Abstract: The certain SHY hydrogen stainless steel double-walled tube outer tube was in place, but the inner pipe ring welds had not been detected. To solve this problem, it was proposed that do not cut the double-walled stainless steel tube, but directly detected the inner tube across the outer tube, combined normative analysis identified the key process parameters of X-Ray detector, and used known defect test block, the test was carried out to verify the effectiveness of the process is reasonable.