Leakage analysis and ground tests of knife edge indium seal to lunar sample return devices

2018 ◽  
Vol 233 (6) ◽  
pp. 2010-2022 ◽  
Author(s):  
Bin Zhang ◽  
Haocen Hong ◽  
Min Yu ◽  
Huayong Yang
Keyword(s):  
Leak Rate ◽  
Knife Edge ◽  
Lunar Sample ◽  
Element Analysis ◽  
Sample Return ◽  
Pressing Force ◽  
Sealing Performance ◽  
Lunar Samples ◽  
Ring Seal ◽  
Key Techniques

This work deals with the lunar sample return project, which requires lunar samples to be returned back to the ground without contamination. In this paper, a knife edge indium seal is proposed as a primary sealing form, where indium–silver alloy is welded into an annular groove of a cylindrical container firstly and then extruded by an annular knife edge of a cylindrical lid. The analysis of the leakage and sealing reliability of knife edge indium seal is the main aim of this paper. Firstly, the pretreatment of knife edge indium seal is discussed. Key techniques on indium welding are studied to evaluate its sealing reliability, with the tensile strength and welding void ratio mainly being discussed. Secondly, by means of “Roth” leakage theory, mathematical models on the leak rate for knife edge seal are established. By means of the finite element analysis, the knife edge geometry is optimized with minimum pressing force required. The results justify that the knife edge seal demands much lower pressing force to achieve a considerable sealing performance, which is suitable for low-powered operation. Finally, the ground tests are carried out to evaluate the feasibility of the indium welding and to measure the leak rate of the knife edge indium seal. Experimental results demonstrate the indium welding onto the stainless steel container is feasible, and the leak rate at room temperature is 3.0 × 10−10 Pa·m3/s, which is much lower than the rubber O-type ring seal. The knife edge indium seal is suitable for lunar sample return devices.

Research on Sealing Structure and Ground Test of Lunar Sample Return Devices

2013 ◽  
Author(s):  
Bin Zhang ◽  
Min Yu ◽  
Huayong Yang ◽  
Haocen Hong
Keyword(s):  
High Vacuum ◽  
Extreme Temperature ◽  
Leak Detection ◽  
Ultra High Vacuum ◽  
Knife Edge ◽  
Lunar Sample ◽  
Test Environment ◽  
Sample Return ◽  
Rubber Ring ◽  
Advantages And Disadvantages

This article is in the background of lunar exploration program, which requires unmanned operation in the environment of ultra high vacuum, extreme temperature, strong radiation and lunar dust. Seal reliability of lunar sample return devices should be guaranteed as well. Principal prototype devices of explosive welding seal and brazing seal are analyzed separately when applied to lunar program, both of their advantages and disadvantages are indicated, and improved schemes are given as well. Besides, a redundant seal combined with o type rubber ring and knife edge indium alloy is put forward, to validate its reliability, a mathematical model based on Roth theory has been developed to describe sealing mechanism and predict the variable leakage, and the ground tests on leak detection for rubber seal and knife edge seal have been set up separately through helium mass spectrometer. According to the test results, nitrile rubber is proved to be better because of its resilience in alternative temperature, lower leakage and permeation. The knife edge indium seal has lower leak rate, and the welding joint quality of indium alloy itself can be guaranteed as well. The redundant seal is considered to have preliminary feasibility while the test environment for leak detection is required to simulate lunar surface still further.

Numerical study on sealing characteristic of rubber X-ring exposed to high-pressure hydrogen by considering swelling effect

2019 ◽  
Vol 71 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Chilou Zhou ◽  
Mohan He ◽  
Guohua Chen ◽  
Saihua Jiang
Keyword(s):  
High Pressure ◽  
Numerical Study ◽  
Mechanical Damage ◽  
Element Analysis ◽  
Content Type ◽  
User Subroutine ◽  
Sealing Performance ◽  
Ring Seal ◽  
Insight Into ◽  
Pressure Hydrogen

