Non-destructive testing(NDT) is a wide group of analysis techniques
Dye penetrant inspection
1. Dye penetrant inspection
From Wikipedia, the free encyclopedia
1. Section of material with a surface-breaking crack that is not visible to the naked eye.
2. Penetrant is applied to the surface.
3. Excess penetrant is removed.
4. Developer is applied, rendering the crack visible.
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Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant
testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects
in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non-
ferrous materials and ferrous materials, although for ferrous components magnetic-particle inspection is
often used instead for its subsurface detection capability. LPI is used to detect casting, forging and
welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue
cracks on in-service components.
Contents
[hide]
1 History
2 Principles
3 Materials
4 Inspection steps
5 Advantages and disadvantages
6 Standards
2. 7 References
8 See also
9 External links
[edit]History
The oil and whiting method used in the railroad industry in the early 1900's was the first recognized use
of the principles of penetrants to detect cracks. The oil and whiting method used an oil solvent for
cleaning followed by the application of a whiting or chalk coating, which absorbed oil from the cracks
revealing their locations. Soon a dye was added to the liquid. By the 1940's, fluorescent or visible dye
was added to the oil used to penetrate test objects.
Experience showed that temperature and soak time were important. This started the practice of written
instructions to provide standard, uniform results. The use of written procedures has evolved, giving the
ability for design engineers and manufacturers to get the high standard results from any properly trained
and certified liquid penetrant testing technician.
[edit]Principles
DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-
breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or
brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a
developer is applied. The developer helps to draw penetrant out of the flaw where a invisible indication
becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending upon
the type of dye used - fluorescent or nonfluorescent (visible).
[edit]Materials
Penetrants are classified into sensitivity levels. Visible penetrants are typically red in color, and represent
the lowest sensitivity. Fluorescent penetrants contain two or more dyes that fluoresce when excited
by ultraviolet (UV-A) radiation (also known as black light). Since Fluorescent penetrant inspection is
performed in a darkened environment, and the excited dyes emit brilliant yellow-green light that contrasts
strongly against the dark background, this material is more sensitive to small defects.
When selecting a sensitivity level one must consider many factors, including the environment under
which the test will be performed, the surface finish of the specimen, and the size of defects sought. One
must also assure that the test chemicals are compatible with the sample so that the examination will not
cause permanent staining, or degradation. This technique can be quite portable, because in its simplest
form the inspection requires only 3 aerosol spray cans, some lint free clothes, and adequate visible light.
3. Stationary systems with dedicated application, wash, and development stations, are more costly and
complicated, but result in better sensitivity and higher samples through-put.
[edit]Inspection steps
Below are the main steps of Liquid Penetrant Inspection:
1. Pre-cleaning:
The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale that could either keep
penetrant out of a defect, or cause irrelevant or false indications. Cleaning methods may
include solvents, alkaline cleaning steps, vapor degreasing, or media blasting. The end goal of this step
is a clean surface where any defects present are open to the surface, dry, and free of contamination.
Note that if media blasting is used, it may "work over" small discontinuities in the part, and an etching
bath is recommended as a post-bath treatment.
2. Application of Penetrant:
The penetrant is then applied to the surface of the item being tested. The penetrant is allowed "dwell
time" to soak into any flaws (generally 5 to 30 minutes). The dwell time mainly depends upon the
penetrant being used, material being testing and the size of flaws sought. As expected, smaller flaws
require a longer penetration time. Due to their incompatible nature one must be careful not to apply
solvent-based penetrant to a surface which is to be inspected with a water-washable penetrant.
3. Excess Penetrant Removal:
The excess penetrant is then removed from the surface. The removal method is controlled by the type of
penetrant used. Water-washable, solvent-removable, lipophilic post-emulsifiable, or hydrophilic post-
emulsifiable are the common choices. Emulsifiers represent the highest sensitivity level, and chemically
interact with the oily penetrant to make it removable with a water spray. When using solvent remover and
lint-free cloth it is important to not spray the solvent on the test surface directly, because this can remove
the penetrant from the flaws. If excess penetrant is not properly removed, once the developer is applied,
it may leave a background in the developed area that can mask indications or defects. In addition, this
may also produce false indications severely hindering your ability to do a proper inspection.
4. Application of Developer:
After excess penetrant has been removed a white developer is applied to the sample. Several developer
types are available, including: non-aqueous wet developer, dry powder, water suspendable, and water
soluble. Choice of developer is governed by penetrant compatibility (one can't use water-soluble or
suspendable developer with water-washable penetrant), and by inspection conditions. When using non-
aqueous wet developer (NAWD) or dry powder, the sample must be dried prior to application, while
4. soluble and suspendable developers are applied with the part still wet from the previous step. NAWD is
commercially available in aerosol spray cans, and may employ acetone, isopropyl alcohol, or a propellant
that is a combination of the two. Developer should form a semi-transparent, even coating on the surface.
The developer draws penetrant from defects out onto the surface to form a visible indication, commonly
known as bleed-out. Any areas that bleed-out can indicate the location, orientation and possible types of
defects on the surface. Interpreting the results and characterizing defects from the indications found may
require some training and/or experience [the indication size is not the actual size of the defect]
5. Inspection:
The inspector will use visible light with adequate intensity (100 foot-candles or 1100 lux is typical) for
visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 micro-watts per centimeter
squared is common), along with low ambient light levels (less than 2 foot-candles) for fluorescent
penetrant examinations. Inspection of the test surface should take place after a 10 minute development
time. This time delay allows the blotting action to occur. The inspector may observe the sample for
indication formation when using visible dye. It is also good practice to observe indications as they form
because the characteristics of the bleed out are a significant part of interpretation characterization of
flaws.
6. Post Cleaning:
The test surface is often cleaned after inspection and recording of defects, especially if post-inspection
coating processes are scheduled.
[edit]Advantages and disadvantages
The main advantages of DPI are the speed of the test and the low cost. The main disadvantages are that
it only detects surface flaws and it does not work on very rough surfaces. Also, on certain surfaces a
great enough color contrast cannot be achieved or the dye will stain the workpiece. [1]
Limited training is required for the operator — although experience is quite valuable. Proper cleaning is
necessary to assure that surface contaminants have been removed and any defects present are clean
and dry. Some cleaning methods have been shown to be detrimental to test sensitivity, so acid etching to
remove metal smearing and re-open the defect may be necessary. [citation needed]
[edit]Standards
International Organization for Standardization (ISO)
ISO 3059, Non-destructive testing - Penetrant testing and magnetic particle testing - Viewing
conditions
5. ISO 3452-1, Non-destructive testing. Penetrant testing. Part 1. General principles
ISO 3452-2, Non-destructive testing - Penetrant testing - Part 2: Testing of penetrant materials
ISO 3452-3, Non-destructive testing - Penetrant testing - Part 3: Reference test blocks
ISO 3452-4, Non-destructive testing - Penetrant testing - Part 4: Equipment
ISO 3452-5, Non-destructive testing - Penetrant testing - Part 5: Penetrant testing at
temperatures higher than 50 °C
ISO 3452-6, Non-destructive testing - Penetrant testing - Part 6: Penetrant testing at
temperatures lower than 10 °C
ISO 12706, Non-destructive testing - Penetrant testing - Vocabulary
ISO 23277, Non-destructive testing of welds - Penetrant testing of welds - Acceptance levels
European Committee for Standardization (CEN)
EN 571-1, Non-destructive testing - Penetrant testing - Part 1: General principles. May be
replaced by EN ISO 3452-1.
