螺栓法兰接头完整性和密封性影响因素分析

发布时间：2018-05-27 21:43

  本文选题：螺栓法兰接头 + 加载顺序　； 参考：《华东理工大学》2013年硕士论文

【摘要】：本文以重整装置高温法兰为研究对象,研究螺栓拧紧顺序,稳态及瞬态热-固耦合,管道外载荷对法兰接头的强度及密封影响,并计算保温结构与不保温结构的能耗之差,分析保温的重要性。 计算模型考虑材料的非线性及垫片的非线性压缩回弹特性,全文计算以金属缠绕型垫片为主,在外载荷计算时对比MMC垫片与缠绕式垫片的性能差别。 螺栓加载顺序为顺序加载方式以及两种交叉加载方式,其中加载步数较多的加载方式在最后一轮加载之后应力分布均匀。而需要较少加载步数的交叉加载方式最终应力分布与前两种方式的相近,但由于所需的加载步数少,具有较高的效率。直径越大,应力变化过程更加均匀。加载过程中螺栓发生径向和环向弯曲。 通过计算法兰的保温与不保温结构温度分布,根据传热学原理计算不同结构的热量损失之差,比较两种结构的能量损耗。得出保温下各部件的温度较高,保温层外壁的温度接近环境温度,说明保温结构合理。一个法兰保温结构比不保温结构每年节省约30吨标油,设计合理的保温结构对法兰保温具有重要意义。保温后应力升高,增加了强度破坏的可能性,同时法兰转角增大,增加了泄漏的可能性。但是仍满足密封要求。 瞬态耦合分析得出法兰、螺栓、垫片的温度变化过程各不相同。由于垫片距内壁较近,垫片的温度变化较早,螺栓温度变化较晚。与加载过程相对应,法兰接头中各部件的应力变化呈现出预紧—加压—最大—稳定四个关键位置,由于各部件的应力变化时间和大小不尽相同,综合作用导致垫片的应力和压缩量呈现降低-增大-降低-稳定的趋势。 利用管道分析软件CAESARⅡ和ANSYS进行了管道中法兰受力分析以及在外载作用下法兰的强度及密封分析,得出外载荷作用后螺栓的弯曲加剧,垫片的内侧应力减小,外侧应力增大,增加泄漏的可能性。缠绕垫法兰受外载后转角增大,而MMC垫片的转角减小,说明MMC垫片的内外环起到了限制法兰转动的作用。
[Abstract]:In this paper, the high temperature flange of reforming unit is taken as the research object, the bolt tightening sequence, steady state and transient thermal-solid coupling, the influence of pipeline load on the strength and seal of flange joint are studied, and the difference of energy consumption between insulation structure and non-insulation structure is calculated. Analyze the importance of heat preservation. The calculation model takes into account the material nonlinearity and the nonlinear compression rebound property of gasket. The full text calculation is mainly about metal wound gasket. The performance difference between MMC gasket and winding gasket is compared in the calculation of external load. The order of bolt loading is sequential loading mode and two cross loading modes, in which the loading mode with more loading steps is uniformly distributed after the last round of loading. However, the final stress distribution of the cross-loading mode which requires less loading steps is similar to that of the former two modes, but it has a high efficiency because of the small loading steps required. The larger the diameter, the more uniform the stress changes. The bolt is bent in radial and circumferential direction during loading. According to the principle of heat transfer, the difference of heat loss of different structures is calculated by calculating the temperature distribution of the insulation and non-insulation structures of the flange, and the energy loss of the two structures is compared. It is concluded that the temperature of each component is higher and the temperature of the outer wall of insulation layer is close to the ambient temperature, which indicates that the insulation structure is reasonable. A flange insulation structure saves about 30 tons of oil per year compared with the non-insulation structure. It is of great significance to design a reasonable insulation structure for flange insulation. The increase of stress increases the possibility of strength failure and the angle of flange increases, which increases the possibility of leakage. But still meet the seal requirements. Transient coupling analysis shows that the temperature variation process of flange, bolt and gasket is different. Because the gasket is close to the inner wall, the gasket temperature changes earlier and the bolt temperature changes later. Corresponding to the loading process, the stress changes of the flange joints show four key positions: pressure-maximum-stability, because the stress variation time and size of each component are different. The stress and compression of gasket show a tendency of decreasing-increasing-decreasing-stabilizing. The stress analysis of flange in pipeline and the strength and seal analysis of flange under external load are carried out by using pipeline analysis software CAESAR 鈪，

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