• Title/Summary/Keyword: 가스용접

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A Study on the Microstructure and Mechanical Properties for the Weldment with Variation of Welding Process of the API 5L-X42 Pipeline for Natural Gas Transmission. (천연가스 수송용 API 5L-X42 강관의 용접방법에 따른 용접부의 미세조직과 기계적 특성에 관한 연구)

  • Baek Jong-Hyun;Kim Cheol-Man;Kim Young-Pyo;Kim Woo-Sik
    • Journal of the Korean Institute of Gas
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    • v.2 no.2
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    • pp.34-39
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    • 1998
  • Demand of the clean and convenient natural gas has continuously increased with recognizing of the environment problem since liquefied natural gas was introduced in Korea. Clean fuel natural gas was supplied to each city through high tensile strength pipeline connected by welding. Grades of pipeline were divided into the high and middle pressure according to supply pressure. Pipeline was welded mainly SMA welding process due to its easy handling, the other welding process was adopted according to the constructing condition. We were examined on the microstructure variation and mechanical properties of weld metal for high pressure pipeline, API 5L X-42.

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A comparison of cutting performance between HOM gas and LPG gas for heavy industry (산수소 가스를 이용한 후판의 산소절단 기술)

  • 이목영;권영각;임명세
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.15-17
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    • 2004
  • 철강재의 산소절단은 연료가스의 연소열 및 철의 산화 반응열을 이용하여 강재를 절단하는 방법이다. 연료가스의 연소열을 이용하여 강재를 가열 및 용융시키고, 여기에 고순도의 산소를 취입하면 강재의 용융물질 중 철의 급격한 산화반응이 발생된다. (중략)

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The Characteristics of Energy Distribution to Arc Length and Hydrogen Mixing in GTA Welding (GTA 용접에서 아크 길이와 수소 혼합에 따른 에너지분포 특성)

  • Oh, Dong-Soo;Baek, Sang-Yeob;Lee, Chil-Soon;Hwang, Dong-Soo;Ham, Hyo-Sik;Park, Kyung-Do;Jung, Yun-Ho;Cho, Sang-Myung
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.30-30
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    • 2009
  • GTA 용접에서 용입, 용접부의 크기와 형상이 형성되는 아크 물리학적 현상을 이해함에 있어서 에너지 분포특성은 매우 중요한 인자이다. GTA 용접에서 아크 길이의 변화와 사용된 실드 가스 종류에 따라 음극인 텅스텐 전극 팁의 아크 루트 직경에 큰 변화를 주며, 양극인 모재 쪽의 에너지 분포에 영향을 미치며 된다. 기존의 연구자들은 저전류나 중전류 영역의 GTA 용접에서 텅스텐 전극의 선단각과 용입 형태와 의 관계를 plasma 기류 등에 의해 고찰하거나, 최대 아크압력에 미치는 전극형상의 영향에 대하여 연구하였다. 용접부에 작용하는 아크 압력의 분포는 결국 운동 에너지의 분포이다. 기존의 연구자들에 비하여 보다 간편한 실험을 통하여 양극 모재위의 아크 압력에 의한 에너지 분포특성을 규명하는 연구가 필요하다. 본 연구의 목적은 GTA 용접의 용접전류 100A~200A 영역에서 아크 길이 변화와 Ar 가스에 $H_2$ 혼합에 따른 측정된 아크 압력으로부터 기존연구자들의 아크 물리학적 결과들을 활용하여 양극 모재 위에 작용하는 전류밀도 분포를 유도하는 것이다. GTA 용접에서 아크 길이의 변화와 Ar 가스에 $H_2$ 혼합은 아크 압력분포에 큰 영향을 미치며, 이에 따라 에너지 분포특성에 많은 영향을 미친다. 아크 길이가 증가함에 따라 Ar가스와 $H_2$ 혼합가스의 에너지 분포는 감소하였고, Ar가스에 $H_2$ 혼합에 의해 아크 에너지가 증가하여 용입형상에 큰 영향을 미칠 것으로 판단된다. 이에 대한 연구는 향후 GTA 용접 응용분야 확대 적용될 것이며, 아크 물리학 연구에 기초적이고 아주 중요한 과학적인 자료가 될 것으로 판단된다.

