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Flashcards in NDT Deck (23):
0

Eddy current

-only one that needs A/C
-very good for checking surface and subsurface cracks beneath paint
-very fast & cheap
-pieces can be non-magnetic and conductive
-coil is the basic component

1

Liquid penetrant

-enters flaw through capillary action
-area around flaw needs to be cleaned at least 1" around
-widely used in leak detection in welded thin walled vessels

2

Solvent removable

-dye penetrant used for small area of a work piece

3

Fluorescent dye penetrant

-requires ultra violet light
-does not detect internal flaws

4

Magnetic particle inspection

-Sprinkle workpiece with dry iron powder or submerge in a liquid with suspended iron particles
-depth of 1/4"
-electric current is used to magnetize,but regular magnets can work as well
-90 degrees or right angles to the defect
-portable equipment

5

Dwell time

-Time a penetrant or developer is in contact with a surface

6

Discontinuity

-interruption in normal structure such as crack, seam, porosity

7

Contrast in X-ray

-different degrees of darkening on the film

8

Definition in X-ray

-sharpness the image is projected on the film

9

Destructive testing

-tensile
-compressive
-torsion
-fatigue
-hardness
-impact

10

Non-destructive

-visual
-dye penetrant
-magnetic particle
-ultrasonic
-radiography

11

Radiography

-Electromagnetic energy
-Uses gamma & X-ray
-can be used for thick materials

12

Ultrasonic

-Up to 20ft
-High frequency sound waves between 20,000 cycles per second and 10,000,000
-for longitudinal & shear waveforms

13

Penetrameter

-Measures quality of radiography
-a plate with 3 holes in it 2% of the thickness of the specimen

14

Ultrasonic sound waves

-Electric pulses generated from the crystals and reflects back
-highly sensitive, but rough or small pieces are hard to test

15

Couplant

-gel, oil or water
-allows the sound beam to go from the transducer to the test piece

16

Retentivity

-easily loses its magnetism

17

Magnetic permeability

-easy to magnetize

18

Direct current

-penetrate the cross section of the part
-use single or three phase with a rectifier

18

Alternating current

-fields are confined to the metal at or near the surface of the part (skin effect)
-should not be used for subsurface discontinuities
-single phase only for magnification purposes

19

Magnetized bars

-magnetic lines of force flow through the bar south to north

20

X-ray

-best for checking engine or compressor cylinder heads

21

Gamma rays

-iridium 192 .25" to 3.5"
-cobalt 60 1" to 7"
-shielding container is the camera
-container holding the material is called the source