation analysis setting
d. to select the proper operating speed
G.39.10-12
one complete circumference of the product
an area defined by the size of the probe coil
one longitudinal line the length of the product
none of the above
C.3-5; 0.353
82. A spinning probe eddy current instrument would be
most useful in:
a. measuring hardness of ferromagnetic steel
products
b. flaw detection in hexagonal and shaped material
c. detecting and precisely locating surface and
subsurface discontinuities
d. inspection of copper bus bars for electrical
conductivity
V.90
83. Which of the following is not a nondestructive testing
method?
a.
b.
c.
d.
87. In a feed-through encircling coil flaw detection eddy
current system, what would be the purpose of running
a calibration defect several times but in various
positions (such as top, bottom left, and right)?
88. In a feedthrough encircling coil eddy current system,
dc saturation would probably be most helpful in
testing:
a.
b.
c.
d.
copper water tubing
titanium tubing
ferromagnetic steel tubing
brass rivet wire
A.56
89. In a feedthrough encircling coil eddy current system,
the test frequency is controlled by the:
a.
b.
c.
d.
ultrasonic testing
fatigue testing
eddy current testing
radiographic testing
oscilloscope
sensitivity setting
oscillator
modulation analysis setting
A.250,252
C.l-5
84. Which of the following is not applicable to spinning
probe-type instruments?
a. the size of product to be inspected is limited by the
dc saturation capability of the system
b. the frequency may be varied to accommodate
various metals and alloys
c. they may be used on straight or coiled wire
products
d. they are useful in seam detection
G.38.36
90. Alloy variations in a nonmagnetic material would
most likely affect:
a. permeability
b. conductivity
c. diameter
d. frequency
G.37.6
91. Which of the following frequencies will provide the
greatest eddy current penetration m aluminum?
a.
b.
c.
d.
85. In a feedthrough encircling coil eddy current system,
a calibration standard may be used to:
a.
b.
c.
d.
1 kHz
10 kHz
3 kHz
300 Hz
A.130
insure repeatability and reliability of the setup
precisely calibrate the flaw depth
reduce sensitivity to vibration
measure the test frequency
A.295-296
16
Eddy Current Testing Method, Level I
92. The coercive force of a soft iron electromagnetic core
would be the
coercive force of a
permanent magnet.
a.
b.
c.
d.
97. When eddy current testing a nonferrous specimen, a
discontinuity will:
a.
b.
c.
d.
greater than
less than
twice
equal to
increase the effective conductivity of the specimen
increase the effective permeability of the specimen
decrease the effective conductivity of the specimen
none of the above
A.188
A.175
98. Demagnetization is generally needed when the
residual field in a specimen:
93. Metals that do not react or react only slightly to
magnetic fields are called:
a.
b.
c.
d.
a. may affect the operation or accuracy of
instruments when the specimen is placed in service
b. may interfere with the proper functioning of the
part
c. might cause particles to be attracted and held to the
surface of moving parts
d. any of the above reasons could make
demagnetization necessary
V.67
diamagnetic metals
paramagnetic metals
nonmagnetic metals
all of the above
A.170-171; G.30.1
94. A symbol commonly used to express conductivity is:
a. n
b. a
99. A term used to define testing that requires that the test
article be loaded and/or sectioned to verify and/or
establish mechanical or physical properties is:
C.2-43
a.
b.
c.
d.
95. A symbol commonly used to express permeability is:
a. | i
b. a
c. X
d. R
C.l-4
L
V.54
96. The method used to generate eddy currents in a test
specimen by means of a coil can most closely be
compared with the action of a:
a.
b.
c.
d.
impedance testing
phase analysis testing
destructive testing
nondestructive testing
transformer
capacitor
storage battery
generator
A.32-33
17
6
Level I Answers
Eddy Current Testing Method
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
c
d
b
d
c
a
b
a
a
a
d
b
d
c
d
b
a
c
c
b
b
d
a
c
b
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
d
b
c
d
a
d
b
d
c
d
b
a
d
a
b
b
c
d
b
d
a
b
c
d
b
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
19
b
c
b
d
b
c
d
b
b
a
c
c
b
c
b
d
b
a
d
b
a
d
c
b
a
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
d
c
d
b
a
b
c
b
a
a
a
b
c
c
b
d
b
d
b
a
a
c
d
c
i
Level II Questions
Eddy Current Testing Method
1.
A method of minimizing the effect of indications
caused by gradual dimensional changes while
retaining the indications caused by discontinuities is
to:
5.
a. include a high-pass filter in the eddy current test
equipment
b. include a low-pass filter in the eddy current test
equipment
c. increase the band pass of the amplifier
d. use the impedance method of testing
A.61
2.
a.
b.
c.
d.
6.
filtering or differentiation
phase discrimination
integration
all of the above
4.
skin effect
high-frequency filtration
low-frequency filtration
any one of the above
0.347; V.80
7.
In order to decrease the effect on conductivity
readings due to variations in test part thickness:
a.
b.
c.
d.
A term used to define the phenomenon where, at very
high frequencies, the eddy current flow is restricted to
an extremely thin outer layer of the conductor is:
a.
b.
c.
d.
E.2-76
3.
fill factor
edge effect
end effect
lift-off
0.357; V.29
Which of the following methods may be used to
improve the signal-to-noise ratio of an eddy current
test system?
a.
b.
c.
d.
A term used to describe the effect observed due to a
change in the electromagnetic coupling between a test
specimen and a probe coil when the distance of
separation between them is varied is:
a.
b.
c.
d.
the test frequency should be increased
the test frequency should be decreased
the fill factor should be decreased
there is no practical method for decreasing this
effect
0.347
0.5 (50%)
0.75 (75%)
1.0(100%)
0.25 (25%)
V.79
8.
When testing by the eddy current method,
discontinuities will be most easily detected when the
eddy currents are:
a. coplanar with the major plane of the discontinuity
b. perpendicular to the major plane of the
discontinuity
c. parallel to the major plane of the discontinuity
d. 90 degrees out of phase with the current in the coil
G.37.18
The fill factor when a 13 mm (0.5 in.) diameter bar is
inserted in a 25 mm (1 in.) diameter coil is:
The teim used to define the difference between actual
instrument output and expected output as defined by a
straight line calibration curve is:
a.
b.
c.
d.
phase shift
nonlinearity
lift-off
skin effect
U.189
9.
Which of the following could be used to suppress
unwanted high-frequency harmonics?
a.
b.
c.
d.
low-pass filter
oscillator
phase discriminator
high-pass filter
D.5-122
21
Eddy Current Testing Method, Level II
10.
The impedance change of an eddy current test coil
due to a change in test part characteristics can be
most easily analyzed as a combined change in:
a.
b.
c.
d.
11.
16.
capacitive reactance and resistance
harmonic frequencies and inductive reactance
signal amplitude and phase
retentivity and harmonic frequencies
G.36.19-20
a. test material permeability
b. test frequency
c. geometry of the test object
d. all of the above
G.36.12
The inductive reactance of a test coil can be
calculated using the formula:
a.
b.
c.
d.
X
X
X
X
L
L
L
L
In a test coil consisting of both a primary and
secondary winding, the voltage across the secondary
is a function of:
17. Eddy current testing relies on the principle of:
a.
b.
c.
d.
= 2rcL
= 0.5nL
= 27tft
= 1R
magnetostriction
electromagnetic induction
piezoelectric energy conversion
magnetomotive force
A.2
G.36.1
18. When the H field strength around a material is
increased and then decreased to zero, the induction
field B within the part does not return to zero. The
term to define this B value when H has returned to
zero is:
12. When conducting an eddy current test, variations in
the test material can be detected as variations in:
a.
b.
c.
d.
test speed
impedance of a pickup coil
none of the above
all of the above
a.
b.
c.
d.
0.346
13.
A.175; V.54
A term used to define two or more coils electrically
connected in opposition such that any
electromagnetic condition which is not common to
both a test specimen and a reference specimen will
produce an unbalance in the system is:
a.
b.
c.
d.
coercive force
residual magnetism
saturation value
hysteresis loss
19. The term used to define the value of H field required
to decrease the remanence of a material to zero is:
a.
b.
c.
d.
differential
absolute
laminar
flying probes
coercive force
magnetizing force
backemf
the overlap value
A.175
U.85
20.
14. Tubing is generally inspected using:
a.
b.
c.
d.
a. electrical conductivity, frequency, and material
geometry
b. density, permeability, and frequency
c. electrical conductivity, permeability, and material
geometry
d. thermal conductivity, electrical conductivity, and
permeability
G.36.2
U-shaped coils
gap coils
encircling coils
none of the above
U.85
15. When testing small parts in an eddy current encircling
coil for permeability measurements, which of the
following test parameters may be considered
important?
a.
b.
c.
d.
The three major specimen parameters that influence
eddy current testing are:
21.
