Visual Testing in NDT:
Visual Inspection is method of visually inspecting the material for deciding the acceptablility of the material.
Infact it is the very first inspection method in Non Destructive Testing methods.
Sometimes the Visual Inspection is carried out with aid of additional Instruments and Devices such as Measurement tools & Vision aids.
What are essentials for visual Inspection ?
Human Eye
Lighting
Acceptance Criteria
Measurement Devices
Human Eye
So in order to make sure the very essential instrument (EYE) is working properly , it is essential to investigate and make sure, it works properly.
So a Visual Acuity Test is recommended Yearly, by most of the standards
Visual Acuity commonly referred to as clarity of Vision.
It is dependent upon optical and neural factors.
i.e., (i) the sharpness of the retinal focus
(ii) the health and functioning of retina
(iii) the sensitivity of the interpretative faculty of the brain.
Vision Problems
Glaucoma (increase in fluid pressure)
Myopia (Near Sightedness)
Hyperopia (Far Sightedness)
Astimatism (Blurry Images & stretched out )
Presbyopia (Age related condition, less abilty to focus close objects – aged lens)
Conjunctivitis (Pink eye)
Eye Tests
Jaeger’s Test J-1(Long Distance 6m)
Jaegers Test J-2 (Short Distance 300mm)
Snellen chart (Visual Acuity)
Ishihara Test (Colour Discrimination)
Grey Test ( Different shades of grey)
Lighting
Natural
Artificial – Incandescent, Fluorescent, Arc Lighting, LED
Measurement of Light
1) Newton’s inverse Square law
E= I / d²
2) Lambert’s Cosine Law
E = I cos Ø
Combination of both laws are used to measure the light requirement stated in the standards
Factors affecting the Visual Testing
Surface Condition of material
– Cleanliness
– Colour
– Texture
Physical Condition of material
– Specimen condition (coatings)
– Shape
– Size
– Temperature
Equipments
Torch light
Magnifier
Mirrors
Boroscope
Fiberscopes
and lot more
Inspection Instruments
Steel Rule
Flexible Rule / Measuring Tapes
Laser Measurement
Vernier Calipers
Micrometer
Height gauges
CMM
Hi-Lo Gauge
Depth Gauge
Bore Dial Gauge
Go-NoGo gauge (Plug, Ring)
Dumpy Level
Theodolite Total Station
Welding Gauges
Bridge-Cam Gauge
AWS weld Gauge
Taper Gauge
V-WAC Gauge
Fillet weld Gauges
An Non Destructive Testing training Institute shall have Samples of all defects , which can be seen visually for familiarization of defect identification- Advanced Quality Centre , Coimbatore, NDT Training Institute for NDT Courses and Certification https://aqcinspection.com/training/
To learn more on NDT training in Coimbatore, NDT courses in coimbatore and Training Institute for specific ndt methods, feel free to contact us at https://aqcinspection.com/training/ and for services Visit our technical and career updates at our Blog site https://advancedqualitycentre.blogspot.com . https://ndtcenter.blogspot.com our website https://aqcinspection.com/news-events/ for many more blogs
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