EXPERIMENTAL STUDIES OF TYPICAL DEFECTS ON LARGE CAPACITY HOOP-WRAPPED COMPOSITE CYLINDER OF STEEL LINER BASED ON X-RAY DIGITAL RADIOGRAPHY TEST

摘要

Tube trailers assembled with large capacity hoop-wrapped composite cylinder of steel liner (i.e., large capacity type 2 tube (LCT2T)) have shown an increasing trend in China. It is an urgent issue to detect nondestructively the defects of cuts, scratches and voids on the composite overwrap, and corrosion, cracks or other defects on the steel liner during their use and manufacturing processes. In this paper, the double-wall single-image technique of X-ray digital radiography (DR) method was studied for the typical defects on the LCT2T by making specimens of cracks and pitting corrosion on the steel liner, as well as cuts, scratches and void defects on the composite overwrap. The optimal penetration parameter was selected based on the identification of image quality indicators (IQI), and the detection sensitivity of the DR method for the typical defects on the LCT2T was obtained. The results showed that the above-mentioned artificial defects were effectively detected with double-wall single-image technique, and this technique had a higher detection sensitivity to longitudinal defects on the composite overwrap of the LCT2T than that to circumferential defects, as well as the detection sensitivity of steel liner defects was higher than that of composite overwrap defects.