Purpose This paper aims to investigate the sealing characteristic of the rubber X-ring combined seal used in high-pressure hydrogen service and clarify the effect of swelling due to dissolved hydrogen on the sealing behavior. Design/methodology/approach A finite element analysis method with a user subroutine is proposed to investigate the sealing characteristic of rubber X-ring seals in conjunction with the swelling effect. Findings The swelling has a noticeable impact on the sealing behavior. The higher peak contact stress suggests that the X-ring seal may be superior to the O-ring seal, while the calculated increase in Mises stress suggests the X-ring exhibits a higher propensity to mechanical damage under low pressure conditions. Originality/value This paper describes a method with a user subroutine developed within ABAQUS to simulate the sealing performance coupled hydrogen swelling. The suitability of X-ring seals is evaluated. This work provides insight into the swelling effect on sealing behavior of an X-ring, which is of great value for the design and application of rubber seals used in hydrogen service.

scholarly journals SEALING PERFORMANCE OF GASKETED FLANGE JOINTS – A PARAMETRIC STUDY

2014 ◽  
Vol 15 (2) ◽  
Author(s):  
Muhammad Abid ◽  
Javed A Chattha ◽  
Kamran A Khan ◽  
Hafiz A Wajid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Porous Media ◽  
Compressive Strain ◽  
Media Theory ◽  
Leak Rate ◽  
Element Analysis ◽  
Porous Media Theory ◽  
Sealing Performance ◽  
Bolted Flange

ABSTRACT: This paper aims at finding the leak rate through ANSI class#150 flange joints using compressed asbestos sheet gasket under combined structural and thermal transient loading conditions. The solution is obtained using two different leak rate models and two different bolt up values. The gasket compressive strain based model employs strains that are determined using finite element analysis. The other model is based on the porous media theory in which gasket is considered as porous media. Leak rates determined using these leak rate models are compared for different tightness classes and discussed. ABSTRAK: Kajian bertujuan mencari kadar bocor menerusi sambungan bebibir kelas ANSI#150 menggunakan gasket kepingan asbestos termampat di bawah kondisi bebanan gabungan struktur dan terma fana. Solusinya diperolehi dengan menggunakan dua model kadar bocor yang berbeza dan dua nilai atas bolt yang berlainan. Model terikan berasaskan pemampat gasket menggunakan terikan yang ditentukan dengan analisis unsur terhingga. Model yang lainnya berasaskan teori bahantara berongga di mana gasket digunakan sebagai medium. Kadar bocor ditentukan dengan menggunakan model kadar bocor, yang kemudiannya dibandingkan pada kelas keketatan yang berbeza dan keputusannya dibincangkan.KEYWORDS: bolted flange; gasket; leak rate; finite element analysis; tightness class compressive strains; porous media

Analysis of Vane Hydraulic Damp Static Seal Mechanism and Performance Influencing Factors

2012 ◽  
Vol 152-154 ◽  
pp. 1774-1778 ◽  
Author(s):  
Wen Rui Wang ◽  
Zhi Hui Sun ◽  
Xiao Qiang Yan ◽  
Qi Jiang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Nonlinear Material ◽  
Analysis Method ◽  
Element Analysis ◽  
Finite Element Analysis Method ◽  
Sealing Performance ◽  
Ring Seal ◽  
And Performance ◽  
Sealing Materials

Based on the performance of Vane hydraulic damp O-ring seal ,simulation about the O-ring seal was applied by nonlinear finite element analysis method. The factors influencing sealing performance are considered, such as initial compressibility, sealing materials. Applying the method, the seal structure was designed and optimized. At the same time, the sealing performance was improved, and the contract pressure was increased. The finite element analysis method can be effectively used to solve nonlinear material and sealing failure problem for the seal design, optimization and performance analysis, which provide a new approach and theoretical guidance to the rubber seal research. The seal material and compression ratio are both great influence on the sealing performance , which should be based on working conditions to select the appropriate sealing materials.

Leakage Analysis of Gasketed Flanged Joints Under Combined Internal Pressure and Thermal Loading

2011 ◽  
Author(s):  
Muhammad Abid ◽  
Kamran Ahmed Khan ◽  
Javed Ahmad Chattha ◽  
David H. Nash
Keyword(s):  
Porous Media ◽  
Thermal Loading ◽  
Compressive Strain ◽  
Leak Rate ◽  
Loading Conditions ◽  
Element Analysis ◽  
Applied Loading ◽  
Porous Media Theory ◽  
Sealing Performance ◽  
Strain Model

Leakage in Gasketed Flanged Joints (GFJs) has always been a great problem for the process industry. The sealing performance of a GFJ depends on its installation and applied loading conditions. This paper aims to finding the leak rate through ANSI class#150 flange joints using a compressed asbestos sheet (CAS) gasket under combined structural and thermal transient loading conditions using two different leak rate models and two different bolt-up levels. The first model is a Gasket Compressive Strain model in which strains are determined using finite element analysis. The other model is based on Porous Media Theory in which gasket is considered as porous media. Leakage rates are determined using both leak rate models and are compared against appropriate tightness classes and the effectiveness of each approach is presented.