Doubling the number of turns on a coil will:
a.
b.
c.
d.
length of the test sample
thickness of the test sample
cross-sectional area of the test sample
all of the above
double the inductance
halve the inductance
decrease the inductance by a factor of four
increase the inductance by a factor of four
G.36.19
G.34.1
22
Eddy Current Testing Method, Level II
22.
Frequency ratio, / / / , can be defined as:
28.
a. the argument of the mathematical function
describing the electromagnetic field within the test
specimen
b. test frequency divided by limit frequency
c. neither of these
d. both of these
G.36.13
23.
a. increasing the rate of displacement of the specimen
through the coil
b. magnetically saturating the test specimen
c. decreasing the rate of displacement of the test
specimen through the test coil
d. testing in an air-conditioned room
C.2-22
When testing tubing, using an encircling (OD) coil,
what is the phase relationship of the output signals
from identical I D and OD discontinuities?
29.
a. the signals are in phase
b. the phase of the OD discontinuity leads the phase
of the I D discontinuity
c. the phase of the OD discontinuity lags the phase of
the I D discontinuity
d. indeterminate
A.25-26
decreases
increases
remains the same
could do any of the above
G.37.9
A term used to define an instrumentation technique
that discriminates between variables in the test part
by the different phase angle changes which these
conditions produced in the test signal is:
a.
b.
c.
d.
I f the test frequency increases while the field strength
is held constant, the surface eddy current density:
a.
b.
c.
d.
30.
24.
The heating effect in magnetic materials caused by
the work required to rotate magnetic domains can be
eliminated by:
As the fill factor decreases, the impedance variation
of a pickup coil produced by a given change in
conductivity will:
a.
b.
c.
d.
phase distortion
phase shifting
phase discrimination
phase analysis
increase
remain the same
decrease
could do any of the above
A.39-40
C.3-13
25.
Figure 2
I f the characteristic frequency ( / ) of a material is
125 Hz, the test frequency required to give an / / /
ratio of 10 would be:
wL
1
wL
a.
b.
c.
d.
o
1.25 Hz
12.5 Hz
1.25 kHz
12.5 kHz
2.25
0.8
26.
A term used to define any change in a sinusoidal
signal when the output is not a linear reproduction of
the input is:
0.6
a.
b.
c.
d.
0.4
distortion
linearity
phase shifting
dynamic range
1
/
2
/
0.2
/
9
5
49
X100
At a fixed test frequency, in which of the following
materials will the eddy current penetration be
greatest?
4(M1
0
* 40 000
0.2
a.
b.
c.
d.
6.25
1 6
/
G.40.41
27.
4
T
G.36.13
aluminum (35 percent LACS conductivity)
brass (15 percent IACS conductivity)
copper (95 percent IACS conductivity)
lead (7 percent IACS conductivity)
0.4
R
wL
o
C.2-31
23
Eddy Current Testing Method, Level I I
31.
The abscissa values on the impedance plane shown in
Figure 2 are given in terms of:
a.
b.
c.
d.
34. In Figure 3, the solid curves are plots for different
values of:
absolute conductivity
normalized resistance
absolute inductance
normalized inductance
heat treatment
b. conductivity
c. fill factor
d. permeability
S.101
S.102
32. In Figure 2 (an impedance diagram for solid
nonmagnetic rod), the / or characteristic frequency
is calculated by the formula:
a.
b.
c.
d.
/
f
f
f
Figure 4
A(oL
2
a
= opyd
= b\\J2
= 5060/aud
= R/L
2
S.101
33. In Figure 2, a change in the / / / ratio will result in:
a. a change in only the magnitude of the voltage
across the coil
b. a change in only the phase of the voltage across the
coil
c. a change in both the phase and magnitude of the
voltage across the coil
d. no change in the phase or magnitude of the voltage
across the coil
S.101
Figure 4 illustrates the fact that eddy current
responses:
a. can be caused by several parameters
b. differ in phase and magnitude with different
parameter changes
c. can be made selective with regard to the variable
of interest
d. all of the above
S.103
Which of the following would be easier to detect in
tubing by the eddy current method using the selfcomparison differential coil arrangement?
a.
b.
c.
d.
gradual changes in diameter
gradual changes in conductivity
changes in temperature
short flaws
S.104
24
Eddy Current Testing Method, Level II
37. The magnetic domains in an unmagnetized
ferromagnetic material are:
a.
b.
c.
d.
40. To eliminate any dependence upon the number of
turns of a test coil, the inductance values of an
impedance diagram are:
arranged to facilitate the conduction of electrons
randomly oriented and neutralize each other
uniformly oriented
create a major north and south pole in the material
C.2-14; V.93
a.
b.
c.
d.
disregarded
normalized
corrected to a value of 1
none of the above
A.36-38
38. When a magnetic material is placed in a region of an
applied magnetizing force (//), magnetic field (B) is
developed in the material by means of:
a.
b.
c.
d.
41. A term used to define a system that indicates only the
magnitude of variations in the total coil impedance
regardless of the phase or direction in which it occurs
on an impedance plane is:
induction
conduction
heat transfer
magnetic domain transfer
a.
b.
c.
d.
G.30.6
inductive reactance magnitude system
feedback-controlled system
impedance-magnitude system
impedance vector analysis system
D.5-30
Figure 5
42. When eddy current testing tubing with a system that
includes a frequency discriminating circuit, which of
the following variables would be classified as a highfrequency variable?
a.
b.
c.
d.
small discontinuities
conductivity changes
diameter changes
wall thickness variations
D.5-123
43. A major problem associated with the eddy current test
method is the:
a. inability of eddy current testing to accurately
measure conductivity
b. need to test at low speeds to prevent skipping
c. large number of known or unknown variables that
appear in the output indication
d. inability of eddy current testing to detect small
discontinuities
C.2-7
44. The atoms of a metal showing magnetic
characteristics are grouped into regions that are the
smallest known permanent magnets. These regions
are called:
a.
b.
c.
d.
Normalized Resistance
39. Figure 5 illustrates the fact that the limit frequency,
/ , equations and impedance diagrams for long solid
rods and long thin-walled tubing are:
lattice structures
cells
domains
planetary spins
C.2-13
a. different
b. identical
c. similar
d. unrelated
G.38.8
25
Eddy Current Testing Method, Level 11
45.
When a coil's magnetizing force is applied to a ferromagnetic material, the flux density in the material is:
51.
a. less than the flux density generated by the test coil
because of heat losses
b. less than the flux density generated by the test coil
because of resistivity
c. the same as the flux density generated by the test
coil
d. greater than the flux density generated by the test
coil
C.2-20
46.
symbol \i
symbol o
letter^
letter H
C.2-38
52.
L
c. Z = -^X
53.
54.
core coupling
magnetic saturation
the coil's magnetic field
magnetic domains
The thickness of nonconductive coatings on a
conductive base can be most simply measured by:
a.
b.
c.
d.
50.
L
+ R
2
A term used to define a surface coil mounted so that
the coil can be rotated about the circumference of a
test specimen is:
bobbin coil
encircling coil
spinning coil
gap coil
C.3-5
55.
observing the lift-off effect caused by the coating
testing both sides of the specimen
varying the current in the test coil
varying the test frequency over a given range
during the test
C.2-25
The use of magnetic shielding around the exciting
coil will generally:
An out-of-phase condition between current and
voltage:
a.
b.
c.
d.
C.2-22
49.
2
+ R
a. can exist only in the primary winding of an eddy
current coil
b. can exist only in the secondary winding of an eddy
current coil
c. can exist in both the primary and secondary
windings of an eddy current coil
d. exists only in the test specimen
C.2-40
symbol \x
symbol a
letter B
letter//
In eddy current testing, the specimen is coupled to the
test coil by:
a.
b.
c.
d.
L
C.2-39
C.2-20
48.
The formula used to calculate the impedance of an
eddy current test coil is:
a.
Z=2nfL
b. Z = X + R
The magnetizing force of an eddy current test coil is
usually designated by the:
a.
b.
c.
d.
diameter of coils
test frequency
overall shape of the coils
distance from other coils
d. Z = ^X
C.2-20
47.
a.
b.
c.
d.
The flux density in a magnetic material is usually
designated by the:
a.
b.
c.
d.
Which of the following is not a factor that affects the
inductance of an eddy current test coil?
A term used to define an eddy current test coil which
uses magnetic material to purposely shape the
magnetic field is:
a.
b.
c.
d.
bobbin coil
encircling coil
spinning coil
gap coil
C.3-7
56.
a. increase the magnetic field extension but decrease
the eddy current penetration
b. increase the magnetic field extension and eddy
current penetration
c. decrease the magnetic field extension but increase
the eddy current penetration
d. decrease the magnetic field extension and eddy
current penetration
C.2-26
The vector-point, ellipse, and linear time-base
methods are all subdivisions of the:
a.
b.
c.
d.
impedance method of testing
the modulation analysis method of testing
the phase analysis method of testing
none of the above
C.3-15
26
Eddy Current Testing Method, Level II
57. It is frequently possible to separate the conductivity
variable from the permeability and dimensional
variables when using:
a.
b.
c.
d.
