[en] In this work the Compton Backscattering Technique is used to detect the superficial defects on bodies with tubular shape. The study was performed using system with a Cesium-137 source with activity of 74 x 10¹⁰ Bq (2 Ci) and a 2 inches Na I(Tl) scintillator detector placed in such a way that it was possible to obtain scattering angles around the 180 degrees. In the first part of the work we use the differential spectrum of scattered radiation to analyse the thickness of know samples. With the calibration obtained was possible determine the thickness with precision of 4% for samples within the calibration limits and 6% for values beyond this limits.In the second part we use the calibration to analyse surface defects. It was possible detect corrosion with 2.0 mm in a 7.73 mm diameter tube wall 6.3 mm thick for corrosion in the first tube wall with the tube positioned 5.0 mm apart of the detector. (author). 6 refs., 12 figs., 1 tab

[en] This work shows the development of a methodology in the comparative analyze between the Computerized Tomography and the ultrasound technique. These techniques were utilized in non-destructive essays in casting pieces in aluminum alloy with the aim of analyzing all kinds of defects aroused in the casting process. The results show that the computerized tomography gives a more precise and easier information to be interpreted. On the other hand, the ultrasound technique is a more sensitive technique that can be utilized as an auxiliary tool for choosing the parameters used in the computerized tomography. The results with the X-ray transmission tomography technique show results of spatial resolution of the order of 0.8 mm. The ultra-sound technique was capable of detecting defects of the order of 0.5 mm of diameter, with resolution of 0.4 mm in the x direction and 0.39 in y direction, besides being sensitive to the porosity presence. (author)

[en] This paper analyses the performance of parallel beam X-ray transmission computerized tomography, in the characterization of melting defects on a aluminium alloy. The results obtained presented a spatial resolution approximately of 0.8 mm. The porosity distribution existent in the piece appears as noise at the tomographic images with impossible detection. From the tomograms analyses it was possible to classify two defect regions at the pieces: empty and large pore concentration