The Future NDT institute in Hyderabad is a reputed institute, which caters to millions of NDT jobs in Hyderabad and all over the world. Here students are trained with various engineering skills such as welding, piping, quality audit and NDT. Besides the expert faculty also teaches other practical skill sets such as visual inspection, radiography testing, ultra sound testing, magnetic particles testing and so on. One can also get NDT training in Chennai, from Future NDT institute in Chennai.
Visual testing (VT)
Visual testing is one of the significant courses taught as a part of NDT training in Chennai. It is a high-end non-destructive training method used to detect flaws, cracks, holes and fusion in welded machinery, beads and gas holes. Often overlooked in listings of NDT methods, visual inspection is one of the most common and powerful means of non-destructive testing. It is a process of enhancement of mechanical systems by human sensory systems like touching, twisting, shaking and smelling alike. Visual inspection uses some of the proper testing tools like microscope, dental picks, magnifying lens and stethoscope, for minute screening of the flaws. Visual testing requires adequate illumination of the test surface and proper eye-sight of the tester. To be most effective, visual testing requires training (knowledge of product and process, anticipated service conditions, acceptance criteria, record keeping, for example).
It is also a fact that all defects found by other NDT methods ultimately must be substantiated by visual testing. Visual testing can be classified into direct visual testing, remote visual testing and translucent visual testing. The equipment needed for visual testing is simple-
A portable light, a mirror on stem, a 2X or 4X hand lens, one illuminated magnifier with magnification 5X or 10X. For internal inspection, light lens systems such as bore scopes, enable examination of remote surfaces.
More sophisticated devices of this nature use fiber optics, to enable the introduction of the device into very small access holes and channels. Most of these systems are equipped with a camera, to permit permanent recording of the visual testing process.
TYPES OF OPTICAL USED IN VISUAL INSPECTION
(A) Mirror
(B) Hand magnifying glass (magnification usually 2–3X).
(C) Illuminated magnifier; field of view more restricted than D (magnification 5–10X)
(D) Inspection glass (magnification 5–10X
(E) Bore scope or intrascope with built-in illumination (magnification 2–3X).
APPLICATION FOR VISUAL TESTING
(a) Checking of the surface condition of the component.
(b) Checking of alignment of mating surfaces.
(c) Checking of shape of the component.
(d) Checking for evidence of leaking.
(e) Checking for internal side defects.
ADVANTAGE OF VISUAL TESTING
(a) Testing is simple
(b) Testing speed is high
(c) Cost is low
(d) Less training
(e) On-line testing possibility
(f) Permanent record available
LIMITATION FOR VISUAL TESTING
(a) Can detect only surface defects
(b) Difficulty in sizing depth of defects
PHYSICAL REQUIREMENTS
Engineering personnel have to go through an annual vision test, to assure natural or corrected near distance acuity, such that they are capable of reading standard J-1 letters, on standard Jaeger test type charts for near vision. Candidates who have equivalent or near vision tests, are acceptable for visual testing process.
DIRECT VISUAL EXAMINATION
Direct visual examination may usually be made when the eye has sufficient access of within 24 in. (600 mm) of the surface to be examined and is at an angle not less than 30 degrees to the surface to be examined.
INSPECTION DOCUMENTATION-
At the end of the visual inspection the following things need to be recorded-
(a) The date of the examination
(b) Procedure identification and revision used
(c) Technique used.
(d) Results of the examination
(e) Examination personnel identity, and, when required by the referencing Code Section, qualification level.
(f) Identification of the part or component examined.
Visual testing is an essential NDT training requirement, quite helpful in increasing the scope for NDT jobs in Hyderabad and all over the world. It is applicable in different industries and manufacturing sectors such as Iron and steel, pharmaceuticals, aviation, automobiles, fabrication and petroleum.
