传统与欧盟法兰连接螺栓预紧力计算方法对比研究

发布时间：2018-06-26 14:15

本文选题：法兰连接 + 计算方法　；参考：《兰州理工大学》2017年硕士论文

【摘要】：法兰螺栓连接系统是化工设备常用的连接装置,大量研究表明泄漏是引起法兰连接系统失效的主要原因,而强度引起的失效则是少数情况。因此对法兰螺栓连接系统的密封特性研究需要引起足够的重视。由于国内法兰连接螺栓预紧载荷的计算基本上采用的是ASME法,对于欧盟法兰连接螺栓载荷的计算方法的研究和应用较少。因此,本文利用两种法兰设计方法计算法兰连接所需的螺栓预紧载荷,同时结合有限元软件对法兰螺栓连接结构进行数值模拟,分析不同法兰设计方法对法兰接头强度和密封性的影响。本文通过理论分析、数值计算和有限元模拟三者相结合的方法对不同法兰连接螺栓载荷计算方法进行更全面、更深入、更客观的研究。首先,本文就目前常用的两类法兰设计方法进行了详细介绍,一类是传统的基于Taylor-Forge法的,以ASME VIII-1法兰设计规范为代表;另一类是有别于Taylor法的欧盟法兰设计方法,以EN13445附录G——法兰设计另一方法为代表。通过对比ASME VIII-1法兰设计规范(以下简称ASME法)和EN13445附录G(以下简称附录G)的理论依据,计算过程以及涉及的参数等因素,从而说明附录G的方法计算出的螺栓载荷值更加精确,更能保证法兰连接的密封性。因此,在工程实际中,能对螺栓载荷的计算提供理论性指导。然后,本文依据某石化公司提供的设备实际运行参数,分别运用ASME法和附录G两种方法计算法兰接头的螺栓载荷。将两种方法计算得到的螺栓载荷值进行对比分析,结果表明,附录G计算所得的预紧和操作两种工况下的螺栓载荷均普遍小于ASME法计算得到的预紧和操作两种工况下的法兰设计螺栓载荷,而附录G的最大螺栓实际安装载荷与ASME预紧工况的法兰设计螺栓载荷相比,有些大于ASME预紧工况法兰设计螺栓载荷,有些则小于。最后,运用有限元分析软件对螺栓法兰连接结构在上述两种方法计算得到的螺栓载荷下的应力-应变进行分析。首先对法兰接头施加温度载荷进行热分析,再将热分析结果导入静力分析中对法兰接头进行热-结构耦合分析。结果显示,施加附录G计算出的螺栓载荷,法兰接头各组件均未超出材料的屈服极限,施加ASME法计算出的螺栓载荷法兰螺栓孔部分最大应力超出法兰材料屈服极限。法兰材料长期在屈服状态下工作将会导致法兰密封失效。另外,ASME螺栓载荷作用下的垫片应力不均匀现象明显,这也将会造成法兰接头密封失效引起泄漏。
[Abstract]:Flange bolt connection system is a common connection device in chemical equipment. A large number of studies show that leakage is the main cause of failure of flange connection system, but failure caused by strength is a few cases. Therefore, enough attention should be paid to the study of sealing characteristics of flange bolt connection system. The ASME method is used to calculate the preload of flange connection bolt in China, but the research and application of the load calculation method for flange connection bolt in EU are few. Therefore, in this paper, two flange design methods are used to calculate the bolt pre-tightening load required for flange connection, and the numerical simulation of flange bolt connection structure is carried out in combination with finite element software. The influence of different flange design methods on the strength and sealing property of flange joint is analyzed. Through theoretical analysis, numerical calculation and finite element simulation, this paper makes a more comprehensive, in-depth and objective study on different flange joint bolt load calculation methods. Firstly, two kinds of flange design methods are introduced in detail, one is based on Taylor-Forge method, represented by ASME VIII-1 flange design code, the other is European flange design method, which is different from Taylor method. Take en 13445 appendix G-flange design another method as an example. By comparing the theoretical basis, calculation process and parameters of ASME VIII-1 flange design code (ASME method) and EN13445 appendix G (hereinafter referred to as appendix G), it is shown that the bolt load value calculated by appendix G method is more accurate. More can guarantee the sealing of flange connection. Therefore, in engineering practice, it can provide theoretical guidance for the calculation of bolt load. Then, according to the actual operation parameters of the equipment provided by a petrochemical company, the bolt load of flange joint is calculated by ASME method and appendix G method respectively. The results show that the load values of bolts calculated by the two methods are compared and analyzed. The bolt loads calculated in Appendix G are generally smaller than those calculated by ASME method under both pre-tightening and operation conditions, and the load of flange design bolts under two operating conditions is generally smaller than that calculated by ASME method. Compared with the flange design bolt load of ASME preloading condition, the load of maximum bolt installation in appendix G is larger than that of ASME pre-tightening flange design bolt, and some is less than that of ASME pre-tightening flange design bolt load. Finally, the stress-strain of bolted flange connections under the above two methods are analyzed by using finite element analysis software. Firstly, the thermal analysis of flange joint is carried out by applying temperature load, and then the thermal analysis results are introduced into the static analysis to analyze the thermo-structural coupling of flange joint. The results show that the bolt load calculated by appendix G does not exceed the yield limit of the flange, and the maximum stress of the bolt hole of the flange calculated by ASME method exceeds the yield limit of the flange. Long-term work of flange material in yield state will lead to flange seal failure. In addition, the stress of the gasket under the load of ASME bolt is obvious, which will also cause the failure of the flange joint seal and the leakage.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ050.2

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