Metal Gasket Research Articles

Mechanical design of experimental apparatus for FIREX cryo-target cooling

Mechanical design of an experimental apparatus for FIREX cryo-target cooling is described. Gaseous helium (GHe) sealing system at a cryogenic environment is an important issue for laser fusion experiments. The dedicated loading system was designed for a metal gasket. We take U-TIGHTSEAL® (Usui Kokusai Sangyo Kaisha. Ltd.) with an indium plated copper jacket as an example. According to its specification, a linear load of 110 N/m along its circumference is the optimum compression; however a lower load would still maintain helium (He) leak below the required level. Its sealing performance was investigated systematically. Our system demanded 27 N/mm of the load to keep He leak tightness in a cryogenic environment. Once leak tightness was obtained, it could be reduced to 9.5 N/mm.

Cool-down performance of the new apparatus for fuel layering demonstrations of FIREX targets

FIREX targets have been developed under two layering strategies: foam shell and cone guide laser heating methods. Basic studies have been conducted by the collaboration research between ILE and NIFS. Then the next stage requires the characterization of a layered solid fuel. The present system is at the disadvantage of optical observations. Therefore, a new apparatus is designed to solve it. Glass windows with a wide aperture are installed for an interferometer and a microscope. To isolate the vibration from a cryocooler, active vibration control units are equipped, and flexible thermal conductive links are utilized. Furthermore, a quick target exchange mechanism is applied to deal with different types of FIREX targets. A target holder is detachable from a main vacuum chamber. A metal gasket with not fixing bolts but a load of ∼ thousand newtons on ensures GHe leak tightness for target cooling. Eventually, the design temperature of 10.00 K at a target container has been achieved. The cool-down performance indecates that the new apparatus provides a cryogenic environment for fuel layering demonstrations.

Development of 25A-Size Three-Layer Metal Gasket by Using FEM Simulation

Development of 25A-Size Three-Layer Metal Gasket by Using FEM Simulation

612 金属ガスケットとフランジの隙間における音響透過損失に関する研究 : 隙間が傾いている場合(OS6-1 機械力学(2)音の解析・制御技術)

612 金属ガスケットとフランジの隙間における音響透過損失に関する研究 : 隙間が傾いている場合(OS6-1 機械力学(2)音の解析・制御技術)

304 バネ効果を利用した金属ガスケットの板厚と変形モードに関する研究(機素潤滑設計I)

304 バネ効果を利用した金属ガスケットの板厚と変形モードに関する研究(機素潤滑設計I)

Contact Stress and Contact Width Analysis of Corrugated Metal Gasket

Previous studies on corrugated metal gaskets have established that the contact width, contact stress, and surface roughness are important design parameters for optimizing gasket performance. However, the contact stress and contact width considering the surface roughness when the leakage occur did not defined yet. In this study, we determined the real contact stress and contact width when leakage started on 25A-size metal gasket. The contact width determined through a comparison between simulation and experimental results. The contact stress determined through a simulation analysis. The experiment involves a helium leakage test using new metal gaskets having different surface roughness levels. The result justified that the real contact width and average contact stress when the leakage started occur were 0.195mm and 800MPa, respectively. There is a good agreement for contact width both by simulation and experiment result. The contact width for flange having surface roughness 1.5μm is longest than the others.

Sealing Performance of Thin Corrugated Metal Gasket

A thin corrugated metal gasket had been developed for low pressure work condition. In this study, thin corrugated metal prototype gasket was tested by using water pressure test. A Kyowa T-150N was used as water pressure tester. The experiment was conducted after ensuring that there was no leakage in each joint part. The leak test can only indicate two conditions of leakage which are leak or no leak. Pressure applied in the water pressure test was 200 psi, with 5 minutes of lapse time. The leakage was determined by the presence of liquid from the flange and the change in pressure gauge. Based on leak test results, it can be denoted that thin corrugated metal gasket can be used for 200 psi working pressure and 2.2 – 3.3 kN tightening load.

A model for analysing the self-tightening coefficient of a metallic lenticular ring gasket joined by a bolted flange

The metallic lenticular ring gasket seal belongs to the half self-tightening category. The self-tightening capability of the gaskets directly determines the sealing performance of the pipeline joined by a bolted flange. Self-tightening coefficients of the lenticular gasket are defined by a mathematical model for the maximum contact pressure and preloaded force of the joint. Following this assumption, new formulae for the gasket stiffness and its member stiffness were derived using the theory of elastic mechanics. The relationship of their deformation coordination to different working conditions was analysed. The theoretical results indicate that the self-tightening capability of the metallic lenticular ring gasket is a function of the member stiffness. To ensure the lenticular ring gasket has self-tightening capability the ratio of member stiffness to gasket stiffness must be greater than a certain value.

