Conventional MPI Question & Answers_General

1. MAGNETIC PARTICLE TESTING
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GENERAL
1. Why do prod tips need to be kept clean and free from contaminants?
a. The contamination reduces the resistance so increasing current flow
b. Clean prod tips have less chance of arcing
c. Clean prods conduct current through scale much better
d. The increase in resistance with dirty prods reduces the current output
e. Both clean prod tips have less chance of arcing and the increase in
resistance with dirty prods reduces the current output
2. For one person to use prods unaided which of the following would be the
most suitable approach?
a. Hold both prods in one hand with the detaching medium in the other
b. Use the residual technique as the detecting medium can be applied
after the Magnetising force
c. Use a magnetic leech attachment to one prod with the other in one
hand and the Detecting medium in the other
d. Prods should not be used by one person due to safety precautions
3. Subjecting a ferromagnetic material to a magnetising force which
reserves in a polarity whilst at the
a. Same time remains the same strength, has what effect?
b. Demagnetisation
c. Magnetisation
d. None of the above
e. Either demagnetisation or magnetisation
4. For the highest possible sensitivity when using the continuous method
which of the following Application techniques should be used?
a. Apply current whilst applying wet magnetic ink by spray
b. Apply current whilst part is immersed in wet ink followed by removal
whilst current still Flows
c. Apply current whilst part is immersed in wet ink. Stop flow of current
whilst removing
d. All the above give the same sensitivity

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5. Which of the following processes could have the effect of reducing the
gradient of the B/H curve for a
a. Particular ferromagnetic material?
b. Cold rolling
c. Subjecting the material to stress
d. Annealing
e. Work hardening
6. An arrangement consisting of 2 C-shaped yokes connected together at right
angles will give rise to
a. Which of the following when testing a weldment?
b. A circular magnetic field
c. A longitudinal magnetic field to detect longitudinal faults
d. A vectored field to detect longitudinal faults only
e. A vectored field which will detect both transverse and longitudinal
faults
7. Which type of surface condition would be most conducive to inspection using
multi direction magnetisation by switching from one field to another at 90
degrees to the first?
a. Rough as cast
b. Brightly machined
c. Electro polished
d. Surface finish has no influence on particle build up using multi -
directional
e. Magnetisation
8. Why is demagnetisation carried out prior to magnetic particle inspection in
areas such as the aerospace industry?
a. There is the possibility of a pre-existing field which will cause an
actual magnetic field Within the tested material in an unfavourable
direction
b. The pre-existing field may nullify the applied field
c. Demagnetisation is not carried out prior to inspection
d. There is the possibility of a pre-existing field which will cause an
actual magnetic field within the tested material in an unfavourable
direction and the pre-existing field may nullify the applied field

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9. When using a central conductor to magnetise a ferromagnetic tube magnetic
field strength is greatest at what point within the system?
a. Outside surface of threading bar
b. Outside surface of tube
c. Inside surface of tube
d. At none of the above positions
10. What is the difficulty when inspecting complex parts with differing cross -
sections?
a. Under magnetisation of large sections
b. Over magnetisation of small sections masking certain areas
c. Demagnetisation prior to inspection
d. Both under magnetisation of large sections and over magnetisation of
small sections
e. masking certain areas could be correct
11. When photographing magnetic particle indications, highest definition is
obtained when which of the
a. Following films are used?
b. Slow film - coarse grain
c. Slow film - fine grain
d. Fast film - coarse grain
e. Fast film - fine grain
12. Which of the following carrier fluids used with wet magnetic inks will ha ve
the smallest change in viscosity between the temperature of 0 degrees
Celsius and 50 degrees Celsius?
a. Water
b. Oil
c. Kerosene
d. All will react in the same way to changes in temperature
13. Permanent magnets can be made out of which of the following materials?
a. Aluminium, Cobalt, and Nickel
b. Molybdenum and Aluminium
c. Copper, Nickel and Iron
d. Copper and Aluminium
e. Both Aluminium, Cobalt and Nickel, and Copper, Nickel and Iron
f. Both Molybdenum and Aluminium, and Copper and Aluminium

