Abstract High-temperature pipelines currently have large-scale application requirements in the chemical and nuclear industries. How to address the issues of thermal stress relief and thermal displacement compensation for high-temperature pipelines is a key focus. Advanced miniature nuclear reactors require the development of metal bellows expansion joints suitable for helium medium, operating at temperatures of 750-800°C and pressures of 3.3MPa. This paper investigates the application of high-temperature metal bellows expansion joints in helium pipelines. Finite element simulations validate the thermal insulation design of expansion joints using alumina fiber materials. Tests were conducted under three different temperatures (700°C, 750°C, 800°C) and four different thicknesses of insulation layers (10mm, 30mm, 50mm, 70mm) to ensure they meet the helium operation conditions at 3.3MPa pressure and 0.64kg/s flow rate. The results show that increasing the insulation layer thickness effectively reduces the outer shell temperature of the expansion joint. When the insulation layer thickness reaches 50mm, the outer shell temperature under 800°C operating conditions is reduced to 374°C, below the creep threshold of 425°C, ensuring structural reliability. These findings establish a robust framework for high-temperature expansion joints in gas-cooled miniature reactors, contributing to the advancement of efficient and reliable nuclear systems.
Wang et al. (Fri,) studied this question.