Papers by Keyword: Welded Pipe

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Authors: Seok Hwan Ahn, Kum Cheol Seok, Ki Woo Nam
Abstract: The locally wall thinned phenomenon of pipes is simulated as metal loss due to erosion/corrosion. Therefore, fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. In this study, monotonic bending tests without internal pressure are conducted on 1.91-inch diameter Schedule 80 STS370 full-scale carbon steel pipe specimens. We investigated fracture strengths and failure modes of locally wall thinned pipes that welded and unwelded by four point bending test. From test results, we could be divided three types of failure modes.
1349
Authors: Yang Zhao, Qiang Ren, Tian Xia Zou, Da Yong Li, Ying Hong Peng
Abstract: Large-diameter pipes used in offshore applications are commonly manufactured through the UOE process. The plate is crimped along its edges, formed into a U-shape and then pressed into an O-shape between two semicircular dies. The pipe is welded closed and then circumferentially expanded to obtain a highly circular shape. In this study, the two-dimensional finite element model of the whole processing of the UOE pipe production has been established, including large deformation and complex contact. The deformed geometries of different steps and distribution of the equivalent plastic strain and variation in load are analyzed. This research is helpful in UOE forming process design and evaluating the capability of the pipe mill.
437
Authors: Wei Su, Hong Zhi Ma, Yu Hui Ma, Qun Hui Wang, Xing Yu Chen
Abstract: Steel pipe applications are more widely used, but there are no comparative analysises about the environmental impact and energy consum of steel pipe and its production processes. This article investigated the environmental implications of three typical steel pipe production processes based on energy materials and life cycle assessment perspective. We modeled scenarios, calculated energy consumed and six aspects which classified as GWP, ODP, AP, EP, POCP and DUST. The rank of energy consumed in descending order is C-Pipe> H-Pipe> W-Pipe. Welded steel pipe is the best energy-friendly material in term of energy consumption. The rank of impact potential according to normalized results in descending order is GWP>AP>DUST>EP>POCP>ODP. The rank of impact potential according to weight factor in descending order is AP>DUST>GWP>ODP>EP>POCP. Acid Potential is the most significant factor. The weight factor of AP is almost twice as much as that of GWP. In environmental terms, the environmental depletion index of welded pipe production process is lowest with minimal environmental impact and the cold drawn pipe production process the highest with largest environmental impact. Welded steel pipe is the best environment-friendly material in term of environmental impact. Utilization of green energy and waste heat can effectively reduce the environmental implications for both hot rolling pipe and cold drawn pipe production processes.
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Authors: Bai Lin Liu, Wen Chen, Lei Li, Qin Ren Xiong
Abstract: To improve the performance data management efficiency of welded pipe used in the 2nd west to east gas pipeline, a distributed performance data acquiring and management system for welded pipe was developed. The system was established by using two-level three-tier Client/Server model. Performance data for welded pipe from different factories was acquired at clients and input to local database. The data then can be analyzed at local, or be transferred to the server through networks for unified storage and analysis. The System has functions as data management, file transferring, standard technology condition management, statistical analysis, figure displaying and statistical analysis report generation, etc. The system was implemented using VC++. Oracle and Access is adopted as database for server and client respectively, XML is as the data encapsulation for transferring file. The developed system plays a significant role in analyzing and evaluating the whole quality of welded pipe, and is useful for pipeline quality control.
1176
Authors: Masanori Kikuchi, Yoshitaka Wada, Yuto Shimizu, Yu Long Li
Abstract: Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. SCC crack growth of a surface crack at inner suface of a pipe under thermal residual stress is simulated in three-dimensional filed. Distributions of residual stress is not axi-symmetric along pipe wall, and it affects the crack growth behavior. Ttwo cases, for axi-symmetric and non-symmetric thermal stress distributions, are assumed and crack growth behaviors are obtaiend and discussed.
577
Authors: Bo Lin He, Ying Xia Yu, Li Xing Huo, Yu Feng Zhang
Abstract: In this paper, the reliability of welded pressure pipe with circumferential surface crack was calculated by using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The calculation of reliability was based on three dimensional elastic-plastic stochastic finite element program which was developed by ourselves. The effects of variables such as fracture toughness, bending moment and the depth of the circumferential surface crack on the structure reliability were also discussed. The calculation results indicate that the crack depth has great effect on the reliability of the welded pipe. When the mean value of the crack depth is changed from 3mm to 7mm, the failure probability of the welded pipe will change from 10-8 to 10-2. The bending moment also has great effect on the reliability of the welded pipe. When the mean value of moment is changed from10000 N.m to 15000 N.m, the failure probability of the welded pipe increases dramatically for the same circumferential crack depth. Irrespective of the changing of moment, the pipe has higher reliability if the crack depth is less than 5mm(a/t<0.5, t is the thickness of the pipe). The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack.
639
Authors: Masanori Kikuchi, Yoshitaka Wada, Yuto Shimizu, Yu Long Li
Abstract: Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. In order to confirm the validity of this analysis, numerical results are compared with previously-reported analytical and experimental results. Then, crack growth analysis in piping structure with welding joint was conducted. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. Using S-FEM, two- and three-dimensional analyses are conducted, and crack growth behavior under thermal stress field is studied and discussed.
431
Authors: Jin Duo Ye, Zhe Li, Yu Ting Xi
Abstract: Understanding the mechanism of the forming of the welded pipe may help the engineer to design the shape of forming rollers and forming technology. It is hard to study the forming process of the welded pipe by both the method of experiment and numerical modeling because of too much nonlinear factors included in the forming process such as elastic-plastic large deformation and non linear contact. Although many research works have been conducted in this field by the method of experiment or numerical modeling, but few of the works deal with the whole forming process of the welded pipe. The main difficulties in the numerical modeling are of huge computational labor time, witch has been over the ability of the hardware and software of the computer. The whole process of roll forming of welded pipe has been simulated by nonlinear finite element method with ANSYS and LS-DYNA solver, the distribution of both stresses and strains have been got successfully. Mapping meshes and the rigid models for rollers have been used in the analysis in order to decrease the number of the elements. Numerical results and parameter study have shown that the forming rollers of both the level and vertical are the key factors to the forming process. It is believe that the method used in the paper can also be used to study the forming process of both cage roll forming and flexible forming.
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