Design method of enhancing the tightness of a spiral wound gasket with PTFE filling (original) (raw)
Related papers
2nd International Conference on Mechanical, Manufacturing and Process Plant Engineering, 2017
Owing to increase in the demand for power, a number of power plants have been installed in the recent past. One of the vital components in these plants is gasketed flange joint. The behaviour of gasketed flange joint is highly dependent on the deformation characteristics of gasket material. In the present study, the deformation characteristic of spiral wound gasket along thickness direction is determined experimentally for different loading rates. Gasket has high nonlinearity under both loading and unloading, with hysteresis. Based on its characteristics, the flange joint is analysed to study its performance and leakage behaviour under static condition. 3D finite element model of flange joint is developed by considering the gasket as interface entity. Finite element analysis of flange joint is performed by including the nonlinear hysteretic behaviour of gasket, under different loading rate and frictional contact between joint members. The influence of different loading and unloading rates is emphasized on the sealing performance of flange joint using leakage pressure. The gasket deforms more when loaded at low rate. This phenomenon also affects the ability to withstand internal fluid without leakage. The maximum safe pressure without leakage increases, when gasket is loaded and unloaded at low rate.
Review on Various Gaskets Based on the Materials, their Characteristics and Applications
Gaskets are extensively utilized in compound and petrochemical enterprises like refineries for most high-pressure framework applications such as channelling frameworks, joint associations, and ribs. Gaskets are also utilised in internal combustion engines, devices used in the medical field, electronics and instrumentation devices, electrical devices such as motors, transformers, generators, etc. Gaskets are traditionally used to give a seal between the mating countenances of the flanged joint, filling-in surface unpleasantness, unevenness and abnormalities in the mating confronts attributable to machining and assembling flaws or impediments. When all is said and done, the reason for gasket fixing is to lessen the outflow rate of media from the framework. In this paper, we have studied about the various classifications of the gasket, their properties and applications. The preliminary studies reveal that gaskets are mainly classified into a) metals b) non-metals c) polymers d) hybrid and each gasket can be utilized for some specific applications. Selection of the wrong gasket can lead to failure of the system and cause significant damage to the surfaces.
International Journal of Pressure Vessels and Piping, 2020
The paper presents the method of modeling the elastic deformations of expanded graphite, a material used as flexible filling in spiral wound gaskets. Five methods (from A to E) were proposed, by means of which the mean values of the effective elasticmodulus were determined on the basis of the experimentally determined stressstrain characteristics of expanded graphite. The values determined in this way constituted the data set into the isotropic material model, reflecting the elastic properties of the expanded graphite tape in the numerical spiral wound gasket model. A different way of modeling the graphite's elastic properties using the numerical model was method F, in which a nonlinear hyperelastic material model proposed by Blatz-Ko was adapted. The basic purpose of the numerical calculations was to determine both the compression curve of the gasket and the stress distribution in the gasket's windings. The obtained numerical results of the gasket's compression were compared with the experimental test, which allowed the assumptions of the numerical models to be validated. The best way to reflect the elastic behavior of expanded graphite in the gasket's numerical model turned out to be the nonlinear material model presented in method F. the joint deformation caused by creep-relaxation and vibrations that reduce the tension of bolts. Proper (required) flexibility of semi-metal gaskets can be achieved, e.g. as demonstrated in Ref. [12-14] by the proper shaping of the metal part. The gasket has to be designed in a way that it does not exceed the allowable stress during both the assembly process and the in-service time, both in the gasket and in all the joint's components, i.e. bolts and flanges. The selection of appropriate gasket features (material and geometry), and the testing of their impact on the load state of the Flange Bolted Joint (FBJ) in a traditional trial and error method is time consuming and not very effective. The most common tool for this type of analysis, accelerating work and optimizing the structure, are commercial programs based on the Finite Element Method (FEM). By using this method to analyze the FBJ, stress and strain in particular components can be accurately assessed [15-18]. The basic step when
Development of New Metallic Gasket and its Optimum Design for Leakage Performance
Journal of Solid Mechanics and Materials Engineering, 2008
This paper introduces a new all-metal gasket that incorporates strategically located circumferential annular lips that form seal lines with the flanges. This gasket, named Super Seal Gasket, by virtue of its special shape, makes use of the material's spring effect, resulting in sealing performance. This change in approach, from the traditional one based on material development to one of mechanical design, brings with it the need for optimization of the different design parameters for leakage performance. We were able to develop an optimization methodology for this new product using the Taguchi method. As a test case, a 25A sized industrial gasket was optimized using this methodology. In FEM analysis, contact stress and deformation information was used to quantify leaking. Helium leak testing reveals considerable improvement in the sealing performance, hence verifying the applicability of the methodology developed. This work has proved that material development is not the only approach towards the development of new, more effective gaskets and novel gaskets, such as the one introduced in this study, have a useful part to play in the sealing of flanged joints.
