Classification of Discontinuities

Question 1

What is a false indication?

Answer 1

an indication produced by something other than a discontinuity; many times a false indication arises from improper handling procedures.

Question 2

Causes of false indications with liquid penetrant:

Answer 2

bad housekeeping, improper cleaning, under-washing, over-developing, dirty hands, lint, improper re-development (wiping with acetone swab), white light (shadows)

Question 3

What is a non-relevant indication?

Answer 3

an indication that is caused by a condition or type of discontinuity that is NOT REJECTABLE.

Question 4

1. Examples of non-relevant indications:

Answer 4

an indication that is too small to be considered relevant.

Question 5

2. Examples of non-relevant indications:

Answer 5

result from intentional interruptions in a part such as a change in section geometry, ie key holes, threads.

Question 6

3. Examples of non-relevant indications:

Answer 6

changes in thickness or hardness, or a physical condition that is not a discontinuity

Question 7

What is a relevant discontinuity?

Answer 7

the result of an actual discontinuity and must be evaluated by a qualified inspector to determine the severity of the discontinuity

Question 8

Relevant discontinuities are …

Answer 8

those indications which have been measured against the applicable code, specification, and/or acceptance criteria and found unacceptable.