Computerized tomography used in non-destructive testing of welded pipes

High quality standards in operation of National Power System is ensured by the use of high performance techniques and systems for Non-Destructive Testing (NDT). In recent years a number of new developments of the non-conventional technologies in the field of NDT have been achieved. In our laboratory there have been developed two computerized technologies using γ-ray computed tomography and ultrasonic imaging methods. The standard techniques for imaging from projection data is computerized tomography. The industrial computerized tomography methods consist in the measurement of thin X - or γ-ray beam attenuation when passing through some selected surface of the tested object, along several directions, so that by means of an adequate mathematical algorithm, a map of linear attenuation coefficients for the scanned surface is obtained. In fact, this map gives the density of materials occurring in the surface plane. Computerized tomography equipment, in various constructive versions, are intended for the following applications: 1) NDT in those fields requiring strict control of product quality, as for instance the nuclear energy, military industry, aeronautics, transportation fields, etc., 2) research in field of materials technology, machine engineering, metallurgy, welding, etc. This paper presents the applications of Computerized Tomography in NDT, by showing the results obtained on welded pipes, as well as the facilities offered by this method. In the final part, the paper presents the concept of a mobile tomography system for industrial pipes testing. (author). 2 figs., 7 refs