EN 1371-1, Founding - Liquid penetrant inspection - Part 1: Sand, gravity die and low pressure
die castings
EN 1371-2, Founding - Liquid penetrant inspection - Part 2: Investment castings
EN 2002-16, Aerospace series - Metallic materials; test methods - Part 16: Non-destructive
testing, penetrant testing
EN 10228-2, Non-destructive testing of steel forgings - Part 2: Penetrant testing
EN 10246-11, Non-destructive testing of steel tubes - Part 11: Liquid penetrant testing of
seamless and welded steel tubes for the detection of surface imperfections
issn1018–5518
TrainingCourse series
45
non-Destructive Testing:
sample Questions for
Conduct of examinations
at Levels 1 and 2
Vienna,2010
non-Destructive Testing: sample Questions for
Conduct of examinations at Levels 1 and 2
TrainingCourse series
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endorsement
or recommendation on the part of the IAEA. CONTENTS
1 LIQUID PENETRANT TESTING (PT) .......................................................................... 1
1.1 Liquid Penetrant Testing Level 1 (PT-1)............................................................ 1
1.1.1 Liquid Penetrant Testing Level 1 (PT-1) General Examination............. 1
1.1.2 Liquid Penetrant Testing Level 1 (PT-1) Specific Examination .......... 17
1.1.3 Liquid Penetrant Testing Level 1 (PT-1) Answers to Questions.......... 25
1.2 Liquid Penetrant Testing Level 2 (PT-2).......................................................... 26
1.2.1 Liquid Penetrant Testing Level 2 (PT-2) General Examination........... 26
1.2.2 Liquid Penetrant Testing Level 2 (PT-2) Specific Examination .......... 36
1.2.3 Liquid Penetrant Testing Level 2 (PT-2) Answers to Questions.......... 46
2 MAGNETIC PARTICLES TESTING (MT).................................................................. 47
2.1 Magnetic Particles Testing Level 1 (MT-1) ..................................................... 47
2.1.1 Magnetic Particles Testing Level 1 (MT-1) General Examination ...... 47
2.1.2 Magnetic Particles Testing Level 1 (MT-1) Specific Examination...... 65
2.1.3 Magnetic Particle Testing Level 1 (MT-1) Answers to Questions....... 83
2.2 Magnetic Particles Testing Level 2 (MT-2) ..................................................... 84
2.2.1 Magnetic Particles Testing Level 2 (MT-2) General Examination ...... 84
2.2.2 Magnetic Particles Testing Level 2 (MT-2) Specific Examination...... 97
2.2.3 Magnetic Particle Testing Level 2 (MT-2) Answers to Questions..... 105
3 RADIOGRAPHIC TESTING (RT).............................................................................. 106
3.1 Radiographic Testing Level 1 (RT-1) ............................................................ 106
3.1.1 Radiographic Testing Level 1 (RT-1) General Examination.............. 106
3.1.2 Radiographic Testing Level 1 (RT-1) Specific Examination ............. 124
3.1.3 Radiographic Testing Level 1 (RT-1) Answers to questions ............. 135
3.2 Radiographic Testing Level 2 (RT-2) ............................................................ 136
3.2.1 Radiographic Testing Level 2 (RT-2) General Examination.............. 136
3.2.2 Radiographic Testing Level 2 (RT-2) Specific Examination ............. 153
3.2.3 Radiographic Testing Level 2 (RT-2) Answers to questions ............. 169
4 ULTRASONIC TESTING (UT) .................................................................................. 170
4.1 Ultrasonic Testing Level 1 (UT-1) ................................................................. 170
12. 4.1.1 Ultrasonic Testing Level 1 (UT-1) General Examination .................. 170
4.1.2 Ultrasonic Testing Level 1 (UT-1) Specific Examination.................. 184
4.1.3 Ultrasonic Testing Level 1 (UT-1) Answers to Questions ................. 199
4.2 Ultrasonic Testing Level 2 (UT-2) ................................................................. 200
4.2.1 Ultrasonic Testing Level 2 (UT-2) General Examination .................. 200
4.2.2 Ultrasonic Testing Level 2 (UT-2) Specific Examination.................. 216
4.2.3 Ultrasonic Testing Level 2 (UT-2) Answers to Questions ................. 226
CONTRIBUTORS TO DRAFTING AND REVIEW ...........................................................
227 1
1 LIQUID PENETRANT TESTING (PT)
1.1 Liquid Penetrant Testing Level 1 (PT-1)
1.1.1 Liquid Penetrant Testing Level 1 (PT-1) General Examination
1. Liquid penetrant testing is based on the principle of:
(a) Polarized sound waves in a liquid
(b) Magnetic domains
(c) Absorption of X rays
(d) Capillary action
2. When a small diameter tube is placed in a glass of water, water rises in the tube to a
level above the adjacent surface. This is called:
(a) Viscosity
(b) Capillary action
(c) Surface tension
(d) Barometric testing
3. How is the size of a liquid penetrant indication usually related to the discontinuity it
represents:
(a) Larger than
(b) Smaller than
(c) Equal to
(d) Not related to
4. A penetrant that is self-emulsifying is called:
(a) Solvent removable
(b) Water washable
(c) Post-emulsified
(d) Dual sensitivity method 2
5. A penetrant process which employs an emulsifier as a separate step in the penetrant
removal process is called:
(a) Solvent removable
(b) Water washable
(c) Post-emulsified
(d) Dual sensitivity method
6. A penetrant process in which excess penetrant is removed with an organic solvent is
called:
(a) Solvent removable
(b) Water washable
(c) Post-emulsified
(d) Dual method
7. Which of the following statements accurately describes the capabilities of liquid
13. penetrant testing?
(a) Liquid penetrant testing is useful for locating subsurface discontinuities in a
test piece
(b) Liquid penetrant testing is useful for locating discontinuities in porous
materials
(c) Liquid penetrant testing is useful for locating discontinuities which are open to
the surface in non-porous materials
(d) none of the above
8. Which of the following discontinuity types could typically be found with a liquid
penetrant test?
(a) Internal slag in a weld
(b) Internal slag in a casting
(c) Sensitization in austenitic stainless steel
(d) Fatigue cracks 3
9. Which of the following chemical elements are normally held to a minimum in liquid
penetrant materials, when testing stainless steel and titanium?
(a) Hydrogen
(b) Chlorine
(c) Carbon
(d) Oil
10. Which of the following chemical elements are normally held to a minimum in liquid
penetrant materials when testing nickel based alloys?
(a) Sulphur
(b) Oxygen
(c) Carbon
(d) Nitrogen
11. Which of the following is the most desirable method of pre-cleaning a test piece prior
to penetrant testing?
(a) Sand blasting
(b) Vapour degreasing
(c) Emery cloth
(d) Wire brushing
12. Which of the following pre-cleaning processes is not recommended?
(a) Detergent cleaning
(b) Vapour degreasing
(c) Shot blasting
(d) Ultrasonic cleaning
13. A wire brush should be used for pre-cleaning:
(a) When grease and oil must be removed
(b) Only as a last resort
(c) When rust is to be removed
(d) When grinding burrs must be removed 4
14. A hydrometer is used to measure:
(a) Penetrant viscosity
(b) Specific gravity of water based wet developers
(c) Penetrant specific gravity
(d) Cleaner specific gravity
14. 15. Visible, solvent removable penetrants are most advantageous for:
(a) Inspecting parts with rough surfaces
(b) Inspecting batches of small parts
(c) Inspecting parts at remote locations
(d) Inspecting parts with porous surfaces
16. For adequate test results, the black light used in fluorescent penetrant examination
should provide what minimum black light intensity at the test surface?
(a) 100 foot candles per square centimetre
(b) 1000 microwatts per square centimetre
(c) 800 foot candles
(d) 35 microwatts per square centimetre
17. What minimum warm-up time is required for acceptable performance of a mercury
Vapour arc black light?
(a) None
(b) 2 minutes
(c) 5 minutes
(d) 10 minutes
18. Which of the following penetrants contains an emulsifying agent?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent 5
19. Which of the following penetrants must be treated with an emulsifier prior to water
removal?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
20. What is the function of an emulsifier?
(a) To remove the excess penetrant
(b) To develop indications with a post emulsifiable penetrant system
(c) To assist penetration with a post emulsifiable penetrant system
(d) To make a post emulsifiable penetrant water washable
21. An oil based emulsifier is called:
(a) Hydrophilic
(b) Hydrophobic
(c) Lipophilic
(d) Fluoroscopic
22. A water based emulsifier is called:
(a) Hydrophilic
(b) Hydrophobic
(c) Lipophilic
(d) Fluoroscopic
23. Methylene chloride, isopropyl, alcohol, naptha and mineral spirits are examples of:
(a) Emulsifiers
(b) Developers
(c) Solvent removers
15. (d) None of the above 6
24. What type of solvent removers may be used with a solvent removable penetrant?
(a) Any organic solvent
(b) Only the cleaner recommended by the manufacturer of the penetrant
(c) Any alcohol based solvents
(d) Only chlorinated hydrocarbons
25. Which of the following is a prerequisite for a penetrant test?
(a) Developer must be applied in a thin, even coat
(b) Any surface coatings or soils must be completely removed
(c) All traces of penetrant materials should be removed after testing is complete
(d) The test object must be non-magnetic
26. Which of the following types of pre-cleaning processes may be used for liquid
penetrant testing?
(a) Wire brushing only
(b) Detergent and water only
(c) Vapour degreasing only
(d) Any process that leaves the part clean and dry, does not harm the part and is
compatible with the penetrant materials
27. What is the likely result of incomplete removal of all excess penetrant from the test
piece surface?
(a) Formation of false indications
(b) Formation of relevant indications
(c) Exaggeration of the size of relevant indications
(d) None of the above
28. What is the preferred pre-cleaning process for removal of oil and grease :
(a) Steam cleaning with a added acid
(b) Vapour degreasing
(c) Steam cleaning
(d) Ultrasonic cleaning 7
29. Which pre-cleaning method may be used with either a solvent or a detergent solution?
(a) Ultrasonic cleaning
(b) Steam cleaning
(c) Detergent wash
(d) Vapour degreasing
30. What is the danger associated with using a wire brush during pre-cleaning?
(a) Bristles from the wire brush may cause false indications
(b) Contaminants from the wire brush may cause delayed hydrogen cracking of
high carbon steels
(c) The wire brush may not adequately remove organic soils
(d) The wire brush may close or smear metal over
31. What is the preferred method of removing paint prior to performing a penetrant
testing?
(a) Sand blast
(b) Chemical removers
(c) Power wire brush
(d) Shot blast
32. What additional surface preparation or cleaning must be performed on a machined or
16. ground aluminium casting prior to penetrant testing?
(a) Vapour degreasing
(b) Etching
(c) Detergent wash
(d) Nothing
33. Acceptable methods of penetrant application are:
(a) Spraying
(b) Dipping
(c) Brushing
(d) All of the above 8
34. The time period during which penetrant remains on the surface of the test piece is
called:
(a) Dwell time
(b) Soaking time
(c) Fixing time
(d) Development time
35. Excess penetrant removal is a two step process with which of the following penetrant
methods?
