Testing of Materials Questions and Answers – Liquid Penetrant & Magnetic Particle Inspection

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This set of Testing of Materials online quiz focuses on “Liquid Penetrant & Magnetic Particle Inspection”.

1. What is the disadvantage of the liquid penetrant test?
a) Expensive
b) Slow
c) Not reliable
d) Depth restriction
View Answer

Answer: d
Explanation: LPI is a fast, non-expensive and reliable test. It is limited by the depth of the defect. So disadvantage of Liquid penetrant testing is depth restriction.
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2. Liquid penetrant test can’t be used on _________ specimen.
a) Large
b) Simple
c) Complex
d) Internally defected
View Answer

Answer: d
Explanation: Penetrant is applied on the surface so surface defects only can be detected. LPI can be applied to large, small, simple or complex shapes.

3. Which is the correct order for the liquid penetrant test?
a) Penetrant apply, development, inspection, surface preparation
b) Surface preparation, penetrant apply, development, inspection
c) Penetrant apply, development, surface preparation, inspection
d) Development, surface preparation, penetrant apply, inspection
View Answer

Answer: b
Explanation: Firstly surface is cleaned. Penetrant is applied and surface flow is made visible. Finally, surface is inspected.
The correct order for liquid penetrant testing is:
–> Surface preparation
–> Penetrant apply
–> Indication development
–> Inspection.
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4. What is general dwell time?
a) 20 seconds
b) 2 minutes
c) 20 minutes
d) 2 hours
View Answer

Answer: c
Explanation: Generally dwell time is kept 20 to 30 minutes. It can be increased depending on size.

5. ___________ increases the visibility of the flaw in liquid penetrant inspection.
a) Developer
b) Penetrant
c) Benzene
d) Spirit
View Answer

Answer: a
Explanation: Function of a developer is to make flaw visible. It provides the required contrast and it sucks out the penetrant from the cracks to make clear indications.
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6. Developer is chosen such as benzene.
a) True
b) False
View Answer

Answer: b
Explanation: Developer is usually a fine chalk or talc powder. It is applied on the surface by dusting or by spraying.

7. Small components are dipped in penetrant.
a) True
b) False
View Answer

Answer: a
Explanation: Dwell time vary with component size. Small components are dipped into a liquid penetrant bath.
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8. Which of the following material can be tested by magnetic particle testing?
a) Diamagnetic
b) Non-magnetic
c) Paramagnetic
d) Ferromagnetic
View Answer

Answer: d
Explanation: Magnetic particle testing works only on materials that can be magnetized easily. Ferromagnetic materials can be magnetized easily and these are also called as permanent magnets.

9. Which of the following material can’t be tested by magnetic particle testing?
a) Co
b) Fe
c) Ni
d) Mg
View Answer

Answer: d
Explanation: Magnesium (Mg) is a non-magnegnetic material. So, it can’t be tested by magnetic particle inspection. Whereas Cobalt (Co), iron (Fe) and Nickel (Ni) are ferromagnetic materials.
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10. What is Curie point for most of the ferrous magnetic materials?
a) 550˚C
b) 760˚C
c) 910˚C
d) 1133˚C
View Answer

Answer: b
Explanation: The Curie point for most of ferrous magnetic materials is760˚C. Above it, these don’t show ferromagnetism.

11. The minimum width of crack, which can be inspected by magnetic particle inspection is _________
a) 1nm
b) 1µm
c) 10µm
d) 1mm
View Answer

Answer: b
Explanation: A surface crack of width as fine as 1µm can be detected. Subsurface flaws can also be inspected using this method.

12. What is the advantage of using direct current in magnetic particle inspection?
a) Battery maintenance
b) Demagnetize easy
c) Variable voltage supply
d) Subsurface detection
View Answer

Answer: d
Explanation: Sub-surface flaws can also be detected by using direct current supply due to its higher penetration. But demagnetization of the specimen becomes difficult.

13. Benzene and alcohol are used to decrease component.
a) True
b) False
View Answer

Answer: a
Explanation: The surface of the component must be cleaned before MPI. Benzene and alcohol are used to decrease.

14. Plain carbon steels are applied with magnetic particles by a residual method?
a) True
b) False
View Answer

Answer: b
Explanation: Plain carbon steels are soft magnetic materials. The method of applying magnetic particles is continuous.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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