For quantitative defect size detection more accurate methods are needed. It seems not to be possible to improve the information gained by the DGS - method. By development of focused probes, however, a better description of the boundaries of a defect become possible (method used by ASME). This technique is dealt shortly with.

At this moment the methods for defect retrieval and for the quantitative evaluation of defect size, i. e. geometrical characteristics are not in a sufficiently developed state. The so called PISC exercise proved this. Examples of the results of PISC will be therefore presented.

The causes of this mishap are, to the opinion of the author, based on insufficient taking into account of the production caused possible defects. Therefore the ultrasonic testing personnel was not in picture what possible defects and in what orientation have to be looked for. Because of that fact only a part of the actual defects have been found.

The sizing of the defects is less of a problem: a defect already detected can be, in function of the apparatus applied and of the skills of the personnel, be brought to a sufficient level of accuracy.

Further quality management actions, like a sufficient description of the task and of the apparatus has to stress the possible types of defects and their orientation, are required.

Because a quantitative evaluation of defects in respect of acceptance limits needs the definition of the state and the amount of stresses, the material properties and the characteristics of the defects according to location, size and shape, such an evaluation needs a much higher effort as usual.

For the state of stresses and of their amount an elastic, or better an elasto-plastic finite elements calculation becomes necessary. The actual material properties, i. e. fracture toughness, have to be sufficiently known. For non-destructive testing the location, size and shape of defects have to be determined for and estimated within acceptable limits. By these means a satisfactory result of the non-destructive evaluation should be achieved.