高温下工作螺栓预紧状态变化研究及应对措施  

Research on Pre-tightened Status' Change of Bolt under High Temperature and Countermeasures

作　　者：管建军[1] 孙一伦[2] 张大群 宋尔明[1] 

机构地区：[1]辽宁石油化工大学机械工程学院,辽宁抚顺113001 [2]中国石化工程建设公司工厂系统室,北京100101 [3]中石化催化剂长岭分公司加氢车间,湖南岳阳414012

出　　处：《轻工机械》2013年第5期104-107,共4页Light Industry Machinery

摘　　要：常温下预紧螺栓升温到高温时螺栓及法兰的应力应变的改变会对密封状态产生影响。文章首先在各应变均匀一致的假设前提下通过理论推导得到预紧后螺栓的应变大小和升温后密封状态的变化,其次采用有限元软件对常温预紧、升温及再次预紧过程中的螺栓、法兰的应力应变变化进行了分析,最后考虑了蠕变和应力松弛效应对螺栓轴力的影响。文中认为在常温下预紧的螺栓在高温工作时应再次拧紧,如此才能保证高温下的密封状态和常温下保持一致。再次拧紧的应变为法兰与螺栓的热应变之差;若高温下再次拧紧后降温则应拧松螺栓,防止损坏垫片;高温时螺栓轴力不能过高,否则易于在较短时间内降低密封性能,而且应定期拧紧螺栓。The stress and strain of the pre-tightened bolt and flange heated to high temperature from ambient temperature would have a change and have an influence on sealing performance. Firstly, the changes of strain and sealing performance were analyzed under the hypothesis that the stain of different parts was uniform. Secondly, the stress and strain under the state of pretightened, heated and re-tightened process were analyzed by FEA software. Lastly, the effect of creep and stress relaxation on axial stress of bolt was estimated. Following conclusions were drawn, the bolt pre- tightened at ambient temperature should be re-tightened to sustain the status of sealing performance when working at high temperature. The re-tighten stain was equal to thermal strain difference of flange and bolt. The re-tightened bolt should be loosened to avoid damage of spacer when cooled to lower temperature. The axial stress of bolt should not sustain high level otherwise the sealing performance would be deteriorated in a short time. It was suggested that the bolt should be tightened at regular intervals.

关 键 词：螺栓 预紧 密封性能 应力松弛 

分 类 号：TH131.3[机械工程—机械制造及自动化]