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14. When attempting to demagnetise with an electromagnetic yoke, which of the
following will be most effective?
a. Use a DC yoke and withdraw whilst switched off
b. Use an AC yoke and withdraw whilst energised
c. Use a DC yoke and withdraw whilst energised
d. Use an AC yoke and withdraw whilst switched off
e. Use a single pole AC electromagnet and withdraw whilst energised
15. As the magnetising force acting upon a ferromagnetic part increases what
will be the effect on the detection of faults parallel to the magnetic field?
a. Substantial increase in the possibility of detection even up to
saturation
b. Substantial increase in the possibility of detection up to approximately
two thirds
c. saturation
d. No increase in the possibility of detection even up to saturation
e. None of the above are correct
16. Which of the following magnetic fields will have the most effect on other
material and equipment affected by external flux leakage and as suc h
will more than likely require demagnetisation?
a. Longential
b. Circular
c. Circumferential
d. Longitudinal
17. When using an encircling coil to longitudinally magnetise a length of bar
material, which of the following factors are important when calculating
the amount of current to satisfactorily magnetise the bar?
a. Cross section of bar
b. Length of bar
c. Diameter of bar
d. All the above
e. Only the length of bar and diameter of bar

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18. Which of the following would not be a reason why demagnetisation would be
required after magnetic particle inspection?
a. The part is to be further machined
b. The part is to be heat treated below the curie point
c. The part is to be plated afterwards
d. The part is to be welded by automatic equipment afterwards
19. If a current of the same amperage is passed through two magnetic
conductors, one of which is twice the diameter of the other, which of the
following statements is true?
a. The magnetic field strength on the surface of the smaller bar is weaker
than on the surface of the larger bar
b. The magnetic field strength on the surface of the larger bar is stronger
than on the surface of the smaller bar
c. The magnetic field strength at the centre of the small bar is stronger
than at the centre of the large bar
d. The magnetic field strength at the centre of the small bar is weaker
than at the surface of the large bar
e. The magnetic field strength on the surface of the smaller bar is
stronger than on the surface of the smaller bar
20. If an AC (RMS) type ammeter reads 700 amps, how much peak current is
actually flowing?
a. 700 amps
b. 490 amps
c. 1400 amps
d. 987 amps
21. When carrying out magnetic particle inspection on plated parts that have
been ground why should some form of direct current be used?
a. To inspect the thickness of the non magnetic plating
b. To detect subsurface faults within the body of the plated material
c. To detect grinding cracks in the parent material below the plating
d. To detect cracks on the plated surface

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22. Non-relevant indications which may occur when inspecting ferromagnetic
parts which have been stressed beyond the yield point may be due to the
presence of?
a. Bend cracks
b. Luder lines
c. Work hardening
d. Non metallic inclusions
23. Magnetic writing indications produced where an electromagnetic yoke leg
has been placed can give indications on further processing called?
a. False
b. Non relevant true
c. Relevant true
d. Both False and Non relevant true could be correct
24. Stress corrosion cracking which occurs predominantly in a direction
perpendicular to the tensile stress whilst also in a corrosive atmosphere
has which of the following characteristics?
a. Transgranular
b. Intergranular
c. Ductile fracture
d. Either transgranular or Intergranular
25. As the depth of a detectable flaw increases below the surface the powder
pattern will become which of the following?
a. Clear and narrow
b. Diffuse and wider
c. Clear and wider
d. Diffuse and narrow
26. In an attempt to depth a crack found with magnetic particle inspection
which other method of NDT
a. Could be used?
b. Liquid penetrant
c. Leak testing
d. Grinding to clear
e. Ultrasonic

