Inspection (5)

Question 1

Minimum Black Light Intensity for Inspection:

Answer 1

1000uW/cm² at 38cm from inspection surface

Question 2

What is Signal to Noise Ratio?

Answer 2

difference between brightness of relevant indications in comparison to the brightness of any non-relevant indications.

Signal = relevant 
Noise = non-relevant

Question 3

Three types of indications:

Answer 3

1. non-relevant
2. false
3. relevant

Question 4

What are non-relevant indications?

Answer 4

caused by bleed out, but indicate a normal condition due to difficulty in removing excess penetrant resultant of the parts natural shape.

Question 5

Examples of non-relevant indications

Answer 5

• threads
• keyways
• rough surfaces
• scale
• rivets
• change of cross section

Question 6

What are False indications?

Answer 6

indications that do not involve bleed out.
Due to:
- poor washing
- lint, dirt, oil
- transfer prints

Question 7

What are relevant indications?

Answer 7

Discontinuities - break in continuous nature of a part.

Defects - condition that adversely affects the use of a part.

Question 8

Interpretation

Answer 8

the process of determining the cause of an indication

Question 9

Evaluation

Answer 9

using a specification or code to call an indication as acceptable or reject-able

Question 10

Parts of interpretation:

Answer 10

• Shape
• Size
• Location

Question 11

Interpretation: Shape

Answer 11

• continuous & elongated
• intermittent & elongated
• round
• small dots
• diffuse weak

Question 12

Interpretation: Size

Answer 12

• brilliance of indication
• persistence after repeated removal
• time or how long it takes for the indication to form

Question 13

Interpretation: Location

Answer 13

• changes in cross section
• corners or edges
• parting/flashlines
• welds (HAZ)
• internal passages (leak testing)

Question 14

What is reject/accept criteria determined by?

Answer 14

• consequence of failure
• cost of replacement
• probability of failure
• size (length, depth, location)
• distribution and frequency
• shape and type
• stress analysis (modeled and experimental)

Question 15

Good reports communicate:

Answer 15

• who (did if and for whom)
• when (the work was done)
• where (the inspection was performed including part location and serial numbers)
• how (the work was done i.e. procedure and methods, equipment)
• what (was discovered i.e. inspection results)