A new solution of the semi-metallic gasket increasing tightness level
Open Engineering, 2019
The paper presents new type of the semi-metallic gasket characterized with elastic core. Thanks to this solution more elastic recovery as well as more uniform contact stress distribution on the gasket’s surface were obtained which consequently caused that tightness level of the flange joint increased by 1000% in contrast to joint gasketed with traditional solution. The tightness characteristic of the traditional as well as new solution of the gaskets were determined experimentally and discussed.
Review on non-woven polymeric Gaskets their Characteristics and Applications
Gaskets are extensively utilized in compound and petrochemical enterprises like refineries for most high-pressure framework applications such as channelling frameworks, joint associations, and ribs. Gaskets are also utilised in internal combustion engines, devices used in the medical field, electronics and instrumentation devices, electrical devices such as motors, transformers, generators, etc. Gaskets are traditionally used to give a seal between the mating countenances of the flanged joint, filling-in surface unpleasantness, unevenness and abnormalities in the mating confronts attributable to machining and assembling flaws or impediments. When all is said and done, the reason for gasket fixing is to lessen the outflow rate of media from the framework. In this paper, we have studied about the various classifications of the gasket, their properties, and applications. The preliminary studies reveal that non-woven polymeric gaskets are mainly classified into a) Polymer with metal gasket b) Polymer with metal non-metallic gasket c) pure polymeric gasket d) hybrid polymeric gasket and each gasket can be utilized for some specific applications. Selection of the wrong gasket can lead to failure of the system and cause significant damage to the surfaces.
Evaluation of uni-axially expanded PTFE as a gasket material for fluid sealing applications
Materials Chemistry and Physics, 2001
A new process was invented for preparing an improved polytetrafluoroethylene (PTFE) sealant material from a paste formed of PTFE resin with special plasticizer. This expanded PTFE sealant material consisted of a special node and fibrous microstructure. The preferred orientation for mechanical strength of the fibrous structure was parallel to the direction of calendering. The expanded PTFE material was investigated for its mechanical properties, including creep relaxation, compressibility, recovery, torque retention, and gas permeability, as defined by the ASTM and DIN standards. The sealing performance of the material was further characterized by the room temperature tightness test established by the Pressure Vessel Research Council (PVRC). The test results suggest that uni-axially expanded PTFE is soft and compressible, with excellent sealability. It is strong, possessing good resistance against creep and cold-flow. These favorable properties of expanded PTFE, as compared to traditional PTFE-based gasket types, make it a promising gasket material for fluid sealing applications.
Leak rate investigation of expanded polytetrafluoroethylene flat gasket
E3S Web of Conferences
This article examines expanded polytetrafluoroethylene (PTFE) flat gaskets used in the industry to seal flange connections that prevent mixing of working fluids and leakage of fluids into the environment. Expanded PTFE gaskets and existing solutions to improve tightness are reviewed. Using test equipment for measuring the mass of gas passed through the gasket per unit time, which is one of the main operating characteristics of the gasket, a comparison of the required contact stress applied to the gasket during installation to achieve the same leakage rates was made. An annular expanded PTFE gasket with locally increased density is presented. Comparative tests were conducted to determine the mass of helium gas passed through the gaskets when changing the density in the sealed area to the inner diameter of the gasket. The results of the tests carried out show an improvement in the sealing ability and indicate a reduction in the mass of passed gas with the application of a lower contac...
2012
At the previous study of new metal gasket, contact width and contact stress were important design parameter for optimizing metal gasket performance. However, the range of contact stress had not been investigated thoroughly. In this study, we conducted a gasket design optimization based on an elastic and plastic contact stress analysis considering forming effect using FEM. The gasket model was simulated by using two simulation stages which is forming and tightening simulation. The optimum design based on an elastic and plastic contact stress was founded. Final evaluation was determined by helium leak quantity to check leakage performance of both type of gaskets. The helium leak test shows that a gasket based on the plastic contact stress design better than based on elastic stress design.