Nondestructive testing of IV type hydrogen storage cylinder liner based on rotating water immersion ultrasonic total focusing method detection system

The plastic liner of the IV type hydrogen storage cylinders was made of multiple segments using laser welding technology, with a small diameter and wall thickness, making it difficult to detect. At present, there were few detection technologies for the plastic liner of hydrogen storage cylinders. On the basis of considering the structural characteristics and typical defects of plastic liners, this paper integrated ultrasonic total focusing method (TFM) imaging technology, curved structure water immersion interface coupling technology, and multi-dimensional automatic control technology to developed a five axis linkage water immersion TFM rotating ultrasonic C-scan detection system for plastic liners. Based on this system, unfused defects, weld cracking defects, and weld misalignment on the external and internal surfaces of the liner were detected. At the same time, industrial computed tomography (CT) technology was used to calibrate the actual size of the damage. At the same time, the actual size of the damage was calibrated using industrial CT scanning detection technology. This detection system was expected to be applied in the process after the liner was formed and before assembly with the carbon fibre shell, to compensate for the evaluation difficulties caused by high sound attenuation in the overall ultrasonic testing of IV type hydrogen storage cylinders.