(a) Water washable
(b) Post emulsifiable
(c) Solvent removable
(d) Liquid oxygen applications
36. A developer aids penetrant bleed out because of:
(a) Adequate removal of the excess penetrant
(b) Providing a contrasting background for visible dye indications
(c) Capillary action
(d) Proper emulsifier action
37. In the solvent removable penetrant process, excess penetrant is removed with:
(a) A water spray
(b) A hydrophilic scrubber
(c) A solvent spray
(d) Clean, lint free towels slightly moistened with solvent
38. Water based wet developer is applied:
(a) Immediately before removal of excess penetrant
(b) Immediately after removal of excess penetrant
(c) After a drying period following removal of excess penetrant
(d) For maximum sensitivity results 9
39. Non-aqueous wet developer is applied:
(a) Immediately before removal of excess penetrant
(b) Immediately after removal of excess penetrant
(c) After the excess penetrant is removed and part surface is dried
(d) For maximum sensitivity results
40. Dry developer is applied:
(a) Immediately before removal of excess penetrant
(b) Immediately after removal of excess penetrant
(c) After drying of the part
(d) For maximum sensitivity results
17. 41. Typical ranges of emulsifier dwell times are:
(a) 5 to 10 minutes
(b) 30 seconds to 1 minute
(c) 1 to 3 minutes
(d) 5 to 10 minutes
42. Actual emulsification times are determined by:
(a) Experiment, during technique qualification
(b) Manufacturer's recommendations
(c) Code requirements
(d) None of the above
43. The colour of fluorescent penetrant under the presence of a UV light is:
(a) Yellow-green
(b) Red
(c) Blue
(d) Green 10
44. What action is necessary if the penetrant is inadvertently allowed to dry on the test
piece?
(a) Repeat the test, beginning with the pre-cleaning operation
(b) Re-wet the penetrant, begin dwell time again and continue
(c) Clean the penetrant off the surface and develop normally
(d) Clean the penetrant off the surface, wait 5 minutes and develop normally
45. What maximum water rinse pressure is considered safe for removal of excess
penetrant in the water washable penetrant process?
(a) As low a pressure as possible, 50 PSI maximum
(b) to 200 PSI
(c) PSI maximum
(d) to 500 PSI
46. During the water rinse step of the water washable penetrant process, what is the
desired angle of the spray to the surface?
(a) Normal
(b) 30 degrees
(c) 45 degrees
(d) 75 degrees
47. Which type of emulsifier is designed to be used as a ‘scrubber’?
(a) Hydrophilic
(b) Hydrophobic
(c) Lipophilic
(d) Fluoroscopic
48. Post cleaning is especially important when:
(a) Post emulsified penetrants are used
(b) Phosphate containing detergents are used
(c) Chlorinated hydrocarbons are used
(d) The test object will be used in a liquid oxygen environment 11
49. When using a hydrophilic emulsifier, the amount of penetrant removed is most
affected by:
(a) Solution strength and time of spray
(b) Penetrant dwell time
18. (c) Emulsifier dwell time
(d) Adequacy of pre-clean
50. If a mercury vapour arc black light is inadvertently turned off, how soon may it be
restarted?
(a) Immediately
(b) 5 minutes
(c) 10 minutes
(d) 15 minutes
51. Which of the following is normally prohibited as a method of removing excess
penetrant when using the solvent removable penetrant process?
(a) A water spray
(b) A hydrophilic scrubber
(c) A solvent spray
(d) Clean with lint free towels moistened with solvent
52. When performing a fluorescent penetrant examination, excess penetrant is normally
removed:
(a) By a hydrophilic scrubber
(b) Under UV light
(c) By solvent spray
(d) By vapour degreasing
53. During a visible, solvent removable penetrant test, complete penetrant removal is
indicated by:
(a) Absence of red indications on the test piece surface
(b) Clean rinse water
(c) Completion of the rinse cycle
(d) Absence of red dye on the cleaning towels 12
54. Which of the following is a function of a developer
(a) Providing a contrasting background for visible dye indications
(b) Making the penetrant water washable
(c) Penetrating into discontinuities open to the surface
(d) Dissolve organic soils on the test piece surface
55. Which of the following is a function of a developer?
(a) Providing a contrasting background for visible dye indications
(b) Accentuates presence of discontinuities by causing a penetrant indication to
spread out over a larger area
(c) Provides capillary paths to aid the bleed out process
(d) All of the above
56. Which of the following developers is applied before the drying operation?
(a) Dry
(b) Non-aqueous wet
(c) Water based wet
(d) None of the above
57. The most sensitive type of developer for the detection of fine discontinuities is:
(a) Water soluble
(b) Non-aqueous wet
(c) Dry
(d) Water suspendable
19. 58. Which of the following is the most sensitive developer in descending order?
(a) Dry, water soluble, water suspendable
(b) Non-aqueous wet, water soluble, water suspendable ,dry
(c) Non-aqueous wet, dry, water soluble
(d) Water suspendable, water soluble, non-aqueous wet 13
59. Low sulphur and chlorine penetrant materials would be used for testing:
(a) Aluminium, steel and plastics
(b) Tool steels, chrome vanadium steel and ferritic stainless steels
(c) Austenitic stainless steels, nickel alloys and titanium
(d) Magnetic materials
60. Which type of developer may be either in suspension or a solution?
(a) Dry
(b) Non-aqueous wet
(c) Water based wet
(d) None of the above
61. The temperature of water rinse used in the water washable penetrant process should
be:
(a) 60 to 110
o
C
(b) 40 to 100
o
C
(c) 16 to 43
o
C
(d) 70 to 140
o
C
62. The danger of over washing during a water washable penetrant test is that:
(a) Excess penetrant will be removed from the test piece
(b) Penetrant will be removed from discontinuities
(c) The waste water will contain too high a concentration of penetrants
(d) A protective oxide coating on the test piece is formed
63. Which penetrant process is best suited to high production rates of many small parts?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent 14
64. Which penetrant process is best suited to detect shallow discontinuities?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
65. Which penetrant process is best suited to the detection of discontinuities in a test piece
having threads and keyways?
(a) Solvent removable
20. (b) Water washable
(c) Post emulsifiable
(d) Fluorescent
66. Which penetrant process is the most sensitive to detect fine discontinuities?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable fluorescent
(d) Water washable fluorescent
67. Which penetrant process is best suited for portable application in the field?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
68. Which penetrant process should be used if repeated examinations are anticipated?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent 15
69. What is a disadvantage of using the fluorescent penetrant process?
(a) Lower visibility of indications
(b) Must be performed in a darkened area with aid of a UV lamp
(c) Easily washed with water
(d) High visibility of indications
70. Which of the following developers is applied by brush, spraying or dipping?
(a) Non-aqueous wet
(b) Water based wet
(c) Dry
(d) Dual sensitivity
71. Which of the following developers is applied by spray only?
(a) Non-aqueous wet
(b) Water based wet
(c) Dry
(d) Dual sensitivity
72. Which of the following developers is applied by immersion or flow on only?
(a) Non-aqueous wet
(b) Water based wet
(c) Dry
(d) Dual sensitivity
73. What is the minimum time considered necessary for dark adaptation of the eyes prior
to evaluating the results of a fluorescent penetrant test?
(a) 1 minute
(b) 2 minutes
(c) 5 minutes
(d) 10 minutes 16
74. What is the likely result of looking directly into a black light?
(a) Burning of the retina of the eye
(b) Temporary inflammation of the cornea
21. (c) Long term tendency toward formation of cataracts
(d) Fluorescence of the fluid in the eye
75. Which type of penetrant process would be best suited to the detection of wide, shallow
discontinuities?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
76. Which type of penetrant process affords most control of test sensitivity level?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
77. Which type of penetrant process is least susceptible to over washing?
(a) Solvent removable
(b) Water washable
(c) Post emulsifiable
(d) Fluorescent
78. What is a disadvantage of the solvent removable penetrant process?
(a) It is the least sensitive of the penetrant processes
(b) It is not well suited for use on rough surfaces
(c) It is highly portable
(d) No water is required for its use 17
79. Which of the following is the proper first step in removal of excess penetrant when
using the solvent removable penetrant process?
(a) Immerse the test piece in solvent
(b) Spray the test piece with water
(c) Wipe the test piece surface with clean, lint free towels slightly moistened
(d) All of the above is correct
1.1.2 Liquid Penetrant Testing Level 1 (PT-1) Specific Examination
1. Which of the following types of penetrants, developers, solvents are used when
conducting a liquid penetrant test on a part that is exposed to a liquid oxygen
environment.
