Destructive Visual Inspection

A comprehensive program that includes predictive maintenance techniques to monitor and analyze critical machines, equipment, and systems in a typical plant. Techniques include vibration analysis, ultrasonics, thermography, tribology, process monitoring, visual inspection, and other non-destructive analysis methods. 

The soundness of welds is checked by visual inspection and by non-destructive testing (radiography). 

Nondestructive Testing. Nondestructive testing (NDT) is far more economical than destructive test methods, and every assembly can be tested if desired. Several nondestructive test methods are used to check the appearance and quality of structures made with adhesives or sealants. The main methods are simple ones such as visual inspection, tap, proof, and more advanced physical monitoring such as ultrasonic or radiographic inspection. The most difficult defects to find are those related to improper curing and surface treatments. Therefore, great care and control must be exercised in surface preparation procedures and shop cleanliness. 

For detection of more localized corrosion, such as crevice corrosion or SCC, other ultrasonic inspection techniques may be useful. Baseline data generated at the time of installation will also be helpful in evaluating results. One benefit derived from this type of inspection technique is that it can often be conducted with little or no interference with production. Periodic planned visual inspection of equipment utilized under conditions likely to cause stress cracking is also an effective technique, especially when combined with non-destructive inspection techniques such as dye penetrant inspection. It may be necessary to remove coatings or insulation from the equipment surface to facilitate inspection. 

Destruction of the polymer binder is caused by inorganic acids that rupture polymer macromolecules and consequently increase deformability and decrease composite strength. Visual inspection of the samples after 180 days of exposure in inorganic acids show that steel fibers do not protrude, but the painted surface of the samples immersed in a 36% solution of hydrochloric acid changed significantly. 

Tests, non-destructive— Inspection tests for the evaluation of bond quaUty without damaging the assembly, e.g., ultrasonics, visual inspection. 

In the manufacture of plant and machinery and subsequent periodic inspections and tests, testing is normally non-destructive and a number of specialised techniques have been developed. Equipment is now available to enable visual inspections to be carried out of inaccessible places using fibre optics and remote-controlled television. A major aim of testing is to check the condition of the material of which the plant is constructed and to identify faults that cannot be seen by eye. Special detection techniques used to highlight the weaknesses orfauits in the material include the use of magnetic particles, penetrant dyes, X-ray and gamma-ray sources, ultrasonic vibrations, microwave and infra-red rays. 

In the last decade confocal laser scanning microscopy (CLSM) was shown to be a helpful tool for various further tasks of microparticle characterization (Lamprecht et al., 2000a, b, c). It minimizes the light scattered from out-of-focus structures, and permits the identification of several compounds through use of different fluorescence labels. Therefore, CLSM can be applied as a non-destructive visualization technique for microparticles. Moreover, CLSM allows visualization and characterization of structures not only on the surface, but also inside the particles, provided the carrier matrices are sufficiently transparent and can be fluorescently labeled by collecting several coplanar cross-sections, a three-dimensional reconstruction of the inspected objects is possible. Figure 6.13 shows the application of CLSM to investigatation of the cross-sectional structures of spray-dried powders of maltodextrin (MD) with a dextrose equivalent value of DE = 2 and 20. Florescein sodium salt was dissolved in the feed solution as a fluorescent probe of the carrier... 

Fig. 1 Correlation between visual inspection for damage (crack) progress with thermal cycling and destructive cross-sectional microphotographs. Ceramic leadless package, 28 castellations, 1.27 mm (0.05 in.) pitch...

Non-destructive testing can be as simple as a visual inspection as a trained eye will detect a surprising number of faulty joints, including close inspection of the adhesive bond line at the joint periphery, misaligned parts or uneven adhesive bond lines. 

Industrial processing of adhesives has made considerable progress from the crude processes of the past [1]. Unfortunately, one of the disadvantages of adhesive bonding as an assembly method is that a bond area cannot be inspected visually. Inspection must be carried out by two methods destructive and nondestructive. Destructive inspection may be carried out on process-control test specimens prepared from the same adherend and adhesive materials as used for the production parts. The process-control specimen, as the name implies, accompanies the production parts throughout the stages of cleaning, assembly, and cure. The adhesives and adherends are all assembled at the same time and cured in the same press or autoclave. 

In glass/polyester structures, the resulting delaminated area can be estimated by visual inspected. In glass/polypropylene pipes this evaluation need the use of more sophisticated NDT (non-destructing testing) testing techniques, such as, C-Scan. 

The introduction of tight personal security procedures and visual or X-ray inspection of carry-on luggage at all domestic and international airports in 1972, resulted in almost complete elimination of skyjacking incidents in the USA. This situation has most likely interrupted or delayed the further development of automatic non-destructive inspection methods for expls in baggage at airline terminals... 

Bond Inspection. After the adhesive or sealant is cured, the joint area can be inspected to detect gross flaws or defects. This inspection procedure can be either destructive or nondestructive. The nondestructive type of tests can be visual or use advanced analytical tests. These types of bond inspections are described below. 

In assessing the suitability of the winder s drums for an increased load or for continued use, the type of construction as well as the presence of any stress-induced defects need to be taken into account. To this end, both visual examination and Non Destructive Testing (NDT), employing Magnetic Particle Inspection (MPI) methods are implemented. An experienced winder engineer will have a good idea of what to expect to find in a winder s drums that have seen many years of service and very often, the decision as to whether it will be economically... 

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