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

1. RAMCO INSTITUTE OF TECHNOLOGY
Mr.M.LAKSHMANAN
Assistant Professor (Senior Grade)
Department of Mechanical Engineering

2. NON DESTRUCTIVE TESTING
AND MATERIALS

3. UNIT I OVERVIEW OF NDT
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.

4. 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.

5. UNIT III THERMOGRAPHYAND EDDY
CURRENT TESTING (ET)
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.

6. UNIT IV ULTRASONIC TESTING (UT) AND
ACOUSTIC EMISSION (AE)
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

7. UNIT V RADIOGRAPHY (RT)
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

8. OBJECTIVES:
• To study and understand the various Non Destructive
Evaluation and Testing methods, theory and their
industrial applications.
OUTCOMES:
• Upon completion of this course, the students can able
to use the various Non Destructive Testing and
Testing methods understand for defects and
characterization of industrial components

9. TEXT BOOKS:
• Baldev Raj, T.Jayakumar, M.Thavasimuthu “Practical
Non-Destructive Testing”, Narosa Publishing House,
2009.
• Ravi Prakash, “Non-Destructive Testing Techniques”,
1st revised edition, New Age International Publishers,
2010

10. REFERENCES:
1. ASM Metals Handbook,”Non-Destructive Evaluation and
Quality Control”, American Society of Metals, Metals Park,
Ohio, USA, 200, Volume-17.
2. Paul E Mix, “Introduction to Non-destructive testing: a training
guide”, Wiley, 2nd Edition New Jersey, 2005
3. Charles, J. Hellier,“ Handbook of Nondestructive evaluation”,
McGraw Hill, New York 2001.
4. ASNT, American Society for Non Destructive Testing,
Columbus, Ohio, NDT Handbook, Vol. 1, Leak Testing, Vol. 2,
Liquid Penetrant Testing, Vol. 3, Infrared and Thermal Testing
Vol. 4, Radiographic Testing, Vol. 5, Electromagnetic Testing,
Vol. 6, Acoustic Emission Testing, Vol. 7, Ultrasonic Testing

11. UNIT I
OVERVIEW OF NDT

22. Destructive Testing (DT)
Destructive testing, (or Destructive Physical Analysis, DPA)
tests are carried out to the specimens failure, in order to
understand a specimens performance or material
behaviour under different loads.
Methods of Testing:
 Hardness
 Tensile
 compression
 Impact
 Fracture Toughness
 Fatigue
 Creep

23. Non-Destructive Testing (NDT)
Non-destructive testing (NDT) is a wide group of
analysis techniques used in science and technology
industry to evaluate the properties of a material,
component or system without causing damage.
NDT can be used to ensure the quality right from raw
material stage through fabrication and processing to
pre-service and in-service inspection. Apart from
ensuring the structural integrity, quality and reliability
of components and plants.

24. The use of non-invasive techniques to:
• Determine the integrity of a material, component
or structure
or
• Quantitatively measure some characteristic of an
object.
(i.e. Inspect or measure without doing harm)
The terms:
• Non-destructive Examination (NDE)
• Non-destructive Inspection (NDI)
• Non-destructive Evaluation (NDE)

25. NDT Methods
• Visual Inspection (VI)
• Liquid Penetrant Testing (LPT)
• Magnetic Particle Testing (MPT)
• Thermography Test (TT)
• Eddy current Testing(ET)
• Ultrasonic Testing (UT)
• Acoustic Emission (AE)
• Radiography Test (RT)

26. Objectives of NDT
 To ensure product integrity, and reliability.
 To detect internal or surface flaws
 To measure the dimensions of materials
 To determine the materials structure
 To evaluate the physical and mechanical properties of
materials.
 To avoid failures, prevent accidents and save human life
 To make a profit for the user
 To ensure customer satisfaction and maintain the
manufacturer's reputation
 To lower manufacturing costs
 To maintain uniform quality level