(a) Water based penetrants
(b) Water based developers
(c) Water based solvents
(d) All of the above
2. The causes of non relevant indications are:
(a) Insufficient removal of excess surface penetrant
(b) Penetrant on operators hands
(c) Threads, keyways, splines, sharp corners, press fits, blind holes, rough surfaces
(d) Contaminated work surfaces
3. Which of the following metals must be tested with low halogen sulphur free penetrant
materials:
(a) Copper, silver, gold
(b) Nickel based alloys, certain stainless steel materials
(c) Steel, iron, aluminium
22. (d) Plastic, wood, paper
4. List two main advantages of ‘wet’ developers.
(a) _____________________________________________________________
(b) _____________________________________________________________ 18
5. Penetrant testing is limited by its inability to test which of the following materials:
(a) Aluminium
(b) Ceramics
(c) Porous materials
(d) Moulded rubber
6. List four cleaning processes that are to be avoided
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
7. Liquid penetrants can be further categorised by the removal method of excess surface
penetrant:
(a) Water washable
(b) Solvent removable
(c) Post emulsified
(d) All of the above
8. The typical temperature ranges for conducting a liquid penetrant test is:
(a) 60 to 100ºC
(b) 10 to 60ºF
(c) 16 to 52ºC
(d) 10 to 20ºK
9. Surface breaking porosity will show what type of relevant indications when a welded
aluminium plate is tested with the liquid penetrant method:
(a) Linear indications
(b) Square indications
(c) Triangular indications
(d) Rounded indications 19
10. Cracks, lack of penetration, lack of fusion which are surface breaking on a welded
aluminium plate which has been liquid penetrant tested will show as:
(a) Linear indications
(b) Rounded indications
(c) Square indications
(d) Triangular indications
11. List two ways of recording relevant indications for record purposes.
(a) _____________________________________________________________
(b) _____________________________________________________________
12. Explain what is meant by LOX compatible penetrant materials.
(a) _____________________________________________________________
(b) _____________________________________________________________
13. Which of the following methods is not recommended for pre-cleaning prior to a liquid
penetrant test:
(a) Steam cleaning, etching, rust and paint removal
(b) Solvent wipe, vapour degreasing, ultrasonic bath cleaning
23. (c) Blasting, grinding, filing, honing, machining
(d) All of the listed methods are not recommended
14. The purpose of using a developer is:
(a) To create a contrasting background for the penetrants to ensure better visibility
of indications
(b) Assists in reverse capillary action due to absorption ability of developers
(c) Prevent the part from corroding after the liquid penetrant test
(d) To ensure that the part has been correctly heat treated
(e) Both a and b are correct 20
15. The typical sequence of conducting a visible solvent removable penetrant is:
(a) Pre-clean with a solvent wipe method
(b) Apply visible penetrant, keep wet, dwell time of 2 minutes
(c) Pour solvent on surface of part and wipe with waste cloth
(d) Spray on a thick layer of developer
(e) Inspect and report
(f) Post-clean
(g) The above listed methods are not correct for various reasons
16. Explain why low halogen, sulphur-free penetrant materials should be used on stainless
steel, titanium and nickel-based alloys.
(a) _____________________________________________________________
(b) _____________________________________________________________
17. The principle on which liquid penetrant testing is based on is:
(a) Capillary action of the penetrant
(b) Capillary action of cleaner/solvent
(c) Capillary action of developer
(d) None of the listed is correct
18. The limitation of a liquid penetrant test is:
(a) Only surface breaking discontinuities can be detected if chemically and
physically clean and dry
(b) Porous materials cannot be tested
(c) There is cleaning problem following penetrant inspection in some cases
(d) All of the listed limitations are correct
19. Name the six basic steps in the correct sequence of how to conduct a typical liquid
penetrant test.
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________ 21
(e) _____________________________________________________________
(f) _____________________________________________________________
20. Penetrants may be applied to the surface of part by :
(a) Spraying
(b) Dipping
(c) Pouring
(d) All of the above methods are acceptable
21. List four properties of a good penetrant.
(a) _____________________________________________________________
24. (b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
22. Which of the following is a reason to post clean a part after a liquid penetrant test:
(a) The part might be further processed
(b) If repairs are necessary
(c) Developers absorb moisture and may result in part being corroded
(d) All of the reasons are correct
23. Which of the following penetrant has a built-in emulsifier
(a) Water washable
(b) Solvent removable
(c) Post emulsified
(d) All of the listed above
24. What is the main function of the emulsifier used in post-emulsification penetrant
process:
(a) _______________________________________________________________
(b) _______________________________________________________________ 22
25. Liquid penetrants can be classified into the types of dyes they contain:
(a) Visible/colour contrast
(b) Fluorescent
(c) Dual sensitivity
(d) All of the listed is correct
26. Explain why an emulsifier is used prior to the removal of excess surface penetrant
when a post emulsified penetrant is used.
(a) _____________________________________________________________
(b) _____________________________________________________________
27. Explain what will happen when the excess surface penetrant of a solvent removable
penetrant is removed by means of solvent sprayed directly onto the surface of a part.
(a) _____________________________________________________________
(b) _____________________________________________________________
28. The advantages of using a visible solvent removable penetrant versus a post
emulsified fluorescent penetrant is:
(a) No UV light is needed
(b) The technique is well suitable for site tests or spot checks
(c) No water or emulsifiers are needed
(d) No extra equipment is needed
(e) All of the advantages listed above are correct
29. Describe two important functions of a developer.
(a) _____________________________________________________________
(b) _____________________________________________________________
30. List four common surface breaking weld discontinuities that can be detected on
welded aluminium, stainless steel materials when conducting a liquid penetrant test.
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
31. The following precautions must be observed when removing the excess surface
25. penetrant with a water wash method using a hose pipe:
(a) The wash angle should be at 45
o
(b) A coarse droplet spray
(c) Temperature of water 16 to 43
o
C
(d) Pressure as low as possible not to exceed 50 psi
(e) All of the precautions listed above are correct 23
32. List four possible causes for false indications that can be observed during a liquid
penetrant test.
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
33. The typical causes for false indications are:
(a) Threads, keyways, splines, rough surfaces
(b) Sharp corners, pop rivets
(c) Insufficient removal of excess surface penetrant, penetrant on operators’ hands,
using cloth/paper towels which are not lint free, dirty work surfaces
(d) Over washing with high pressure hose pipes
34. Name four methods of pre-cleaning the surface of a part prior to conducting a liquid
penetrant test.
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
35. Liquid penetrants can be further categorised by the removal method of excess surface
penetrant:
(a) Water washable
(b) Solvent removable
(c) Post emulsified
(d) All of the above
36. The advantages of using a visible solvent removable penetrant versus a post
emulsified fluorescent penetrant is:
(a) No UV light is needed
(b) The technique is well suitable for site tests or spot checks
(c) No water or emulsifiers are needed
(d) No extra equipment is needed
(e) All of the listed is correct 24
37. Match the type of penetrant to the list of advantages and disadvantages as listed
below:
Advantages Disadvantages
Portable Penetrant removal is time consuming
No UV light needed Difficult to remove from rough
surfaces
Suited for spot checks Materials are flammable
26. Good sensitivity Cannot be used in open tanks
(a) Visible water wash
(b) Visible solvent removable
(c) Visible post emulsified
(d) Fluorescent water wash
38. How will the excess surface penetrant be removed if a post emulsified penetrant was
used:
(a) Dip or spray emulsifier onto part
(b) Wait correct dwell time
(c) Water wash part observing correct recommended rules
(d) Dry part and apply developer
(e) All of the listed steps are correct
39. List four basic safety rules to be followed when conducting a liquid penetrant test.
(a) _____________________________________________________________
(b) _____________________________________________________________
(c) _____________________________________________________________
(d) _____________________________________________________________
40. The six basic steps on how to conduct a typical liquid penetrant test is:
(a) Pre-clean surface to be tested
(b) Apply penetrant, keep wet, observe dwell time
(c) Remove excess surface penetrant
(d) Apply developer in a thin even layer
(e) Inspect and report
(f) Post-clean
(g) All of the listed steps are correct 25
1.1.3 Liquid Penetrant Testing Level 1 (PT-1) Answers to Questions
Liquid Penetrant Testing Level 1 Answers to Questions
General Examination Specific Examination
1 d 35 b 69 b 1 a 35 d
2 b 36 c 70 b 2 c 36 e
3 a 37 d 71 a 3 d 37 b
4 b 38 b 72 b 4 c 38 c
5 c 39 c 73 c 5 d 39 *
6 a 40 c 74 d 6 a 40 g
7 c 41 c 75 c 7 a
8 d 42 a 76 c 8 b
9 b 43 a 77 c 9 b
10 a 44 a 78 b 10 c
11 b 45 a 79 c 11 d
12 c 46 c 12 a
13 c 47 a 13 d
14 b 48 d 14 b
15 c 49 a 15 d
16 b 50 c 16 c
17 c 51 c 17 a
18 b 52 b 18 b
19 c 53 d 19 c
27. 20 d 54 a 20 b
21 c 55 d 21 b
22 a 56 c 22 c
23 c 57 b 23 a
24 b 58 b 24 d
25 b 59 c 25 d
26 d 60 c 26 c
27 a 61 c 27 a
28 b 62 b 28 d
29 a 63 b 29 c
30 d 64 c 30 d
31 b 65 b 31 b
32 b 66 c 32 b
33 d 67 a 33 b
34 a 68 a 34 d 26
Asnt PT Level 1 sample question.
