The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Ilbeom Choi - One of the best experts on this subject based on the ideXlab platform.
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gasket integrated carbon silicone elastomer composite bipolar plate for high temperature pemfc
Composite Structures, 2015Co-Authors: Ilbeom ChoiAbstract:Abstract The primary components of proton exchange membrane fuel cell (PEMFC) systems are bipolar plates, end plates, membrane electrode assemblies (MEAs), gas diffusion layers (GDLs), and Gaskets. The PEMFC composed of many components induces sealing problem of the stack, which affects the fuel efficiency, reliability, and maintenance costs of the system. Conventional PEMFCs are sealed with numerous elastomeric Gaskets to seal the stack, which increases the manufacturing and assembly costs. To reduce the assembly time and to increase the sealing reliability without the use of Gaskets, a gasket-integrated carbon/silicone elastomer composite bipolar plate is developed. Silicone elastomer is employed rather than conventional glassy thermoset or thermoplastic polymers for the matrix of the composite bipolar plate, where the silicone elastomer works as Gaskets due to its resilience. The mechanical and electrical properties of the developed carbon/silicone elastomer composite are investigated at both room temperature and operating temperature of high-temperature PEMFCs (HT-PEMFCs). The sealability of the gasket integrated composite bipolar plate is tested.
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Gasket-integrated carbon/silicone elastomer composite bipolar plate for high-temperature PEMFC
Composite Structures, 2015Co-Authors: Ilbeom ChoiAbstract:Abstract The primary components of proton exchange membrane fuel cell (PEMFC) systems are bipolar plates, end plates, membrane electrode assemblies (MEAs), gas diffusion layers (GDLs), and Gaskets. The PEMFC composed of many components induces sealing problem of the stack, which affects the fuel efficiency, reliability, and maintenance costs of the system. Conventional PEMFCs are sealed with numerous elastomeric Gaskets to seal the stack, which increases the manufacturing and assembly costs. To reduce the assembly time and to increase the sealing reliability without the use of Gaskets, a gasket-integrated carbon/silicone elastomer composite bipolar plate is developed. Silicone elastomer is employed rather than conventional glassy thermoset or thermoplastic polymers for the matrix of the composite bipolar plate, where the silicone elastomer works as Gaskets due to its resilience. The mechanical and electrical properties of the developed carbon/silicone elastomer composite are investigated at both room temperature and operating temperature of high-temperature PEMFCs (HT-PEMFCs). The sealability of the gasket integrated composite bipolar plate is tested.
Toshiyuki Sawa - One of the best experts on this subject based on the ideXlab platform.
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FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Connections With Larger Nominal Diameter Inserting PTFE Blended Gasket Under Internal Pressure
Volume 2: Computer Technology and Bolted Joints, 2018Co-Authors: Koji Sato, Toshiyuki Sawa, Xing ZhengAbstract:The sealing performance prediction of bolted pipe flange connections with Gaskets is important factor. However, it is known that the sealing performance of the larger nominal diameter connection is worse than that with smaller nominal diameter connection due to the flange rotation. Furthermore, recently PTFE blended Gaskets were developed newly and the excellent sealing performance in the bolted pipe flange connection with smaller nominal diameter is found. So, it is necessary to examine the sealing performance and the mechanical characteristics of pipe flange connections with larger nominal diameter under internal pressure. The objectives of present study are to examine the mechanical characteristics of the pipe flange connection with PTFE blended gasket under internal pressure such as the load factor, the contact gasket stress distribution and the sealing performance using FEM and experiments. Using the obtained contact gasket stress distribution and the fundamental leak rate for smaller PTFE gasket, the leak rate of the connection is predicted under internal pressure. In the FEM calculation, the effects of the nominal diameter of pip flange connections on the mechanical characteristics are shown. In the experiments, ASME class 300 24” pipe flange connections is used and the gasket is chosen as No.GF300 in PTFE blended Gaskets. The FEM results of the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the leak rate obtained from the FEM calculations are fairly coincided with the measured results. The mechanical characteristics of pipe flange connection with PTFE blended gasket are compared with those with spiral wound gasket.