62. The conductivity value for a metal is a function of
the:
a.
b.
c.
d.
the vector-point method of testing
the ellipse method of testing
the linear time-base method of testing
any of the above methods of testing
heat treatment given the metal
cold working performed on the metal
aging process used on the metal
all of the above
C.4-6
C.3-14
63. The ratio of the specific diameter of a probe to the
minimum discontinuity of interest should be:
58. When eddy current testing by the ellipse method, the
normal indication when the test specimen and
reference standard are the same is approximately:
a.
b.
c.
d.
a.
b.
c.
d.
a straight horizontal line on a cathode ray tube
an ellipse on a cathode ray tube
a null reading on a meter
a clean base line on a strip chart
C.3-16
C.5-3
64. Which of the following materials would be more
likely used as a mounting material for a probe coil?
59. When eddy current testing by the ellipse method, one
variable may be indicated by the angle of the ellipse
or straight line while another variable may be
indicated by the:
a.
b.
c.
d.
less than 2
greater than 2
greater than 4
greater than 10
a.
b.
c.
d.
aluminum
fiberglass
copper
steel
C.5-4
brightness of the ellipse
horizontal length of the straight line
size of the ellipse opening
sinusoidal shape of the waveform
65. A term used to define a surface or internal rupture
that is attributed to processing at too low a
temperature or excessive working or metal movement
during the forging, rolling, or extruding operation is:
C.3-16
60. When eddy current testing by the linear time-base
method,
is applied to the vertical
deflection plates of a cathode ray tube when the test
specimen and reference standard are the same and the
balance controls are properly adjusted.
a.
b.
c.
d.
a cold shut
microshrinkage
burst
an inclusion
C.7-8
a. a sinusoidal wave in phase with the timing voltage
b. a sinusoidal wave 90 degrees out of phase with the
timing voltage
c. a sawtooth waveform
d. zero net voltage
C.3-18
61. When eddy current testing by the linear time-base
method, what is applied to the vertical deflection
plates of a cathode ray tube when a condition of
unbalance exists between the test specimen and the
reference standard?
a.
b.
c.
d.
66. A term used to define the timing relationships
involved in alternating current signals is:
a.
b.
c.
d.
magnitude
phase
impedance
reactance
A.19-21
67. When eddy current testing a nonferrous material, the
choice of test frequency is determined by the:
a sinusoidal wave
a sawtooth wave
a square wave
no voltage
a.
b.
c.
d.
C.3-19
27
degree of phase discrimination required
eddy current penetration needed
rate of response required
all of the above
A.27,36; V.84-85
Eddy Current Testing Method, Level II
68.
When testing ferrous materials, a small but detectable
portion of the magnetic flux in the material will pass
outside the metal when a surface discontinuity is
encountered. This flux is called:
a.
b.
c.
d.
73.
a. the specimen should be of the same size and shape
as the piece to be tested
b. the specimen should have the same heat treatment
as the piece to be tested
c. the surface finish of the specimen should be the
same as the piece to be tested
d. i f the material is aluminum, the surface should be
anodized
C.3-27
air flux
leakage flux
induced flux
none of the above
V.330
69.
A term to define a property of a test system which
enables the separation of signals due to
discontinuities in the test specimen that are located in
close proximity to each other is:
a.
b.
c.
d.
74.
dynamic range
sensitivity
linearity
discontinuity resolution
A term used to define a material having a
permeability less than that of a vacuum is:
a.
b.
c.
d.
diamagnetic
ferromagnetic
paramagnetic
magnetic
A.171
75.
71. The inductive reactance of a coil is measured in units
of:
a.
b.
c.
d.
A n eddy current test coil's magnetic field intensity in
air:
a. increases with distance outside the coil and varies
across the diameter inside the coil
b. decreases with distance outside the coil and varies
across the diameter inside the coil
c. decreases with distance outside the coil and is
assumed to be constant across the diameter inside
the coil
d. increases with distance outside the coil and is
assumed to be constant across the diameter inside
the coil
D.2-7
G.43.49
70.
Which of the following conditions are not important
when selecting specimens to be used as reference
standards?
The circuits which make it possible to minimize the
effect of signals caused by variables of no interest on
the readout mechanism are based on differences in:
a.
b.
c.
d.
mhos
ohms
henrys
gauss
V.77
72.
Which of the following coil arrangements would
eliminate or decrease the effects of minor variations
in diameter, chemical composition, hardness, etc.,
which occur gradually along the length of a wire?
a.
b.
c.
d.
76.
amplitude
phase
frequency
any one or a combination of the quantities listed
above
A.109-116
When a nonmagnetic rod is placed inside an eddy
current test coil:
a. the magnetic field generated by the coil is
increased in intensity
b. the distribution of eddy currents is uniform
through the rod's cross section
c. the distribution of eddy currents is at a maximum
at the rod's surface, or near the surface, and
decreases to essentially zero at the rod's center
d. the temperature of the rod decreases
D.2-13
external reference differential
self-comparison differential
single coil absolute
double coil absolute
C.3-11
77.
The symbol commonly used to signify impedance is:
a.
b.
c.
d.
Z
Xe
R
X
s
c
C.2-32
28
Eddy Current Testing Method, Level II
78. A decrease in conductivity is equivalent to:
a.
b.
c.
d.
83. The two voltages (Vj and V ) shown in Figure 6 are:
2
an increase in permeability
an increase in resistivity
a decrease in permeability
a decrease in resistivity
a.
b.
c.
d.
in phase
45 degrees out of phase
90 degrees out of phase
180 degrees out of phase
C.2-8
C.2-36
79. If the conductivity of a test part in an eddy current
test coil decreases, the magnitude of the eddy currents
at a given depth in the test specimen:
a.
b.
c.
d.
increases
remains the same
decreases
may increase or decrease
C.2-8
80. When the voltage applied to a circuit and the current
through the circuit both reach their maximums and
minimums at the same time, the voltage and current
are:
a.
b.
c.
d.
84. The two voltages (Vj and V ) in Figure 7 are:
additive
in phase
regenerative
out of phase
2
a.
b.
c.
d.
C.2-36
in phase
45 degrees out of phase
90 degrees out of phase
180 degrees out of phase
C.2-37
81. Which of the following is not a commonly used eddy
current testing readout mechanism?
a.
b.
c.
d.
signal generator
meter
cathode ray tube
strip-chart recorder
C.2-7
82. Which of the following materials would have the
highest resistivity value?
a.
b.
c.
d.
aluminum with a 42 percent IACS rating
magnesium with a 37 percent IACS rating
cast steel with a 10.7 percent IACS rating
zirconium with a 3.4 percent IACS rating
C.2-32
85. In Figure 8, H represents:
a.
b.
c.
d.
the
the
the
the
coil's magnetizing force
material's flux density
material's permeability
material's conductivity
C.2-18
29
Eddy Current Testing Method, Level II
86.
In Figure 8, B represents:
a.
b.
c.
d.
the
the
the
the
92.
coil's magnetizing force
material's flux density
material's permeability
material's conductivity
For age hardenable aluminum and titanium alloys,
changes in hardness are indicated by changes in:
a.
b.
c.
d.
C.2-18
retentivity
permeability
conductivity
magnetostriction
V.104
87.
In Figure 8, the distance represented by A is a
measure of the material's:
a.
b.
c.
d.
93.
permeability
conductivity
retentivity
coercive force
a. test frequency or conductivity of the specimen is
decreased
b. test frequency is decreased or conductivity of the
specimen is increased
c. test frequency, conductivity of the specimen, or
permeability of the specimen are increased
d. permeability of the specimen is decreased
A.24
C.2-18
88.
In Figure 8, the distance represented by C is a
measure of the material's:
a. permeability
b. conductivity
c. residual magnetism
d. coercive force
94.
The ratio of a material's flux density to a test coil's
magnetizing force, (B/H), can be used to determine
the material's:
a.
b.
c.
d.
conductivity
resistivity
lift-off
permeability
95.
C.2-14
90.
96.
91. The impedance of a test coil usually can be
represented by the vector sum of:
a.
b.
c.
d.
When testing magnetic materials in an ac field,
increasing the field strength:
a.
b.
c.
d.
The magnetic field generated by eddy currents
induced in a test specimen:
a. opposes the magnetic field that induced the eddy
currents
b. reinforces the magnetic field that induced the eddy
currents
c. cancels the magnetic field that induced the eddy
currents
d. has no effect on the magnetic field that induced the
eddy currents
C.2-8
When the electrical current in an eddy current coil
reverses direction:
a. the direction of the eddy currents in a part remains
the same
b. the eddy currents in the test part will change phase
by 45 degrees
c. the direction of the eddy currents in the part also
reverses
d. the eddy currents in the part remain the same
C.2-5
C.2-18
89.