Liquid Penetrant Testing Method (40 Questions)
1. Which one of the following conditions will affect the rate and the extent a liquid
penetrant will enter cracks, fissures, and other small openings?
a. the hardness of the specimen being tested
b. the surface condition of the specimen being tested
c. the color of the penetrant
d. the conductivity of the specimen being tested
2. Which of the following is a commonly used classification for penetrant?
a. post-emulsifiable penetrant
b. nonferrous penetrant
c. chemical etch penetrant
d. nonaqueous penetrant
3. A generally accepted method for removing excess nonwater-washable penetrant is:
a. repeatedly dipping the test specimen in a cleaner
b. soaking the test specimen in hot detergent water
c. blowing the excess penetrant off the surface of the part with compressed air
d. wiping and cautiously cleaning the test specimen with a cleaner-dampened cloth
4. All of the following parts can be tested by the liquid penetrant method except:
a. an iron casting
b. an aluminum forging
28. c. a part made from a porous plastic material
d. a part made from a non-porous material
5. Which of the following discontinuities can be found by the penetrant test method?
a. a surface crack
b. a subsurface crack
c. an internal inclusion
d. none of the above
6. Which of the following is generally the more acceptable method for cleaning parts
prior to penetrant testing?
a. sand blasting
b. wire brushing
c. grinding
d. vapor degreasing
7. All of the following methods are commonly used to clean parts prior to penetrant
testing except:
a. vapor degreasing
b. liquid solvent
c. power wire brushing
d. alkaline cleaner
8. Cutting oils may be effectively removed from parts before penetrant testing by:
a. pre-heating
b. vapor degreasing
c. washing with water
d. all of the above
9. The most common type of contaminant in fluorescent penetrant fluid is:
a. metal filings
b. oil
c. detergents (from cleaning)
d. water
10. Black light, with a proper functioning filter in place, used for fluorescent penetrant
inspection can cause permanent damage to:
a. human tissues
b. human eyes
c. human blood cells
d. none of the above
29. 11. All of the following basic inspection principles apply to the penetrant methods
except-
a. the penetrant must enter the discontinuity in order to form an indication
b. indications glow when illuminated with a black light
c. a longer penetration time is required for smaller discontinuities
d. if the penetrant is washed out of the discontinuity, an indication will not be
formed by that discontinuity
12. Subsurface discontinuities can be best detected by:
a. the post-emulsification penetrant method
b. the visible dye penetrant method
c. the fluorescent, water-washable penetrant method
d. none of the above
13. Visible penetrant may be applied by:
a. brushing
b. spraying
c. dipping
d. none of the above
14. The first step in conducting a liquid penetrant test on a surface that has been
painted is to :
a. carefully apply the penetrant over the surface
b. completely remove the paint
c. thoroughly wash the surface with a detergent
d. wire brush the surface to roughen the smooth surface coating of paint
15. When using a post-emulsification penetrant, it is necessary to apply the emulsifier:
a. before applying the penetrant
b. after the water wash operation
c. after the dwell time has elapsed
d. after the develonment time has elapsed
16. When conducting a water-washable liquid penetrant test, the wet developer is
applied:
a. immediately after the penetrant has been applied
b. immediately before the penetrant is applied
c. after removal of the penetrant
d. after removal of the emulsifier
17. The term used to describe the action of a particular developer in soaking up the
penetrant in a discontinuity, so as to cause the maximum bleed-out of the liquid
penetrant for increased contrast and sensitivity, is known as:
30. a. blotting
b. capillary action
c. concentration
d. attraction
18. Using a black light lamp with a cracked filter or without the filter in place can cause
damage to human eyes because the lamp emits:
a. black light
b. ultraviolet light
c. infrared light
d. none of the above
19. The term used to define the period of time in which the test part is covered with
penetrant is:
a. waiting time
b. soak time (drain time)
c. penetration time (dwell time)
d. bleed-in time
20. Usually, the most desirable method of removing excess water-washable penetrant
after the dwell time is by using:
a. a low pressure coarse water spray
b. water and brush
c. a solid stream of water
d. water and clean rags
21. When conducting a liquid penetrant test using a post emulsifiable visible dye
penetrant, the generally accepted method for applying the wet developer is by:
a. brushing
b. swabbing
c. dipping
d. spraying
22. Which of the following characteristics does not apply to liquid penetrant testing?
a. this method can accurately measure the depth of a crack or discontinuity
b. this method can be used for on-site testing of large parts
c. this method can be used to find shallow surface discontinuities
d. this method can be made more or less sensitive by using different
penetrant materials
23. Which of the following discontinuities is most likely to be missed due to improper
rinse techniques?
a. a forging lap
31. b. deep pitting
c. shallow and broad discontinuities
d. the rinse technique will not affect the detection of discontinuities
24. When conducting a fluorescent penetrant test, a commonly used technique for
assuring that the excess penetrant has been removed prior to the application of a
developer is to:
a. blow compressed air over the surface
b. chemically etch the surface
c. blot the surface with absorbent paper
d. scan the surface with a black light
25. Which of the following surface conditions could have a detrimental effect on a
liquid penetrant test?
a. a wet surface
b. a rough weld
c. an oily surface
d. all of the above
26. Liquid penetrant testing is capable of detecting:
a. intergranular stress corrosion cracking discontinuities
b. discontinuities open to the surface
c. subsurface discontinuities
d. all of the above
27. Black light equipment is required when penetrant testing by:
a. the.fluorescent penetrant method
b. the visible dye penetrant method
c. the non-fluorescent penetrant method
d. all of the above
28. The term used to define the tendency of certain liquids to penetrate into small
openings such as cracks or fissures is:
a. saturation
b. capillary action
c. blotting
d. wetting agent
29. Excess penetrant (all penetrant except that which is in discontinuities) is removed
from the specimen:
a. after the required penetrant dwell time has elapsed
b. before the application of an emulsifier if a post-emulsifier penetrant is used
c. by means of a steam cleaner
32. d. only when water-washable penetrants are used
30. When using a post-emulsifiable penetrant, the emulsifier time should be:
a. as long as the penetrant dwell time
b. half the penetrant dwell time
c. the same as the developer time
d. only as long as necessary to remove the interfering background
31. When an inspector is working in a darkened area, he/she should become adjusted
to the dark before inspecting parts. The generally accepted time period for becoming
accustomed to the dark is:
a. 1 minute
b. 5 to 0 minutes
c. 10 to 15 minutes
d. no waiting period is necessary
32. When applying penetrant by dipping, heating the penetrant prior to dipping:
a. will increase the sensitivity of the test
b. will increase the capillary action of the penetrant
c. will increase the stability of the penetrant
d. is not generally recommended
33. A penetrant inspection cannot find:
a. surface p orosity
b. surface cracks
c. an internal cavity
d. a surface forging lap
34. All of the following materials can be tested by the usual liquid penetrant tests
except:
a. unglazed porous cerai
b. titanium
c. high alloy steel
d. cast iron
35. Liquid penetrant testing can be used to detect:
a. discontinuities 1.6 mm (0.06 in.) below the surface
b. internal discontinuities
c. discontinuities open to the surface
d. all discontinuities
36. Which of the following are commonly accepted methods for applying penetrant?
a. dipping the part in penetrant (dipping)
33. b. pouring the penetrant over the test specimen (flowing)
c. spraying the penetrant on the test specimen (spraying)
d. all of the above
37. A solvent used to clean the surface of a test specimen must possess all of the
following characteristics except that the:
a. cleaner must be capable of dissolving oils and greases commonly found on the
surface
b. cleaner must not be flammable
c. cleaner must be free of contaminants
d. cleaner must leave a minimal residue on the surface
38. Which of the statements below best states the danger of sandblasting (without
subsequent chemical etching) for cleaning surfaces to be penetrant tested?
a. the discontinuities may be peened over and closed
b. oil contaminants might be sealed in the discontinuities
c. the sand used in the sandblasting operation may be forced into the discontinuity
d. the sandblasting operation may introduce discontinuities
39. The penetrant applied to the surface of a test specimen:
a. seeps into discontinuities
b. is absorbed by discontinuities
c. is drawn into discontinuities by capillary action
d. is drawn into discontinuities by gravity
40. Which of the following statements concerning liquid penetrant testing is correct?
a. fluorescent penetrants will produce red against white discontinuity indications
b. non-fluorescent penetrants require the use of black lights
c. fluorescent indications will be seen when exposed to black light
d. nonfluorescent discontinuities glow in the dark for easy viewing and interpretation
ANSWER
1.B 2.A 3.D 4.C 5.A 6.D 7.C 8.B 9.D 10.D
11.B 12.D 13.D 14.B 15.C 16.C 17.A 18.B 19.C 20.A
21.D 22.A 23.C 24.D 25.D 26.B 27.A 28.B 29.A 30.D
31.B 32.D 33.C 34.A 35.C 36.D 37.B 38.A 39.C 40.C
34. Level I Questions
Liquid Penetrant Testing Method
1. Which one of the following conditions will affect the rate and the extent a liquid
penetrant will enter cracks, fissures, and other small openings?
