为研究温度对法兰结构螺栓预紧力的影响，采用 ANSYS 有限元软件对液化天 然气超低温球阀中法兰在不同温度下的螺栓预紧力和密封状况进行分析，对比了不同线 膨胀系数的螺栓材料在常温和低温下的预紧力状态。结果表明: 螺栓材料选用 B8M、 XM-19 时，预紧力随温度的降低而增大，低温工况下较常温时分别增加了 24. 93% 、 6. 28% ; 螺栓材料选用 Inconel625 时，预紧力随温度的降低而减小，低温工况下较常温 时减小了 26. 39% ; 金属缠绕垫片的密封比压随温度的降低呈现出与螺栓预紧力相同的 变化趋势。

In order to study the effect of temperature on the bolt pretension of flange structure，the bolt pretension and sealing conditions of flange in liquified natural gas ( LNG) ultra-low temperature ball valve at different temperatures were analyzed by ANSYS finite element software，and the pretension states of bolt materials with different linear expansion coefficients at room temperature and low temperature were compared． The results show that when the bolt material is B8M and XM-19，the preload force increases with the decrease of temperature，and the pretension under the low temperature conditions increases by 24. 93% and 6. 28% respectively compared with normal temperature; when the bolt material is Inconel625，the pretension decreases with the decrease of temperature，and the pretension under the low temperature condition decreases by 26. 39% compared with normal temperature． At the same time，the variation of the sealing specific pressure of the metal spiral wound gasket with temperature exhibits the same trend with the bolt pretension．