X-ray radiometric inspection of circumferential welded joints in the construction of transmission gas pipelines

摘要

Radiometric inspection is characterised by the lowest spatial resolution in comparison with other radiation methods but this shortcoming may be compensated by the highest contrast sensitivity. This results in the detection and measurement of unacceptable defects in the inspected components. Radiometric inspection can be carried out using both x-ray equipment and radionuclide sources. 3-4 standard dimensions of the detectors are sufficient for radiometric inspection in the thickness range 10-200 mm. Radiometric inspection can be used widely for the examination of a large volume of components of the same type, it is characterised by hyperactivity, operating speed and automation. This method can be used in the construction of transmission gas and oil pipelines, in pipe-producing companies, in the construction of cisterns for corrosive media, in engineering companies, in aviation and missile construction, etc. According to the statistical data, in the thick-wall welded joints, up to 70 percent of defects are found in the weld root. Usually, the thick-wall components in which only the root was welded cannot be transferred to the x-ray chamber for technological inspection. Radiometric equipment can be used for the inspection of the weld root directly on the welding platform, without disconnecting heating of the welded components. The rapidly developing electronic and computing technologies open extensive possibilities for improving and reducing the cost of radiometric equipment. The measurements, taken using the panoramic x-ray equipment RPD-200P, show that the x-ray systems of this type may be used for the development of radiometric inspection systems.