27. Common Application of NDT
 Inspection of Raw Products
 Inspection Following Secondary Processing
 In-Services Damage Inspection
In the field of:
• Power Plant Inspection
• Wire Rope Inspection
• Storage Tank Inspection
• Aircraft Inspection
• Jet Engine Inspection
• Pressure Vessel Inspection
• Rail Inspection
• Bridge Inspection
• Pipeline Inspection
• Special Measurements

28. Importance of NDT
 Applied directly to the product
 Tested parts are not damaged
 Various tests can be performed on the same
product
 Specimen preparation not required
 Can be performed on parts that are in service
 Low time consumption
 Low labour cost

29. Common Defects
 Porosity
 Undercutting
 Rollover or “ColdLap”
 Slag inclusion
 Poor penetration
 Hydrogen Embrittlement
 Cracks
 Corrosion
 Wear

30. Comparison of Destructive and Non Destructive
Testing
Destructive Testing
Advantages:
• Measurements are direct and
reliable
• Usually quantitative
measurements
• Correlation between test
measurements and material
properties is direct
Non Destructive Testing
Limitations:
• Measurements are indirect
• Usually qualitative
measurements
• Skilled judgment and
experience are required to
interpret indications

31. Destructive Testing
Limitations:
• Tests are not made on the objects
directly.
• A single test may measure only
one or a few of the properties.
• In-service testing is not possible.
• Preparation of the test specimen
is costly.
• Time requirements are generally
high.
Non Destructive Testing
Advantages:
• Tests are made directly on the
object.
• Many methods can be applied
on the same part .
• In-service testing is possible.
• Repeated checks over a period
of time are possible.
• Very little preparation is
sufficient.
• Most test methods are rapid.

32. Visual Inspection (VI)
Visual inspection is a common method of quality
control, data acquisition, and data analysis. Visual
Inspection, used in maintenance of facilities, mean
inspection of equipment and structures using either or
all of raw human senses such as vision, hearing, touch
and smell and/or any non-specialized inspection
equipment.

33. Principle:
• The basic procedure used in visual NDT involves
illumination of the test specimen with light,
usually in the visible region.
• The specimen is then examined with eye or by
light sensitive devices such as photocells.
• The equipment required for visual inspection is
extremely simple, but adequate illumination is
absolutely essential.
• The surface of the specimen should be adequately
cleaned before being inspected.

34. Methods of Visual Inspection
• In Human eye
• Magnifying Glass/Mirror
• Fillet Gauge/Weld Gauge
• Microscope
• Boroscope/Endoscope
• Flexible fiber optic Boroscope
• Video Image

35. In Human eye
• Illuminate the test specimen with light and examine the
specimen with the eye.
• The most valuable NDT tool is the human eye. The eye
has excellent visual perception.
• The sensitivity of the human eye varies for light with
different wave lengths.
• Under ordinary conditions, the eye is most sensitive to
yellow-green light. Which has a wave length of 5560A.
• The human eye will give satisfactory vision over a wide
range of conditions.

36. Advantages:
• Inspection performed rapidly
• Ability to inspect complex sizes and shapes of any
material
• Minimum part preparation required
Limitations:
• Only surface defects are detectable.
• Surface finish, roughness, cleanliness can interfere
with inspection.

37. Magnifying Glass/Mirror
Magnifying Glass:
Generally consists of a single lens for lower power
magnification and double or multiple lenses for higher
magnification.
Magnifying Mirror:
This one is a concave reflective surface, such as a dental
mirror may be used to view restricted areas of aircraft
not accessible with a magnifying glass.

38. Advantages:
• Magnifier reduces the focal length of your sight.
• It will show up defects that eyes cannot see.
• Cheap and portable.

39. Fillet Gauge/Weld Gauge
Fillet Gauge:

40. Weld Gauge:

41. Advantages:
• It is suitable for checking edges and corners of
work pieces in any position.
• It can be able to measure reinforcement on a
butt weld.

42. Microscope
• Its an optical instrument consisting of a lens or
combination of lenses for making enlarged images of
minute objects.
• It is a multiple element magnifier, providing very
high power magnification, is used for the inspection
of parts removed from the aircraft.

