VISUAL METHOD (VT)
The Visual Method usually applied in combination with another non-destructive method as initial test. In practical terms, at this stage large discontinuities to the surfaces are often detected (forging, welding, hardening cracks, undercuts, lack of joint penetration, concavities), defects to the element shapes (displaced edges, angular deformations, corrosion-related losses, porous surfaces or voids) which helps to save time and measures, especially in production. The tests are run on a direct basis (naked eye) or indirect one with the use of the following devices: magnifying glass, endoscopes, periscopes, sets of mirrors and videoscopes. This method is used at various stages of steel structures production: preparation of elements for welding, joint control during welding and the ready joint. It also plays an important role in testing the facilities in operation (rotors, turbines, tanks, pumps, pipelines, heat exchangers, vessel and aircraft parts, etc.), and for many of such devices this is the only possible check-up method.