As energy crisis and environment pollution all around the world threaten the widespread use of fossil fuels, compressed natural gas (CNG) vehicles are explored as an alternative to the conventional gasoline powered vehicles. Because of the limited space available for the car, the composite pressure vessel (Type II) has been applied to the CNG vehicles to reach large capacity and weight lightening vehicles. High pressure vessel (Type II) is composed of a composite layer and a metal liner. The metal liner is formed by the deep drawing and ironing (D.D.I.) process, which is a complex process of deep drawing and ironing. The cylinder part is reinforced by composite layer wrapped through the filament winding process and is bonded to the liner by the curing process. In this study, an integrated design method was presented by establishing the techniques for FE analysis of entire processes (D.D.I., filament winding and curing processes) to manufacture the CNG composite pressure vessel (Type II). Dimensions of the dies and the punches of the 1st (cup drawing), 2nd (redrawing-ironing 1-ironing 2) and 3rd (redrawing-ironing) stages were calculated theoretically, and shape of tractrix die to be satisfied with the minimum forming load was suggested for life improvement and manufacturing costs in the D.D.I. process. Thickness of the composite material was determined in the filament winding process, finally, conditions of the curing process (number of heating stage, curing temperature, heating rate and time) were proposed to reinforce adhesive strength between the composite layers.

In combined cycle power plants (CCPPs), the bypass butterfly valve is a key component to facilitate regulation of exhaust gas energy available at the turbine and to not produce too much boost pressure. The conventional damper valve causes leakage, back flow into the turbine, and damage of the blade, and the existing dual-layered seal with polytetrafluoroethylene (PTFE) and metal should be frequently replaced owing to its low durability and deterioration of mechanical properties under a high temperature. This study devised a triple offset butterfly valve with a new type of seal by alternatively laminating stainless steel and graphite to improve valve performance at the high temperature (350 °C). The slope angles of the seal contact surface to prevent friction were calculated using the mathematical models of the triple offset. Thermal-structure coupled analyses by varying the number of graphite and thickness were conducted, and the seven-layer model with the graphite thickness of 0.8 mm, which shows airtightness and smooth operation, was chosen. The contact stresses behaviors of the graphite at 350 °C and at −196 °C were investigated, and it was found that the graphite is in charge of improving driving performance of the disc at the high temperature and sealing performance at the cryogenic temperature. The performance tests and the field tests of the suggested model verified its performance at the working temperature.

This paper highlights the significance of safety and reliability in modern industries, particularly in sectors like petroleum and LNG, where safety valves play a critical role in ensuring system safety under extreme conditions. To enhance the reliability of these valves, this study aims to develop a deep learning-based prognostics and health management (PHM) model. Past empirical methods have limitations, driving the need for data-driven prediction models. The proposed model monitors safety valve performance, detects anomalies in real time, and prevents accidents caused by system failures. The research focuses on collecting sensor data, analyzing trends for lifespan prediction and normal operation, and integrating data for anomaly detection. This study compares related research and existing models, presents detailed results, and discusses future research directions. Ultimately, this research contributes to the safe operation and anomaly detection of pilot-operated cryogenic safety valves in industrial settings.