A Study of the Sealing Performance of a New High-Pressure Cone Valve for Deep-Sea Gas-Tight Water Samplers

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Shi-Jun Wu ◽  
Can-Jun Yang ◽  
Ying Chen ◽  
Yan-Qing Xie
Keyword(s):  
Finite Element Analysis ◽  
High Pressure ◽  
Deep Sea ◽  
Hydrothermal Fluid ◽  
Contact Model ◽  
Element Analysis ◽  
Sea Trial ◽  
Sealing Performance ◽  
Pressure Cone ◽  
Gas Tight

The cone valve plays an important role in high-pressure sealing applications. In this paper, a new high-pressure cone valve, based on the titanium alloy poppet-to-polyetheretherketone seat sealing structure, is proposed for deep-sea gas-tight water samplers. In order to study the sealing performance of the new valve, both the conforming poppet-seat contact model and the nonconforming poppet-seat contact model were evaluated. Finite element analysis based on the two models was performed and validated by experiments. The results indicate that the nonconforming poppet-seat contact model has a better sealing performance than the conforming poppet-seat contact model. The new cone valve also was applied in a gas-tight hydrothermal fluid sampler and successfully tested in a sea trial during the KNOX18RR cruise from 9 July to 12 August 2008.

Apollo 12 Lunar Samples: Trace Element Analysis of a Core and the Uniformity of the Regolith

Science ◽  
1970 ◽  
Vol 170 (3957) ◽  
pp. 533-535 ◽  
Author(s):  
R. Ganapathy ◽  
R. R. Keays ◽  
E. Anders
Keyword(s):  
Trace Element ◽  
Trace Element Analysis ◽  
Element Analysis ◽  
Lunar Samples

The Mechanical Characteristics and Sealing Performance Evaluation of Bolted Pipe Flange Connections With Metallic Flat Gaskets Subjected to Internal Pressure

2016 ◽  
Author(s):  
Koji Kondo ◽  
Koji Sato ◽  
Satomi Takahashi ◽  
Toshiyuki Sawa
Keyword(s):  
Plastic Deformation ◽  
Mechanical Characteristics ◽  
Experimental Results ◽  
Leak Rate ◽  
Effect Of Temperature ◽  
Load Factor ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Higher Temperature

Bolted pipe flange connections with metallic gaskets have been used under higher pressure as well as higher temperature. However, a few researches on the mechanical characteristics in connections with metallic gaskets have been carried out. It is necessary to examine the mechanical characteristics such as the contact gasket stress distributions which govern the sealing performance, the deformation of the metallic gaskets, changes in axial bolt forces and the hub stress under higher pressure and temperature. In the present paper, the objectives are to examine the changes in axial bolt forces, the hub stress and the contact gasket stress distributions and the sealing performance of the pipe flange connections with metallic flat gaskets. Firstly, the mechanical characteristics of the connections under higher pressure are analyzed using FEA. Then, experiments were carried out to measure the load factor, the hub stress and the leak rate (the sealing performance). The relationship between the average contact gasket stress and the leak rate was measured using platen device at room temperature. The FEA results are fairly coincided with the experimental results. It is shown that the leak rate decreases as the contact gasket stress increases and when the plastic deformation of gaskets occurs, the sealing performance increases. The leak rate was measured in the range of 10−4∼10−7 [Pa·m3/s]. It is found that the sealing performance increases as the gasket width increase in the elastic deformation range while it is independent of the gasket width when the plastic deformation occurs. The effect of temperature on the mechanical characteristics of the connection is also examined. The FEA results are in a fairly good agreement with the experimental results. It is found that the sealing performance increases as the temperature increases. In addition, a method how to determine the bolt preload for increasing the sealing performance is proposed.

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