GS0104-201 高圧力作用下における金属ガスケット単体の密封性能試験および応力解析

In order to examine the sealing mechanism of a connection with a metal gasket, the sealing test according to JIS B2490 and FEM analysis were carried out. The dimensions of platen used in the test are according to JIS B 2490 and the metal gasket types are chosen as metal flat and ring joint gasket. The material of the gaskets was aluminum. The ring joint gasket types are chosen as octagonal and oval. The effect of internal pressure on the sealing performance of connection with the metal flat gaskets was measured. The relationship between the gasket compression stress and amount of leakage through inter faces on the metal flat gasket was obtained. And also, the relationship between compression load and amount of leakage through inter faces on the ring joint gaskets was obtained. The von Mises stress distributions on the interface on the metal gaskets were calculated using FEM. Using the results of sealing test and FEM, it was suggested that the sealing performance was improved, when the von Mises stress more than the gaskets material of the yield stress adequately. Furthermore, it was suggested experimentally that the ratio of the maximum of von Mises stress in the gaskets material of yield stress was 1.015.

陽極酸化皮膜を用いたガスケット絶縁技術の開発

In this article, we describe an unique technique for electrical insulation of metallic gasket to perform simultaneous measurements of electrical resistivity and neutron diffraction under high pressure. The anodic oxide coating was adopted as the insulation layer of the aluminum (JIS A2017) gasket used in the hybrid-anvil device for neutron diffraction. In the feasibility tests of the coated gaskets, maximum pressure of about 6 GPa was generated without electrical breakdown of the coating or disconnection of Au leads.

The Influence of Characterization of Metallic Gasket Rough Surface on Gas Sealing Performance in Seal Structure

To investigate the influence of the roughness characteristics of the metallic gasket on the gas leakage rate, a mathematical model of a rough surface based on the Gauss distribution function and exponential auto-correlation function was built. According to this model, a 3D geometrical model of a sealing clearance with two rough surfaces was configured. Effect of the roughness parameters on the gas sealing performance was numerical analyzed, and through the comparison with the classical smooth parallel plate leakage model, the relationship between the leakage rate and the roughness parameters of the sealing surfaces was built. Furthermore, the relationship between contact pressure and the leakage rate for the different roughness surfaces was studied based on the current model. The results show the methodology proposed in current work is effective in predicting the actual sealing performance of static seal structure.

507 温度変動を受ける金属ガスケット付き管フランジ締結体の力学特性

507 温度変動を受ける金属ガスケット付き管フランジ締結体の力学特性

Communication: A novel method for generating molecular mixtures at extreme conditions: the case of hydrogen and oxygen.

We have successfully created a segregated mixture of hydrogen and oxygen at high pressure in a diamond anvil cell using hard x-ray photochemistry. A keyhole (two holes connected by an opening) sample chamber was created in a metallic gasket to support two segregated powders of ammonia borane and potassium perchlorate, respectively, in each hole at a pressure of ~5.0 GPa. Both holes were separately irradiated with synchrotron hard x-rays to release molecular oxygen and molecular hydrogen, respectively. Upon irradiation of the first KClO4-containing hole, solid reddish-orange O2 appeared in the region of irradiation and molecular oxygen was found to diffuse throughout the entire sample region. The second ammonia borane-containing hole was then irradiated and H2 was observed to form via Raman spectroscopy. Water also was observed in the ammonia borane-containing hole and possibly (in the form of ice VII) in the second hole. This unique experiment demonstrates the ability to easily create solid mixtures of simple molecular systems via x-ray irradiation and then react them via further irradiation which will aid the study of chemistry under extreme conditions.

Optimum Shape and Dies Design for New Thin Metal Gasket by Using Simulation Experiment

In this study, new thin corrugated metal gasket will be developed by using simulation experiment. The optimal design and dies design for gasket manufacturing is determined by using computer simulation based on finite element analysis (FEA). In the design stage, the Taguchi method is used to predict optimal design of new thin corrugated metal gasket. The L9 orthogonal array was concerned to design experimental matrix for four factors with three levels. In the manufacturing stage, gasket product is simulated by using ANSYS 14.5 and experimental press forming process by using press hydraulic machine. From the result, the optimal design is the model with R = 3 mm, p = 6 mm, OH = 3 mm and h = 0.2 mm. Based on simulation results and experimental press forming product, it can be concluded that the virtual design from computer simulation results can be used for predicting the real product.

