DIN EN 583-4:2002-12

This part of the standard defines the principles for tandem- and LLT -examination for the detection of discontinuities perpendicular to the surface. The general principles required for the ultrasonic examination of industrial products are described in EN 583-1. List of symbols and equations are given in EN 583-2. The tandem- or LLT-examination should be used for the detection of planar discontinuities with distance to the surface greater than 15 mm. This standard has been prepared for the examination of metallic materials with a thickness between 40 mm and 500 mm and parallel or concentric surfaces.