To meet the lightweight requirements of deep‑sea vehicles and address the issues of high residual stress and poor reliability associated with traditional welded internal ribbed heads，a new configuration of spiral‑ribbed ellipsoidal head suitable for integrated manufacturing is proposed.Through axial compression tests and finite element simulations，the compressive and buckling performance of four types of 6061-T6 aluminum alloy heads，namely without ribs，with transverse ribs，with longitudinal ribs，and with spiral ribs，was systematically compared.The overall formability was verified by spinning simulation and trial production.The results show that the structure with longitudinal internal ribs exhibits the best mechanical performance，with its ultimate compressive strength and critical buckling pressure increased by 8.7% and 5%，respectively，compared to the structure without ribs.The structure with spiral internal ribs，while maintaining good mechanical performance，can achieve overall forming with non‑deformed internal ribs and high filling quality by means of the spinning process.In contrast，structures with transverse internal ribs and longitudinal internal ribs are prone to forming defects.The structure with longitudinal internal ribs has the most outstanding load‑bearing capacity，while the structure with spiral internal ribs has a significant advantage in integrated forming，balancing mechanical performance and forming feasibility.This study provides new ideas for high‑performance design and integrated manufacturing of pressure components for deep‑sea equipment.

This study focuses on the application of expansion technology to rupture disc safety relief devices for high‑pressure hydrogen storage vessels，using ultra‑high purity （UHP） AISI 316L austenitic stainless steel.Internal inclusions act as hydrogen traps and corrosion initiation sites，directly influencing the material's susceptibility to hydrogen embrittlement as well as the triggering accuracy and reliability of the rupture disc.Currently，the industry lacks a systematic evaluation and comparison of cleanliness and inclusion control for such materials.In this study，a systematic quality assessment was carried out by comparing materials produced by different manufacturers using vacuum induction melting combined with vacuum arc remelting （Material A），as well as the argon‑oxygen decarburization process followed by VAR （Material B）.Innovatively，this study employed a combination of microscopic characterization techniques including metallographic microscopy，scanning electron microscopy，and energy‑dispersive X‑ray spectroscopy，coupled with thermodynamic calculations to simulate the evolution of inclusions during cooling.This approach revealed the characteristics and distribution patterns of inclusions resulting from different processes and sources.The results indicate that among the evaluated samples，Material B produced by China Factory A exhibited the best cleanliness，with both inclusion density and area fraction significantly lower than those of the other samples.This finding is in strong agreement with the thermodynamic simulation predictions，confirming the reliability of the adopted methodology.The results provide important guidance for the selection and process optimization of ultra‑high purity 316L stainless steel used in critical hydrogen‑containing rupture disc safety components，and also offer a reference framework for the quality assessment and control of similar high‑cleanliness materials.

To address the forming challenges of plastic liners for type Ⅳ hydrogen storage cylinders with large diameter and large length‑to‑diameter ratio，a hot melt welding process with unique low‑cost advantages is adopted to solve the comprehensive optimization problem of weld quality.Taking weld strength and weld morphology as the core optimization objectives，the coupled influence of key process parameters including liner groove size，heating temperature，welding feed speed，and welding feed amount on welding quality is systematically investigated.Through systematic welding experiments，welded pipe specimens are prepared，and their tensile stress-strain curves are tested to evaluate mechanical properties.Combined with macroscopic observation of weld cross‑section morphology and microscopic analysis of fracture structure，the effects of various process parameters on welding forming quality and failure mechanism are revealed.On this basis，the range analysis method is used to comprehensively balance and optimize multiple objectives，and the optimal combination of process parameters is determined：groove size 2.88 mm，heating temperature 252.56 ℃，welding feed speed 1 mm/s，welding feed amount 1.5 mm.This study provides a reliable methodological basis and direct process guidance for the evaluation of hot melt welding process effects and quality improvement of cylindrical plastic liners with large diameter and large length‑to‑diameter ratio.

To address the lack of high‑temperature irradiation performance data for the austenitic stainless steel 316H，the material used for the reactor pressure vessel of a fourth‑generation high‑temperature gas‑cooled microreactor，at the design operating temperature of 550 ℃，a research plan involving irradiation damage tests and aging tests was proposed.The SRIM software was used to simulate the trajectories and irradiation damage defects of energetic ions （He²⁺） incident on the material.Combined with high‑temperature irradiation tests under different cumulative irradiation doses （0.005，0.05，0.5 dpa） and an irradiation aging test at 650 ℃ for 100 h，the evolution laws of the material's high‑temperature damage behavior and aging behavior with microstructure were established.The results show that at the design temperature of 550 ℃，316H exhibits good irradiation resistance.The irradiation damage layer is approximately several micrometers thick，and the damage mainly manifests as microvoids and dislocations.After aging at 650 ℃ for 100 h，carbides precipitate along grain boundaries，with C and Mo elements enriching at the grain boundaries and Cr element depleting near the grain boundaries，presenting a certain risk of failure.This study provides a reference for subsequent engineering implementation of in‑reactor irradiation tests.

