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High pressure hydrogen storage tank is a key component in hydrogen supply systems of the fuel cell vehicles. Composite hydrogen storage tanks own some advantages such as high stiffness, density and strength, and the composite tanks for storage of 70 MPa hydrogen is the hotspot of research. However, composite hydrogen storage tanks have the potential leakage and explosion hazards in the process of using due to the flammable and explosive storage medium. hydrogen cycle test is an important means to detect the macroscopic strength, safety margin, structure design rationality and reliability of composite hydrogen storage tanks. The relevant standard of 70MPa composite hydrogen storage tanks is not yet introduced in China. At present, the european union, Japan and the international standardization organization have formulated the composite hydrogen storage tanks standard or code, which have an important reference for the formulation of the relevant standards in china. In this study, foreign standards related hydrogen cycling test content such as (EU) 406-2010, ANSI HGV 2-2014, ISO CD 19881-2015, SAE J2579-2013 and ECE/TRANS/180-2013 are systematically studied, which could be helpful for the establishment of relevant standards in China and the development of hydrogen cycle test equipment.

Tubesheet is the main part of high pressure heater, which is very thick based on chinese code GB151 for the design of heat exchangers. Increased tubesheet with large thermal stress are not conducive to manufacture, heat transmission and detection. The stress and structure of tubesheet are so complex that the time costs too large during the analysis design, and stress classification exists uncertainty. Limit load method contributes to tubesheet lightweight. 3-D finite element model used for analysis design should be simplified reasonably. In this paper, the effect of mechanical model on limit load analysis of high pressure heater tubesheet conforming to the design-by-analysis code is researched. It is found that the tubesheet could pass the plastic collapse assessment, and the thickness of tubesheet could be decreased. The difference between the equivalent sold tubesheet model and the whole tubesheet model exists during plastic collapse assessment. Though the local stress distribution is different, the limit load results occurred plastic collapse by the equivalent sold tubesheet model is close to that by the whole tubesheet model. The limit load occurred plastic collapse is influenced by max circular diameter of tube layout little. The reason is attributed to original tubesheet owning enough rigidity related to thickness, and high stress appeares on the inner wall of jointing of tubesheet with head. The equivalent sold tubesheet model could be used for primary evaluation of limit load, and the whole tubesheet model is suited for partial analysis. The results provide some reference for the design-by-analysis of high pressure heater tubesheet.

Responding to non-conductive, non-magnetic material characteristics of polyethylene (PE) pipe, this paper comes up with the ground penetrating radar (GPR) detection for urban PE gas pipeline visualization research in order to solve the problems of positioning difficulty, and to avoid potential safety hazards caused by undefined positioning of PE pipeline, so that it can provide some experience to the application of position detection technology to locate buried polyethylene pipeline. Responding to the special material properties and welding form and based on the analysis of traditional ultrasonic testing for polyethylene butt-fusion joint, this paper comes up with an ultrasonic phased array dynamic focusing and S scanning imaging technology, to make a testing experiment on polyethylene butt-fusion joint. Results of the phased array ultrasonic testing of cracks in polyethylene butt-fusion joints shows that the testing method is feasible, and verifies the buried polyethylene butt-fusion joints engineering. This research would provide experience to the application of ultrasonic phased array technology in buried polyethylene pipeline inspection.