ISO 16826:2012定义了垂直于表面的不连续检测的串联和纵向纵向（LLT）波检验的原理。 在ISO 16810中描述了工业产品超声波检测所需的一般原则。ISO 16811中给出了符号和方程式列表。 串联或LLT检查应用于检测距离大于15 mm的表面的平面不连续性。 ISO 16826:2012已准备好用平行或同心的表面检查厚度在40毫米与500毫米之间的金属材料。然而，如果采取特殊措施，则可以使用其他材料和更小的厚度

ISO 16826:2012 defines the principles for tandem‑ and longitudinal-longitudinal-transverse (LLT) wave‑examination for the detection of discontinuities perpendicular to the surface. The general principles required for the ultrasonic examination of industrial products are described in ISO 16810. A list of symbols and equations is given in ISO 16811. The tandem‑ or LLT‑examination should be used for the detection of planar discontinuities with distance to the surface greater than 15 mm. ISO 16826:2012 has been prepared for the examination of metallic materials with a thickness between 40 mm and 500 mm with parallel or concentric surfaces. It can, however, be used for other materials and smaller thickness provided special measures are taken.