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Magnetic Particle Inspection MT Flashcards

1
Q

And inspection method in which an initial magnetizing force is applied to a part and then reduce to a lower continuous value was called

A

Surge method

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2
Q

The term used to refer to the total opposition to flow of current represented by the combined effect of resistance, inductance, and capacitance of a circuit is

A

Impedance

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3
Q

Discontinuities in plate , sheet or strip caused by internal fissures, inclusions, or blow holes in the original ingot which after rolling, are usually flat and parallel to the outside surface are called

A

Laminations

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4
Q

The cumulation of particles at a site on the part surface, collected at and held to the site by the magnetic leakage field, is called

A

An indication

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5
Q

The leakage field strength is controlled by

A

The materials permeability, the depth and width of the discontinuity and the relative strength of the applied magnetic flux

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6
Q

Primarily a qualitative inspection, detecting changes in volume

A

Magnetic flux leakage - tank floor scanning, in line inspection of pipelines, wire rope, coil tubing and rail inspections

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7
Q

Relatively thin coating of paint or plating on the surface can cause a surface crack to appear as

A

Broad and fuzzy

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8
Q

When matters is place within an external magnetic field, the magnetic moments of that material’s electrons maybe reorientated. When this occurs the material produces its own macroscopic magnetic field this is known as

A

Faraday’s Law of magnetic induction

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9
Q

Any material with a negative relative permeability that is slightly less than one is

A

Diamagnetic - Mercury gold bismuth and zinc

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10
Q

When the internal magnetic field of a material is aligned in the same direction as the applied external field, and the material has a small positive suspect ability and a positive relative permeability that is slightly more than one the material is called

A

Paramagnetic- aluminum platinum copper sulfate and wood

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11
Q

When the internal magnetic field of the material is aligned in the same direction as the applied external field, and the material has a high positive suspect ability and a high positive permeability that is much greater than one, the material is called

A

Ferromagnetic

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12
Q

When an electric current is passed through the part the part is the conductor of the electric current and a circling magnetic field is established both within the inside and outside the conductor

A

Direct magnetization

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13
Q

Magnetism that results when a ferromagnetic material is influenced by an external field. Devices such as central conductors, coil’s, and yokes

A

Indirect magnetization

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14
Q

Coil where the length is greater than the diameter

A

Solenoids

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15
Q

Term used to refer to the total opposition to flow of current represented by the combined effect of resistance, inductance, and capacitance of a circuit

A

Impedance

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16
Q

Lines of force that form a path around the crack in a ring magnet

A

Magnetic lines

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17
Q

Earths field this week, how week?

A

0.3 gauss

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18
Q

Particle sizes for wet method testing ranges from

A

1 to 25 µm (micrometer)

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19
Q

When magnetic material reaches its curie temperature, the material becomes

A

Paramagnetic

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20
Q

Which type of radiation can most damage human tissue?

A

UV-B

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21
Q

µ =

A

Permeability =B/H

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22
Q

B =

A

Flux density measured in gauss (SI units measured in tesla)