The penetration of eddy currents in a conductive
material is decreased when:
inductive reactance and resistance
capacitive reactance and resistance
inductive reactance and capacitive reactance
inductance and capacitance
Impedance diagrams have been mathematically
derived and experimentally verified for materials of
any conductivity and permeability having rectangular,
cylindrical, or spherical symmetry. To test all
specimens of similar geometry under the same
condition, it is only necessary to choose a test
frequency, / , so that frequency ratio / / / lies at the
same point on the impedance diagram for each
specimen. This principle is based upon:
a.
b.
c.
d.
G.36.1
has no effect
increases eddy current penetration
decreases eddy current penetration
decreases eddy current penetration to some
minimum value, and then increases it to its
maximum value when the specimen becomes
magnetically saturated
G.38.21
Ohm's Law
KirchoffsLaw
the Similarity Law
none of the above
G.37.10
30
Eddy Current Testing Method, Level II
97. To be useful, limit frequency equations must be:
a.
b.
c.
d.
101. Two test coils are often used in a bridge circuit to:
used with their impedance diagrams
used to determine their impedance diagrams
both of these
neither of these
A.158
a. eliminate skin effect
b. determine the differences between a known
standard sample
c. increase the conductivity of the circuit
d. decrease the system sensitivity
A.69
98. When a rod is placed in an encircling type of coil, the
density of eddy currents will be the greatest:
a.
b.
c.
d.
102. In inspecting ferromagnetic materials, relatively lowfrequencies are normally used because of the:
at the surface
at the center
midway between the surface and the center
none of the above
a.
b.
c.
d.
G.37.8
Low penetrability of these materials
higher resolution
lower resolution
higher penetrability of these materials
A.132
99. The term fill factor applies to:
a.
b.
c.
d.
103. The actual frequencies used in any specific eddy
current inspection should be selected on the basis of
the:
a surface coil
coaxial cable
an encircling coil
all of the above
a.
b.
c.
d.
e.
C.2-25
100. An eddy current system using handling equipment
with automatic marking of the defective areas
primarily makes it possible to:
thickness of the material
desired depth of penetration
degree of sensitivity or resolution required
purpose of the inspection
all of the above
V.84
104. In modulation analysis testing, which of the following
would not modulate the test frequency applied to the
test coil?
a. remove defective areas of the product, if desired
b. eliminate test surface contamination
c. allow an inexperienced operator to establish the
defect cause
d. pass rejectable material
G.41.3
a.
b.
c.
d.
discontinuities in the test specimen
dimension changes of the test specimen
chemical composition of the test specimen
a filter in the test circuit
D.5-119
31
Level II Answers
Eddy Current Testing Method
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
a
d
a
b
d
a
d
b
a
c
c
b
a
c
d
d
b
b
a
c
d
b
b
d
c
a
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
d
b
b
c
b
c
c
c
d
d
b
a
a
b
c
a
c
c
d
c
d
c
a
d
b
d
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
33
c
c
d
c
d
a
c
d
a
d
a
b
c
b
d
b
d
a
b
b
d
b
d
c
a
b
79.
80.
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
100.
101.
102.
103.
104.
c
b
a
d
a
c
a
b
c
d
d
a
a
c
c
c
d
c
a
a
c
a
b
a
e
d
Level III Questions
Eddy Current Testing Method
1.
In a feedthrough encircling coil eddy current system,
what would be the purpose of running a calibration
defect several times but in various positions (such as
top, bottom, left and right)?
4.
a. to check the phase selectivity
b. to ensure proper centering of the material in the
test coil
c. to select the modulation analysis setting
d. to select the proper operating speed
F.E571-9.3
2.
a. detection of surface and subsurface inclusions
b. detection of surface defects such as overlaps and
seams
c. detection of internal piping or burst
d. all of the above
A.194
5.
In a feedthrough encircling coil eddy current system,
a calibration standard may be used to:
a.
b.
c.
d.
A product can be viewed in terms of electrical
magnetic effects. A diameter change of the product in
an encircling coil is:
a.
b.
c.
d.
insure repeatability and reliability of the setup
calibrate the approximate depth of detectable flaws
both a and b
measure the test frequency
C.4-30
an electrical effect
a conductivity effect
a magnetic effect
all of the above
D.4-6
6.
3.
Spinning probe-type eddy current instruments are
most useful in:
A calibration standard may be used with a spinning
probe eddy current instrument to:
a. produce an indication relative to the depth of the
flaw
b. check the instrument for repeatability and freedom
from drift
c. check probe coil for possible damage
d. all of the above
C.4-30
In Figure 9, ac flowing through a primary coil set-up
a magnetic field and causes a flow of eddy currents in
the rod. The voltage of the secondary coil is
dependent upon:
a.
b.
c.
d.
these eddy currents
the primary coil
the generator
all of the above
C.2-40
Figure 9
Primary Coil
Generator
T
Secondary Coil
35
v
Eddy Current Testing Method, Level HI
7.
Which of the following is not a method that may be
used to improve the signal-to-noise ratio?
13. Lift-off certainly reduces the amplitude of the flux
leakage signal. The other significant effect it has on
the signal is a change in:
a. change to a test frequency that will decrease the
noise
b. increase the amplification of the test instrument
c. improve the fill factor
d. add filter circuits to the instrument
E.2-76
8.
a. phase
b. frequency
c. increasing lift-off which reduces the apparent
width of the defect
d. none of the above
P.31A
In eddy current testing, the theoretical maximum
testing speed is determined by the:
a.
b.
c.
d.
14.
magnetic flux density
testing frequency
conveyor drive
test coil impedance
a.
b.
c.
d.
A.57; C.4-33
9.
In eddy current testing of ferromagnetic materials, the
dc saturating field may be provided by:
a.
b.
c.
d.
The tubular product parameter having the greatest
influence on the flux density of the magnetic field in
the part (assuming the magnetizing force, H, remains
constant) is the:
surface roughness of the product
diameter of the product
wall thickness of the product
length of the product
V.330
15.
an encircling solenoid
a magnetic yoke
both a and b
none of the above
Any handling of equipment used in an eddy current
system must take into consideration:
a. the operator's abilities
b. the use of the product being tested
c. speed, frequency of test, sorting speed, and
physical control of the product
d. all of the above
F.E571-11.5
10. Which of the following is a property of eddy currents
induced in a conductor by an encircling coil?
G.41.19
a. the magnitude of eddy current flow is large
compared to the current flow in the coil
b. the eddy current flow is affected by permeability
variations in the sample
c. the eddy current flow dissipates no power in the
conductor
d. none of the above
C.2-21
16.
A n eddy current system lends itself to quality ratings
such as "Quality Numbers" where the product being
inspected:
a.
b.
c.
d.
11. Which of the following is a property of eddy currents
induced in a homogeneous conductor by an encircling
coil?
a. they are weakest on the conductor surface
b. the phase of the eddy currents varies throughout
the conductor
c. they travel in straight lines
d. they are maximum along the coil axis
A.177
is not defective
does not allow defective areas to be removed
is of inferior quality
has inconsistent quality
G.41.10
17. When inspecting material with eddy currents in an
automatic handling system, it is advisable to calibrate
and adjust the sensitivity levels to:
a.
b.
c.
d.
some electronic source
another NDT method
an NBS standard
an actual test part being inspected
G.41.10
12. Which factor does not affect the phase shift between
the transmitted signal and the reflected signal for a
reflection-type coil (assuming the part is
nonferromagnetic) ?
a.
b.
c.
d.
the
the
the
the
18. A distinct advantage of using handling equipment in
an eddy current test system is to reduce the error
caused by:
a.
b.
c.
d.
e.
conductivity of the sample
magnitude of the transmitted signal
thickness of the sample
presence of defects in the sample
A.177
instrument drift
lift-off
skin effect
all of the above
none of the above
C.2-24
36
Eddy Current Testing Method, Level III
19. Decreased coupling or fill factor results in decreased
test sensitivity because:
23.
a. reduced coupling between the driver coil and the
specimen induces less eddy current flow in the
specimen
b. reduced coupling between the specimen and the
pickup coil results in smaller voltages across the
pickup coil
c. electrical circuits designed to provide fill factor
compensation may prove to be inadequate,
depending upon the extent of fill factor loss
d. all of the above
A.35
20.
a. the coil becomes magnetically saturated
b. the permeability raises the inductance of the test
coil
c. the magnetic test sample's conductivity increases
the reactance value of the coil
d. this effect is described mathematically by the
B _
equation ,7 M—
A.53
24.
Why is it desirable to hold the fill factor or lift-off
constant?
a. to avoid arcing between the coil and the specimen
b. to minimize tester output signal changes that are
not relevant to conditions within the specimen to
be tested
c. a fill factor or lift-off change will shift the
operating frequency
d. to minimize the load on the constant current ac
excitation circuits
A.35
21.
The reactance component is decreased by placing a
conducting object in the coil's electromagnetic field.
Why is this so?