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FEM Stress Analysis and the Sealing Performance Evaluation of Bolted Pipe Flange Connections With Large Nominal Diameter Subjected to Internal Pressure
Volume 2: Computer Technology and Bolted Joints, 2016Co-Authors: Akira Muramatsu, Koji Sato, Maksud Uddin Khan, Toshiyuki SawaAbstract:The gasket fundamental characteristics such as the stress-strain curves of compressed sheet Gaskets (CSG) and the spiral wound Gaskets (SWG) and the relationship between the average gasket stress and the leak rate using rigid platens were measured. Then, using the measured data of the gasket properties, the mechanical characteristics of bolted pipe flange connections under internal pressure are examined such as the contact gasket stress distribution, hub stress and changes in axial bolt forces (the load factor) using FEM. FEM code employed is ABAQUS. Using the obtained gasket stress distributions and the fundamental gasket relationship between the gasket stress and the leak rate, the leak rates of bolted pipe flange connections are predicted. In addition, the effect of nominal diameters (from 2” to 24”) on the mechanical characteristics is examined. For verification of the FEM calculations, experiments to measure the load factor, the hub stress and the leak rates were performed using 2” and 24” bolted pipe flange connections. The FEM results of the load factor, the hub stress and the leak rate are in a fairly good agreement with the measured results. The value of the load factor is found to be positive for 2” pipe flanged joints, while it is negative for 24” pipe flanged connection due to the flange rotation. It is noticed that the values of the load factor decreases with an increase of the nominal diameter of pipe flanges. The hub stress is kept constant when the gasket stress is held constant for each connection with each nominal diameter while it increases as the nominal diameter increases according to ASME codes. In addition, the leak rate increases as the nominal diameter increases.
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A Determination Method of Bolt Preload for Bolted Pipe Flange Connections With Metal Gaskets Under Internal Pressure
Volume 2: Computer Technology and Bolted Joints, 2015Co-Authors: Koji Kondo, Toshiyuki SawaAbstract:FEM calculations and leakage experiments are carried out for bolted flanged connections with metal flat Gaskets. It is found that the sealing performance of bolted flanged connections with raised face metal Gaskets under internal pressure is improved significantly when the contact gasket stress reaches the gasket yield stress. In our FEM calculations it is demonstrated that the contact gasket stress at the outside diameter is bigger than that at the inside diameter due to the flange rotation. It is also found from the leakage test results and the FEM calculations that the sealing performance of the bolted flange connections with metal flat gasket is better than that of the metal gasket in platen device tests,. In addition, the contact stress in the joints with RTJ (ring type joint) gasket is examined and 4 stress peaks on the oval type and 8 peaks on the octagonal type are found. From the obtained results, a method for determining the bolt preloads in the bolted joints using flat metal Gaskets and RTJ Gaskets under internal pressure is proposed taking account the given allowable leak rate. Finally, the leak rates for bolted flanged connections tightened under internal pressure are compared with the experimental results. The new method can be proposed for determining the bolt preload for bolted flange connections with metal Gaskets under internal pressure at room temperature.Copyright © 2015 by ASME
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Sealing Performance Evaluation in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure
Volume 2: Computer Technology and Bolted Joints, 2013Co-Authors: Koji Kondo, Toshiyuki Sawa, Koji Sato, Shota Tsubaki, Yuya OmiyaAbstract:Bolted flange connections with ring type joint Gaskets have been used to seal the inner fluid under higher pressure and higher temperature conditions when soft Gaskets cannot be used in the connections. However, few researches on the characteristics and the sealing performance evaluation for the bolted flange connections with metal ring gasket have been conducted. Therefore, assembly procedures and tightening methods of the connection with ring type joint Gaskets is empirically and not fully elucidated. It is important to know the characteristics such as the contact gasket stress distribution which governs the sealing performance prediction, the sealing performance and the sealing mechanism in the bolted flange connections for determining optimum tightening methods and the bolt preload. In this paper, the differences of the sealing performance for the bolted flange connections (3″) by the re-use octagonal and oval type ring Gaskets are examined. In the FEM calculations the contact gasket stress distributions and the range of plastic deformation are examined and the sealing mechanism is discussed. It is found that the basic sealing mechanism is caused by the plastic deformation at the contact area of the gasket. In addition, the leakage tests for the bolted flange connections with the nominal diameter of 20″ with the octagonal ring type joint Gaskets being inserted are conducted, where the bolt tightening for the connection is carried out according to both ASME PCC-1 and JIS B2251, respectively. Using these results, the optimum tightening methods for the connection with ring type joint Gaskets are discussed.
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The Sealing Characteristics of Bolted Flanged Connection With Metal Gasket
Volume 2: Computer Technology and Bolted Joints, 2012Co-Authors: Koji Kondo, Toshiyuki Sawa, Koji Sato, Tsutomu Kikuchi, Shota TsubakiAbstract:Metal Gaskets have been used in bolted flanged connections under high pressure and high temperature conditions. However, it is difficult to estimate an amount of leakage from the metal contact interfaces in the connections. Recently, it has been noticed that a tiny leakage occurs from the gasket interfaces in bolted flanged connections. Thus, it is necessary to study on the sealing characteristics of the metal to metal contact gasket in the connections under internal pressure and high temperature.In the present paper, for clarifying the characteristic of the metal Gaskets, some experiments were conducted at room temperature. The Gaskets are used aluminum, copper and mild steel flat Gaskets. Firstly, according to JIS B 2490, the sealing behavior was measured taking account the surface roughness of the metal Gaskets. The Gaskets were compressed using a material testing machine while the amount of leakage was measured. Secondly, the amount of leakage was measured for bolted flanged connections with metal Gaskets. The flange nominal diameter used was 2″. Finally, the contact gasket stress distributions in the connection were analyzed using 3-D FEM analysis. Using these results, discussion was made on the sealing behavior of the metal Gaskets. In the result, it is found that plastic strain is important for the sealing performance of the metal gasket.Copyright © 2012 by ASME
