Liquid Penetrant Testing

Question 1

What types of defects can liquid penetrant be used for?

Answer 1

Surface defects in a solid, non-porous material

Question 2

What materials can liquid penetrant be used on?

Answer 2

Most materials such as:
1) Ferrous
2) Non-ferrous
3) Ceramic or glass

Question 3

What materials do not work with liquid penetrant testing?

Answer 3

Materials that are absorbent, porous, or are subject to corrosion

Question 4

What size openings can be inspected by sensitive penetrants?

Answer 4

Openings that are 75 nm to 125 nm in width

Question 5

What is the procedure when using LPI?

Answer 5

1) Clean and degrease the surface
2) Apply penetrant and allow for a dwell time of 10-60 min for the penetrant to seep into the defects
3) Excess penetrant is removed
4) Apply developer to the specimen
5) The defects are examined
6) Clean the specimen of the developer and the penetrant

Question 6

What are the advantages of using LPI?

Answer 6

1) Easy to use
2) Can be used on a variety of materials
3) Can cover and test large areas quickly
4) Can inspect irregular shaped parts
5) Defects are shown right on the surface
6) Low cost and portable

Question 7

What are the disadvantages of using LPI?

Answer 7

1) Surface preparation is crucial
2) Surface cleaning after inspection is required
3) Only detects surface defects
4) Chemical handling precautions are crucial
5) Penetrant and developer have to be from the same manufacturer

Question 8

What are the two types of penetrant used and which one is the most sensitive?

Answer 8

1) Fluorescent (most sensitive)
2) Visible

Question 9

What are the 2 roles of developer?

Answer 9

1) Enhances indication by providing a color contrast between the penetrant and the background
2) Acts as a blotter to draw penetrant out of the discontinuity

Question 10

What are the 2 uses of LPI?

Answer 10

1) Defect detection
2) Leak detection