25.
The test coil excitation current should be held
constant so that the test piece information obtained by
an eddy current system will:
a. contain only flaw information and not indicate
variations in magnetic field strength
b. not contain signals generated by cross talk
c. not contain electrical noise
d. all of the above
A.21
26.
Test coils may be shielded with conducting material
or magnetic material to:
a.
b.
c.
d.
e.
When an excitation voltage is applied to a primary
winding, only the magnetic flux is in phase and the
secondary magnetic flux is minor. When a test object
is inserted in this coil, what action takes place?
a. the object gets hot and no information is available
b. insertion of the object cancels all information
c. the insertion of the test object intensifies the
secondary magnetic flux producing a new total
magnetic flux which can be used to supply test
information
d. by subtracting the primary voltage from the
secondary voltage, the net voltage is obtained
A.21
a. the secondary field is exactly in phase with the
primary field
b. the secondary field is at precisely 90 degrees with
the primary field
c. the phase angle between the two field components
is always greater than 90 degrees which partially
cancels the primary field
d. the secondary field is 180 degrees out of phase
with the primary field which causes a large phase
shift
A.53
22.
When a magnetic bar is placed in the coil's
electromagnetic field, the coil's reactance is
increased. What causes this phenomena?
Eddy currents flowing in the test object at any depth
produce magnetic fields at greater depths, which
oppose the primary field, thus reducing its effect and
causing what kind of change in current flow as depth
increases?
a.
b.
c.
d.
shape field
increase sensitivity
increase resolution
all of the above
none of the above
a decrease
an increase
a frequency change
none of the above
A.24
A.68
27.
Skin effect causes eddy currents to tend to flow near
the surface of the test piece. Which of the following
factors alter the skin effect?
a.
b.
c.
d.
e.
testing frequency
test piece temperature
test piece hardness
test piece permeability
all of the above
A.24
37
Eddy Current Testing Method, Level III
28.
Which of the following is not a common undesirable
effect to the test coil caused by the testing
environment?
a.
b.
c.
d.
e.
31. A n ac current produces eddy currents in a test object.
The vector H represents the secondary ac field in the
test piece. What function occurs to produce a
workable test situation? (See Figure 10.)
temperature variation
crack in test sample
test object making contact with test coil
foreign object in the test coil field
test coil vibration
a. changes in the test specimen such as a crack,
metallurgical or dimensional change alter the
secondary field phase and amplitude
b. the primary ac current must be 60 cycles to
produce this effect
c. a temperature rise in the specimen
d. a mismatch of the H and H fields produces a
change in the output
G.36.1
A.27
29. There is one function that responds to variations in
eddy current flaw and magnetic field conditions. This
function actually produces the output signal from the
coil. What is this function?
p
s
Figure 11
a.
b.
c.
d.
phasing
resistance
reactance
impedance
I A^i J J_ d component
A.199
30. The inductive reactance of a test coil, which is one of
the most important impedance quantities, depends
upon which of the following?
a.
b.
c.
d.
e.
frequency, coil inductance, coil resistance
coil inductance only
coil resistance and inductance only
frequency and coil resistance only
frequency and coil inductance only
G.36.1
Figure 10
32. To separate cracks and diameter effects for steel
cylinders, the optimum frequencies correspond to
/ / / ratios of less than (see Figure 11):
a.
b.
c.
d.
e.
10
15
50
100
150
G.37.26,37.27
38
Eddy Current Testing Method, Level III
34.
Figure 12
-0.3
-0.2
+0.2
—J
+0.3
1
10
Figure 13 indicates that the largest eddy current
indications from subsurface cracks will occur when
the frequency ratio (f/f ) is:
g
- 2
>
a.
b.
c.
d.
5 or less
15
50
150 or more
G.37.25
35.
Figure 13 indicates that the magnitude of a signal
from a subsurface crack will increase when the
frequency ratio (f/f ):
g
a.
b.
c.
d.
remains the same
decreases
increases
none of the above
G.37.24
Au
Figure 14
real
0.06
33.
a.
b.
c.
d.
0.1 and
0.4 and
2.4 and
4.0 and
-1
1
1
depth of crack
in % of diameter
Thin-walled tubes should be tested for cracks, alloy
or wall thickness at frequency ratios between (see
Figure 12):
G
0.05
0.4
2.4
4.0
10
G.38.6,38.7
Figure 13
0.12
V
\
Subs urface C ack 30% Depth
r
5
0.10
50 100 150
///,g
0.08 P
3" °-°
10 15
36.
Figure 14 indicates that when inspecting for surface
cracks in nonferromagnetic cylinders, the opdmum
frequency ratio ( / / / ) is between:
6
a.
b.
c.
d.
flf = 5
g
0.04
flf -
5 and 10
10 and 50
50 and 100
100 and 150
G.37.23,37.24
g
0.02
1
37.
= 50
2.5
~d!5(5
5
7.5
An operating frequency of 100 kHz will have the
deepest penetration in:
10
a.
b.
c.
d.
% of Diameter
titanium
copper
stainless steel
aluminum
V.80
39
Eddy Current Testing Method, Level HI
38. As the operating frequency is increased, the
impedance of the empty coil:
a.
b.
c.
d.
42. Of the following test coil systems, which would be
considered best for definitive detection of small
discontinuities in tubing?
increases
decreases
remains the same
none of the above
a.
b.
c.
d.
V.81
encircling coils
inside probe (ID) coils
surface probe coils
both a and b
G.38.25,38.36
39. Disadvantages of using a surface probe coil for the
inspection of small-diameter tubing include:
a.
b.
c.
d.
e.
43. In a test coil system, when the sensing coil is placed
near the excitation coil, which of the following
statements is true?
inability to detect small discontinuities
slow inspection speed
inherent mechanical problems
both a and c
both b and c
a. almost the same magnetic flux threads both coils
b. signals from either coil can be used to provide
information about the test piece
c. the arrangement is never sensitive to small
discontinuities
d. all of the above
e. both a and b
A.34
G.38.25
Figure 15
44. In linear time-base equipment:
a. the balance control will not affect the phase of the
signal on the CRT
b. the balance control changes the horizontal position
of the signal displayed on the CRT
c. the phase control permits initial smoothing of the
input signals
d. the phase control shifts the signal to the left or
right on the CRT
E.2-60
45. Filters are used in modulation analysis to:
40. Differential coil systems can be of which of the
following types? (see Figure 15)
a.
b.
c.
d.
e.
a. amplify crack or other discontinuity signals
b. reduce the signal-to-noise ratio
c. eliminate effect of small random changes in
conductivity and permeability of test sample
d. separate conductivity variations from permeability
variations
E.2-79
sketch no. 1
sketch no. 2
sketch no. 3
all of the above
both a and b
A.36-38; G.38.25
41. The sensing element in an eddy current system can be
which of the following?
a.
b.
c.
d.
e.
46. In modulation analysis, the type of display usually
used is:
a.
b.
c.
d.
the secondary winding of a differential coil
an absolute coil
a single winding coil
all of the above
both a and b
A.181-182
cathode ray tube
analog meter
chart recorder
digital voltmeter
E.2-70
40
Eddy Current Testing Method, Level III
47.
When the slit technique is used with the linear timebase method:
51.
a. a straight line trace will appear when the two
voltages applied to the deflection plates are 90
degrees out of phase
b. the presence of a crack in a test specimen will
generally produce a phase shift
c. changes in diameter of a rod cannot be separated
from crack effects
d. a circle w i l l appear on the screen whenever no
voltage is applied to the vertical plates
G.40.24
a. a shift in phase will move the waveform on the
CRT to the left or right
b. after calibration, the waveform on CRT will move
up or down when a discontinuity appears
c. the equipment can be adjusted so that permeability
and conductivity changes will show little or no
change in the slit value
d. dimension effects will not be displayed at the slit,
when the conductivity effect is on the horizontal
line
E.2-68
48.
52.
In linear time-base equipment, which type of signal is
applied to the horizontal deflection plates?
a.
b.
c.
d.
In the ellipse method, the following (see Figure 16)
indication should be interpreted as:
53.
a.
b.
c.
d.
change in dimension
change in conductivity and dimension
change in conductivity
no change
E.2-44
When using an inspection system having an "ellipse
display" readout, the signal applied to the vertical
input of the scope is related to that applied to the
horizontal input as follows:
a. the vertical signal is demodulated; the horizontal
signal is not
b. the vertical and horizontal signals are of the same
frequency
c. the vertical and horizontal signals are always in
phase
d. none of the above
G.40.23,40.24
Figure 16
54.
50.
Eddy current test instruments that indicate only the
magnitude of variation in total impedance of the test
coil are:
a. unable to sort aluminum rods having different
diameters, but the same chemical composition
b. normally used to measure wall thickness variations
in as-cast pipe
c. not used with cathode-ray tube indicators
d. more sensitive to dimensional changes than
variations in electrical conductivity
G.40.7
sinusoidal voltage
square-wave voltage
sawtooth voltage
amplitude-modulated sinusoidal voltage
E.2-51
49.
