Liquid Penetrant Testing and Magnetic Particle Testing - Principles, techniques

1. KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY
(AUTONOMOUS)
NAMAKKAL- TRICHY MAIN ROAD, THOTTIAM
DEPARTMENT OF MECHANICAL ENGINEERING
ME8097 NON DESTRUCTIVE TESTING AND EVALUATION
SEVENTH SEMESTER
UNIT-II
PRESENTED BY
M.DINESHKUMAR,
ASSISTANT PROFESSOR,
DEPARTMENT OF MECHANICAL ENGINEERING,
KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY.

2. ME8097 NON DESTRUCTIVE TESTING AND EVALUATION
OBJECTIVE:
To study and understand the various Non Destructive Evaluation and Testing methods, theory and their industrial applications.
UNIT I OVERVIEW OF NDT 9
NDT Versus Mechanical testing, Overview of the Non Destructive Testing Methods for the detection of manufacturing defects as
well as material characterisation. Relative merits and limitations, Various physical characteristics of materials and their
applications in NDT., Visual inspection –Unaided and aided.
UNIT II SURFACE NDE METHODS 9
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.
UNIT III THERMOGRAPHY AND EDDY CURRENT TESTING (ET) 9
Thermography- Principles, Contact and non contact inspection methods, Techniques for applying liquid crystals, Advantages and
limitation - infrared radiation and infrared detectors, Instrumentations and methods, applications. Eddy Current Testing-Generation
of eddy currents, Properties of eddy currents, Eddy current sensing elements, Probes, Instrumentation, Types of arrangement,
Applications, advantages, Limitations, Interpretation/Evaluation.
UNIT IV ULTRASONIC TESTING (UT) AND ACOUSTIC EMISSION (AE) 9
Ultrasonic Testing-Principle, Transducers, transmission and pulse-echo method, straight beam and angle beam, instrumentation,
data representation, A/Scan, B-scan, C-scan. Phased Array Ultrasound, Time of Flight Diffraction. Acoustic Emission Technique –
Principle, AE parameters, Applications.
UNIT V RADIOGRAPHY (RT) 9
Principle, interaction of X-Ray with matter, imaging, film and film less techniques, types and use of filters and screens, geometric
factors, Inverse square, law, characteristics of films -graininess, density, speed, contrast, characteristic curves, Penetrameters,
Exposure charts, Radiographic equivalence. Fluoroscopy- Xero-Radiography, Computed Radiography, Computed Tomography.
TOTAL : 45 PERIODS

3. 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.

4. 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.

5. STAGES/TEST PROCEDURE OF LPI

7. FLOW CHART LPI

8. 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

9. 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

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

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

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

15. 4.REMOVAL OF EXCESS PENETRANT

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

17. 5.APPLICATION OF DEVELOPER

18. Types of developer

19. 6.EXAMINAION, INTERPRETATION AND EVALUATION

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

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

22. 7.POST PROCESS CLEANING

23. PENETRANT MATERIALS

24. PENETRANT

25. 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.

26. Florescent Vs Visible Penetrant

27. CHARACTERISTICS OF GOOD PENETRANT

28. CHARACTERISTICS OF GOOD PENETRANT
(Conti..)

29. PROPERTIES OF PENETRANTS

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

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

32. 3.Viscosity:
4. Sp. Gravity:

33. 5.Flash point:
6.Volaility:

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

35. 9.Removability:

36. Dye penetrants Fluorescent penetrants

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

38. TYPES OF DEVELOPER

43. Equipment for liquid penetrant testing

44. Penetrant Developer Reveal the flaw

45. 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

46. 1.Water washable penetrant Technique

47. Water washable penetrant Technique-Process flow chart

48. Water washable penetrant Technique (Conti..)

49. 2.Post Emulsifiable Penetrant Technique

50. Post Emulsifiable lipophilic Technique

51. Post Emulsifiable Hydrophilic Technique

53. 3.Solvant Removable Penetrant Technique

54. 3.Solvant Removable Penetrant Technique

55. Application of LPI

57. 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.

58. 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

61. 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

62. Testing Procedure/Process of MPI

63. Step:1 Cleaning/ Surface preparation

64. Step:2 Demagnetization

65. Step:3 Magnetizing the object

66. Step:4 Addition of magnetic particles

67. Step:5 Illumination during inspection

68. Step:6 Interpretation

69. Step:7 Documentation and reporting

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

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

72. STEPS IN DRY PARTICLE INSPECTION TECHNIQUE

73. DRY PARTICLE INSPECTION TECHNIQUE (CONTI..)

74. DRY PARTICLE INSPECTION TECHNIQUE (CONTI..)

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

76. WET PARTICLE INSPECTION TECHNIQUE

77. OVERVIEW OF MAGNETISM
Theory of Magnetism

78. MAGNETIC PROPERTIES AND HYSTERESIS LOOP

79. HYSTERESIS LOOP

80. Primary magnetic properties

81. 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

82. Longitudinal magnetic field orientation in MPI

83. Circular magnetic field orientation in MPI

84. 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

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

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

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

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

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

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

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

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

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

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

96. Hall Effect gauss meter

98. Pie gauge

102. Magnetic Particle