The stresses of a pipe flange connection with a spiral-wound gasket under internal pressure are analyzed taking account a nonlinearity and a hysteresis of the gasket by using an axisymmetric theory of elasticity and the finite element method (FEM). The leakage tests were also conducted using an actual pipe flange connection with a spiral-wound gasket. Using the contact stress distribution of the pipe flange connection with 3-in. nominal diameter under internal pressure and the tightness parameter, the values of the new gasket constants are obtained by taking into account the changes in the contact stress. A difference in the new gasket constants between the estimated values obtained from the actual pipe flange connection and the values obtained by the PVRC procedure is small. In addition, a method to determine the bolt preload for a given tightness parameter is demonstrated. The obtained results of the bolt preload for the pipe flange connection are in a fairly good agreement with those obtained by the PVRC procedure under a lower pressure application. However, a difference in the bolt preload is about 10% when an internal pressure is increased.
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.
It is known that the bolt loads of gasketed flanged joints decrease in some degree after the assembly due to the creep-relaxation characteristics of gasket. If the bolt loads are greatly reduced, the emission from flanged joints may increase and serious accidents shall occur if things come to the worst. The effect of the creep-relaxation characteristics on the bolt loads of gasketed flanged joints must be clarified. A gasketed bolted joint, in which two hollow cylinders and a gasket is tightened by a set of nut and bolt, is used to clarify the effects of the creep-relaxation characteristics of gaskets on the reduction of bolt loads in this paper. We tried to clarify the phenomena and necessary modeling and experiments were carried out. It is pointed out that the reduction of bolt load cannot be overlooked when stiffer bolts are used in gasketed joints.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.