Indigenous Development of Cryo Compatible Flexible Vacuum Jacketed Cryo Line for 80 K

The transfers of liquid cryogens over any distance in a plant, whether indoors or outdoors, require special low loss thermal insulated piping. The basic structure of the transfer line consists of two concentric tubes, inner process tube wrapped with a super insulation material. Inner piping is fixed inside the outer pipe jacket supported inside the low thermal conductive glass fibre insulation material – serve as "spacer". Static vacuum of order of better than 10-2 mbar is maintained between inner and outer piping. Such component is not commercially available in local markets. To reduce the cost factor, dependency and delay delivery aspect; on imported item and to promote the Indian Industrial collaboration and interest to promote R & D activities, this flexible cryo line was developed indigenously. As a start-up attempt on indigenous development activities, small size of prototype 1 inch NB, 1.5 meter length line developed for laboratory experimental purpose. The developed transfer line found acceptable in all performance tests. Flexible line passed and shows the stringent helium leak tightness at cryogenic temperature, minimum heat leaks and helium leak tightness of <10-8 mbar l/s, nominal pressure drop of line could be comparable with imported foreign make lines. In this paper, design, performance test at 300 K and 77 K, heat load, pressure and flow analysis and its test results shall be presented. The works also highlight the technical challenges and fabrication experience also during development. (author)