• The Journal of Korea Robotics Society
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• v.16 no.3
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• pp.223-231
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• 2021

In this paper describes the research and development of a pipe robot for pipe rehabilitation construction of old water pipes. After the water supply pipe construction, the pipe is leaking, damaged, and aging due to corrosion. Eventually, resistance to the flow of water in lower supply efficiency and contaminated water such as rusty water, finally in various consumer complaints. In order to solve this problem, rehabilitation construction robot technology is required to secure the construction quality of pipe rehabilitation construction and restore the function of the initial construction period. The developed pipe rehabilitation construction robot required a hydraulic actuator for high traction and was equipped with a small hydraulic supply device. In addition, we have developed a hydraulic cylinder and a link system that supports the pipe inner diameter to develop a single pipe robot corresponding to 500 to 800mm pipe diameter. The analysis and experimental verification of the driving performance and unit function of the developed pipe reconstruction robot are explained, and the result of the integrated performance test of the pipe reconstruction robot at the water supply pipe network site is explained.

• Structural Engineering and Mechanics
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• v.30 no.3
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• pp.263-278
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• 2008

Structural pipe-in-pipe cross-sections have significant potential for application in offshore oil and gas production systems because of their property that combines insulation performance with structural strength in an integrated way. Such cross-sections comprise inner and outer thin walled pipes with the annulus between them fully filled by a selectable thick filler material to impart an appropriate combination of properties. Structural pipe-in-pipe cross-sections can exhibit several different collapse mechanisms and the basis of the preferential occurrence of one over others is of interest. This paper presents an elastic analyses of a structural pipe-in-pipe cross-section when subjected to external hydrostatic pressure. It formulates and solves the static and elastic buckling problem using the variational principle of minimum potential energy. The paper also investigates a simplified formulation of the problem where the outer pipe and its contact with the filler material is considered as a 'pipe on an elastic foundation'. Results are presented to show the variation of elastic buckling pressure with the relative elastic modulus of the filler and pipe materials, the filler thickness and the thicknesses of the inner and outer pipes. The range of applicability of the simplified 'pipe on an elastic foundation' analysis is also presented. A brief review of the types of materials that could be used as the filler is combined with the results of the analysis to draw conclusions about elastic buckling behaviour of structural pipe-in-pipe cross-sections.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.31-37
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• 2006

In this study, the ability for the function of double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for the circulating of liquid of high temperature and high pressure and low temperature and low pressure at the same time is presented. And in this double pipe, liquid pipe of high temperature and pressure is used to connect condenser and expansion valve and gas pipe of low temperature is used to connect evaporator and compressor. Also, when liquid refrigerant of high temperature and gas refrigerant of low temperature is circulated by reversed flow in the double pipe. The contribution of liquid gas heat exchange pipe is studied by comparison of the effect of heat transfer by temperature difference when liquid pipe and gas pipe is installed separately.

• Tribology and Lubricants
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• v.25 no.6
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• pp.374-380
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• 2009

This paper presents the stress and displacement characteristics of oil pipe using the finite element analysis. Displacement in axial direction and von Mises stress of a pipe were analyzed with three design factors, which are the pipe thickness, the corrugation pitch and the corrugation height, under uniform oil pressure. The FE computed results are presented between a conventional round pipe and a rectangular pipe, which is manufactured in this study. The computed FE results show that maximum displacement in axial direction and von Mises stress of pipe are increased linearly as the oil pressure increases. Also, they are increased linearly as the corrugation pitch, corrugation height and pipe thickness increases. von Mises stress of a rectangular pipe at the edge increases sharply compared with that of a conventional round pipe. Therefore, the strength of rectangular pipe is superior to that of a conventional round pipe.

• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.779-791
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• 2023

Long-termly used in water supply, an underground concrete pipe is easily subjected to the coupled action of pressure loading and flowing water, which can cause the chemo-mechanical damage of the pipe, resulting in its premature failure and lifetime reduction. Based on the leaching characteristics and damage mechanism of concrete pipe, this paper proposes a coupled chemo-mechanical damage and failure model of underground concrete pipe for water supply, including a calcium leaching model, mechanical damage equation and a failure criterion. By using the model, a numerical simulation is performed to analyze the failure process of underground concrete pipe, such as the time-varying calcium concentration in concrete, the thickness variation of pipe wall, the evolution of chemo-mechanical damage, the distribution of concrete stress on the pipe and the lifetime of the pipe. Results show that, the failure of the pipe is a coupled chemo-mechanical damage process companied with calcium leaching. During its damage and failure, the concentrations of calcium phase in concrete decrease obviously with the time, and it can cause an increase in the chemo-mechanical damage of the pipe, while the leaching and abrasion induced by flowing water can lead to the boundary movement and wall thickness reduction of the pipe, and it results in the stress redistribution on the pipe section, a premature failure and lifetime reduction of the pipe.

