X-RAY CONTROL OF WELDED JOINTS ACCORDING TO GOST AND ISO SYSTEMS

Abstract

The results of comparative analysis of assessing modes, parameters and means of radiographic control of welded joints of critical duty using the Russian (GOST) and international (ISO) standards are presented. Comparison was carried out by the sensitivity of control, permissible radiation energy (affecting the formation of the contrast of the radiation image), and minimum focal length (determining the sharpness of the resulting optical image). Requirements of the ISO system for the sensitivity of control are higher, than that of the State standard specification system. The sensitivity assessment in the ISO system is carried out using the wire indicator, the dimensions of which are smaller than the dimensions of the grooves of the groove sensitivity standard, regulated by GOST. However, the choice of the radiation energy in the system requirements GOST is stricter than that in the ISO system. This provides enhanced contrast of the generated radiation image. The conversion of the radiation image into an optical one using the ISO system is carried out using film systems of a high optical density. According to the ISO requirements transformation of the radiation image to the optical one is to be carried out using film systems of the certain class. And, as a result, transformation of the radiation image to the optical occurs in the field of high gradients. GOST imposes no requirement to film systems, since there is the only one class of domestic film on the market. The requirements to the minimum allowable focal length (GOST) are higher compared to the ISO system, which makes it possible to obtain better sharpness of radiographic images. Performance monitoring according to GOST also exceeds that of ISO. As a result, we can conclude that the quality welded joints should be monitored using the complete set of the accepted standards.