43. Scanning Electron Microscope (SEM) is
becoming a valuable new tool for the non
destructive inspection, examination and
evaluation of materials, both metallic and non-
metallic, as well as assemblies and surfaces.

44. Advantages:
• Higher magnification (20,000 times)
• Higher resolution
• it's less expensive and readily available.
• Simple setup with very little preparation
required.

45. Boroscope/Endoscope
Boroscope is a precision optical instrument with
built in illumination. Borescopes sometimes
called 'endoscopes' or 'endoprobes', which
consists with superior optical systems and high
intensity light sources, some boroscopes
provides magnification option, zoom controls or
accessories.

47. Advantages:
• Cheap. Much simpler in design, rigid
boroscopes tend to be more economical than
the flexible variant.
• Easy to use. With their straightforward design,
rigid boroscopes are easy to manipulate.
• High-quality images. Rigid boroscopes offer
clear images and the ability to identify
imperfections like cracks as minute as 0.001.

48. Flexible Fiber Optic Borescope
Permits manipulation of the instrument around
cameras and through passages with several
directional changes. Woven stainless steel
sheathings protects the image relay bundle
during repeated flexing. The working lengths are
normally 60 to 365 cm with diameters from 3 to
12.5 min.

49. • Viewing directions: 0°, 90°
(with adapter)
• Field of view: 45° or 60°
• Bending: 2fold and 4fold

50. Advantages:
• High degree of free movement.
• Greater area coverage at a farther distance.
• Versatility and economy.
• Great image quality.

51. Video Imagescope
The video Imagescope is similar to a Fiberscope
with the exception that video camera and its
connections have replaced the image bundle and
a TV monitor has replaced the eyepiece. This
image may be magnified for precise viewing.
The field of vision is up to 90 degree and probe
tip has four way articulation. Presently the
smallest diameter is 9.5 mm with working length
up to 100 feet. It can be used to peek into curvy
pipes, ducts, vents, even chimneys.

54. Advantages:
• It can easily connect to PC.
• It also have a built-in removable storage media
(memory card).
• See more area and more distant or higher magnified.
• Decrease the eye strain as it is much easier to watch
higher resolution images on a big monitor.
• Inspectors can record test results and perform instant
image analysis.

59. VISUAL
Inexpensive Highly portable
Immediate results Minimum
training Minimum part preparation
Surface discontinuities only Generally only
large discontinuities Misinterpretation of
scratches
DYE PENETRANT
Portable Inexpensive Sensitive to
very small discontinuities 30 min.
or less to accomplish Minimum
skill required
Locate surface defects only Rough or porous
surfaces interfere with test Part preparation
required (removal of finishes and sealant, etc.)
High degree of cleanliness required Direct
visual detection of results required
MAGNETIC
PARTICLE
Can be portable Inexpensive
Sensitive to small discontinuities
Immediate results Moderate skill
required Detects surface and
subsurface discontinuities
Relatively fast
Surface must be accessible Rough surfaces
interfere with test Part preparation required
(removal of finishes and sealant, etc.) Semi-
directional requiring general orientation of
field to discontinuity Ferro-magnetic materials
only Part must be demagnetized after test.

60. EDDY CURRENT
Portable Detects surface and
subsurface discontinuities Moderate
speed Immediate results Sensitive to
small discontinuities Thickness
sensitive
Surface must be accessible to probe Rough
surfaces interfere with test Electrically
conductive materials Skill and training
required Time consuming for large areas
ULTRASONIC
Portable Inexpensive Sensitive to very
small discontinuities Immediate results
Little part preparation Wide range of
materials and thickness can be
inspected
Surface must be accessible to probe Rough
surfaces interfere with test Highly sensitive
to sound beam discontinuity orientation High
degree of skill required to set up and
interpret Couplant usually required
X-RAY
RADIOGRAPHY
Detects surface and internal flaws Can
inspect hidden areas Permanent test
record obtained Minimum part
preparation
Safety hazard Very expensive (slow process)
Highly directional, sensitive to flaw
orientation High degree of skill and
experience required for exposure and
interpretation Depth of discontinuity not
indicated

61. REVIEW