a. the hardness of the specimen being tested
b. the surface condition of the specimen being tested
c. the color of the penetrant
d. the conductivity of the specimen being tested
A.6-6
2. Which of the following is a commonly used classification for penetrant?
a. post-emulsifiable penetrant
b. nonferrous penetrant
c. chemical etch penetrant
d. non-aqueous penetrant
A.6-2
3. A generally accepted method for removing excess nonwater-washable penetrant is:
a. repeatedly dipping the test specimen in a cleaner
b. soaking the test specimen in hot detergent water
c. blowing the excess penetrant off the surface of the part with compressed air
d. wiping and cautiously cleaning the test specimen with a cleaner-dampened
cloth
A.6-19
4. All of the following parts can be tested by the liquid penetrant method except:
a. an iron casting
b. an aluminum forging
c. a part made from a porous plastic material
35. d. a part made from a non-porous material
A.6-1
5. Which of the following discontinuities can be found by the penetrant test method?
a. a surface crack
b. a subsurface crack
c. an internal inclusion
d. none of the above
A.6-1
6. Which of the following is generally the more acceptable method for cleaning parts
prior to penetrant testing?
a. sand blasting
b. wire brushing
c. grinding
d. vapor degreasing
A.6-6
7. All of the following is generally the more acceptable method for cleaning parts prior
to penetrant testing?
a. vapor degreasing
b. liquid solvent
c. power wire brushing
d. alkaline cleaner
A.6-6
8. Cutting oils may be effectively removed from parts before penetrant testing by:
a. pre-heating
b. vapor degreasing
c. washing with water
d. all of the above
36. D.106
9. The most common type of contaminant in fluorescent penetrant fluid is:
a. metal filings
b. oil
c. detergents (from cleaning)
d. water
A.7-33
10. Black light, with a proper functioning filter in place, used for fluorescent penetrant
inspection can cause permanent damage to:
a. human tissues
b. human eyes
c. human blood cells
d. none of the above
A.7-35
11. All of the following basic inspection principles apply to the penetrant methods
except:
a. the penetrant must enter the discontinuity in order to form an indication
b. indicates glow when illuminated with a black light
c. a longer penetration time is required for smaller discontinuities
d. if the penetrant is washed out of the discontinuity, an indication will not be
formed by that discontinuity
A.6-5
12. Subsurface discontinuities can be best detected by:
a. the post-emulsification penetrant method
b. the visible dye penetrant method
c. the fluorescent, water-washable penetrant method
d. none of the above
A.6-1
13. Visible penetrant may be applied by:
a. brushing
37. b. spraying
c. dipping
d. all of the above
D.234
14. The first step in conducting a liquid penetrant test on a surface that has been painted
is to:
a. carefully apply the penetrant over the surface
b. completely remove the paint
c. thoroughly wash the surface with a detergent
d. wire brush the surface to roughen the smooth surface coating of paint
A.6-6
15. When using a post-emulsification penetrant, it is necessary to apply the emulsifier:
a. before applying the penetrant
b. after the water wash operation
c. after the dwell time has elapsed
d. after the development time has elapsed
A.6-9
16. When conducting a water-washable liquid penetrant test, the wet developer is
applied:
a. immediately after the penetrant has been applied
b. immediately before the penetrant is applied
c. after removal of the penetrant
d. after removal of the emulsifier
F.33
17. The term used to describe the action of a particular developer in soaking up the
penetrant in a discontinuity, so as to cause the maximum bleed-out of the liquid
penetrant for increased contrast and sensitivity, is known as:
38. a. blotting
b. capillary action
c. concentration
d. attraction
F.25
18. Using a black light lamp with a cracked filter or without the filter in place can cause
damage to human eyes because the lamp emits:
a. black light
b. ultraviolet light
c. infrared light
d. none of the above
A.7-17
19. The term used to define the period of time in which the test part is covered with
penetrant is:
a. waiting time
b. soak time (drain time)
c. penetration time (dwell time)
d. bleed-in time
A.6-3
20. Usually, the most desirable method of removing excess water-washable penetrant
after the dwell time is by using:
a. a low pressure coarse water spray
b. water and brush
c. a solid stream of water
d. water and clean rags
A.6-7
21. When conducting a liquid penetrant test using a post-emulsifiable visible dye
penetrant, the generally accepted method for applying the wet developer is by:
39. a. brushing
b. swabbing
c. dipping
d. spraying
A.6-17
22. Which of the following characteristics does not apply to liquid penetrant testing?
a. this method can accurately measure the depth of a crack or discontinuity
b. this method can be used for on-site testing of large parts
c. this method can be used to find shallow surface discontinuities
d. this method can be made more or less sensitive by using different penetrant
materials
A.8-2
23. Which of the following discontinuities is most likely to be missed due to improper
rinse techniques?
a. a forging lap
b. deep pitting
c. shallow and broad discontinuities
d. the rinse technique will not affect the detection of discontinuities
A.6-5
24. When conducting a fluorescent penetrant test, a commonly used technique for
assuring that the excess penetrant has been removed prior to the application of a
developer is to:
a. blow compressed air over the surface
b. chemically etch the surface
c. blot the surface with absorbent paper
d. scan the surface with a black light
A.6-7
40. 25. Which of the following surface conditions could have a detrimental effect on a
liquid penetrant test?
a. a wet surface
b. a rough weld
c. an oily surface
d. all of the above
A.6-6
26. Liquid penetrant testing is capable of detecting:
a. intergranular stress corrosion cracking discontinuities
b. discontinuities open to the surface
c. subsurface discontinuities
d. all of the above
F.20
27. Black light equipment is required when penetrant testing by:
a. the fluorescent penetrant
b. the visible dye penetrant method
c. the non-fluorescent penetrant method
d. all of the above
A.6-24
28. The term used to define the tendency of certain liquids to penetrate into small
openings such as cracks or fissures is:
a. saturation
b. capillary action
c. blotting
d. wetting agent
F.21
41. 29. Excess penetrant (all penetrant except that which is in discontinuities) is removed
from the specimen:
a. after the required penetrant dwell time has elapsed
b. before the application of an emulsifier if a post-emulsifier penetrant is used
c. by means of a steam cleaner
d. only when water-washable penetrants are used
F.21
30. When using a post-emulsifiable penetrant , the emulsifier time should be:
a. as long as the penetrant dwell time
b. half the penetrant dwell time
c. the same as the developer time
d. only as long as necessary to remove the interfering background
F.35
31. When an inspector is working in a darkened area, he/she should become adjusted to
the dark before inspecting parts. The generally accepted time period for becoming
accustomed to the dark is:
a. 1 minute
b. 5 to 10 minutes
c. 10 to 15 minutes
d. no waiting period is necessary
D.126
32. When applying penetrant by dipping, heating the penetrant prior to dipping:
a. will increase the sensitivity of the test
b. will increase the capillary action of the penetrant
c. will increase the stability of the penetrant
d. is not generally recommended
A.7-34
33. A penetrant inspection cannot find:
a. surface porosity
42. b. surface cracks
c. an internal cavity
d. a surface forging lap
A.6-1
34. All of the following materials can be tested by the usual liquid penetrant test
except:
a. unglazed porous ceramic
b. titanium
c. high alloy steel
d. cast iron
A.6-1
35. Liquid penetrant testing can be used to detect:
a. discontinuities 1.6 mm (0.06 in.) below the surface
b. internal discontinuities
c. discontinuities open to the surface
d. all discontinuities
A.6-1
36. Which of the following are commonly accepted methods for applying
penetrant?
a. dipping the part in penetrant (dipping)
b. pouring the penetrant over the test specimen (flowing)
c. spraying the penetrant on the test specimen (spraying)
d. all of the above
F.32
37. A solvent used to clean the surface of a test specimen must possess all of
the following characteristics except that the:
a. cleaner must be capable of dissolving oils and greases commonly
found on the surface
b. cleaner must not be flammable
c. cleaner must be free of contaminants
d. cleaner must leave a minimal residue on the surface
D.141
38. Which of the statements below best states the danger of sandblasting
(without subsequent chemical etching) for cleaning surfaces to be penetrant
tested?
a. the discontinuities may be peened over and closed
43. b. oil contaminants might be sealed in the discontinuities
c. the sand used in the sandblasting operation may be forced into the
discontinuity
d. the sandblasting operation may introduce discontinuities
A.8-5
39. The penetrant applied to the surface of a test specimen:
a. seeps into discontinuities
b. is absorbed by discontinuities
c. is drawn into discontinuities by capillary action
d. is drawn into discontinuities by gravity
F.21
40. Which of the following statements concerning liquid penetrant testing is
correct?
a. fluorescent penetrants will produce red against white discontinuity
indications
b. nonfluorescent penetrants require the use of black lights
c. fluorescent indications will be seen when exposed to black light
d. nonfluorescent discontinuities glow in the dark for easy viewing and
interpretation
A.6-2
41. When removing excess penetrant from the surface of a test specimen:
a. the penetrant removal operation must not remove the penetrant from
discontinuities
b. sufficient excess penetrant must be removed to eliminate an
interfering background
c. the use of a solvent-dampened cloth is a common method of
penetrant removal
d. all of the above
F.23-24
42. The most widely accepted method for removing excessive water-washable
penetrant from the surface of a test specimen is by:
a. using a wet rag
b. using a water spray rinse
c. washing the part directly under water running from a tap
d. immersing the part in water
A.6-7
43. The inspection of a test specimen for discontinuities should take place:
44. a. immediately after the developer has been applied
b. any time after the developer has been applied
c. after the developer has been on the test specimen for the proper
development time
d. immediately after the rinse operation
F.33
44. Which of the following is an advantage of visible dye penetrants over
fluorescent penetrants?