A. Fitzgerald Waterland - One of the best experts on this subject based on the ideXlab platform.
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Stress Multiplier for Segmented Gaskets
Volume 2: Computer Technology and Bolted Joints, 2018Co-Authors: A. Fitzgerald Waterland, Jeffery WilsonAbstract:The use of segmented joint technology allows gasket manufacturers to fabricate and supply Gaskets in discrete segments, rather than the conventional one-piece construction. Segmented Gaskets are required when using sheet type Gaskets for flange diameters larger than the available sheet size. Typical gasket sheets are 60” × 60” or 70” × 70” square, for instance. Flanges designed for these lower stress sheet Gaskets that are larger than the available sheet size to fabricate the Gaskets are typically fabricated as segmented Gaskets. Segmented Gaskets are also utilized in smaller flange applications to facilitate maintenance activities. When replacing the tube sheet gasket in a shell and tube exchanger the entire tube sheet must be removed in order to utilize a solid, one-piece ring gasket. In some cases this is not practical or desired, so a segmented gasket is utilized which only requires the tube sheet to be removed a short distance to allow access to the sealing surface. This same scenario exists with other common process piping and vessel flanges including thermowells, lance tubes, agitator or mixer shafts, etc. Valid concerns exist when using segmented Gaskets as potential leak paths are created at every joint. If the gasket material and joint design are not correctly specified and fabricated the segmented gasket may not provide the same sealing performance and reliability as the solid, un-segmented gasket. This paper will discuss the research and data found that identifies the stress multiplier for segmented/jointed Gaskets to achieve the same (similar) leak rate as their solid, unsegmented gasket counterpart. This assembly or design stress multiplier will be a dynamic number that will vary based upon the gasket material and the joining technology used. Two jointing methods are evaluated in this research; the industry standard “dovetail” and the Engineered Interference Tortuous Path (EITP) joint. In practice there is currently no guidance available to guide the design or assembly of these segmented gasket applications. The purpose of this paper is to provide guidance for both design and assembly purposes.
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Exploring M & Y Gasket Factors and Their Degree of Correlation With Proposed PVRC Gasket Factors
Volume 2: Computer Technology and Bolted Joints, 2017Co-Authors: Dale A. Rice, A. Fitzgerald Waterland, Anita R. BausmanAbstract:The well-known gasket factors, m & y were introduced in 1943 as per ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 for purposes of flange design. The test procedure for determining these factors, ASTM Standard F586, was published in 1979 but then ultimately withdrawn in 1998 with the assumption that these test standards would be replaced by a new test method and with it the generation of improved gasket constants. The original m & y constants had several shortcomings including the fact that many of the listed values assumed asbestos fiber Gaskets while new gasket materials such as PTFE (polytetrafluoroethylene) and FG (flexible graphite) were not addressed. Additionally, gasket manufacturers were allowed to publish m and y values for their own specific gasket materials and styles using their own test methods, thus dispensing with industry-wide standardization. ASTM Method F3149-15, “Standard Practice for Determining the Maintenance Factor (m) and Yield Factor (y) Loading Constants Applicable to Gasket Materials and Designs” represents an improvement over F586 but is not linked to standardized tightness levels. The proposed PVRC method with a new set of gasket constants is based on a load versus leakage test standard known as ROTT (Room Temperature Tightness Test). Following the ROTT method, ASTM WK39360, “New Test Method for Leak Rates Versus Y Stresses and M Factors for Gaskets derived from the Room Temperature Test Practice”, is being contemplated. This paper provides a review of the past inconsistencies of m & y values as published as well as an initial assessment of the degree of correlation between m & y values and tightness calculations achieved through the use of a previously documented fugitive emissions calculator for gasket materials which makes use of published ROTT data, and the operating pressure, flange NPS, gasket stress, and other inputs.
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Environmental Considerations for Gasket Selection and the Development of an Emissions Calculator for Gasket Materials
Volume 2: Computer Technology and Bolted Joints, 2014Co-Authors: Dale A. Rice, A. Fitzgerald WaterlandAbstract:The choice of gasket type for flanged connections has typically been determined on the basis of temperature, pressure, and chemical nature of the contained fluid; sealability; ease of handling and installation; expected service life; comparable cost; and other factors. Of ever increasing importance is the environmental performance of the selected gasket with an emphasis on fugitive emissions reduction. All Gaskets have some level of fluid leakage but this may vary significantly depending on the type selected. A practical tool using Microsoft® Excel® has been developed that can help predict anticipated fugitive emissions of Gaskets for which Room Temperature Testing (ROTT) data are available. The construction and application of this tool are described and a relative comparison of tightness parameters and projected fugitive emissions for example gasket types are documented.
