The document discusses two non-destructive testing methods: liquid penetrant testing and magnetic particle testing. Liquid penetrant testing uses liquid that is drawn into surface cracks by capillarity, then a developer reveals the flaws. The process involves surface cleaning, penetrant application, dwell time, developer application and inspection. Magnetic particle testing uses magnetism to detect subsurface flaws in ferromagnetic materials. Iron particles are attracted to cracks when the part is magnetized. The process involves demagnetization, magnetization, particle application and inspection under lighting. Both are widely used to inspect parts for cracks and defects.

1. UNIT II SURFACE NDE METHODS
Liquid Penetrant Testing - Principles, types
and properties of liquid penetrants, developers,
advantages and limitations of various methods,
Testing Procedure, Interpretation of results.
Magnetic Particle Testing- Theory of
magnetism, inspection materials Magnetisation
methods, Interpretation and evaluation of test
indications, Principles and methods of
demagnetization, Residual magnetism.

2. Liquid Penetrant Testing
The principle of liquid penetrant tests is that the
liquid penetrants are drawn into surface flaws such
as cracks or porosities by capillary action. Then the
developer material in conjunction with visual
inspection reveals the surface flaw.
Characteristics:
• To locate cracks, porosity and other defects that
breaks the surface as a material and has enough
volume to trap and hold the penetrant material.
• To inspect large areas very effectively and will
work on most non-porous materials.

3. STAGES/TEST PROCEDURE OF LPI

5. FLOW CHART LPI

6. STAGES/TEST PROCEDURE OF LPI
1.Surface preparation
2. Application of penetrants
3.Dwell or penetrant time
4.Removal of excess penetrant
5.Application of Developer
6.Examinaion, interpretation and evaluation
7.Post process cleaning

7. 1.SURFACE PREPARATION
The test surface should be thoroughly cleaned
and dried before the penetrant is applied by
(i) Mechanical cleaning method
(ii) Chemical cleaning method
(iii)Solvent cleaning method

10. 2. APPLICATION OF PENETRANTS
Penetrant is a liquid capable of wetting the entire
surface and being drawn into fine openings.

11. 3.DWELL OR PENETRANT TIME
It is the period of time from when the penetrant applied to the surface until it is
removed.

12. 3.DWELL OR PENERANT TIME(Conti..)

13. 4.REMOVAL OF EXCESS PENETRANT

14. 4.REMOVAL OF EXCESS PENETRANT (Conti..)

15. 5.APPLICATION OF DEVELOPER

16. Types of developer

17. 6.EXAMINAION, INTERPRETATION AND EVALUATION

18. 6.EXAMINAION, INTERPRETATION AND EVALUATION(CONTI..)

19. 6.EXAMINAION, INTERPRETATION AND EVALUATION(CONTI..)

20. 7.POST PROCESS CLEANING

21. PENETRANT MATERIALS

22. PENETRANT

23. Florescent Penetrant:
They are usually green in color and they
contain a dye or several dyes that fluoresce when
exposed to ultraviolet radiation.
Visible Penetrant:
It contain a red dye that provides high contrast
against the white developer background.

24. Florescent Vs Visible Penetrant

25. CHARACTERISTICS OF GOOD PENETRANT

26. CHARACTERISTICS OF GOOD PENETRANT
(Conti..)

27. PROPERTIES OF PENETRANTS

28. 1.Surface wetting capability (Wettability)
It is the ability of penetrant to free wet surface of the object being
inspected.
(i)Contact angle:

29. (ii) Surface tension (Surface Energy):
2. Capillarity:

30. 3.Viscosity:
4. Sp. Gravity:

31. 5.Flash point:
6.Volaility:

32. 7.Fluorescent dye thermal stability:
8.Penetrant color and fluorescence:

33. 9.Removability:

34. Dye penetrants Fluorescent penetrants

35. DEVELOPERS
Developer is an absorbent material capable of drawing traces of
penetrants from the discontinuities back into the surface.
Characteristics of Good Developer:

36. TYPES OF DEVELOPER

41. Equipment for liquid penetrant testing

42. Penetrant Developer Reveal the flaw

43. LIQUID PENETRANT TESTING
METHODS / TECHNIQUES
1.Water washable penetrant Technique
2.Post Emulsifiable Penetrant Technique
(a)Post Emulsifiable lipophilic Technique
(b)Post Emulsifiable Hydrophilic Technique
3.Solvant Removable Penetrant Technique