a. visible dye penetrants do not require black light
b. visible dye penetrants are more sensitive than fluorescent penetrants
c. visible dye penetrants are superior in penetrating characteristics
d. visible dye penetrants are not toxic while fluorescent penetrants are
toxic
F.31
45. The terms “dry,” “aqueous wet,” and “nonaqueous wet” are used to describe
three different types of :
a. emulsifiers
b. cleaners
c. developers
d. penetrants
F.26
46. Which of the following is a true statement concerning the application of a
standard temperature penetrant to a test specimen while the specimen is
hot?
a. the penetrant is likely to become entrapped in the specimen as it
cools
b. the test will be less sensitive than when the penetrant is applied on a
cool specimen
c. there is no difference in applying penetrant to a heated specimen and
a cool specimen
d. the penetrant may be heated to the point where some of the
penetrant’s constituents are driven off, causing volatile fumes and
leaving a residue on the surface
A.7-34
47. Which of the following is not a generally accepted method for applying
penetrants?
a. rubbing the penetrant over the surface
b. brushing the penetrant on the part
45. c. spraying the penetrant on the part
d. dipping the part in the penetrant
A.6-2, 7, 13,19
48. Which of the following is the most commonly used method for removing
nonwater-washable visible dye penetrant from the surface of a test
specimen?
a. dipping in a solvent
b. spraying
c. hand wiping
d. blowing
A.6-19
49. Which of the following is an acceptable method applying wet developers?
a. application with a soft brush
b. application with a hand powder bulb
c. rubbing with a saturated cloth
d. spraying or dipping
A.6-7, 15
50. When using solvent-removable penetrants, the excess penetrant may be
removed by:
a. dipping the part in solvent
b. spraying the part with water and a solvent
c. rubbing the part with a wet rag
d. wiping the part with a rag or cloth that has been dampened with
solvent
A.6-19
51. While conducting a penetrant test, all of the following health precautions
should be applied except:
a. keeping the work area clean
b. washing any penetrant from skin with soap and water as soon as
possible
c. keeping penetrant off clothes
d. washing any excess penetrant from skin using gasoline
A.7-35
52. Which of the following surface contaminants cannot be removed by cleaning
parts in a vapor degreaser?
a. grease
b. rust
46. c. heavy oil
d. soluble oil
A.6-6
53. Before conducting a liquid penetrant test, it is important to ensure that the
surface of the part is free of:
a. oil or grease
b. acids or chromates
c. traces of water
d. all of the above
A.6-6
54. When performing a penetrant test using a post-emulsification penetrant,
which of the following is the most critical with respect to proper timing?
a. dwell time
b. developing time
c. emulsification time
d. drying time
A.6-12
55. Which of the following is the most likely result of an excessive emulsification
time when penetrant testing with post-emulsification penetrants?
a. a large number of nonrelevant indications could appear on the part
b. shallow discontinuity indications could be lost
c. excess penetrant could remain after the wash operation
d. the emulsifier could harden, preventing the developer from blotting
the penetrant in discontinuities
A.8-8
56. In penetrant testing, developers should be able to perform all of the
following functions except:
a. blotting penetrant from discontinuities
b. aiding in providing in providing an image of a discontinuity
c. adding fluorescence to penetrants
d. helping control bleed-out
A.6-5
57. Which of the following is the primary limitation of liquid penetrant testing?
a. penetrant testing cannot be used on ferromagnetic material
b. penetrant testing cannot locate shallow surface discontinuities
47. c. penetrant testing cannot be used on non-metallic surfaces
d. penetrant testing cannot locate subsurface discontinuities
D.21-24
58. In penetrant testing, the time period from the developer application to
inspection is often referred to as the:
a. emulsification time
b. development time
c. dwell time
d. none of the above
A.6-15
59. Liquid penetrant testing is a nondestructive test that can be used for:
a. locating and evaluating all types of discontinuities in a test specimen
b. locating and determining the length, width, and depth of
discontinuities in a test specimen
c. determining the tensile strength of a specimen
d. locating discontinuities open to the surface
A.6-1
60. When conducting a penetrant test using fluorescent penetrant, black light
equipment is required to:
a. cause the penetrant to fluoresce
b. aid the normal capillary action characteristics of a penetrant
c. neutralize excess penetrant on the surface
d. decrease the surface tension of the part
A.6-2
61. The method used to remove excess visible dye penetrant from a test
specimen is primarily determined by:
a. the surface roughness of the specimen
b. the type of material being tested
c. the length of penetration time
d. all of the above
A.6-19
62. Which of the following is a type of developer used in penetrant inspection?
a. dry
b. aqueous particulate
c. non-aqueous particulate
d. water-soluble
e. all of the above
48. F.26
63. When penetrant testing parts, the temperature of the parts should be near
room temperature. If the part is at a low temperature when tested, the:
a. penetrant may become viscous
b. penetrant may evaporate very rapidly
c. color intensity of the penetrant will decrease
d. penetrant will tend to adhere to the surface of the part
A.8-7
64. If a part to be penetrant tested is first heated to a high temperature, the
penetrant:
a. may become viscous
b. may “flash” or evaporate very rapidly
c. may lose some of its color brilliance
d. will better show discontinuities
A.8-7
65. Penetrants may be classified or subdivided by the method used to remove
excess penetrant. Which of the following is a proper classification in
accordance with this statement?
a. nonsolvent-removable
b. vapor-degreased
c. brush-removable
d. water-washable
A.8-7
66. The problem with retesting a test specimen that has been previously tested
using liquid penetrant is that:
a. the penetrant may form beads on the surface
b. the dried penetrant residue left in discontinuities may not readily
dissolve and the retest may be misleading
c. the penetrant will lose a great deal of its color brilliance
d. none of the above are correct statements
D.128
67. Which of the following conditions will decrease the life of a black light bulb?
a. line voltage fluctuations
b. dust on the face of the bulb
c. changes in room temperature
d. all of the above
A.7-16
49. 68. When a penetrant is applied to a part by submerging the part in a penetrant
bath, the part must:
a. remain in the penetrant bath during the entire penetration time
b. remain in the penetration time for at least one-half the penetration
time
c. remain in the penetration bath only long enough to ensure that the
surface is covered with penetrant
d. not remain in the penetrant bath for a period more than 5 minutes
A.6-7
69. Which of the following statements does not apply to developers used during
penetrant testing?
a. developers are highly fluorescent
b. developers often furnish a contrasting background during inspection
c. developers absorb or blot the penetrant that remains in
discontinuities after the rinse operation has been completed
d. developers may be either wet or dry
A.6-2
70. Which of the following statements is true?
a. sandblasting is a generally accepted method for cleaning a surface
that is to be penetrant tested
b. parts should be heated prior to the application of a penetrant
c. if the dryer is too high, the heat may degrade the effectiveness of the
penetrant
d. development time should be at least twice the penetration time
A.7-34
71. When using a wet developer:
a. a thick layer of developer is better than a thin layer for showing very
fine cracks
b. compressed air should be used to remove excess developer
c. a black developer will show better contrast than a white developer
d. a thin layer of developer is better than a thick layer for showing very
fine cracks
A.8-8
72. Which of the following statements is false?
a. sandblasting is not a recommended method for preparing for a
penetrant test
50. b. it is not necessary to remove a film of oil from a part prior to penetrant
testing because the penetrant is basically an oil
c. vapor degreasing is a very good method for removing oil from the
surface of the part to be penetrant tested
d. a voltage regulator should be used with a black light if the line voltage
fluctuates
A.6-6
73. A red against white background discontinuity image is most likely to be seen
when:
a. dry developers are used
b. visible dye penetrants are used
c. fluorescent post-emulsification penetrants are used
d. wet developers are used
A.6-2
74. Which of the following can be removed from the surface of a test a
specimen by vapor degreasing?
a. oil
b. paint
c. phosphate coatings
d. oxides
A.6-6
75. The purpose for using a developer on a test specimen is to:
a. promote penetration of the penetrant
b. absorb emulsifier residues
c. absorb penetrant from discontinuities and to provide a contrasting
background
d. help to dry the surface for better observation
F.25
76. Which one of the following statements is an incorrect use of crack panels
(blocks)?
a. to establish a standard size of crack that can be reproduced as
needed
b. to determine the relative sensitivities of two different penetrants
c. to determine if a penetrant has lost or has reduced brilliance on
fluorescent penetrants because of contamination
d. to determine the degree or method of cleaning necessary to remove
penetrant on the surface without removing it from the cracks
51. A.7-24
77. Which of the following is generally accepted as the most important
precaution when using water-washable penetrants?
a. be sure that the part is washed thoroughly during the rinse operation
b. be sure that the recommended dwell time is not exceeded
c. avoid over-rinsing the part
d. avoid over-application of emulsifier
F.33
78. Which of the following is generally accepted as the most important
precaution when using solvent-removable penetrants?
a. do not apply an excessive amount of emulsifier
b. do not apply an excessive amount of solvent
c. do not use an insufficient rinse pressure
d. be sure to use a black light to determine if the excess penetrant has
been rinsed away
F.25
79. Insufficient rinsing of fluorescent penetrants will result in:
a. subsequent corrosion of the surface
b. difficulty in the application of developer
c. excessive bleed-out
d. excessive background fluorescence
F.32
80. Which of the following safety precautions does not apply when handling
penetrant materials?
a. prolonged contact of penetrant with skin should be avoided because
the oil or solvent base may cause skin irritation
b. excessive amounts of developer powders should not be inhaled
c. air-line respirators and complete protective clothing must be worn at
all times
d. because the solvents used with the visible penetrant process are
flammable, this material should be kept away from open flames
F.26
81. How long must a part be kept wet with penetrant before the removal process
is started?
