• Title/Summary/Keyword: Zinc coated steel pipes

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Development of Semi-automatic Gas Metal Arc Welding Equipment for Fire Piping and Evaluation of Characteristics of Weld Joints (소방배관용 강관을 위한 반자동 가스메탈아크용접장치 개발과 용접부 특성평가)

  • Lim, Young-Min;Oh, Tae-Suk;Jo, Hyun;Koh, Jin-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.4
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    • pp.1460-1465
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    • 2012
  • The semi-automatic gas metal arc welding equipment was developed and the weldability of zinc coated steel pipes was evaluated in terms of strength, porosity and welding parameters including shielding gas composition. The good bead appearance and the reduction of porosity in the welds could be possibly obtained by adding $O_2$ to Ar. The strength and joint efficiency of welds made by the semi-automatic welding equipment was about 1.8 times higher compared with welds manually made. The integrity of welds was confirmed by the water pressure test as well, Finally, it is expected that the weld productivity will be enhanced even unskilled welders can produce quality welds by operating the semi-automatic welding equipment.

Experimental Study on the Adhesion and Performance Evaluation of Joints for Modified Polyethylene Coated Steel Pipes (개질 폴리에틸렌 코팅 강관의 부착 및 체결부 성능 평가 연구)

  • Myung Kue Lee;Sanghwan Cho;Min Ook Kim
    • Composites Research
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    • v.37 no.3
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    • pp.238-245
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    • 2024
  • In this study, as part of the development of a monitoring system for the efficient maintenance of steel pipes, an experimental study was conducted to evaluate the performance of steel pipes treated with modified polyethylene coating. In the case of the conventional mechanical pre-coating method, there was a deterioration in polyethylene adhesion during expansion testing, which led to the application of a chemical pre-treatment process using a calcium-mixed phosphate zinc film to resolve this issue. SEM and EDX analyses showed that the densest structure was observed at a Zn/Ca ratio of 1.0, and improved heat resistance compared to the conventional method was confirmed. Additionally, to prevent coating detachment during expansion, an evaluation of adhesion and elongation was conducted on steel pipes with modified polyethylene coating, incorporating materials such as elastomers based on maleic anhydride grafting, metal oxides, blocking agents, and slip agents. Experimental results showed that the specimen (S4) containing all modified materials exhibited more than a 25% performance improvement compared to the specimen (S2) containing only metal oxides. Lastly, the development and performance evaluation of wedge-shaped socketing and pressing wheels, which are part of the pipe fixing accessories, were conducted to prevent surface coating damage on the completed pipes.

Effect of Welding Parameters on Bead Shape, Microstructure and Hardness of Galvanized Steel Pipe Welds with GMAW (아연도금강관의 GMAW에서 용접변수가 비드형상과 미세조직과 경도에 미치는 영향)

  • Lim, Young-Min;Lee, Wan Kyu;Kim, Se-Cheol;Koh, Jin-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.2
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    • pp.535-541
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    • 2013
  • The present study was carried out to investigate the effects of welding parameters such as current, voltage and shielding gases on the bead shape, microstructures and hardness. It was confirmed that bead height was lowered and bead depth was increased with increasing voltages while height, depth and width of beads increased with welding currents. The hardness of weld metals with Ar+10% $O_2$ and Ar+20% $CO_2$ was low due to the formation of grain boundary and polygonal ferrites while that of weld metals with Ar+2% $O_2$ was high due to the presence of acicular, bainitic and sideplate ferrites.