Abstract
Steel layered high-pressure hydrogen vessel is one of different kinds of high-pressure vessel, which is invented in China and is widely equipped in hydrogen refueling stations for its good safety and storage functions. Many of these vessels are put into application these years, and it is nearly the time for these vessels to go through periodic inspection. However, there is no such a method for the periodic inspection especially on the butt weld connecting the double-layer head and the interface forging. To conquer the difficulties about the periodic inspection, a set of periodic inspection methods was first proposed in a lasted released Chinese group standard, in which the inner ultrasonic phased array is considered to be the most complicated detecting approach. To establish effective inspection parameters, simulations and experiments were conducted on the factors, including coupling, elements and aperture, focal law, scanning approaches and ultrasound field. Standard test block and contrast test block were designed and machined and tested, then a series of feasible parameters were determined. Thus, specific probe, wedge and instrument were manufactured, and the inspection on the actual vessel product was carried out. The results showed that the proposed ultrasonic method and its inspection parameters could meet the periodic inspection well. Finally, the periodic inspection methods were established and issued as a standard.