In cathode ray tube ellipse testing:
Which material should be selected to provide the
most effective shielding of a test coil from an external
RF field?
a.
b.
c.
d.
The ellipse test method, used with feed through coils:
fiberglass
austenitic stainless steel
copper
brass
C.4-7
a. can test rods, tubes, and wires for surface and
subsurface cracks
b. cannot be used for measuring diameter of rods that
have surface cracks
c. has limited value in the alloy sorting of nonferrous
rod
d. is not affected by lift-off variations
G.40.28
55.
To allow maximum current to flow through the coil,
the capacitor should be adjusted so that:
a. the capacitive
impedance
b. the capacitive
c. the capacitive
reactance
d. the capacitive
impedance is equal to the generator
impedance is minimum
reactance is equal to the inductive
impedance is maximum
G.40.43
41
Eddy Current Testing Method, Level 111
56. A primary-secondary coil inspection system is being
used. To suppress the primary coil signal induced in
the secondary coil, one might:
62. When performing modulation analysis testing, the
type of test coil:
a.
b.
c.
d.
a. use a differential-type secondary coil
b. add a 180 degree out-of-phase signal to the
induced signal
c. subtract an in-phase signal from the induced signal
d. any of the above
C.2-40,2-41
C.4-29
63. A major limitation of modulation analysis is that the
system is based on:
57. Which type of readout oscilloscope would be best for
examining a nonrepetitive flaw indication during high
speed testing?
a.
b.
c.
d.
a.
b.
c.
d.
a storage type
a sampling type
a type having a short persistance screen
a dual beam type
static tests
moving tests
absolute coil arrangements
differential coil arrangements
C.3-26
64. Chemical composition, alloy changes, and heat treat
changes usually have a frequency modulation that is:
G.38.36
58. An ink-writing strip chart recorder generally provides
an accurate representation of its input signal:
a.
b.
c.
d.
must be of the differential type
must be of the absolute type
can be any basic type
a and b are the best answers
i f the signal frequency is 2 000 Hz or greater
i f the signal frequency is at least 200 Hz
i f the signal frequency is limited to 20 Hz
only i f the signal frequency is limited to 2 Hz
a.
b.
c.
d.
low
medium
high
very high
C.3-25
65. Modulation would be defined as:
V.88
a. a process of comparing an instrument reading with
a standard
b. a process of grouping articles by their response to
eddy currents
c. a process of applying a variable effect to
something that is constant
d. the point where increases in the coil's magnetizing
force does not increase the material's flux density
D.5-116
59. A probe coil inspection system is being used to detect
cracks in bars. I f the cracks have a minimum length
of 6 mm (0.25 in.), reliable inspection is best
achieved by making the coil diameter:
a.
b.
c.
d.
6 mm (0.25 in.)
13 mm (0.5 in.)
any multiple of 6 mm (0.25 in.)
coil diameter is irrelevant
G.38.31
66. In modulation analysis, the coil's excitation
frequency is being modulated by:
60. To ensure reliable flaw detection, the maximum
velocity of tubing through an encircling coil must be
limited. This limitation is determined by:
a.
b.
c.
d.
the inspection coil length
the desired flaw size resolution
the test frequency
all of the above
a.
b.
c.
d.
D.5-126
C.4-29
67. Impedance changes produced by small lift-off
variations are greatest when:
61. Normal test speeds for modulation analysis testing is:
a.
b.
c.
d.
test article conductivity
test article dimensions
test article defects
all of the above
a. there is a nonconductive coating on the test
material
b. the coil is usually in contact with the test material
c. lower test frequencies are used
d. large diameter coils are used
U.280
0-1.2 m (0-4 ft)/min
1.2-9 m (4-30 ft)/min
9-91 m (40-300 ft)/min
91-1 219 m (400-4 000 ft)/min
C.4-29
42
Eddy Current Testing Method, Level HI
68.
When testing for the unknown conductivity of a
metal, the measured conductivity is strongly affected
by:
a.
b.
c.
d.
74.
PR
material thickness
coil diameter
specimen temperature
Limit frequency, f , is defined when the argument of
the mathematical function describing the
electromagnetic field within a test specimen is set
equal to:
a.
b.
c.
d.
V.78
6.25
1
0.37
0
G.36.13
69.
In selecting a coil for multifrequency tests:
a.
b.
c.
d.
70.
Figure 17
bandwidth is of major importance
frequency response is of minor importance
the Q of the coil should be less than 1
the Q of the coil should be less than the inductance
A.216
wL
O
In developing a multifrequency test, the parameter
separation limitations are greatest for those
parameters producing:
a.
b.
c.
d.
• 4
nearly similar signals
0 degrees to 90 degrees phase shifts
signals having no electrical relation
90 degrees to 110 degrees phase shifts
/
the effect two coils have on each other
the coupling between the test coil and test part
a and b
none of the above
6
0.2
/ ®
X100
yX.400
0
W 40 000
0.2
Leakage flux testing is most applicable for the
inspection of:
a. shallow surface seams on finished roller bearings
b. heavy-wall copper tubing
c. surface and subsurface cracks in hot-rolled rough
surface ferromagnetic pipe
d. soft spots on polished steel bar stock
N.122
0.4
R
wL
o
75.
Referring to Figure 17, suppose a test is being
conducted at an / / / ratio of 1. Due to a mix in
alloys, a new test piece with a conductivity value four
times as great as the original material is inserted in
the coil. The new / / / ratio will be:
a.
b.
c.
d.
Increasing the heat-treating temperature of nonferrous
metals:
a.
b.
c.
d.
1
6.25
9
/
0.4
R.29
73.
1
0.6
Mutual inductance describes:
a.
b.
c.
d.
72.
^» 2.25
0.8
A.216
71.
1
c
wL
increases electrical conductivity
will have no effect on electrical conductivity
will decrease electrical conductivity
may either increase or decrease electrical
conductivity, depending upon the alloy and the
nature of the heat treatment
G.42.19
0.25
4
16
unchanged
S.101
43
Eddy Current Testing Method, Level III
77.
Figure 18
(PL
Figure 19 illustrates:
a.
b.
c.
d.
imag
78.
variations in fill factor for a solid rod
variations in fill factor for a thin-walled tube
transition between a solid rod and thin-walled tube
all of the above
G.38.9
Figure 20 illustrates the impedance diagram for
tubing where the ratio of the inside diameter to
outside diameter is 80 percent. It is possible to
calculate an approximate limit frequency, / , by using
only the outside diameter. Thus the maximum test
sensitivity for effects of conductivity, wall thickness
and cracks occurs at a frequency ratio of:
a.
b.
c.
d.
6.25
13
25
400
GJ8.11,38.12
Figure 20
76.
Figure 18 illustrates that the separation of diameter
effects and conductivity effects:
a.
b.
c.
d.
can be accomplished at any f/f.e
can best be accomplished at / / / larger than 4
can best be accomplished at f/f less than 4
cannot he accomplished at any f/f e
G.37.2
Figure 19
= too
Normalized Resistance
79.
The electromagnetic field in a test specimen during
eddy current testing is described by:
a.
b.
c.
d.
Bessel functions
exponential functions
algebraic functions
all of these
G.36.13
44
I I Answers
Level HI
Eddy Current Testing Method
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
b
c
d
b
c
d
b
b
c
b
b
b
b
c
d
b
d
b
d
b
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
c
d
b
c
a
a
e
b
d
e
a
a
b
a
b
b
c
a
e
d
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
45
d
c
e
d
c
c
a
c
b
a
b
d
b
c
c
d
a
c
a
d
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
c
c
b
a
c
d
b
d
a
a
c
c
d
b
b
b
c
b
d
6
Level I Questions
Flux Leakage Testing Method
1.
In flux leakage testing of a ferromagnetic object,
magnetized close to the saturation point using an
encircling coil as a sensor, what is a primary
condition which needs to be met in order to obtain a
response from the flaw?
4.
Flux leakage may occur at a surface defect in a
ferromagnetic material:
a.
b.
c.
d.
a. using a coil with a high number of turns
b. providing electrical connection between coil and
tested object
c. moving the tested object in relation to the coil
d. shielding the cable which connects the coil with
the recorder
e. using a strip chart recorder
EE.62
when the magnetizing force is present
after the magnetizing force has been removed
aandb
none of the above
Z.51
5.
Flux leakage inspection can normally be applied to:
a.
b.
c.
d.
ferromagnetic and nonmagnetic material
nonmagnetic materials only
ferromagnetic materials only
nonconductors only
U.330
Figure F L - 1
£§3
Rotational transverse magnetization in bar or pipe
testing is used for the detection of:
1 x 7 Strand
What will be the relative flux leakage level on the
surface of the 1 x 7 strand cable (Figure FL-1) caused
by an outer wire break compared with that caused by
an inner wire break? (Assume that the gap between
the ends of broken wire is the same in both cases.)
a.
b.
c.
d.
