• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.222-227
• /
• 2004

The failure assessment for corroded pipeline has been considered with the full scale burst test and the finite element analysis. The burst tests were conducted on 762 mm diameter, 17.5 mm wall thickness and API 5L X65 pipe that contained specially manufactured rectangular corrosion defect. The failure pressure for corroded pipeline was measured by burst testing and classified with respect to corrosion sizes and corroded regions - the body, the girth weld and the seam weld of pipe. Finite element analysis was carried out to derive failure criteria of corrosion defect on the pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.7-10
• /
• 2007

In case of large steel water pipe, it have been observed that its fracture mostly occurs due to the complicated outside fatigue load on the pipe in the underground. It is also well known that its damage and leakage happen mainly in a weld zone. In this study we evaluated the fatigue characteristics based on size effect and residual stress by comparing the test results on the standard specimen collected from real pipe with those on full scale pipe.

• Ocean Systems Engineering
• /
• 제3권4호
• /
• pp.309-325
• /
• 2013

Ocean Thermal Energy Conversion (OTEC) systems utilize the temperature difference between the surface water and deep ocean water to generate electrical energy. In addition to ocean surface waves, wind and current, in certain locations like the Andaman Sea, Sulu Sea and the South China Sea the presence of strong internal waves may become a concern in floating OTEC system design. The current paper focuses on studying the dependence of the CWP hydrodynamic drag on relative velocity of the flow around the pipe, the effect of drag amplification due to vortex induced vibrations and the influence of internal waves on the floating semi and the cold water pipe integrated OTEC system. Two CWP sizes are modeled; the 4m diameter pipe represents a small scale prototype and the 10m diameter pipe represents a full commercial size CWP. are considered in the study.

• 한국안전학회지
• /
• 제25권2호
• /
• pp.7-11
• /
• 2010

Difficulties associated with full-scale pipe tests are rather obvious. That is, it is not only difficult to perform them but also very expensive and it requires lots of experience. And the process of the fracture test for the pipe specimen is very difficult and complicated. Because the pipe specimen, the test jig and the test equipment are very large and heavy, it requires lots of costs and times. In this study, to easily perform the fracture toughness test for a pipe specimen, load line displacement data was obtained using the image processing method.

• 한국안전학회지
• /
• 제23권6호
• /
• pp.122-130
• /
• 2008

The cracking behavior of prestressed concrete members is important for the rational evaluation of PCC pipes. However, the test data on the cracking behavior of PCC pipes are very limited. The purpose of the present study is to investigate the cracking behavior of PCC pipes under different settlement conditions. In this paper, experimental test on the full scale model of PCC pipe was conducted and observed in order to study cracking load in PCC pipes. Based test and FEM analysis results, this paper also presents the cracking load prediction in PCC pipe. Based on the numerical analysis results performed in this research, the cracking behaviors of PCC pipe with the variation of the settlement conditions were evaluated.

• International Journal of Concrete Structures and Materials
• /
• 제8권4호
• /
• pp.269-278
• /
• 2014

When concrete is being transported through a pipe, the lubrication layer is formed at the interface between concrete and the pipe wall and is the major factor facilitating concrete pumping. A possible mechanism that illustrates to the formation of the layer is the shear-induced particle migration and determining the rheological parameters is a paramount factor to simulate the concrete flow in pipe. In this study, numerical simulations considering various rheological models in the shear-induced particle migration were conducted and compared with 170 m full-scale pumping tests. It was found that the multimodal viscosity model representing concrete as a three-phase suspension consisting of cement paste, sand and gravel can accurately simulate the lubrication layer. Moreover, considering the particle shape effects of concrete constituents with increased intrinsic viscosity can more exactly predict the pipe flow of pumped concrete.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2001년도 봄 학술발표회 논문집
• /
• pp.323-330
• /
• 2001

The existing bonding methods of steel pipe piles into pile caps have many problems during construction or design. To overcome these, the composite bonding method of the bolting type and the welding type are proposed in this stud\ulcorner. The full scale test and the numerical analysis using finite element method were performed to verify the function of them. As results, the method of the filled with concrete in steel pipe piles head was good effective to increse strength. And the composite bonding methods are effective to protect the damage caused by earthquake than the bolted bonding method. Also, the composite bonding methods are cheaper than the existing bonding methods and a good construction as well.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제12권1호
• /
• pp.60-70
• /
• 2020

The outfitting design of ships and offshore structures is mainly undertaken in a restricted space. Pipes occupying a large portion of outfitting design are normally manufactured outside the shipyard. This complicated manufacturing process results in frequent delivery delays. Inevitable design modifications and material changes have also resulted in inefficient pipe installation works. In this study, an algorithm is proposed to systematically determine the pipe installation sequence. An accurate and fast algorithm to identify the geometric relationship of piping materials is presented. To improve the calculation efficiency, the interference is gradually examined from simplified to complicated shapes. It is demonstrated that the calculation efficiency is significantly improved with successive geometric operations such as back-face culling and use of bounding boxes. After the final installation sequence is determined, the entire installation process is visualized in a virtual reality environment so that the process can be rendered and understood for a full-scale model.

• Nuclear Engineering and Technology
• /
• 제46권5호
• /
• pp.633-640
• /
• 2014

In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.

• 한국압력기기공학회 논문집
• /
• 제12권2호
• /
• pp.1-24
• /
• 2016

The original fracture criteria developed by Maxey/Kiefner for axial through-wall and surface-cracked pipes have worked well for many industries for a large variety of relatively low strength and toughness materials. However, newer line pipe steels have some unusual characteristics that differ from these older materials. One example is a test data that has demonstrated that X80 line-pipe with an axial through-wall-crack can fail at pressures about 30 percent lower than predicted with commonly used analysis methods for older steels. Thus, it is essential to review the currently available models and investigate the applicability of these models to newer high-strength line pipe materials. In this paper, the available models for predicting the failure behavior of axial-cracked pipes (through-wall-cracked and external surface-cracked pipes) were reviewed. Furthermore, the applicability of these models to high-strength steel pipes was investigated by analyzing limited full-scale pipe fracture initiation test results. Based on the analyzed results, the shortcomings of the available models were identified. For both through-wall and surface cracks, the major shortcomings were related to the characterization of the material toughness, which generally leads to non-conservative predictions in the J-T analyses. The findings in this paper may be limited to the test data that were consider for this study. The requisite characteristics of a potential model were also identified in the present paper.