Accepted Manuscripts

Huan Sheng Lai and Kang Lin Liu
J. Pressure Vessel Technol   doi: 10.1115/1.4036531
Shells and tubes are usually failure in the form of buckling under external pressure. Charts are used in the design of shells and tubes in the standards of ASME VIII-1 and EN13445-3, in order to simplify the calculation process, while the Proportional Law is a more effective and simply method when it compares with the charts. In this paper, the relationships among the Proportional Law and the charts used in the standards were researched; finite element method (FEM) was used to compare the accuracy among the Proportional Law and the charts. It was theoretically proved that the Proportional Law and the charts were same in calculating the critical buckling pressure; they were different forms of the dimensionless tension stress-strain curves. The simulation results showed that the Proportional Law had the same accuracy as the charts in calculating the critical buckling pressure. Therefore, the Proportional Law can be a candidate method included in the standards for the design of shells and tubes under external pressure.
TOPICS: Design, External pressure, Shells, Buckling, Pressure, Finite element methods, Stress-strain curves, Simulation results, Tension, Failure
Ludek Stratil, Filip Siska, Ivo Dlouhy and Marta Serrano
J. Pressure Vessel Technol   doi: 10.1115/1.4036532
This contribution deals with determination of the reference temperature of JRQ steel using miniaturized specimens. The dimensions of used miniaturized specimens were 3 × 4 × 27 mm (thickness × width × length). This specimen type offers the utilization of limited amount of test material or broken halves of pre-cracked Charpy and larger specimens. The test material comes from the broken halves of 0.5T SEB specimens previously tested for purposes of the reference temperature determination in Ciemat, Madrid. The fracture toughness tests of the specimens were performed in the transition region of the steel according to the recommendations of standard ASTM E1921 and according to Wallin’s recommended temperature range for miniaturized specimens. The determined reference temperature of the Master Curve was very similar to the determined ones from three point bend specimen of sizes 0.2T, 0.4T and 0.5T. The obtained results confirm a necessity of conduct of tests at low temperatures and testing sufficient number of specimens in order to generate enough valid data for determination of the reference temperature.
TOPICS: Temperature, Steel, Testing equipment, Low temperature, Testing, Fracture toughness, ASTM International, Dimensions
Jian-Guo Gong, Qiwei Xia and Fu-Zhen Xuan
J. Pressure Vessel Technol   doi: 10.1115/1.4036533
Based on a tee joint, the simplified creep design methods of ASME code, elastic-perfectly plastic (EPP) analysis of Code Case N-861 (CC N-861) and the inelastic analysis by isochronous stress strain (ISS) curve were evaluated and compared to nonlinear finite element creep analysis (FECA). Results indicated that both EPP and FECA lead to the greater inelastic strain than ISS curve-based results. By contrast, the ISS-based analysis induces a smaller usage fraction (damage) than FECA due to the underestimated inelastic strain. In addition, the smallest usage fraction (damage) is obtained by using EPP analysis for which the remarkable bending strain is involved.
TOPICS: Design methodology, Creep, Temperature, Damage, Stress, Finite element analysis, Inelastic analysis, ASME Standards
Vishwas ChandraKhan, Balaganesan Gurusamy, Arun Pradhan and Sivakumar M. Srinivasan
J. Pressure Vessel Technol   doi: 10.1115/1.4036534
This paper presents the analysis of repair of pipelines using nano filler dispersed composites. Steel pipe with part wall loss as per standard is repaired using glass/epoxy composites with and without nanoclay reinforcement and burst test is performed in order to assess the performance and effectiveness of nanocomposites based repair system. A simple methodology is developed to find out the failure pressure of pipelines and is compared with the experimental and standard repair code results. It is also analytically studied the thickness of composite wrap for 1% -5% nano filler dispersion in the epoxy for various pipe wall loss and live pressures of pipe lines. The results are analysed to find effectiveness of clay dispersion and effect of live pressure for various percentage of wall loss. It is observed that the dispersion of nano filler improves the bursting resistance of composite wrapping over outer surface of pipe.
TOPICS: Steel, Maintenance, Polymer composites, Pipelines, Composite materials, Fillers (Materials), Pipes, Epoxy adhesives, Pressure, Epoxy resins, Glass, Failure, Nanocomposites, Nanoclays
Akira Maekawa, Michiyasu Noda, Michiaki Suzuki, Takeshi Suyama and Katsuhisa Fujita
J. Pressure Vessel Technol   doi: 10.1115/1.4036512
The vibration-induced fatigue failure of small-bore piping is one of the common causes of failure trouble at nuclear power plants. Therefore, the purpose of this study is to develop the measurement methods of vibration-induced stress for the screening to prevent from fatigue failure troubles of small-bore piping using portable vibrometers. Firstly, the validity of a measurement method using a single-mass model was conducted, and then a measurement method using a two-mass model developed as an improvement calculation model was conducted. Next, for small-bore piping with typical pattern configurations consisted of several masses and supports, the model considering the supports and the center of gravity being out of pipe centerline was developed and proposed. Finally, for the more complex small-bore piping with general piping configurations consisted of many bends, branches or joints, the method based on the finite element method analysis and using the values measured by a portable vibrometer was developed. In this method, the analytical model was optimized, and the stresses were obtained considering vibration modes as dynamically.
TOPICS: Pipes, Vibration, Stress, Laser Doppler vibrometers, Fatigue failure, Center of mass, Finite element methods, Failure, Nuclear power stations
Review Article  
Omesh K. Chopra, Gary L. Stevens, Robert Tregoning and A. S. Rao
J. Pressure Vessel Technol   doi: 10.1115/1.4035885
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) provides rules for the design of Class 1 components of nuclear power plants. However, the Code design curves do not address the effects of light water reactor (LWR) water environments. Existing fatigue strain-vs.-life (e-N) data illustrate significant effects of LWR water environments on the fatigue resistance of pressure vessel and piping steels. Extensive studies have been conducted at Argonne National Laboratory and elsewhere to investigate the effects of LWR environments on the fatigue life. This article summarizes the results of these studies. Existing fatigue e-N data were evaluated to identify the various material, environmental, and loading conditions that influence fatigue crack initiation; a methodology for estimating fatigue lives as a function of these parameters was developed. The effects were incorporated into the ASME Code Section III fatigue evaluations in terms of an environmental correction factor, Fen, which is the ratio of fatigue life in air at room temperature to the life in the LWR water environment at reactor operating temperatures. Available fatigue data were used to develop fatigue design curves for carbon and low-alloy steels, austenitic stainless steels, and nickel-chromium-iron (Ni-Cr-Fe) alloys and their weld metals. A review of the Code Section III fatigue adjustment factors of 2 and 20 is also presented and the possible conservatism inherent in the choice is evaluated. A brief description of potential effects of neutron irradiation on fatigue crack initiation is presented.
TOPICS: Fatigue life, Water, Light water reactors, Fatigue, Alloys, Steel, Design, Fatigue cracks, Fatigue design, Pipes, ASME Boiler and Pressure Vessel Code, Iron, Nuclear power stations, Stainless steel, Pressure vessels, Irradiation (Radiation exposure), ASME, Carbon, Temperature, Neutrons, Metals, Nickel, ASME Standards, Operating temperature

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