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27. A large turbine gear shaft is in the preliminary stages of machining, when
periodic inspection reveals a rather gross crack. Which of the following
would be the best way to proceed?
a. Grind a notch across the crack to size the depth and determine if the
entire crack can be removed within dimensional tolerances
b. Carry on and machine the part hoping that the crack will clear
c. Fully grind out the crack to determine the depth all along the length to
make sure it can be removed within dimensional tolerances
d. Scrap the part as any discontinuity will cause a stress concentration
even if it was eventually removed within tolerance
28. Which of the following faults would not be detected on a sand casting
which has been machined after the initial casting process?
a. Shrinkage crack
b. Fatigue crack
c. Blow hole
d. Cold shut
e. Unfused chaplet
29. Non metallic inclusions can also be found with magnetic particle inspection
as well as cracks. This is due to a change in what property of the
inclusion in relation to the parent materials?
a. Conductivity
b. Flux leakage
c. Hysteresis
d. Permeability
30. A fault on the surface of a rolled bar is present due to blowholes elongating
along the length of the bar. How would this fault be termed?
a. Underfill
b. Seam
c. Roke
d. Crack

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31. The following is a description for the formation of magnetic particle
indications when testing a weldment with HWDC to give the dry powder
mobility. 'A very weak and not clearly defined indication'. Which of the
following would produce such indications?
a. Subsurface crack
b. Surface breaking porosity
c. Subsurface porosity
d. Surface breaking crack
32. Metallurgic al changes of the like which appear close to the centre of a cold
chisel due to heat treatment may give rise to what type of indication?
a. False
b. False - non relevant
c. True
d. True - non relevant
e. Both False - non relevant and True non - relevant are correct
33. On completion of a butt weld after cooling the entire weld and HAZ is
inspected with MPI revealingno faults. On subsequent inspection 48
hours later again with MPI prior to service conditions a linear indication
is found within the HAZ running in the same direction as the weld bead.
Which of the following is the most likely name for this fault?
a. Hot crack
b. Fatigue crack
c. Cold crack
d. The fault could be any of the above
34. The following is a description of a fault which occurred in four positions at
90 degrees to each other towards one end of a cast steel tube on the
outer periphery made by sand casting. The individual indications range in
size but seem to indicate a linear circular fault which in once case is a
complete circle. Which of the following best describes the fault?
a. Cold shut
b. Hot tear
c. Unfused chaplet
d. Porosity
e. Both Cold shut and unfused chaplet
f. Both Hot tear and porosity

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35. Which of the following techniques would be considered to be the most
sensitive for detection of surface breaking faults on materials with high
Retentivity if the length of time taken to carry out the inspection is of no
consequence?
a. Continuous - wet
b. Residual - wet
c. Continuous - dry
d. Residual – dry
36. When magnetic particles from a wet magnetic ink bec ome stranded in
drainage lines such as the toe of a weld when the carrier fluid drains
away, what type of indication can build up?
a. False indication
b. True - non relevant indication
c. True - relevant indication
d. Crack - line indication
37. When using circular magnetisation to check bar material an overall pattern
of circular bands is observed with a bristling of the particles. What is this
phenomena called?
a. Fuzzing
b. Gaussing
c. Furring
d. Under magnetisation
38. When using prods with HWDC to inspect a single V plate butt weld two
slightly subsurface parallel lines were observed quite weak and poorly
defined running in the direction of the weld. What is the most likely
cause for these indications?
a. Lack of root penetration
b. Undercut
c. Slag indications
d. Cooling cracks

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39. A very fine indication was observed on an in-service inspection of a
rotating shaft in a pump at a sharp change in section and was originally
considered to be non relevant. On subsequent inspection 6 months later
it was observed that the indication had grown by nearly 25%. What is the
most likely cause for this indication?
a. Grinding crack
b. Fatigue crack
c. Stringer
d. Inclusion propagation
40. Which of the following could give rise to true non-relevant magnetic
particle indications?
a. Areas of cold work
b. Heavy rough machining
c. Brazed joints
d. Both areas of cold work and brazed joints
e. All of them
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11. MAGNETIC PARTICLE TESTING
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1. e 11. c 21. c 31. c
2. c 12. d 22. b 32. d
3. c 13. e 23. b 33. c
4. b 14. b 24. d 34. e
5. d 15. d 25. b 35. b
6. e 16. d 26. e 36. a
7. a 17. d 27. c 37. c
8. d 18. b 28. b 38. c
9. c 19. e 29. d 39. b
10. d 20. d 30. b 40. e