The document discusses visual inspection and optical aids used for visual inspection. It describes visual inspection as the most basic and common non-destructive testing method. It involves illuminating the test specimen and examining it with the eye or light-sensitive devices. Various optical aids like microscopes, borescopes, and endoscopes are used to magnify defects and enable inspection of inaccessible areas. The document outlines the principles, advantages, and applications of visual inspection and different optical aids used to enhance visual inspection capabilities.

1. VISUALINSPECTIONANDOPTICALAIDS FORVISUAL
INSPECTIONAPPLICATION
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2. The use of non destructive
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.
Definition of NDT

3. Six Most Common NDT Methods
 Visual
 Liquid Penetrant
 Magnetic
 Ultrasonic
 Eddy Current
 X-ray
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4. IMPORTANCE OF NDT
Non-destructive testing is a descriptive
term used for the examination of materials and
components in such a way that allows materials to
be examined without changing or destroying their
usefulness.
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5. VISUAL INSPECTION
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6. PRINCIPLE OF INSPECTION
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The basic procedure used in visual
NDT involves illumination of test
specimen with light, usually in the visible
region. The specimen is then examined
with eye or by light sensitive device such
as photo cells. The surface of the
specimen should be adequately cleaned
before being inspected.

7. Visual Inspection
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Most basic and common inspection
method.
 Robotic crawlers permit observation in
hazardous or tight areas, such as air
ducts, reactors, pipelines.
 Portable video inspection unit with zoom
allows inspection of large tanks and
vessels, railroad tank cars, sewer lines.
 Tools include fiberscopes, borescopes,
magnifying glasses and mirrors.

8. Most valuable NDT tool
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The most valuable NDT tool is HUMAN EYE.
The eye has excellent visual perception.
The sensitivity of the human eye varies for light
with different wave length.
The eye is most sensitive to yellowgreen light
which has a wave length of 5560Å.
Eye cannot be a good judge for distinguishing the
differences in brightness or intensity except under
the most restricted conditions.

9. Defects can detected by unaided visual inspection
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The general condition of the component.
The presence or absence of oxide film or corrosive product
on the surface.
The presence or absence of cracks, orientation of cracks
and position of cracks.
The surface porosity, unfilled craters, contour of the weld
bead.
Mechanical weakness such as sharp notch or
misalignment, etc.

10. Safety measures in visual inspection
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The adequate lightening is about 800
– 1000 lux.
It is allowed to work only for 2 hours
on continuous basis to avoid error due
to decrease in visual reliability and
discrimination.

11. Optical aids
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12. Optical aids
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 The use of optical instruments in visual inspection is
beneficial and is recommended to,
Magnify defects that cannot be detected by a
unaided eye.
Permit visual checks of areas not accessible to
the unaided eye.
 The magnifying devices and lighting aids should be
used wherever appropriate.
 In many cases, area to be inspected should be
cleaned before examination.

13. Optical aids
Microscope
Borescope
Endoscope
Telescope
Holography
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14. microscope
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An optical microscope is a combination of lenses
used to magnify the image of a small object.
Minute defects and details of fine structure on a
surface can be detected easily with microscope.
Optical microscopes are used to evaluate with
respect to shape and orientation of cracks.

15. Borescope
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A borescope is an instrument designed to enable
an observer to inspect the inside of a narrow tube,
bore or chamber.
Borescope consist of precision built in
illumination system.
The size of the visual field usually varies with the
diameter, for a given magnification system.

16. Endoscope
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It is much like a borescope except that it has a
superior optical system and a high intensity light
source.
A unique feature of endoscope is that objects are
constantly in focus from about 4mm to infinity.
The “no focusing” feature of endoscope makes it
much easier to use than a borescope.

17. telescope
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It is used to obtain magnified images of objects at
considerable distance from the eye.
It is particularly useful for providing visual
examination of the surface.
It consists of two lenses called objective or eye
piece.

18. holography
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Holography is name given to the method of obtaining an
accurate 3-D image of a given object.
It is used for the NDT of surfaces of highly complicated
and precision components without the dis-advantages of
having to use a high power microscope.
It can provide a record of the image of an entire surface
which can be readily compared with that of a standard
defect free surface.

19. ADVANTAGES
Cheapness
Portability
Immediate result
Minimum special skills
Minimum part preparation
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20. DIS - ADVANTAGES
Suitable only for surface which can be viewed
Generally detect only larger defects
Misinterpretation of cracks and scratches
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21. applications
Misalignment of parts in equipments
Inspection of plant system and component for any
leakage, abnormal operation etc.
Corrosion, erosion, cracks, fracture etc.
Minute discontinuities with the help of optical aids
in pump, compressors.
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22. Thank you
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BEFORE
YOU
JUDGE
ME
MAKE
SURE
YOU’RE
PERFECT