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Jia X.,Tsinghua University | Chen H.,Tsinghua University | Li X.,Ningbo Tiansheng Sealing Packing Co. | Wang Y.,Tsinghua University | Wang L.,Eaton Corporation
Nuclear Engineering and Design

Double metallic C-rings are used in pressure vessel of pressurized water reactor (PWR) to seal the bolt-connected flanges. To evaluate the sealing performance, it is necessary to study both the C-rings' intrinsic properties and their behavior in reactor pressure vessel (RPV) under various loading conditions. The compression-resilience property and linear load are the basic information to evaluate the performance of a well-designed C-ring's. An equivalent model of C-ring is constructed by means of ANSYS to analyze its intrinsic properties, and is also validated by experiments on scaled samples. This model is applied to develop a 2D-axisymmetric FE model of sealing system including RPV and C-rings with the consideration of nonlinear material, contacting problem and multiple coupled effects. The simulation results of RPV deformation under the hydraulic test condition agree well with the data of factory hydraulic test. With the verified model, an analysis under the designing condition is performed to study C-rings' behavior in the RPV, and then provides a reliable evaluation on the sealing performance of RPV. © 2014 Elsevier B.V. Source

Jia X.,Tsinghua University | Chen H.,Tsinghua University | Li X.,Ningbo Tiansheng Sealing Packing Co. | Wang Y.,Tsinghua University
Qinghua Daxue Xuebao/Journal of Tsinghua University

Graphite gaskets are widely used static seals. This study examines the mechanical properties on the seal interface which is significant to the sealing performance. The study uses finite element simulations based on a test rig structure and elastic-plastic material properties. The compression-resilience curve is measured in the same test rig. The simulations show the changes in the contact pressure and deformation distribution during loading and unloading. The simulated compression-resilience curves agree with the measured data to validate the finite element model. The results explain the sealing mechanism of high contact stiffness, load stability, and installation repeatability for this kind of gasket. © 2016, Press of Tsinghua University. All right reserved. Source

Shen M.,Zhejiang University of Technology | Peng X.,Zhejiang University of Technology | Xie L.,Zhejiang University of Technology | Meng X.,Zhejiang University of Technology | Li X.,Ningbo Tiansheng Sealing Packing Co.
Nuclear Engineering and Technology

This paper provides a reference to determine the seal performance of metallic O-rings for a reactor pressure vessel (RPV). A nonlinear elastic-plastic model of an O-ring was constructed by the finite element method to analyze its intrinsic properties. It is also validated by experiments on scaled samples. The effects of the compression ratio, the geometrical parameters of the O-ring, and the structure parameters of the groove on the flange are discussed in detail. The results showed that the numerical analysis of the O-ring agrees well with the experimental data, the compression ratio has an important role in the distribution and magnitude of contact stress, and a suitable gap between the sidewall and groove can improve the sealing capability of the O-ring. After the optimization of the sealing structure, some key parameters of the O-ring (i.e., compression ratio, cross-section diameter, wall thickness, sidewall gap) have been recommended for application in megakilowatt class nuclear power plants. Furthermore, air tightness and thermal cycling tests were performed to verify the rationality of the finite element method and to reliably evaluate the sealing performance of a RPV. © 2015 Published by Elsevier Korea LLC on behalf of Korean Nuclear Society. Source

Li Y.,Nuclear Power Institute of China | Chen C.,Nuclear Power Institute of China | Fu X.,Nuclear Power Institute of China | Pei L.,Nuclear Power Institute of China | And 4 more authors.
Hedongli Gongcheng/Nuclear Power Engineering

This paper analyzed the structure option and studied the function parameter of the seal material. Numerical analysis was used to analyze the seal structure. Based on all above, the one-to-one scale hot state verification test was carried out. The test results showed that there was no leakage after the wedge graphite seal structure experienced the 100 cold-hot cycling test. And also the results showed the seal structure was easy to install and dismounte. The engineering feasibility of the wedge graphite seal structure was verified. © 2015, Editorial Office of Nuclear Power Engineering. All right reserved. Source

Li X.,Zhejiang University of Technology | Li X.,Ningbo Tiansheng Sealing Packing Co. | Shen M.,Zhejiang University of Technology | Wang C.,Nuclear Power Qinshan Co. | And 4 more authors.
Huagong Xuebao/CIESC Journal

The leakage ratio, compression recovery and stress-relaxation of flexible graphite corrugated metal composite gaskets with 316L and A3 steel as framework were tested on an automatic multi-function gasket testing rig. The effects of flexible graphite cover layer thickness, frame material and gasket stress on sealing performance and mechanical properties were investigated. The residual thickness of corrugated metal was determined at different thicknesses of cover layer and gasket stresses. The sealing performance of the composite gasket was mainly dependent upon the thickness of cover layer with flexible graphite, and optimal sealing performance was observed for the corrugated metal when the thickness of cover layer was 0.6 mm. The composite gaskets had good carrying capacity and sealing performance, which was especially suitable for complex applications, such as pressure and temperature fluctuations. Also outstanding recovery of the composite gaskets could be obtained by pre-compression. In addition, as gasket stress increased, sealing and compression recovery performance of 316L composite gaskets became obviously better than the composite gaskets with A3 steel as framework, and the former had distinct improvement than the latter in resisting stress relaxation and creep behavior. ©, 2015, Chemical Industry Press. All right reserved. Source

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