Leak tightness of bolted flange gasketed joints and stuffing box packings

众所周知，螺栓连接和阀门失效的主要原因是泄漏。最新的北美调查显示，这两个压力容器组件的泄漏占工业设备产生的总逸散排放的重要数量。在这些设备中用作密封元件的垫片和填料函填料并不是唯一要责备的参数。随着当今环境意识的增强和环保法律的严格，人们不仅关注密封产品的改进，还关注如何实施更好的设计计算方法，以最大限度地减少工业过程设备的无组织排放。虽然多年来，目前广泛使用的法兰设计方法的有效性引起了越来越多的质疑，但填料函的设计方法没有文件。尽管已经为减少逸散性排放做出了巨大的努力，但防止泄漏仍然是最大的挑战之一。为了确定泄漏控制参数，必须对螺栓连接中的垫片或填料盒中的压缩填料的一般行为有一个基本的了解。我们最近对垫片的研究表明，它们的性能不仅取决于工作条件（压力和温度），还取决于它们所安装的机械部件（刚度、表面几何形状、表面粗糙度）。拟议的研究项目旨在改进垫片并优化其在设备中的总体性能。其目标是从事螺栓垫片连接的基础研究工作。与此同时，我们的目标是将获得的知识扩展到填料盒填料的研究。尽管应用领域不同，但填料的泄漏流动机理实际上是由类似的参数控制的，如接触压力、表面粗糙度、几何形状、流体类型和温度。工作的一个重要部分将致力于发展解析模型和数值有限元模型。这些模型将在实际螺栓密封接头和填料盒填料上进行实验验证。

It is well established that the major cause of failure of bolted joints and valves is leakage. The latest North American survey showed that leakage from these two pressure vessel components represents an important amount of the total fugitive emissions produced by industrial equipments. The gaskets and stuffing box packings used as sealing elements in these equipments are not the only parameters to blame. With today's increasing environmental consciousness and strict environmental protection laws, attention has focused not only on improving sealing products, but also implementing better design calculation methods that minimize fugitive emissions from industrial process equipments. While over the years the validity of the current extensively used flange design method has raised increasing inquiries, there is no documented design method for stuffing boxes. Even though a substantial effort has been put towards reducing fugitive emissions, preventing leakage remains one of the biggest challenges. A fundamental understanding of the general behaviour of the gasket in a bolted joint or the compression packing in a stuffing box must be conducted in order to delimit the leakage controlling parameters. Our recent studies on gaskets show that their performance depends not only on the working conditions (pressure and temperature), but also on the mechanical components (rigidity, facing geometry, surface roughness) on which they are mounted. The proposed research project aims at improving gaskets and optimizing their general performance within the equipment they are used. Its objective is to pursue fundamental research work on bolted gasketed joints. In parallel, it is our goal to extend the gained knowledge to the study of stuffing box packings. Although, the application is different, the leakage flow mechanism of pakings is practically controlled by similar parameters such as contact pressure, surface roughness, geometry, type of fluid and temperature. An important part of the work will be devoted to the development of analytical models and numerical FEM models. These models will be validated experimentally on real bolted gasketed joints and stuffing box packings.