Comparative analysis on flexibility requirements of typical cryogenic transfer lines

The cryogenic systems and their applications, primarily in large Fusion devices, utilize multiple cryogen transfer lines of various sizes and complexities in terms of layout to transfer cryogenic fluids from plant to the various user/applications. These transfer lines are composed of various critical sections like tee sections, elbows, flexible components etc. The mechanical sustainability (under failure circumstances) of these transfer lines are primary requirement for safe operation of the system and applications. The transfer lines need to be designed for multiple design constraint conditions like line layout, support locations and space restrictions. The transfer lines are subjected to single load and multiple load combinations, such as operational loads, seismic loads, leak in insulation vacuum etc. The analytical calculations and flexibility analysis using CAESAR II software are performed for the typical transfer lines without any flexible component, the results were analysed for functional and mechanical load conditions. The failure modes were identified along the critical sections. The same transfer line was then refurbished with the flexible components and analysed for failure modes. Inclusion of these components provides additional flexibility to the transfer line system and makes it safe. The optimization was performed by selection of the appropriate flexible components to meet the design requirements as per ASME B31.3/EN 13480 codes. This paper describes the results obtained from the analytical calculations, which are compared and validated with those obtained from the flexibility analysis software calculations. (author)