移动罐车螺栓法兰接头密封失效与防护研究

发布时间：2018-08-10 19:16

【摘要】：在危化品介质的诸多运输方式中,移动罐车因其高效灵活、运输方便的特点,成为目前一种主要的运输形式。但罐车运输途中各类泄漏事故频发,严重危害着公路运输安全,罐车的安全运输问题日渐引起社会的高度关注和相关管理机构与研究人员的重视。本文以罐车液相法兰密封系统为研究对象,综合考虑系统的结构安全与密封可靠性,从法兰的变形协调关系理论和垫片的强制密封条件出发,通过有限元分析方法,建立了密封系统的非线性结构模型,分析了静力学中系统结构、预紧方式、温度、内压以及动力学中固有振动特性、振动环境等对液相法兰密封性能的影响规律,提出了保障法兰接头密封安全的综合性预防与泄漏处理措施。研究表明,当前液相法兰结构设计所引起的垫片变形,使垫片的密封面积减少20.87%;液相法兰预紧过程中,密封系统的机械交互作用以及螺栓之间的弹性相互作用,对螺栓的残余载荷以及垫片的最终压应力分布有很大的影响。机械交互作用会随着预紧载荷的增大而减小,其损失系数最大达0.19;弹性相互作用在各种预紧方式中呈现出不同的特点,损失系数的范围在0.44~0.5之间;环境温度波动所导致的材料变形现象,显著改变密封系统的预紧状态,低温环境中局部的应力下降最大可达19.7%,高温环境中局部的应力最大增幅为14.4%,而内压载荷的波动则不会对预紧密封产生明显影响。罐车液相法兰不同预应力下的固有振动特性可以作为识别密封状态的参考,振动环境将引起密封垫片上介质泄漏通道的产生。在前述研究基础上,本文提出了基于静力学考虑的结构设计改进、基于动力学考虑的设计参考,同时建议现场施工操作应采用至少1.5倍的理论预紧载荷进行三轮交叉预紧;此外,针对移动罐车法兰的紧急泄漏事故,提出了两种应急处理的带压密封措施。
[Abstract]:Among the transportation modes of dangerous chemicals, mobile tank truck has become one of the main modes of transportation because of its high efficiency and flexibility and convenient transportation. However, various kinds of leakage accidents occur frequently during the transportation of tankers, which seriously endanger the safety of highway transportation. The safety transportation of tankers has been paid more and more attention to by the society and the relevant management organizations and researchers. In this paper, the liquid flange sealing system of tank truck is taken as the research object. Considering the structural safety and sealing reliability of the system, starting from the deformation coordination theory of the flange and the forced sealing condition of the gasket, the finite element analysis method is adopted. The nonlinear structural model of sealing system is established, and the influence of system structure, pretightening mode, temperature, internal pressure, inherent vibration characteristics in dynamics and vibration environment on the seal performance of liquid flange is analyzed. The comprehensive prevention and leakage treatment measures are put forward to ensure the sealing safety of flange joint. The research shows that the deformation of gasket caused by the structural design of liquid flange reduces the sealing area of gasket by 20.87.The mechanical interaction of sealing system and the elastic interaction between bolts during the pre-tightening of liquid flange are studied. It has great influence on the residual load of bolt and the final compressive stress distribution of gasket. The mechanical interaction decreases with the increase of preload, and its loss coefficient reaches the maximum of 0.19.The elastic interaction shows different characteristics in various preloading modes, and the range of loss coefficient is between 0.440.5.The loss coefficient of mechanical interaction decreases with the increase of preloading load, and the loss coefficient of mechanical interaction decreases with the increase of preloading load. The deformation of materials caused by ambient temperature fluctuation significantly changes the pre-tightening state of the sealing system. The maximum decrease of local stress in low temperature environment can be as high as 19. 7, and the maximum increase in local stress in high temperature environment is 14. 4%, while the fluctuation of internal pressure load will not have a significant effect on pre-tightening seal. The natural vibration characteristics of liquid flange of tank car under different prestress can be used as a reference to identify the seal state. The vibration environment will cause the leakage channel of the medium on the seal gasket. On the basis of the above research, this paper puts forward the structural design improvement based on statics considerations and the design reference based on dynamics considerations. It is also suggested that at least 1.5 times theoretical preload should be used in site construction to carry out three rounds cross preloading. In addition, in view of the emergency leakage of the flange of moving tank truck, two kinds of pressure sealing measures for emergency treatment are put forward.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ086.52

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