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2A2-5: Testing of Metals > Objective 09: Radiographic Testing > Flashcards

Objective 09: Radiographic Testing Flashcards

1
Q

What kinds of flaws does Radiographic Testing reveal?

A

Flaws that are internal or on an inside surface

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2
Q

What kind of images does Radiographic Testing produce nowadays

A

Filmless radiography captures an image, digitally enhances it, and sends the image anywhere in the world

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3
Q

What is the benefit of Radiographic Testing producing digital images?

A

They don’t deteriorate with time

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4
Q

What is the state of equipment nowadays used for Radiographic Testing?

A

They use small, light, and portable equipment that produces high-quality x-rays. Linear acceletators generate extremely short wavelength, highly penetrating radiation.

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5
Q

What principle is Radiographic Testing based on?

A

In the presence of flaws there is a differential absorption of penetrating radiation. Variations in density, composition and thickness result in the component being radiographed while absorbing different amounts of penetrating radiation.

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6
Q

What is the basic procedure of Radiographic Testing?

A
  1. Unabsorbed radiation passes through the test component and exposes a film
  2. The exposed film indicates the varying amounts of radiation passing through the component and gives a permanent record of test
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7
Q

What source of radiation is used to produce X-rays for Radiographic Testing?

A

X-rays are produced by high-speed electrons striking a metal target, causing a transfer of energy. An X-Ray tube in an x-ray machine produces the high-speed electrons.

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8
Q

What source of radiation is used to produce X-rays for Radiographic Testing?

A

X-rays are produced by high-speed electrons striking a metal target, causing a transfer of energy. An X-Ray tube in an x-ray machine produces the high-speed electrons.

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9
Q

What source of radiation is used to produce Gamma Rays for Radiographic Testing?

A

Gamma rays are emitted from radioisotopes, e.g. Cobalt 60 and Iridium 192, as they decay

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10
Q

What are some applications of Radiographic Testing in the pressure equipment industry?

A
  1. If something is inside a pressure component
  2. Material thickness measurements to help determine corrosion rates
  3. Testing of welds
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11
Q

What discontinuities can be revealed by Radiographic Testing?

A
  1. Voids
  2. Porosity
  3. Incomplete Penetration
  4. Cupping
  5. Incomplete fusion
  6. Internal Bursts
  7. Thickness variations
  8. Corrosion, thinning and pitting
  9. Shrinkage cracks
  10. Slag inclusions
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12
Q

What discontinuities can be revealed by Radiographic Testing?

A
  1. Voids
  2. Porosity
  3. Incomplete Penetration
  4. Cupping
  5. Incomplete fusion
  6. Internal Bursts
  7. Thickness variations
  8. Corrosion, thinning and pitting
  9. Shrinkage cracks
  10. Slag inclusions
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13
Q

What are the 4 essential steps to completing Radiographic Testing?

A
  1. Source Selection
  2. Set-Up
  3. Exposure of test component to the radiation source
  4. Film development
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14
Q

What are the 4 essential steps to completing Radiographic Testing?

A
  1. Source Selection
  2. Set-Up
  3. Exposure of test component to the radiation source
  4. Film development
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15
Q

How much time is devoted to Set-Up for Radiographic Testing?

A

60%

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16
Q

Why is so much time devoted to Set-Up for Radiographic Testing?

A

Radiographic Testing requires constant attention to safety. Large doses of x-rays or gamma rays kill human cells and massive doses can cause severe dsability or death. Safety is a concern for both operators and anyone else in areas where Radiographic Testing is used.

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17
Q

How do workers measure their exposure to radiation?

A

By wearing a Dosimeter clipped to their clothing

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18
Q

How do workers measure their exposure to radiation?

A

By wearing a Dosimeter

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19
Q

Dosimeter

A

A pen shaped device that measures the cumulative dose of radiation it receives

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20
Q

What are the main components of a Dosimeter?

A
  1. Ionization chamber which is sensitive to radiation
  2. Quartz fibre electrometer to measure the charge
  3. Microscope to read the shadow of the fibre on a reticle
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21
Q

What is the composition of the reticle of a Dosimeter?

A

It consists of a network of dots, wires, crosshairs or fine lines in the focal plane of an optical instruments eyepiece

22
Q

What is the composition of the electrometer of a Dosimeter?

A

It contains 2 electrodes, one of which is a movable quartz fibre

23
Q

What is the intial state of the electrometer of a Dosimeter?

A

It is charged to a predetermined voltage which causes its electrodes to assume a calibrated separation

24
Q

How is the reading from a Dosimeter read?

A

Illumination for the optical system is obtained by pointing the dosimeter at any convenient light source. Light passes through the clear glass bottom seal to illuminate the reticule

25
Q

How is a Dosimeter charged?

A

An insulated charging pin is contained in the bellows. When charging, the charging pin moves up to contact the electrometer, thereby closing the circuit. Sufficient voltage is applied to recharge the system.

26
Q

What factors are considered when selecting a Radiographic Testing technique?