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23
Q

Best technique for testing of large flat area

A

Prods

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24
Q

H =

A

Magnetizing force measured in oersted

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25
Most common wattage of mercury vapor bulbs florescent MT exams
100 W
26
Amp turns L/D, yoke, coil around part are all types of this field
Longitudinal
27
Prods, central conductor, headshot, passing current directly through part or all types of this field
Circular
28
The field established in a part when it is placed next to a conductor carrying a current, which should be avoided
Parallel magnetization
29
Useful when orientation of discontinuities are unknown (proper sequence) magnetize, apply particles, shut off current, and inspect
Multidirectional magnetization
30
Produced by simultaneously imposing two magnetizing forces in two directions where one is stronger than the other upon a magnetizable article
Vector field
31
N*I = ``` N= number of turns I = current (amps) ```
45,000/(L/D)
32
Advantage to demagnetize a part
Position east to west
33
Check concentration of particles for wet method
Settling test
34
Unit of viscosity
Centistokes
35
MT machine is calibrated with
A shunt and a calibrated ammeter
36
Determines amperage being used
Ammeter
37
Fill factor equals
10% or 10 to 1
38
One line of flux per square centimeter is
Gauss (flux density)
39
Interruption or break in the normal physical structure
Discontinuity
40
Accumulation of particles
Indication
41
Plated parts can be reliably tested at what thickness
.1 mm or.004
42
To retain a magnetic field
Retentivity or remnant
43
The ease which something can be magnetized
Permeability
44
Best subsurface inspection
Dry continuous half wave DC with prods (Deepest Penetration)
45
Best surface and subsurface
Half wave rectified AC with dry particles (most effective with greatest particle mobility)
46
Best surface
Wet fluorescent continuous AC shallowest penetration
47
Easiest to demagnetize
Longitudinal fields
48
Harder to demagnetize
Circular fields
49
Current for skin affect
AC
50
Greater in hard materials than soft materials
Resistance to demagnetization
51
When a magnetic field is at 90° to the defect, it will cause an abrupt change in this of the part
Permeability
52
Sub microscopic regions inside of material
Magnetic domains
53
Permeability less than one
Diamagnetic
54
One or slightly more
Paramagnetic
55
Many more times more than one
Ferromagnetic
56
MT particles need to have
High permeability and low retentivity
57
Human vision range is
380nm to 770 nm violet to red
58
A nano meter equals
Billionth of a meter
59
Black light is how far outside of the humans range
365 nm
60
Fluorescent particles absorb at
365 nm or 3650 angstroms
61
Fluorescent particles released at
550 nm or 5500 Å yellow green
62
Required visible light for visible MT
100 foot candles
63
Magnetic particle building from the discontinuity the strongest one the discontinuity is orientated
90° to the magnetic flux flow
64
The number of lines of flux intercepting in area perpendicular to the flux
Flux density
65
Prod spacing less than___________is usually not practical because the particles tend to band around the prize, making interpretation difficult
3 inches
66
The source that supplies the most power for magnetizing is
Three phase alternating current, full wave rectified
67
Half wave direct current is obtained from
Single phase alternating current power
68
Full wave, three phase rectified alternating current produces
Low ripple direct current
69
The timer on a bench should have an accuracy of
+/-.1 second
70
Field that is easiest to detect, but hardest to demagnetize
Circular
71
Field that is easier to demagnetize
Longitudinal
72
Shuts off current at its maximum causing the collapsing magnetic field to produce eddy currents that compensate for decreased flux density at the ends of parts
Quick break
73
Typical average output for mobile equipment is
1.5 KA to 4000 amperes
74
Single phase equipment require how many more times then three phase unit
1.73
75
Alternating current is available in voltages ranging from
120 to 440 V
76
The level of fluorescent particles and suspension should be maintained consistently, from
.1 to .4 mL in 100 mL settling test
77
Most military and commercial specifications require the test site to be darkened to
20 luxs or 2 ftc
78
The settling rate is inversely proportional to the
Liquids viscosity
79
Skin depth for 60 Hz alternating current fields is typically about
1 mm or .04 inch
80
Detects field strength because the fields creates a voltage difference between two sides of the sensor in proportion to the field strength
Hall Effect Probe
81
The hall effect probe sensitivity is increased using a ferrite ring because
Increased permeability and higher B value
82
Most likely subsurface discontinuity detectable by Mt
Stringer
83
Most difficult to detect by MT
Porosity
84
Longer shots are required with magnetic rubber due to
Higher viscosity
85
Provides information about particle concentration, magnetic properties of the particles, and the functioning of magnetizing machine
Ketos Ring Test
86
The magnetization of a ferromagnetic substance by increasing magnetic field takes place in discontinuous steps rather than continuously
Barkhausen Effect
87
A single shot magnetization method using discharge from the bank of capacitors. A means by which electrical current is built up and stored until a sufficient level is achieved to provide a predetermined magnetic field in a test object, usually saturation
Capacitor discharge method
88
A potential difference developed across a conductor at right angles to the direction of both the magnetic field and the electric current. Produce when a current flows along the rectangular conductor subjected to a transverse magnetic field. The magnitude of the voltage is proportional to the applied field.
Hall Effect
89
Radiant energy generated to the 400 to 700 nm or 4000 to 7000 angstroms wave range
Visible light
90
Yokes produce either alternating current or alternating current half wave direct current output from
120 V or 240 V alternating current single phase
91
The shot timer is typically adjustable from
.5 seconds to 1 second
92
Why is the shot timer usually set between .6 seconds and .9 seconds?
Because the timing device used to calibrate the timer has an accuracy of plus or minus .1 second
93
Mobile power supply normally operate on
240 V or 480 V
94
Mobile power supplies provide both alternating current and half wave direct current output up to
6000 A
95
Amps per 1 inch diameter of cross-section with alternating current
500 to 600 A
96
Amps per 1 inch of diameter or cross section with direct current or rectified alternating current
800 to 1000 A
97
The level of visible particles and suspension should be maintained consistently, from
1.2 to 2.4 100 mL
98
The most visible indications generally result when the depth exceeds
Five times the width

NDT Methods (9 decks)

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