52. a. it varies depending on the type of penetrant used, the type of material
to be tested, and the type of discontinuities to be detected
b. since the penetrant will penetrate a discontinuity of any size in a
matter of seconds, the removal process should start as soon as
possible after the penetrant has been applied
c. 3 minutes
d. 10 minutes
F.32
82. Which of the following factors will affect resolution of penetrant indications?
a. the sensitivity of the penetrant materials used
b. the surface condition of the part
c. the temperature of the part and/or penetrant
d. all of the above
A.8-5, 6, 7
83. A serious loss of water in a wet developer mix or an excessive over-
concentration of developer powder can cause:
a. a loss of fluorescence during the inspection operation
b. nonrelevant indications
c. cracking of the developer coating during the drying operation
d. none of the above
A.7-29
84. What could happen if a person looks directly into a black light?
a. it will cause permanent damage to the eyes
b. it will possibly cloud the vision of the person looking into the light for a
short period of time
c. it will cause temporary total blindness
d. none of the above
A.7-17
85. When using dry developer, the drying operation is performed:
a. immediately after removal of excess penetrant
b. before the inspection step
c. thoroughly
d. all of the above
D.104, 105, 119
86. The failure to completely remove acid materials from a part before
fluorescent penetrant is applied will result in:
a. a decrease in the fluorescence of the penetrant
53. b. a need to double the penetrating time
c. a permanent stain on the part
d. all of the above
D.78
87. Penetrant is applied to a part by dipping. The part is then placed on a rack
while the penetrant seeps into discontinuities. If the penetration time is too
long, it will be difficult to rinse the penetrant from the part. If this happens,
the normal rinsing properties can be restored by:
a. chilling the part to a temperature of 4ºC (40ºF)
b. heating the part to a temperature of 54ºC (130º F)
c. re-dipping the part
d. applying a wet developer before attempting to rinse the part
A.6-7
88. When drying parts during a penetrant test, the parts:
a. are normally dried at room temperature
b. are normally dried by a circulating hot-air dryer
c. should be dried in an oven set at a temperature of 54º C (130º F)
d. should be dried by cool forced air
F.32
89. The contamination of a water-washable penetrant with an excessive amount
of water will:
a. reduce the penetrating quality of the penetrant
b. adversely affect the washability of the penetrant
c. both a and b are correct
d. neither a nor b are correct
A.7-34
90. Which of the following penetrant methods requires a source of electricity?
a. the water-washable fluorescent penetrant method
b. the post-emulsification fluorescent penetrant method
c. the visible dye penetrant method
d. none of the above
A.6-18
91. When using a fluorescent penetrant, the actual inspection must be
performed:
a. in a brightly lighted room
b. with the part at a temperature between 10 and 79ºC (125 and 175ºF)
c. immediately after the developer has been applied
54. d. in a darkened area under a black light
A.6-17
92. Which of the following penetrants can be used when inspection must take
place under ordinary lighting conditions?
a. visible dye penetrant
b. water-washable fluorescent penetrant
c. post-emulsification fluorescent penetrant
d. any of the above
A.6-18
93. All of the following materials can be effectively tested with liquid penetrant
except:
a. aluminum
b. unglazed ceramics
c. glass
d. magnesium
A.6-1
94. Which of the following is a disadvantage of using the liquid penetrant testing
method?
a. the liquid penetrant test method is adaptable to production inspection
of small parts
b. liquid penetrant testing can locate fine cracks
c. the liquid penetrant test method is a relatively simple test method
d. the liquid penetrant test method is effective at any temperature
A.7-34
95. A good penetrant must do all of the following except:
a. be able to readily penetrate very fine openings
b. evaporate very rapidly
c. be able to remain in relatively coarse openings
d. be easily removed from the surface after testing
A.7-18
96. Which of the following is not a property of a developer used in liquid
penetrant testing?
a. the material must be absorbent
b. the material must form a thin and uniform coating over a surface
c. the material must be fluorescent if used with fluorescent penetrants
d. the material must not contain ingredients harmful or toxic to the
operator
55. F.25
97. If improperly used, developers:
a. may obscure indications
b. may be difficult to remove
c. may become contaminated
d. all of the above
D.95, 98, 123
98. Color-contrast penetrants are commercially available in which of the
following variations?
a. normal solvent clean type
b. water-wash type
c. post-emulsification type
d. all of the above
F.24
99. Which of the following could be a source of false indications on a test
specimen?
a. penetrant on the test table
b. penetrant on the hands of the inspector
c. contamination of dry or wet developer with penetrant
d. all of the above
D.377
100. Cleaning of the part prior to penetrant inspection is:
a. not required
b. important because if the part is not clean, the developer cannot be
improperly applied
c. essential because surface contaminants may prevent penetrant from
gaining access to discontinuities
d. required to eliminate possibility of showing nonrelevant indications
A.6-6
101. When using fluorescent water-washable penetrant, adequate rinsing of the
part is assured by:
a. timing of rinse cycle
b. scrubbing of part surface
c. rinsing under black light
d. using high pressure air with water
A.6-7
56. 102. What can happen if a part processed by visible dye penetrant inspection is
reprocessed by the fluorescent penetrant method?
a. developer may remain on the surface causing background
b. most visible dyes kill fluorescence
c. penetrants are not compatible
d. interpretation will be difficult
D.2-40
103. A suitable filter must be used at all times over a black light bulb because:
a. too much white light will be present if the filter is not in place
b. the human eye may be damaged without it
c. the filter filters out undesired wave lengths
d. all of the above
D.203-204
104. A good commercial penetrant should have a:
a. low flash point
b. bigh flash point
c. medium flash point
d. flash point is not a factor to be considered
D.43
105. A material that is applied over the film of the penetrant on the surface of a
part, mixes with the penetrant, and enables the penetrant to be washed
off the surface is called:
a. an emulsifier
b. a penetrant
c. a developer
d. an isomer
D.32
106. The time allowed for the penetrant to enter discontinuities that may be
present is the:
a. emulsification time
b. application time
c. penetration time
d. drain time
D.32
107. Which of the following penetrant systems is generally considered to be the
least sensitive?
![Dye penetrant inspection
From Wikipedia, the free encyclopedia
1. Section of material with a surface-breaking crack that is not visible to the naked eye.
2. Penetrant is applied to the surface.
3. Excess penetrant is removed.
4. Developer is applied, rendering the crack visible.
This article needs additional citations for verification. Please help improve this article by adding
citations to reliable sources. Unsourced material may be challenged and removed.(November 2009)
Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant
testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects
in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non-
ferrous materials and ferrous materials, although for ferrous components magnetic-particle inspection is
often used instead for its subsurface detection capability. LPI is used to detect casting, forging and
welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue
cracks on in-service components.
Contents
[hide]
1 History
2 Principles
3 Materials
4 Inspection steps
5 Advantages and disadvantages
6 Standards](https://image.slidesharecdn.com/dyepenetrantinspection-121128230237-phpapp01/85/dye-penetrant-inspection-1-320.jpg)
![7 References
8 See also
9 External links
[edit]History
The oil and whiting method used in the railroad industry in the early 1900's was the first recognized use
of the principles of penetrants to detect cracks. The oil and whiting method used an oil solvent for
cleaning followed by the application of a whiting or chalk coating, which absorbed oil from the cracks
revealing their locations. Soon a dye was added to the liquid. By the 1940's, fluorescent or visible dye
was added to the oil used to penetrate test objects.
Experience showed that temperature and soak time were important. This started the practice of written
instructions to provide standard, uniform results. The use of written procedures has evolved, giving the
ability for design engineers and manufacturers to get the high standard results from any properly trained
and certified liquid penetrant testing technician.
[edit]Principles
DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-
breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or
brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a
developer is applied. The developer helps to draw penetrant out of the flaw where a invisible indication
becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending upon
the type of dye used - fluorescent or nonfluorescent (visible).
[edit]Materials
Penetrants are classified into sensitivity levels. Visible penetrants are typically red in color, and represent
the lowest sensitivity. Fluorescent penetrants contain two or more dyes that fluoresce when excited
by ultraviolet (UV-A) radiation (also known as black light). Since Fluorescent penetrant inspection is
performed in a darkened environment, and the excited dyes emit brilliant yellow-green light that contrasts
strongly against the dark background, this material is more sensitive to small defects.
When selecting a sensitivity level one must consider many factors, including the environment under
which the test will be performed, the surface finish of the specimen, and the size of defects sought. One
must also assure that the test chemicals are compatible with the sample so that the examination will not
cause permanent staining, or degradation. This technique can be quite portable, because in its simplest
form the inspection requires only 3 aerosol spray cans, some lint free clothes, and adequate visible light.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)