3.
a.
b.
c.
d.
e.
AA.16
7.
greater
smaller
the same, i f diameters of both wires are the same
the same, even i f diameters of both wires are
different
EE.63
With rotational flux leakage detection systems,
distinctions between similar OD and I D defects are
accomplished by:
a.
b.
c.
d.
e.
What method of magnetization can be used in flux
leakage testing?
a.
b.
c.
d.
e.
transverse defects
defects that have a longitudinal component
only longitudinal defects
both transverse and longitudinal defects
only holes
observing a difference in amplitude
measurement of impedance change
observing the signal to noise ratio
frequency analysis
only by visual observation of test piece
L.54
permanent magnet
high frequency ac
dc
a and b
a and c
Z.43
47
Flux Leakage Testing Method, Level I
Figure F L - 2
Point of Interest
Lines of
Flux
8.
Using Figure FL-2, what is the vertical component of
the leakage flux at the middle of the defect gap of a
surface defect?
a.
b.
c.
d.
e.
13. The curve shown in Figure FL-3 is called a:
a.
b.
c.
d.
e.
zero
maximum
equal to horizontal component
divergent
convergent
hysteresis loop
minor loop
recoil curve
magnetization curve
permeability curve
G.33.3
Y.91
9.
In circular magnetization, the recommended
magnetizing current in amperes per linear inch of
section thickness is:
a.
b.
c.
d.
e.
200 to 400
400 to 600
600 to 800
800 to 1 000
1 000 to 1 200
G.30.13
10. Flux leakage techniques can normally examine for:
a.
b.
c.
d.
14. A Hall effect probe measures:
a.
b.
c.
d.
e.
surface flaws only
subsurface defects only
defects at any location
surface and near-surface defects
G.30.1
11. A relative motion between specimen and a.
is needed in order to pick-up leakage flux.
a.
b.
c.
d.
e.
15.
The ratio B/H is equivalent to a material's:
a.
b.
c.
d.
e.
search coil
hall probe
magneto probe
magneto resistor
piezoelectric crystal
O.302
permeability
conductivity
tangential field strength
field strength perpendicular to the probe surface
reluctance
G.33.11
field strength
reluctance
permittivity
permeability
relative permeability
G.33.15
12. For a given crack with a given magnetic field, more
magnetic lines of force are deflected out of the
magnetic path when the:
a. length of the crack is parallel to the magnetic lines
of force
b. length of the crack is perpendicular to the magnetic
lines of force
c. length of the crack is diagonal to the magnetic
lines of force
d. edges of the crack are polarized
G.30.3-4
48
Flux Leakage Testing Method, Level I
16. Which discontinuity in Figure FL-4 would show the
strongest indication?
a.
b.
c.
d.
18. In the flux leakage examination of tubular products,
which of the following discontinuities can be
detected?
A
B
C
D
a.
b.
c.
d.
U.46
longitudinally oriented
transversely oriented
slivers
all of the above
DD.627
Figure F L - 4
Magnetic
Fiell
19. In the flux leakage testing of tubular products, the
amplitude of the signal received from a discontinuity
w i l l depend upon:
Discontinuity A
D
B C
a. the depth of the discontinuity
b. the orientation of the discontinuity
c. the distance between the flux leakage sensor and
the tube
d. all of the above
e. a and c
DD.629
4>
< e - / < — ^
Magnetizing
Current
17
20. Flux leakage inspection can reveal the presence of:
a.
b.
c.
d.
e.
The optimum angle at which the magnetic field must
intersect a discontinuity in a test specimen is:
a.
b.
c.
d.
discontinuities
voids
inclusions
either b or c
a, b, and c
C.10-2
90°
60°
45°
30°
U.46
49
Level II Questions
Flux Leakage Testing Method
i.
In flux leakage inspection of wire ropes using an
encircling coil as a sensor, the response of the coil
depends on what parameters of the wire break?
a.
b.
c.
d.
6.
cross-sectional area of broken wire
location of broken wire within the cross-section
gap between the ends of the broken wire
all of the above
BB.144-46
Using Figure FL-5, flux leakage strength decreases
with distance (d) from the defect surface and is
approximately proportional to:
a.
b.
c.
d.
e.
d
1/d
1/d
1/d
1/d
2
3
4
Y.91
2.
The highest sensitivity of a Hall generator is obtained
when the direction of the magnetic field in relation to
the largest surface of the Hall probe is:
a.
b.
c.
d.
e.
parallel
at an angle of 46°
at an angle of 30° or 60°
perpendicular
none of the above
G.33.11
3.
The best flaw detection sensitivity is obtained when
the magnetizing flux is:
a.
b.
c.
d.
Using Figure FL-6, the relation between the depth
(D) of defects and signal amplitude (A) of leakage
flux is approximately ( K = constant of
proportionality):
parallel to the flaw's longest dimension
perpendicular to the flaw's shortest dimension
perpendicular to the flaw's longest dimension
none of the above
U.330
a.
b.
c.
d.
e.
In flux leakage inspection for flaws, the part being
inspected should be magnetized:
a.
b.
c.
d.
beyond saturation
to saturation or near saturation
well below saturation
using a combination of ac and dc fields
=
=
=
=
=
kl/D
kD
kD
kD
kD*
2
3
L.54
U.330
5.
A
A
A
A
A
An advantage that flux leakage testing has in
comparison with eddy current testing is that flux
leakage testing is:
a. less sensitive to interferences due to surface
roughness
b. useful on products at temperatures above the Curie
point
c. useful on austenitic steels
d. capable of much higher inspection rates
N.122-123
51
Flux Leakage Testing Method, Level 11
8.
What particular type of defect is not indicated by flux
leakage techniques?
a.
b.
c.
d.
e.
14. The number of broken wires at a particular location
on a wire rope cannot always be determined because:
overlap
grain boundary crack
slag inclusion with crack
surface contamination
longitudinal seam
a. the broken ends overlap
b. a visual inspection for verification is impossible
because the breaks are inside the rope
c. the strip chart recorder speed was too slow
d. the conditions stated above are all possibilities
e. the strip chart recorder speed was too fast
C C . l l , 16,18,19
AA.16
9.
Electric current flowing in a magnet will alter the
direction of magnetic fields in a magnet.
15. As a general rule, hard materials have:
a. true
b. false
a. high coercive force and are easily demagnetized
b. high coercive force and are not easily
demagnetized
c. low coercive force and are easily demagnetized
d. low coercive force and are not easily demagnetized
e. none of the above
G.30.22
G.30.30-34
10.
The strength of the magnetic field in the interior of a
long solenoid is determined by:
a.
b.
c.
d.
e.
the number of turns in the solenoid
the strength of applied current
the length of the solenoid
all of the above
none of the above
16. The point (P) shown on the hysteresis loop in Figure
FL-7 is called the:
a.
b.
c.
d.
e.
O.307
11.
In longitudinal magnetization by a coil, for most
effective magnetization, the part to be magnetized
should be:
a.
b.
c.
d.
12.
G.30.22
held against the inside wall of the coil
positioned in the center of the coil
held near the outside wall of the coil
held half way between the wall and center of the
coil
G.30.14
Due to the unique construction and great lengths of
wire ropes, a practical and reliable NDT technique for
testing is:
a.
b.
c.
d.
e.
acoustic emission
ultrasonics
magnetic techniques
radiation
none of the above
EE.62
13.
coercive force
initial permeability
residual field
leakage flux
demagnetization point
17. The field strength over a crack is directly proportional
to the relative permeability of the steel and the ratio:
In dc magnetic testing of steel wire ropes, one type of
magnetizing method is preferred over the other for
the following reasons:
a. crack depth
crack width
b. crack width
crack depth
a. permanent magnet: constant magnetic field
intensity, no magnetizing current
b. electromagnet: fluctuating magnetic field intensity,
heavier, more rugged construction
c. electromagnet: constant magnetic field intensity,
lighter-weight construction
d. permanent magnet: fluctuating magnetic field
intensity, heavier, more rugged construction
FF.4
c. crack length
crack depth
d. crack length
crack width
X.194
52
Flux Leakage Testing Method, Level II
A calibration standard is prepared using holes. With
respect to the reference size, it is considered good
practice to:
22. In the examination of tubular products, a
circumferential (transverse) magnetic field can be
established by:
a. include holes larger in diameter than the reference
size
b. include holes smaller in diameter than the
reference size
c. include holes both larger and smaller in diameter
than the reference size
d. include holes of the reference size only
DD.630
When testing tubes, i f the sensor bounces along the
surface this may:
a.
b.
c.
d.
In flux leakage testing, the greatest tube wall
thickness for which maximum sensitivity can be
maintained in mm (in.) is:
24. Calibration standards used in the flux leakage
examination of tubular products should be carefully
prepared since the flux leakage signal response from
the notch will be affected by:
0.08 mm (0.003 in.)