In response to the significant risks associated with hydrogen storage cylinders under extreme fire conditions，this study adopts a method combining fire accident analysis with fire test data to systematically evaluate key parameters such as the burst pressure of hydrogen storage tanks.The results show that the pressure‑bearing capacity of hydrogen storage tanks decreases significantly under fire exposure：For a tank with a nominal working pressure（NWP） of 35 MPa，the burst pressure drops from 122.7~126.0 MPa at room temperature to 41.1~53.5 MPa；For a 70 MPa NWP tank，it drops from 209.8~226.8 MPa at room temperature to 98.9~112.3 MPa.The time from fire exposure to tank explosion ranges from 9 to 22 min.When the pressure relief setting of the tank is close to its burst pressure，the damage tolerance is low，resulting in a high risk of explosion under fire conditions.After fire exposure and subsequent cooling，the tanks still exhibit relatively high residual strength，approximately 2.09~3.37 times the NWP.It is recommended that，with the objective of “pressure release first”，the safety threshold for tank burst strength under fire conditions be further refined，and that standardized testing methods for post‑fire residual strength be established.This study provides a technical basis for the comprehensive safety assessment of hydrogen storage tanks in fire scenarios.

To implement GB/T 4732.3—2024 Pressure vessels design by analysis-Part 3：Formulae method，this paper systematically elaborates on the development practice and key considerations of the fixed tubesheet heat exchanger module in the SW7 software.The research focuses on several issues not mandated by the standard but of significant engineering significance，and conducts theoretical modeling，formula derivation，and functional expansion.The main contents include：Expanding the mechanical models to include the tubesheet embedded welding structure and the flat cover with a central nozzle opening，enhancing the engineering applicability of the software；Incorporating the effects of thermal bending deformation caused by temperature differences across the tubesheet thickness and the differential thermal expansion between the tubesheet and flange materials，achieving refined analysis of thermal loads；Based on the deformation coordination relationship of the flange-bolt-gasket system，proposing a method for determining a single bolt preload load that meets sealing requirements under multiple operating conditions；Innovatively proposing a nonlinear analysis theory for the variable‑stiffness elastic foundation plate，revealing the coupling mechanism by which tubesheet bending leads to a reduction in the axial stiffness of peripheral heat exchange tubes；Improving the stress evaluation system for key components such as the channel shell and shell‑side shell ends，and the flat cover，while clarifying the priority conditions for stability checks of heat exchange tubes and the criteria for selecting strength theories under biaxial stress states.SW7 software is not only a programmatic implementation of the new analysis and design standard，but also a beneficial supplement and engineering extension to the standard content.The release of its trial version is expected to promote the advancement of industry technical level.

To address the issue of frequent cracking in the weld of the desuperheating water spray nozzle of a high‑pressure bypass valve in a 1 000 MW ultra‑supercritical unit，the failure mechanism of the weld was revealed and a structural optimization scheme was proposed by means of metallographic structure analysis，microhardness testing，and other physical and chemical inspection methods combined with finite element numerical simulation technology.The results show that the high hardness of the weld between the desuperheating water inlet pipe and the nozzle，together with the low‑cycle strain fatigue induced by structural constraints，mutually superimposed to promote the rapid initiation and propagation of cracks in the fillet weld，thereby leading to leakage of the desuperheating water pipe.For the optimization scheme of lengthening the vertical desuperheating water pipe to enhance pipeline flexibility，finite element analysis shows that when the vertical pipe length is increased to 380 mm，the stress at the fillet weld significantly decreases to 65 MPa，effectively avoiding stress concentration.The research results can provide reference for the structural design and safe operation of similar high‑pressure bypass valves.

To address the difficulty in accurately obtaining electrical parameters of key components for the inductive coupling wireless ultrasonic monitoring systems，the accuracy of existing coil inductance calculation methods and piezoelectric transducer impedance modeling techniques were compared.Taking planar spiral coils as the research objects，the filament method，area integral method，and finite element simulation were used to calculate self‑inductance and mutual inductance，with results compared against experimental values.A finite element model of the piezoelectric transducer and workpiece coupling system was established to obtain the impedance spectrum，which was compared with experimental values.The component parameters were incorporated into a three‑coil coupling circuit model to construct an monitoring system and conduct thickness inspection verification.The results indicate that the filament method is suitable for self‑inductance calculation，with a self‑inductance calculation error of less than 3%.The area integral method is appropriate for mutual inductance calculation，with a mutual inductance calculation error of less than 5% within a lift‑off distance range of 2 to 10 mm.The finite element simulation accurately predicts the resonant frequency of the piezoelectric transducer.The constructed monitoring system successfully achieveds thickness detection.This study provides methodological references and experimental basis for component selection and parameter design in inductive coupling wireless ultrasonic inspection systems.