• Title/Summary/Keyword: pipes

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A study on improvement of weldment design for large steel water pipes (수도용 대형 강관의 용접부 설계 개선에 관한 연구)

  • 배강열;나석주
    • Journal of Welding and Joining
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    • v.9 no.4
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    • pp.50-59
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    • 1991
  • Large steel water pipes in Korea are joined prevalently by bell end method and welded at inside as well as outside of the pipes with the length of leg which is same as or larger than the thickness of pipes. This results in an excessive consumption of material and labor compared with foreign counturies such as USA, so that in our recent situation of requiring a number of water pipes such consumption is very ineffective and an improvement in weld design of water pipes is urgently necessary. In this experimental study, the possibility of reducing the length of leg to 85% of the pipe thickness was investigated through observations of microstructure and cross section of weldments, the tensile test, and the impact test of the field and laboratory specimens. As the results of this study, it was revealed that water pipes which have the leg of fillet about 0.8xthickness show a good weldability, have a greater strength than the base metal and absorb the enough energy to be safe in the working condition of the pipes.

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Development of a one-dimensional system code for the analysis of downward air-water two-phase flow in large vertical pipes

  • Donkoan Hwang;Soon Ho Kang;Nakjun Choi;HangJin Jo
    • Nuclear Engineering and Technology
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    • v.56 no.1
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    • pp.19-33
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    • 2024
  • In nuclear thermal-hydraulic system codes, most correlations used for vertical pipes, under downward two-phase flow, have been developed considering small pipes or pool systems. This suggests that there could be uncertainties in applying the correlations to accident scenarios involving large vertical pipes owing to the difference in the characteristics of two-phase flows, or flow conditions, between large and small pipes. In this study, we modified the Multi-dimensional Analysis of Reactor Safety KINS Standard (MARS-KS) code using correlations, such as the drift-flux model and two-phase multiplier, developed in a plant-scale air-inflow experiment conducted for a pipe of diameter 600 mm under downward two-phase flow. The results were then analyzed and compared with those based on previous correlations developed for small pipes and pool conditions. The modified code indicated a good estimation performance in two plant-scale experiments with large pipes. For the siphon-breaking experiment, the maximum errors in water flow for modified and original codes were 2.2% and 30.3%, respectively. For the air-inflow accident experiment, the original code could not predict the trend of frictional pressure gradient in two-phase flow as / increased, while the modified MARS-KS code showed a good estimation performance of the gradient with maximum error of 3.5%.

An Applicability Estimation of Plastic Vertical Pipes using Electric Fusion Fittings through Measurement (실측을 통한 융착식 플라스틱 입상배관 성능 평가)

  • Park, Yool;Ahn, Young-Chull;Kim, Hyun-Dae;Kim, Jeong-Su;Goark, You-Shik;Kim, Young-Kyoung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.11
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    • pp.595-599
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    • 2013
  • The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.

The Behavior of Corrugated Steel Pipes on Underground Structures According to the Depth of Cover (파형 강관 지중구조물의 토피고에 따른 거동특성)

  • Yook, Jeong-Hoon;Kim, Nag-Young
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.1
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    • pp.65-73
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    • 2004
  • The analysis of corrugated steel pipes is depending on a second dimension frame analysis or compressed ring model. This is the analysis not to consider the behavior of soil-structure interaction. The behavior of load resistance system is varied according to the depth of cover and the spacing of corrugated steel pipes structure. Therefore, the behavior characteristic of corrugated steel pipes was confirmed through finite element analysis to consider the activity of soil-structure interaction. If soil cover is filled up to the more of optimal depth, behavior of corrugated steel pipes are similar to those of ductile steel pipes according to the earth pressure distribution and effects of traffic loads are decreased. But, If soil cover is filled up to the less of optimal depth, corrugated steel pipes can't behave completely as ductile steel pipes because the passive earth pressure acting on side of corrugated steel pipes is decreased according to the decrement of vertical earth pressure, and the traffic loads influence on the section forces is increased, so that the traffic loads dominated the behavior of corrugated steel pipes.

