Study On The Performance Of Cryogenic Seal With Flange-Seal Structure

Sealing structures have been applied in many devices with high pressure, vacuum, and liquid containers. Many standards and technical specifications have been set up from the attentions of scientific research and engineering practice. However, the sealing structures in cryogenic systems are distinguished from those in room-temperature systems because of the great difference in material thermal properties at corresponding temperatures, especially such as thermal expansion, cryogenic brittleness, phase change in material microstructure. Hence, the feasibility of conventional sealing structure, material and pre-tightening force being applied in cryogenic environment should be reconsidered, and the related research should be carried out, aiming for an effective technical specification for practical operation. Under this background, the present work will focus on the sealing technology in cryogenic systems, in order to obtain some guides for the engineering applications. The pre-tightening force of the flange-sealing-bolt structure, with indium as sealing material, has been experimentally and numerically studied. The main research contents are listed as follows.1) An experimental system was designed and built up for the flange-indium seal-bolt structure to test its sealing performance, which mainly includes a high pressure sealing structure, a measurement system for bolt pre-tightening force, and a data acquisition system.2) The influence of working pressure, pre-tightening force and operating temperature on the leakage rate of was experimentally studied, in which two methods of pre-tightening were adopted. The experimental results were analyzed to summarize the influence factors for the leakage rates of the flange-indium seal-bolt structure.3) The flange-indium seal-bolt structure was numerically studied to explore the influence of working pressure, pre-tightening force and temperature on the stress distribution of the whole sealing structure. Analysis will be also made on the causes of leakage and their regular patterns.