Visual Inspection
Visual inspection is the monitoring
of specific parameters by visual and optical assessments
of test objects and surfaces using visible portion
of the electromagnetic spectrum.
Visual Inspection may be by the use of the eye alone
or can enhanced using optical systems such as magnifiers
and microscopes. A variety of equipment is available
to the visual inspector including mirrors and gauges,
which can be used for profile assessment, borescopes
and endoscopes, which are used on parts with limited
access, and video or computer enhancement systems.
Although a Visual Inspection test is a test in its
self, it also forms an integral part of many other
non-destructive testing methods, For example, magnetic
and penetrant inspection requires visual observation
and assessment of the detected indication; radiographs
require visual inspection for the interpretation of
results; ultrasonic inspection requires the visual
assessment of the trace on a CRT.
Visual In-Service Inspection
Visual inspection is a vital pert of in-service inspection, which may or may not be backed up by other NDT methods. The examinations made are for fatigue cracks, creep failure, corrosion, erosion, abrasion, mechanical damage, wear and tear, distortion, and poor workmanship. The ability to differentiate between different damage mechanisms, which may to an untrained, experienced visual inspector have similar appearances, often results in incorrect diagnosis. The trained, experienced visual inspector can elicit a great deal of information, and could use this information to decide which other tests to perform in order to confirm a diagnosis of the problem.
Conditions required for visual inspection
Visual inspection must take place in a clean, comfortable
environment with adequate lighting. There should be
reasonable access to the parts to be inspected and
attention should be paid to safety, working position,
and atmospheric conditions. The test piece should
be clean and free from protective coatings. Any equipment
to be used would be checked for accuracy and its operation
understood by the inspector.
Radiography
Positive Material Identification
Dye Penetrant Inspection
High Pressure Testing
Magnetic Particle Testing
Positive Material Identification