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Environmental Considerations for Gasket Selection and the Development of an Emissions Calculator for Gasket Materials
Volume 2: Computer Technology and Bolted Joints, 2014Co-Authors: Dale A. Rice, A. Fitzgerald WaterlandAbstract:The choice of gasket type for flanged connections has typically been determined on the basis of temperature, pressure, and chemical nature of the contained fluid; sealability; ease of handling and installation; expected service life; comparable cost; and other factors. Of ever increasing importance is the environmental performance of the selected gasket with an emphasis on fugitive emissions reduction. All Gaskets have some level of fluid leakage but this may vary significantly depending on the type selected. A practical tool using Microsoft® Excel® has been developed that can help predict anticipated fugitive emissions of Gaskets for which Room Temperature Testing (ROTT) data are available. The construction and application of this tool are described and a relative comparison of tightness parameters and projected fugitive emissions for example gasket types are documented.Copyright © 2014 by ASME
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Spiral Wound Gasket Compressibility and Pressure Ratings
Volume 2: Computer Technology and Bolted Joints, 2013Co-Authors: John Mccarthy, A. Fitzgerald Waterland, Dan ReidAbstract:The industry practice of using pressure rating nomenclature to describe spiral wound gasket compressibility can contribute to some level of confusion regarding the proper design and selection of these Gaskets. This situation can result in a misconception that a more easily compressed “soft” gasket (for example, “0–999 psi” rating) cannot be used in a higher pressure application. This is not necessarily true, and in many cases a softer (less dense) gasket construction can actually be beneficial in both high and low pressure applications. This article addresses both the terminology used to describe spiral wound gasket compressibility and the design characteristics of these Gaskets in an effort to improve the understanding of this subject.Copyright © 2013 by ASME
Hu Hui - One of the best experts on this subject based on the ideXlab platform.
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Analysis of sealing performance of a kind of profiled rubber gasket used in the radial contact seal structure
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2020Co-Authors: Xinyi Song, Song Huang, Hu HuiAbstract:Sealing performance of standard rubber Gaskets in the radial contact seal structure are observed through the experiment. A kind of profiled rubber gasket is proposed to replace the standard gasket. Leakage experiment and numerical simulation are carried out to study the sealing performance and failure mode of the profiled gasket. Several equations are presented to help analyze the failure reason. Results show that sealing performance of the profiled rubber gasket is more reliable than that of the standard rubber gasket. The failure reason of the profiled rubber gasket is that the friction force between the gasket external face and tube wall cannot balance the tube internal pressure. Dimension precision of the metal compressive ring has a great effect on the failure pressure.
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Analysis of sealing performance of a kind of profiled rubber gasket used in the radial contact seal structure
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2020Co-Authors: Xinyi Song, Song Huang, Hu HuiAbstract:Sealing performance of standard rubber Gaskets in the radial contact seal structure are observed through the experiment. A kind of profiled rubber gasket is proposed to replace the standard gasket....
Da-jun Yuan - One of the best experts on this subject based on the ideXlab platform.
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Material properties of the seal gasket for shield tunnels: A review
Construction and Building Materials, 2018Co-Authors: Chen Yang, Shui-long Shen, Dong-wei Hou, Shao-ming Liao, Da-jun YuanAbstract:Abstract This paper reviews the material properties of the seal Gaskets of shield tunnels. In order to understand the function of sealing Gaskets, the significance and structure of Gaskets in tunnel segments are briefly introduced. Then, the material types of gasket are presented. Gasket materials include two categories: (i) the traditional elastic gasket and (ii) the hydrophilic composite elastic gasket. The traditional elastic gasket is composed of chloroprene rubber (CR) and ethylene propylene diene rubber (EPDM), in which the sealing function is implemented as a result of the elastic properties of the materials. The hydrophilic composite elastic gasket includes vulcanized water swelling rubber (WSR) and water swelling polyurethane (WSP), in which the sealing function is obtained from both the elastic properties and the water absorption ability of the gasket material. CR and EPDM were the earliest materials used in engineering practice; however, EPDM is the main material of the gasket today. The sealing mechanism of both CR and EPDM is presented at the molecule level. After that, the water absorption process for both WSR and WSP in hydrophilic composite is reviewed. Methods to improve the sealing behavior of WSR are also summarized. Furthermore, the aging of the gasket material is discussed. Finally, perspectives for future developments of new materials or ways to improve the performance of seal Gaskets are proposed.