In the pipe flange connection with a raised face, the non-uniform gasket contact stresses in the radial direction are occurred due to the flange rotation. The gasket contact stress distributions have dominant effects on the sealing performance of the pipe flange connection. However, the leak testing of a gasket is usually performed under the uniform gasket contact stress using the rigid platen. It is very important to establish a method which predicts the leak rate from the actual pipe flange connection using the results of the leak test conducted under the ideal condition. To do so, there is a need to know the sealing performance of the actual pipe flange connection. In this study, the leakage tests and the finite element simulations are conducted for some pipe flange connections with different gasket width and different flange thickness, which might cause different flange rotation angle. The effects of the flange rotations on the sealing performance and the mechanical behavior of the pipe flange connection are examined.
With the recent increase of safety and environmental concern, the estimation of leak rate of a gasketed flanged connection in piping systems is an important subject to be studied. In order to estimate the leak rate, the sealing behavior of a gasket must be known. Currently, evaluation methods of the sealing behavior are proposed in the North America and Europe independently. One of the problems is that the representations of the sealing behavior are rather complex in both the methods. Thus, gasket tests take a long time to perform and cost much. The authors have carried out investigations on the sealing behavior of compressed fiber sheet gaskets and have shown that the leak rate is uniquely determined by the compressive strain of gasket. This fact makes the test procedure much easier eliminating complex loading-unloading sequences. A simplified leak testing procedure, in which a simple one-way loading is employed, has proposed. Furthermore, an equation for the sealing behavior of gasket, in which the effect of dimensions of gaskets is taken into consideration, has proposed. In this study, investigations on the sealing behaviors are overviewed first. Then, it is shown that the conventional sealing behavior based on the gasket stress is easily obtained from the sealing behavior based on the gasket strain and the stress-strain diagram of gasket. Both the sealing behavior and the stress-strain diagram of gasket are expressed by equations in this method. Finally, it has also shown that the sealing behavior obtained by the simplified test can be fully converted to the ROTT (ROom Temperature Tightness Test) forms.
With the recent increase of a safety and environmental concern, it is important to estimate the leak rate of gasketed flanged connections in piping system. In order to estimate the leak rate, the sealing behavior of a gasket must be known. Currently, evaluation methods of the sealing behavior are proposed in the North America and Europe independently. However, the effects of the internal pressure and the gasket width are not sufficiently considered in both the methods. We have already proposed an evaluation method of sealing behavior based on the gasket strain in a mathematical form, in which the internal pressure and the gasket width are considered. In this paper, the effects of the internal pressure and the gasket width on the leak rate are discussed by applying the evaluation method to ASME and JIS flanges. Comparing the estimated results with those of PVRC and CEN methods, problems are pointed out.
Recently, it has been reported that the dynamics of mechanical structures can be used as a computational resource-also referred to as morphological computation. In particular soft materials have been shown to have the potential to be used for time series forecasting. Although most soft materials can be modeled by mass-spring systems, a limited number of researches has been performed on the computational capabilities of such systems. In this paper, we propose an array of masses linked in a gridlike structure by spring-damper connections to investigate systematically the influence of structural (size) and dynamic (stiffness, damping) parameters on the computational capabilities for time series forecasting. In addition, such a structure gives us a good approximation of two-dimensional elastic media, e.g., a rubber sheet, and therefore a direct pathway to potentially implement results in a real system. In particular, we compared the mass-spring array to echo state networks, which are standard machine learning techniques for this kind of problems and are also closely related to the underlying theoretical models applied when exploiting mechanical structures for computation. Our results suggest a clear connection of morphological features to computational capabilities.
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