44. 1.Water washable penetrant Technique

45. Water washable penetrant Technique-Process flow chart

46. Water washable penetrant Technique (Conti..)

47. 2.Post Emulsifiable Penetrant Technique

48. Post Emulsifiable lipophilic Technique

49. Post Emulsifiable Hydrophilic Technique

51. 3.Solvant Removable Penetrant Technique

52. 3.Solvant Removable Penetrant Technique

53. Application of LPI

55. Magnetic Particle Inspection
Magnetic particle
Testing (MPT) is used for
the testing of material which
can be easily magnetized
(Ferromagnetic materials).
This method is
capable of detecting surface
and subsurface flaws such
as cracks and inclusions.

56. Basic Principles of Magnetic Particle (MPT)
• When a bar magnet is broken in
the center of its length, two
complete bar magnets will result.
• If the magnet is just cracked but
not broken completely in two, a
north and south pole will form at
each edge of the crack.
•
• If iron particles are sprinkled on a
cracked magnet, the particles will
be attracted to the poles at the
edges of the crack

59. Testing Procedure/Process of MPI
Step:1 Cleaning/ Surface preparation
Step:2 Demagnetization
Step:3 Magnetizing the object
Step:4 Addition of magnetic particles
Step:5 Illumination during inspection (e.g. UV lamp)
Step:6 Interpretation
Step:7 Documentation and reporting

60. Testing Procedure/Process of MPI

61. Step:1 Cleaning/ Surface preparation

62. Step:2 Demagnetization

63. Step:3 Magnetizing the object

64. Step:4 Addition of magnetic particles

65. Step:5 Illumination during inspection

66. Step:6 Interpretation

67. Step:7 Documentation and reporting

68. MPI- INSPECTION TECHNIQUES
• Dry particle inspection technique
• Wet particle inspection technique

69. DRY PARTICLE INSPECTION TECHNIQUE
Dry particles are applied on to the surface of the
test object as the item is magnetized.

70. STEPS IN DRY PARTICLE INSPECTION TECHNIQUE

71. DRY PARTICLE INSPECTION TECHNIQUE (CONTI..)

72. DRY PARTICLE INSPECTION TECHNIQUE (CONTI..)

73. Wet Particle Inspection Technique (or)
Wet Magnetic Particle Testing
• The particles are applied while they are suspended
in a liquid carrier.

74. WET PARTICLE INSPECTION TECHNIQUE

75. OVERVIEW OF MAGNETISM
Theory of Magnetism

76. MAGNETIC PROPERTIES AND HYSTERESIS LOOP

77. HYSTERESIS LOOP

78. Primary magnetic properties

79. MAGNETIC FIELD ORIENTATION IN MPI
• In MPI, the orientation of magnetic lines of
forces is important in detection of cracks or
other defects.
• Types of Magnetic field,
– Longitudinal Magnetic field
– Circular Magnetic field

80. Longitudinal magnetic field orientation in MPI

81. Circular magnetic field orientation in MPI

82. EQUIPMENT USED IN MAGNETIC PARTICLE TESTING
1. Magnetization equipment
I. Portable
a) Permanent magnets
b) Electromagnetic yokes
c) Prods
d) Portable coils
II. Stationary
2. Portable power supplies
3. Lighting equipment
a) Visible color particle
b) Fluorescent particle

83. EQUIPMENT USED IN MPI (Conti..)
1.Magnetization equipment in MPI

84. EQUIPMENT USED IN MPI (Conti..)
I. Portable Magnetization equipment
a. Permanent magnets

85. EQUIPMENT USED IN MPI (Conti..)
b. Electromagnetic yokes

86. EQUIPMENT USED IN MPI (Conti..)
c. Prods

87. EQUIPMENT USED IN MPI (Conti..)
d. Portable coils

88. EQUIPMENT USED IN MPI (Conti..)
II. Stationary Magnetization equipment

89. EQUIPMENT USED IN MPI (Conti..)
2.Portable power supplies

90. EQUIPMENT USED IN MPI (Conti..)
3.Lighting equipment

91. EQUIPMENT USED IN MPI (Conti..)
3.Lighting equipment

92. EQUIPMENT USED IN DETERMINATION OF MAGNETIC
FIELD STRENGTH AND DIRECION

94. Hall Effect gauss meter

96. Pie gauge

100. Magnetic Particle