• Journal of the Korea Institute of Building Construction
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• v.6 no.2 s.20
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• pp.111-117
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• 2006

In case of carrying out vortical crossing water distribution system in expressways or general roads construction, VR(Vibrated and Rolled reinforced concrete) pipes are restricted because of their specification of reinforced spun concrete pipe or on-site made pipe. Therefore, in order to apply VR pipes to those constructions, through the structural behavior experiments of the pipes, VR pipes are compared and verified with reinforced spun concrete pipe and the results are obtained as the following. From the experiments and analyses of Pipe Stiffness(PS) of the pipes, cracking loading is approved to satisfy the KS regulations. Through a direct load test, the cracking loading strength and the maximum load test of VR pipe is larger compared with reinforced spun concrete pipe. Particularly, even if side weld is thin, there is no little change in the cracking strength of VR pipe. The results of the direct load test analysis show that the structural behavior of VR pipe is equivalent or higher compared with reinforced spun concrete pipe in performance and VR pipe could be used as the water distribution pipe for roads. In this study, through pipe stiffness, direct load test and load teat on earth, reinforced spun concrete pipe and VR pipe are compared. And as a result, the structural behavior of VR pipe is comprehensively excellent. From the structural behavior tests, VR pipe's section shows more thickness and has uniform characteristics so that VR pipe is considered more favorable than reinforced spun concrete pipe.

• Journal of Ocean Engineering and Technology
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• v.20 no.5 s.72
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• pp.9-14
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• 2006

This paper presents an analytical method, application of expansion, mechanical design, and integrated expansion design of subsea insulated pipe-in-pipe (PIP) systems. PIP system consists of a flowline and a casing pipe for the transport of high temperature and high pressure product from the subsea wells. To prevent heat lass from the fiowline, insulation material is applied between the pipes. The fiawline pipe and the casing pipe have mechanical connections through steel ring plate (water stops) and bulkheads. Pipeline expansion is defined by temperature, internal pressure, soil resistance, and interaction force between the flowline and the casing pipe. The results of the expansion analysis, the mechanical design of connection system of the two pipes and tie-in spool design are integrated for the whole PIP system.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.1004-1012
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• 2021

High density polyethylene (HDPE) pipe has many advantages over metallic pipe, and has been used in non-safety related application for years in some nuclear power plants (NPPs). Recently, HDPE pipe was introduced into safety related applications. The main difference between safety-related and non-safety-related pipes in NPPs is the design method of extra loadings such as gravity, temperature, and earthquake. In this paper, the mechanical behavior of HDPE pipe under various loads in pipe gallery was studied by finite element analysis (FEA). Stress concentrations were found at the fusion regions on inner surface of mitered elbows of HDPE pipe system. The effects of various factors were analyzed, and the influence of various loads on the damage of HDPE pipe system were evaluated. The results of this paper provide a reference for the design of nuclear safety-related Class 3 HDPE pipe. In addition, as the HDPE pipes analyzed in this paper were suspended in pipe gallery, it can also serve as a supplementary reference for current ASME standard on Class 3 HDPE pipe, which only covers the application for buried pipe application.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.665-675
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• 2002

It is very closely related with the reliability of the pipe network to predict pipe burst and diminish burst effect in water distribution system. Most of the engineers have not consider pipe layout and the effect of pipe burst in conservative pipe network design. In this study, The effect of pipe burst in the network is analyzed with respect to pipe network geometric topology and the method of increasing the system reliability is presented by reducing pipe-burst effect. In existing pipe system, it is only designed to the closed loop system but in case of each pipe burst, it cannot transmit appropriate water to consumers and occurs severe hydraulic head drop in many nodes. The techniques developed in this study allow proper pipe diameter and pipe layout to pipe system through the analysis of pipe-burst effect. Thus, when each pipe is bursted, pipe system is prevented from severe pressure head drop in demand nodes and can supply stable flowrate to consumer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1295-1302
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• 2003

In order to evaluate a failure behavior of pipe with notch-type wall thinning, the present study performed full-scale pipe tests using the 102mm, Schedule 80 pipe specimen simulated notch- and circular-type thinning defects. The pipe tests were conducted under the conditions of both monotonic and cyclic bending moment at a constant internal pressure of 10 MPa. From the results. of experiment the failure mode, load carrying capacity, deformation ability, and fatigue life of a notch-type wall thinned pipe were investigated, and they were compared with those of a circular-type wall thinned pipe. The failure mode of notched pipe was similar to that of circular-type thinned pipe under the monotonic bending load. Under the cyclic bending load, however, the mode was clearly distinguished with variation in the shape of wall thinning. The load carrying capacity of a pipe containing notch-type wall thinning was about the same or slightly lower than that of a pipe containing circular-type wall thinning when the thinning area was subjected to tensile stress, whereas it was higher than that of a pipe containing circular-type thinning defect when the thinning area was subjected to compressive stress. On the other hand, the deformation ability and fatigue life of a notch-type wall thinned pipe was lower than those of a circular-type wall thinned pipe.