911 金属ガスケットとフランジの隙間における音響透過損失に関する研究 : 実験および理論解析(OS10-2 機械力学(2)音の解析・制御技術,オーガナイズドセッション10:「機械力学(2)音の解析・制御技術」)

911 金属ガスケットとフランジの隙間における音響透過損失に関する研究 : 実験および理論解析(OS10-2 機械力学(2)音の解析・制御技術,オーガナイズドセッション10:「機械力学(2)音の解析・制御技術」)

Contact Width Analysis of Corrugated Metal Gasket Based on Surface Roughness

Contact width is important design parameter for optimizing design of new metal gasket. The contact width was found have relationship with helium leak quantity. Increasing axial force, the contact width will increase and helium leakage will decrease. This study we conducted the surface roughness evaluation of 25A-size metal gasket before and after use. The results denote the real contact width after contact with flange having different surface roughness. The real contact width for the flange having smoother surface roughness is wider than the rougher one.

Effect of reducing impurity concentration of microcrystalline silicon thin films for solar cells using radio frequency hollow electrode enhanced glow plasma

Microcrystalline silicon (μc-Si) thin films with low impurity (oxygen) concentrations were prepared by radio frequency hollow electrode enhanced glow plasma (RF-HEEPT). By using metal gasket seals with the RF-HEEPT system, the oxygen concentration in the thin films was reduced to 3.0 × 1017 cm−3, which is approximately two orders of magnitude less than that of films fabricated in a system using rubber gasket seals. Under the reduced oxygen conditions, we were able to deposit μc-Si thin films at a maximum deposition rate of 10.0 nm/s. We also investigated the spectral response of μc-Si thin-film solar cells. The spectral response of the solar cells fabricated with a low oxygen concentration was improved, especially in the near-infrared region. However, with increasing deposition rate of the thin films, the peaks of the spectral response shifted toward shorter wavelengths and the magnitudes decreased, especially in the near-infrared region, indicating that grain boundaries or defects in the thin films increased at higher deposition rate.

Influence of surface roughness on leakage of new metal gasket

Previous studies of new metal gaskets have established that the contact width, contact stress, and simulation process are important design parameters for optimizing the metal gasket performance. Optimum designs are thus realized based on the elastic and plastic contact stress. However, the influence of the flange surface roughness has not been investigated thoroughly. In this study, we developed a gasket model that includes the flange surface roughness effect. A flange can have different surface roughness levels. A finite element method was employed to develop the simulation solution. The contact width, contact stress, and force per unit length for gasket in contact with a flange having different surface roughness levels were obtained through the simulation. The leakage performance improved with an increase in the contact width and contact stress. The slope of the force per unit length increased with a decrease in the surface roughness level. Furthermore, the slope of the force per unit length for a gasket in 400-MPa mode was higher than that for one in 0-MPa mode. The higher slope suggests that the gasket and flange are pressed together strongly. Finally, the helium leakage quantity was determined to evaluate the leakage performance. The experimental result shows that the gasket in 400-MPa mode shows better sealing performance than the gasket in 0-MPa mode. For a low axial force, changes in the surface roughness caused significant changes in the leakage; the same was not observed for a high axial force.

A Study of The Preload Performance of Subsea Wellhead Connector with a New Locking Mechanism

Abstract Subsea wellhead connector plays an important role in offshore drilling operation, it meets high reliability and safety requirement by guaranteeing the preload performance. In this paper, a new effective non-frictional locking mechanism was developed, and then a connector-wellhead system finite element model was built to analyze and compare the preload capacity of connector under two main load cases. Bolts and metal gasket were the confirmed governing components. Friction and tolerances were important factors that influent preload. The experimental setup including rig and measuring equipment was described. Tensile experiments with inner pressure were performed on the prototype of connector. The experiment results and finite element analysis showed a well agreement on locking pressure, hub face separation point and friction sensitivity, which validated availability and accuracy of analysis method, and provided technical supports for other types of subsea wellhead connector.

Mass Imbalance Measurement of Incomplete Spherical Superconducting Rotor With Air Suspension

For an incomplete spherical superconducting rotor, which has a flat face at the top and a hole at the bottom, respectively, and with highly rotational speed, the mass imbalance is very necessary. However, because of the special structure, the air suspension of the rotor fails as soon as the flat or the hole contacts with the air hole of an air-suspending cavity. Then, the rotor cannot be suspended steadily by air suspension. A metal gasket is added at the bottom of the rotor hole to control the rotor. In addition, an air-suspending cavity with six air holes symmetrically on the side of the cavity instead of at the bottom is used to carry out the air suspension of the rotor steadily. In this paper, a new method of mass imbalance measurement for the superconducting rotor with air suspension is introduced including the theoretical analyses and the experiments.