0.8 mm (0.03 in.)
8 mm (0.3 in.)
76 mm (3 in.)
a.
b.
c.
d.
e.
U.330
The following are used in determining magnetic flux
leakage:
a.
b.
c.
d.
e.
23. In the examination of tubular products where the flux
23.
sensor measures the leakage field at the outside
surface of the tube:
a. OD discontinuities are detected
b. both OD and ID discontinuities may be detected
c. both OD and ID discontinuities can be detected but
generally cannot be distinguished from each other
d. both OD and I D discontinuities can be detected
and can generally be distinguished from each other
DD.625
make it difficult to estimate fault severity
cause false signals
decrease speed of inspection
distort the magnetizing system
DD.628
a.
b.
c.
d.
a. properly positioning north and south poles of a
magnet with respect to the tube
b. using a central conductor positioned in the tube
c. a and b
d. neither a nor b
DD.629
notch orientation
notch width
notch length
notch depth
all of the above
DD.630
coil
magnetic tape
Hall element
all of the above
a and b
0.316-317
53
Level HI Questions
Flux Leakage Testing Method
1.
In flux leakage testing of wire rope, the system of two
different diameter search coils is frequently used.
What is the main reason for using such a system?
(See Figure FL-8.)
a.
b.
c.
d.
e.
to compensate the influence of testing speed
to find the radial location of wire breaks
to detect corrosion
to detect small cracks inside the rope
to detect gradual decreasing of rope diameter
GG.378
Figure F L - 8
Outside Coil
3.
Which devices are used to detect flux leakage?
a. coils, Hall probes, and transistors
b. piezoelectric crystals, Hall probes, and magnetic
diodes
c. piezoelectric crystals, transistors, and magnetic
diodes
d. coils, Hall probes, and magnetic diodes
N.123
4.
In Figure FL-10, the flux leakage at slot A w i l l be
than that at slot B.
a.
b.
c.
d.
Inside Coil
Tested Rope
greater
smaller
broader
less readily detected
Z.50
Magnet Poles
2.
Figure FL-10
Detection Probe
In flux leakage testing of wire rope, two separate
outer broken wires will produce two separate
indications i f there is sufficient distance between the
breaks. What is the maximum rope speed in feet per
minute that would produce two separate indications
when the cutoff frequency of the recorder is 60 kHz
and the breaks are 25 mm (1 in.) apart? (See Figure
FL-9.)
a.
b.
c.
d.
e.
Travel
I
0.5 mm (0.2 in.) |
60 fpm
120 fpm
240 fpm
300 fpm
360 fpm
GG.378
,
5.
Figure F L - 9
10.5 mm (0.2 in.) |
|
0.5 mm
(0.2 in..
10 mm
(0.4 in..
Slot A
Slot B
In a properly operating flux leakage system, pipe
defects occurring at increased depths from the
surface will generate signals with:
a.
b.
c.
d.
25 mm
(1 in.)
I
increased phase differences
higher frequency characteristics
lower frequency characteristics
increased signal noise ratios
L.54
55
Flux Leakage Testing Method, Level III
Figure FL-11
/ Leakage Flux
c
30
6.
A
\ 7Defect
-T
Lift-off reduces the amplitude of the flux leakage
signal. The other significant effect it has on the signal
is a:
a.
b.
c.
d.
10.
change in phase
change in frequency
change in signal noise ratio
all of the above
The tubular product parameter having the greatest
influence on the flux density of the magnetic field in
the part (assuming the magnetizing force (H) and the
material's permeability remains constant) is the:
a.
b.
c.
d.
P.31A
> Lines of Flux
chemistry of the product
diameter of the product
wall thickness of the product
length of the product
U.330
7.
Eddy current shielding, the name given to the
unidirectional eddy current flow in products inspected
by the flux leakage method, is caused by:
11. A defect having an inclined angle to the surface has a
flux leakage that is (see Figure FL-11):
a. the interaction between the test magnetic field and
a residual field in the product
b. fluctuations in the dc magnetizing current
c. rapidly occurring flux changes in the product
created by the rotation of the magnetic field
d. rapidly occurring impedance changes in the pickup coils
AA.16
a.
b.
c.
d.
Y.91
12.
A flux leakage pipe inspection system with two
inspection heads, each having 152 mm (6 in.) long
scan paths and rotating at 180 rpm on a 178 mm
(7 in.) diameter tube, can have a maximum
throughput speed of
per minute for
100% inspection coverage.
a.
b.
c.
d.
e.
lower than a similar normal defect
equal to a similar normal defect
higher than a similar normal defect
all of the above
Too high a rotational test speed or too high active
pole rotating head speed can cause the loss of an
indication from an I D defect. What can this be
attributed to?
a.
b.
c.
d.
e.
excessive generated surface noise
limitations of the flux sensor elements
eddy current shielding
reverse magnetization effect
none of the above
AA.16
201 m (660 ft)
55 m (180 ft)
49 m (162 ft)
27 m (90 ft)
25 m (81 ft)
13.
A current carrying conductor is surrounded by a tube
(see Figure FL-12). Magnetic fields exist in the tube,
i f the tube is made of:
U.330,338
a.
b.
c.
d.
e.
A flux leakage pipe inspection system with two
inspection heads, each having 152 mm (6 in.) long
inspection areas and rotating at 180 rpm on a 178 mm
(7 in.) diameter pipe, would require a throughput
speed of
per minute to provide a 110%
inspection coverage.
a.
b.
c.
d.
e.
60 m
49 m
45 m
25 m
22 m
steel
copper
aluminum
lead
all of the above
G.30.6
(198 ft)
(162 ft)
(146 ft)
(81 ft)
(73 ft)
P.22A
56
Flux Leakage Testing Method, Level III
16. What is the SI unit for magnetic flux density?
Figure FL-12
a.
b.
c.
d.
e.
U4
Tube
W.71
17.
A tube is magnetized by passing a uniform current
through the tube. There are inside and outside defects
in the tube (see Figure FL-13). The two defects have
the same dimension and geometry. The defect signal
strength:
Weber
Tesla
Ampere
Henry
Ampere per meter
W.71
18. What is the SI unit for magnetic permeability?
a.
b.
c.
d.
e.
a. is stronger for the outside defect than for the inside
flaw
b. is stronger for the inside defect than for the outside
flaw
c. is the same for both defects
d. is an uncertainty
e. depends on the permeability of the tube
G.30.6
Ampere per meter
Henry per meter
Henry
Gauss per meter
Tesla
W.72
19. A ferromagnetic part can be demagnetized by:
a.
b.
c.
d.
e.
Figure FL-13
Inside Defect
1 | -<
What is the SI unit for magnetic field strength?
a.
b.
c.
d.
e.
Conductor
14.
Weber
Gauss
Tesla
none of the above
all of the above
20.
1 u — Outside Defect
<
Figure FL-14 shows an arrangement of probe-coils in
a Forester probe used for measuring:
a.
b.
c.
d.
e.
Probe
raising its temperature above the curie point
withdrawing the part from an ac coil
alternately reversing and reducing the applied field
none of the above
all of the above
G.30.22-23
the static field component
the normal component of the tangential field
the tangential component of the normal field
the field gradient
all of the above
G.33.1
15. A discontinuity in a steel wire rope may be detected
with a dc magnetic instrument if:
Figure FL-14
a. the rope is magnetized to saturation, the
discontinuity is polarized, the speed of the rope is
great enough to induce a detectable voltage across
the discontinuity
b. the area surrounding the discontinuity is
magnetized to saturation, the discontinuity is
polarized, the speed of the rope is great enough to
induce a detectable voltage across the discontinuity
c. the rope is magnetized to saturation, the speed of
the rope is great enough to induce a detectable
voltage across the discontinuity
d the rope is magnetized to saturation, the
discontinuity is polarized
CC.10
Coil A
1
1
CoilB
57
Flux Leakage Testing Method, Level III
21. In flux leakage testing the maximum permissible
speed of probe or tube movement with respect to the
other is:
a.
b.
c.
d.
914 m/min (3 000 ft/min)
91m/min(300ft/min)
9 m/min (30 ft/min)
0.9 m/min (3 ft/min)
U.338
58
Level I, n, and III Answers
Flux Leakage Testing Method
Level I
1. c
2. a
3. e
4. c
5. c
6. b
7. d
8. a
9. c
10. d
11. a
12. b
13. d
14. d
15. d
16. d
17. a
18. d
19. d
20. e
Level II
1. d
2. d
3. c
4. b
5. a
6. c
7. b
8. d
9. a
10. d
11. a
12. c
13. a
14. d
15. b
16. c
17. a
18. c
19. b
20. c
21. d
22. c
23. d
24. e
59
Level m
1. b
2. d
3. d
4. a
5. c
6. b
7. c
8. b
9. b
10. c
11. a
12. c
13. e
14. a
15. b
16. c
17. e
18. b
19. e
20. d
21. b