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Structural Analysis of Gas Pipeline Repaired by Carbon Fiber Composite Materials (탄소 섬유 복합재료로 보수된 가스 배관의 구조 해석)

  • Park, Sungho;Kim, Hansang
    • Journal of the Korean Institute of Gas
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    • v.18 no.2
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    • pp.62-68
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    • 2014
  • Composite repair methods besides welding methods such as surfacing and sleeve welding have been used as repair of damaged gas pipelines in foreign countries. Importance of safety management of city gas pipelines have been emphasized recently and our own repair manuals and codes for repair of city gas pipelines are required. It is right time to conduct research on the composite repair methods since the composite repair was introduced rather recently compared to the welding repair methods which have been investigated for long time. In this study, as a starting point of safety assessment of gas pipeline repaird by composite materials, structural analysis of gas pipeline repaired by carbon fiber composite materials was conducted using finite element analysis(FEA) method and the results was discussed.

Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (I) - Effect of Type and Flow Rate of Shielding Gases on Weldability - (티타늄 판재의 파이버 레이저 용접시 공정변수에 따른 용접특성 (I) - 실드가스 종류 및 유량에 따른 영향 -)

  • Kim, Jong Do;Kim, Ji Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.12
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    • pp.1047-1053
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    • 2016
  • In this study, welding of pure titanium was carried out by using a continuous wave fiber laser with a maximum output of 6.3 kW. Because brittle regions form easily in titanium as a result of oxidation or nitriding, the weld must be protected from the atmosphere by using an appropriate shielding gas. Experiments were performed by changing the type and the flow rate of shielding gases to obtain the optimal shielding condition, and the weldability was then evaluated. The degree of oxidation and nitriding was distinguished by observing the color of beads, and weld microstructure was observed by using an optical microscope and a scanning electron microscope. The mechanical properties of the weld were examined by measuring hardness. When the weld was oxidized or nitrified, the bead color was gray or yellow, and the oxygen or nitrogen content in the bead surface and overall weld tended to be high, as a result of which the hardness of the weld was thrice that of the base metal. A sound silvery white bead was obtained by using Ar as the shielding gas.

The Study on the Corrosion Characteristics of STS 304 Pipeline Steel Weldment for Gas Cooling & Heating System (가스 냉온수기용 STS 304 배관 용접부의 부식특성에 관한 연구)

  • Kim, Hwan-Sik;Lim, Uh-Joh
    • Journal of the Korean Institute of Gas
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    • v.11 no.2 s.35
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    • pp.31-36
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    • 2007
  • In order to study on the corrosion characteristics of STS 304 pipeline steel weldment for gas cooling & heating system. the electrochemical polarization test and corrosion test by impressed potential in 0.5M $H_2SO_4+0.01M$ KSCN solution was carried out. Also, SEM and hardness of welding zone was measured. And then passive behavior, corrosion behavior by the impressed potential and SEM aspect and hardness behavior of base metal(BM) and heat affected zone(HAZ) for STS 304 pipe were investigated. The main results are as follows: 1) The critical anodic current density of heat affected zone(HAZ) is drained more highly than that of base metal(BM), and primary passive potential of HAZ become higher than that of BM. 2) The passive current density of TUE is drained more highly than that of BM, and passive region of BM become bigger than that of HAZ. 3) By the impressed potential, the current density of HAZ is drained more than that of BM.

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Effect of welding quality to wear of Contact Tips for GMA Welding (GMA용접 동안 콘택트팁 마모가 용접품질에 미치는 영향)

  • 김남훈;김희진;유회수
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.188-190
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    • 2004
  • 가스메탈아크용접(gas metal arc welding, 이하 'GMA용접' 이라고 함)은 용가재로서 소모전극 와이어를 일정한 속도로 용융지에 공급하면서 와이어 선단과 모재 사이에서 전기적 아크가 발생되도록 하는 용접법이다. (중략)

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