WHAT IS VISUAL TESTING IN NDT?
About Visual Testing (VT)
Visual testing (VT) is additionally called visual testing examination, nondestructive examination, or nondestructive analysis or examination. Visual testing is that the most ordinarily technique that's utilized in trade currently a days. as a result of largely check strategies need the operator vision at the surface that half being inspected, visual examination is inherent in most of the opposite testing strategies. because the name implies that, American state involves the visually determined the surface of a check material to judge the presence of surface discontinuities. American state examination technique could also be by victimization line-of sight vision, Direct Viewing, or could also be increased or increases the clarity with the assistance of optical instruments like magnifying glasses, charge-coupled devices (CCDs), mirrors, boroscopes, and computer-assisted viewing systems (Remote Viewing). placement within the material, Corrosion, physical harm and cracks square measure some of the discontinuities which will be detected by visual examinations.
Application of Visual Testing:-
- Examine the leakage in the material.
- Examine the Misalignment in the material.
- Crosscheck the measurement of material according to the control charts or standard.
- Examine the surface conditions of the material.
- Where examination is not possible with the naked eye we can use optical automatic aids.
Equipment of Visual Testing:-
- Magnifying glasses.
- Fillet weld gauge.
- Computer equipment.
- Illuminated magnifiers.
- Inspection glasses.
- Naked eye.
What is visual acuity and why do NDT Engineer need it.
The eyes are a more important piece of equipment that an NDT technician uses in order to perform inspections
Introduction:- What is Visual Acuity?
Visual acuity is outlined because of the clarity of vision, measured by the flexibility to spot letters or numbers at a specific distance. You perhaps performed a visible acuity take a look at with a watch chart at the doctor's cabin. the quality for visual sense is 20/20 vision. If you have got 20/20 vision, then you'll be able to simply scan and determine the conventional quantity of visual info at a distance of twenty feet. If you have got 20/80 vision, then your vision at twenty feet is capable someone standing eighty feet away with normal vision. many of us don't meet the 20/20 vision normal, therefore thanks to that drawback that individuals use optical lenses, and different optical things to corrective there vision.
How does vision work? Light enters through the pupil in our eye. It passes through the lens and is projected on the retina at the rear of the attention. The retina is created from photoreceptors cells called rods and cones. The motive of Rods, Basically employed in dark conditions, because they're sensitive to blue and green light with a maximum sensitivity of 498 nm wavelength. Cones give us our basic chromatic vision within the daylight, and that they are comprised of L-cones, M-cones, and S-cones.
L-Cones: Detect red light with a peak sensitivity of 564 nm
M-cones: Detect green light with a peak sensitivity of 533 nm
S-cones: Detect blue light with a peak sensitivity of 437 nm
NDT Visual Acuity Requirements.
According to ASNT, visual certification for Associate in Nursing NDT technician needs visual sense in a minimum of one eye. visual sense is checked by someone properly reading the coastal diving bird J1 eye test chart, or equivalent, at a distance of thirty.5 cm or twelve in. in addition, Associate in Nursing NDT technician should be able to differentiate between the colours utilized in NDT ways. Eyes checks may be performed by a medical man or someone that's certified to offer the test.
Why is Visual Acuity Important for NDT Engineers?
Whether it's supersonic testing, eddy current testing, or liquid penetrant testing, all NDT ways involve some kind of visual examination. for example, photography testing uses X-rays to come up with a picture on film, however that film should be rigorously examined by the technician so as to get flaws. to boot, most nondestructive testing starts with the optic through visual scrutiny. Flaws seldom stand out sort of a waving red flag; scrutiny of an element is needed. that is why NDT technicians should be trained and authorized. Otherwise, anyone might perform this work.
Advantages of Visual Testing.
- Easy to perform.
- Inspection is done quickly.
- Reliability and stability are good.
- Low-cost method.
- No much-qualified operator is req.
- Sensitivity is high.
Disadvantages of visual Testing.
- Good eyesight required or eyesight corrected to 20/40.
- It can miss internal defects.
- The report must be recorded by the inspector.
- Open to human error.