5: Techniques & Processes Flashcards

1
Q

Name 3 reasons to use Straight-Beam Testing:

A
  1. Measure thickness
  2. Detect corrosion
  3. Find disbanding/other discontinuities mostly parallel to surface
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2
Q

Name 2 reasons for Angle-Beam testing:

A
  1. Find discontinuities at an angle to front surface

2. Common for weld inspection

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3
Q

What is the reason for using Surface-Wave testing:

A

Surface breaking discontinuities with restricted access (must be a smooth surface)

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4
Q

What is Plate Wave testing used for?

A

Very thin sheets.

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5
Q

What is the most commonly used testing technique?

A

Pulse-Echo

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6
Q

What is the main component of Pulse-Echo testing?

A

A piezoelectricity charged crystal

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7
Q

What is the difference between Through-Transmission and Pitch & Catch? **

A

Through-Transmission is 2 transducer used in OPPOSITE sides of each other, but Pitch & Catch transducer can be opposite, adjacent, etc.

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8
Q

Through-Transmission is best for testing what type of material?

A

Very thick specimens

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9
Q

What are the 6 parts of an immersion tank?

A

Tank, transducer, manipulator, scan tube, carriage and bridge.

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10
Q

What type of water is used for immersion testing?

A

Room temperature and de-aerated.

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11
Q

What 3 agents are commonly added to the water?

A

Wetting agent, anti-bio agent and corrosion inhibitors.

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12
Q

How do you calculate the minimum water distance?

A

1/4 part thickness plus 6 mm

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13
Q

How do you set the water delay in immersion?

A

By calculating the minimum correct water distance

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14
Q

DACs don’t generally work on what type of lens’?

A

Spherically ground lens’

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15
Q

Resonance testing is used for….. (main purpose)

A

THICKNESS MEASUREMENT

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16
Q

What is resonance testing mainly used on?

A

Thin material.

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17
Q

When standing waves are formed, the points where the two waves constantly cancel each other out are called what?

A

Nodes

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18
Q

The points of maximum amplitude between nodes are called what?

A

Antinodes

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19
Q

The fundamental resonant frequency is what? And what is the formula?

A

The lowest frequency at which a specimen will resonate.

F = V/2T

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20
Q

The frequencies that are exact multiples of the fundamental frequency are called what?

A

Harmonics

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21
Q

When using the formula to find the fundamental frequency, as the harmonics increase by 1, what does the formula increase by?

A

1/2

Ex. FF:
T = 1/2 LAMBDA

2nd Harmonic:
T = 1 LAMBDA

3rd Harmonic:
T = 1 1/2 LAMBDA

22
Q

The thickness of a material is determined with what formula?

A

T = V/2f

23
Q

What are harmonics used for?

A

Sensitivity

24
Q

When you use harmonics, you can see a change in what?

A

Amplitude

25
Q

Describe B-Scan.

A

The method of locating probe position from the edge of part required.

26
Q

What part of the B-Scan is able to locate probe position from edge of part?

A

An encoder

27
Q

What is the most common type of B-Scan?

A

Wheel transducer

28
Q

Besides A-Scan, what is the other most common type?

A

C-Scan.

29
Q

What is a disadvantage about using a C-Scan?

A

Limited, IF ANY, info about the depth of defects.

Computers can now override this problem by converting to a different scan to determine

30
Q

Resonance is important for 2 key roles:

A
  1. Determines crystal thickness to produce probe of given frequency
  2. A form of thickness measurement (Resonance Testing)
31
Q

How are standing waves created?

A

2 similar plane waves of identical frequency, amplitude and direction of oscillation… BUT DIFFERENT direction of propagation

32
Q

Resonance causes a drastic increase in what?

A

Vibration of amplitude

33
Q

What type of wave does resonance testing use?

A

Continuous longitudinal wave (not pulsed)

34
Q

What type of waves have to meet to create standing waves?

A

Transmitted AND reflected

35
Q

Resonance does not employ what type of waves?

A

Lamb waves

36
Q

Rectification on an A-Scan instrument allows technician to read in…

A

Radio frequency (RF) or video display

37
Q

What type of view do you get with a B-Scan instrument?

A

Cross-Sectional View

38
Q

What type of view do you get with a C-Scan instrument?

A

Plan view

Similar to a radiograph display

39
Q

What are 3 advantages of a Pulse-Echo method?

A
  1. Can locate where a defect is in material
  2. One sided access required
  3. Can find multiple discontinuities at the same time
40
Q

What are two disadvantages of the Pulse-Echo method?

A
  1. Near field & dead zone effects

2. More attenuation from sound travelling twice through a material

41
Q

Through-Transmission is advantageous for both thick and thin effects because…

A

Thin: lack of dead zone effects
Thick: less attenuation (suited for automated tests on large parts)

42
Q

Two disadvantages of Through-Transmission testing?

A
  1. Need access to both sides

2. Needs to be lined up exactly

43
Q

How is the quality of a material measured with Through-Transmission?

A

A defective part will result in partial/complete loss of sound transmission.

44
Q

How is the quality of the material measured with pulse echo?

A

The pip can be interpreted and evaluated.

45
Q

What are 4 advantages of immersion testing over contact testing?

A
  1. Easier angulation of transducer
  2. Higher sensitivity possible with higher frequency
  3. Limited near zone effects
  4. Better near surface resolution
46
Q

What are the 3 different immersion testing types?

A

Bubbler/squirter, conventional and wheel transducer

47
Q

What are 3 advantages of focused transducer testing over regular immersion testing?

A

Improves sensitivity & resolution, diminishes effects caused by rough front surface/scattering

48
Q

What info does a B-Scan give?

A

Thickness of material, depth of discontinuity from front surface and the size of the discontinuity in one direction.

49
Q

What info does a C-Scan give?

A

AREA of discontinuity but not depth/orientation to front surface

50
Q

When would a C-Scan likely be used?

A

With an automated system

51
Q

What are the 3 main areas of resonance testing?

A
  1. Thickness measurement (parallel surfaces)
  2. Bond testing
  3. Detect large discontinuity oriented parallel to front surface