A
  1. The size and geometry of the component being tested
  2. Typical defect type, size, location, and orientation
  3. Whether shop or field testing is necessary
  4. Assurance of personnal safety
  5. Size of discontinuity anticipated
  6. Whether both sides of the component can be accessed as this is required to place the film
27
Q

How large must flaws be in order to be detected by Radiographic Testing?

A

At least as large as 2% of the penetration thickness

28
Q

What are the 3 basic steps to interpreting radiographs from Radiographic Testing?

A
  1. Detection
  2. Interpretation
  3. Evaluation
29
Q

What does interpretaion of radiographs require from the radiographer?

A

Visual acuity

30
Q

Visual Acuity

A

The ability to detect a spatial pattern in an image

31
Q

What 2 factors aid a radiographers visual acuity?

A
  1. Lighting condition in the place of viewing

2. Experience level for recognizing various features in the image

32
Q

Which discontinuities are typical of all types of welding?

A
  1. Cold Lap
  2. Porosity
  3. Cluster Porosity
  4. Slag Inclusions
  5. Incomplete Penetration (IP)/Lack of Penetration (LOP)
  6. Incomplete Fusion
  7. Internal Concavity/Suck Back
  8. Internal or Root Undercut
  9. External or Crown Undercut
  10. Offset or Mismatch
  11. Inadequate Weld Reinforcement
  12. Excess Weld Reinforcement
  13. Cracking
33
Q

Cold Lap

A

Condition where the weld filler metal does not properly fuse with the base metal or the previous weld pass material (interpass cold lap). The arc does not melt the base metal sufficiently and causes the slightly molten puddle to flow into the base material without bonding.

34
Q

Porosity

A

Void in the material due to gas entrapment in the solidifying metal which has a radiographic density more than the surrounding area and often appears as dark round or irregular spots or specks appearing singularly, in clusters or rows.

35
Q

Wormhole Porosity

A

Porosity that results from gas attempting to escape while the metal is still in a liquid state and appears elongated with a tail

36
Q

Cluster Porosity

A

Porosity that is caused when flux coated electrodes are contaminated with moisture that turns into gases when heated and then become trapped in the weld during the welding process. It appears like regular porosity in the radiograph, but the indications are grouped close together.

37
Q

Slag Inclusions

A

Non-metallic solid material entrapped in a weld metal or between weld and base metal that appear as dark, jagged asymmetrical shapes within the weld or along the weld joint areas on radiographs

38
Q

Incomplete Penetration (IP)/Lack of Penetration (LOP)

A

Lack of penetration which occurs when the weld metal fails to penetrate the joint and creates a stress riser from which a crack may propagate. On a radiograph it appears as a dark area with well-defined, straight edges that follows the land (root face) down the centre of the weldment

39
Q

Incomplete Fusion

A

Condition where the weld filler metal does not properly fuse with the base metal and appears as a dark line or lines oriented in the direction of the weld seam along the weld preparation or joining areas.

40
Q

Internal Cavity/Suck Back

A

Condition where the weld metal has contracted as it cools and has been drawn up into the root of the weld and looks on a radiograph similar to lack or penetration but with irregular edges and often quite wide in the centre of the weld image

41
Q

Internal or Root Undercut

A

Erosion of the base metal next to the root of the weld which appears on the radiographic image as a dark, irregular line offset from the centerline of the weld

42
Q

External or Crown Undercut

A

Erosion of the base metal next to the crown of the weld and appears on the radiograph as a dark irregular line along the outside edge of the weld area

43
Q

Offset or Mismatch

A

Condition where 2 pieces being welded together are not properly aligned and on the radiographic image, there is a noticeable difference in density between the 2 pieces

44
Q

Inadequate Weld Reinforcement

A

Area of a weld where the thickness of weld metal deposited is less than the thickness of the base material. This area appears darker on a radiograph than the surrounding base material

45
Q

Excess Weld Reinforcement

A

An area of a weld that has weld metal added in excess of what is specifyed by engineering drawings and codes and that appears as a localized, lighter area of the weld.

46
Q

How does Cracking appear in radiographs?

A

It can only be detected if the crack is propogating in a direction that produces a change in thickness parallel to the x-ray beam and appears as jagged and often very faint irregular lines

47
Q

What discontinuities are peculiar to TIG Welds?

A
  1. Tungsten Inclusions

2. Oxide Inclusions

48
Q

How do Tungsent Inclusions occur?

A
  1. Tungsten electrode accidentally contacts the weld puddle
  2. Tungsten electrode contacts the filler rod
  3. Current settings are excessive, causing the tungstem electrode to overheat
  4. Electrode is improperly installed in the gun
  5. Electrode is damaged (internal cracks)
  6. Improper shielding gas is used
  7. Shielding gas supply is interuppted or inadequate
49
Q

How does Tungsten Inclusion appear on a radiograph?

A

Since tungsten is denser than aluminum or steel, it appears as a lighter area with a distinct outline

50
Q

Oxide Inclusion

A

Usually visible on the surface of material being welded and, due to being less dense than the surrounding materials, appear as dark, irregularly shaped discontinuities

2A2-5: Testing of Metals (12 decks)

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