INSPECTION AND TESTING METHODS
Visual testing is the simplest and foremost testing procedure. It must precede any other type of investigation. It consists in examining the surface of the materials, welds, and equipment with the naked eye under satisfactory lighting conditions and at the appropriate distance.
Visual testing can be supplemented by the use of optical means (magnifying glass, binocular, and endoscope), but also by the use of gauges and measuring instruments (Vernier caliper).