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Molecular Structure and Tensile Properties Change of Crosslinked Polyethylene Pipes during Oxidative Degradation Process (산화열화과정 중 가교폴리에틸렌 파이프의 분자구조 및 인장 특성 변화)

  • Park, Sung-Gyu;Kim, Dae-Su
    • Polymer(Korea)
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    • v.33 no.6
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    • pp.520-524
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    • 2009
  • The effects of oxidative degradation on the performance of crosslinked polyethylene pipes were analyzed by the investigation of tensile properties and chemical structure change of the pipes during oxidative degradation. Annealing at high temperatures or UV irradiation method was used to induce the oxidative degradation of the crosslinked polyethylene pipes and the effects of the die temperature on the oxidative degradation of the pipes were also investigated. The tensile properties and chemical structure change of the pipes were investigated by universal testing machine and FT-IR, respectively. With the progress of thermo-oxidative degradation the tensile strength of the pipes slowly decreased but the elongation at break rapidly decreased, and the chemical structure of the pipes also changed considerably because of the introduced oxygen molecules. These results would be useful in estimating the performance deterioration of the crosslinked polyethylene pipes due to the oxidative degradation during production and storage.

Estimation on Formability of ]Knife Press Forming Process for the Thick Pipes (Knife Press Forming 공정의 후육관 성형성 예측)

  • Park, J.W.;Noh, H.G.;Ku, T.W.;Kang, B.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.319-322
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    • 2009
  • Roll bending process has been used for manufacturing the pipes. However, it is not suitable process for the thick pipes. Knife press forming is acceptable process for the thick pipes. Recently, the knife press forming process using brake bending press have been performed. In this study, the estimation on formability of knife press forming process for the thick pipes is carried out. From the results, it is ensured that the thick pipes could be obtained by the knife press forming process.

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Failure Analysis of Welded Pipe in Water Supplies for Apartment

  • Lee, Jong Kwon;Hong, Kyung Tae;Hwang, Woon Seok;Koh, Yong Tae;Park, Yong Soo
    • Corrosion Science and Technology
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    • v.3 no.2
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    • pp.67-71
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    • 2004
  • Galvanized Steel pipes have been widely used in industries and apartments, Unexpected early leakage has been found in an apartment. Tunneling corrosion or penetration was found in the water supply pipes. The chemical compositions of the pipes and properties of coating layer were evaluated. The pipes met the specification of KS D 3507. The cause of early failure was analyzed through the examination of macrostructures and microstructures, It was found that the pipes were failed by grooving corrosion, which resulted from galvanic corrosion of weld bead and matrix.

Evaluation Method of Plastic Pipe for High-Strength Water Supply (고강도 수도용 PVC관의 성능평가 연구)

  • Park, Jong-II;Lee, Chang Suck
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.1
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    • pp.44-49
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    • 2018
  • High-strength plastic water supply pipe evaluation method was evaluated in this study. Up to date, high strength water supply pipes that we install are mostly ductile cast iron pipes. Sometimes, a few PVC pipes are installed. Metal pipes have rust problem on the surface, causing serious damage to metal pipes and reducing the expected life span of water piping system. Nowadays, depending on technology development, some companies have improved properties of general PVC pipe performance with remarkable properties that exceed KS and ASTM standard. Here, we suggest a new method of performance evaluation for high-strength water plastic pipes.

development of small size corrosion monitoring system for under ground metal structures (지중 금속구조물 부식감시를 위한 측정단자함 인입형 소형 계측 장치개발에 관한 연구(II))

  • Lee, Jae-Duck;Bae, Jeong-Hyo;Ha, Tae-Hyun;Lee, Hyun-Gu;Ha, Yun-Chul;Kim, Dae-Kyeong
    • Proceedings of the KIEE Conference
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    • 2004.11c
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    • pp.104-106
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    • 2004
  • There are many under grounds facilities like oil pipes, gas pipes, water pipes, oil tanks, etc. and severe corrosion of these facilities made big problems. Fire, wide area water and soil pollution, massive and hazardous explosion, etc. can make big problems and cause big economical loss. So, various technologies were developed to keep these undergrouns facilities safely, and cathodic protection is one of it. For cathodic protection, one must detect potential of pipes, and there are so many test box to check pipes potentials. In this thesis, we describe on the development of small size corrosion monitoring system that measure pipes potentials easily and economically.

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A Case Study of between Pipe Deformation-Compaction Ratio using Flexible Sewer Pipe (하수도용 연성관의 다짐정도에 따른 관거의 거동에 대한 사례연구)

  • Kim, Young-Jin;Lee, Soo-Heon;Ahn, Chang-Keun;Oh, Jin-Ki
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.1012-1017
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    • 2010
  • Sewer Pipes are not being managed for twenty years after laying. So, The life span of sewer pipes is on the decrease. For solve the life span decrease of sewer pipes, correct checking of questions and measure preparation are necessary through investigation in sewer pipes. This research investigated on the state of sewer pipes in the housing and industrial sites through CCTV(closed-circuit television) and device of digitalized strain investigation. And, a result is as follows. A results of PE, PVC, GRP, CSP investigations were found of pipe-transformation state by earth pressure and external load.

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