• Title/Summary/Keyword: Girth weld

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A Study on Prediction of Temperature Distribution in Pipe Girth Welding by Mapping Theory (사상 이론을 이용한 파이프 원주 용접의 온도 분포 예측에 관한 연구)

  • Jo, Yeong-Tae;Na, Seok-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.2935-2944
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    • 2000
  • Gas tungsten arc(GTA) welding is used to rrpiar the seat ring in swing type check valve in power plant because of its high weld quality. In order to automate the welding process, it is needed to analyze the process of inside pipe girth welding. In this study, the shapes of weld bead on pipe inside and outside were predicted and its validity was investigated. On the assumption that the welding arc had a bivariate gaussian distribution, analytical solution was derived to predict the temperature distribution in pipe weld using mapping under consideration of physical relationships. The size of weld bean could be predicted from this equation and its accuracy was verified by experiments.

The Evaluation of Burst Pressure for Corroded Weld in Gas Pipeline (가스배관에서 원주 및 심 용접부의 부식손상 부위에 대한 파열압력 평가)

  • Kim Yeong Pyo;Kim U Sik;O Gyu Hwan
    • Proceedings of the KWS Conference
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    • v.43
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    • pp.165-167
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    • 2004
  • 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. 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.

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The Evaluation of Burst Pressure for Corroded Weld in Gas Pipeline (가스배관 용접부위 부식에 대한 파열압력 평가)

  • Kim, Young-Pyo;Kim, Woo-Sik;Lee, Young-Kwang;Oh, Kyu-Hwan
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.222-227
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    • 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.

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Effect of Heat Input on Girth welds properties of High strain steel pipe (입열량이 고변형률 강관 원주 용접부 특성에 미치는 영향)

  • Lee, Jin-Woo;Song, Woo-Hyun;Seo, Dong-Han;Lee, Jong-Sub
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.71-71
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    • 2010
  • SBD (Strain-based design) of pipe lines have gained world-wide attention in recent years. The present research aims to evaluate the fracture characteristics of API (America Petroleum Institute) SBD X100 girth weldment that typically applied for cold climate and deep water offshore, with the focus on the influence of heat input changing with 6kJ/cm and 10kJ/cm from GMAW (Gas Metal Arc Welding). At a low heat input at 6kJ/cm, the weld metal had Multi-phase matrix (Acicular ferrite + Banite + Martensite) that could fill up both fracture toughness and strength as reported previously. Also, the weld metal exhibited 859MPa YS (Yield strength), 108J impact toughness at $-40^{\circ}C$ and 0.52mm CTOD (Crack Tip Open Displacement) at $-10^{\circ}C$. These results can be satisfied with the requirement of API SBD X100 girth weldment and Alaska pipe line project.

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Effect of Heat Input on Girth Welds Properties of High Strain Steel Pipe (입열량이 고변형률 강관 원주 용접부 특성에 미치는 영향)

  • Lee, Jin-Woo;Song, Woo-Hyun;Seo, Dong-Han;Lee, Jong-Sub
    • Journal of Welding and Joining
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    • v.27 no.6
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    • pp.25-30
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    • 2009
  • SBD (Strain-based design) of pipe lines have gained world-wide attention in recent years. The present research aims to evaluate the fracture characteristics of API (America Petroleum Institute) SBD X100 girth weldment that typically applied for cold climate and deep water offshore, with the focus on the influence of heat input changing with 6kJ/cm and 10kJ/cm from GMAW (Gas Metal Arc Welding). At a low heat input at 6kJ/cm, the weld metal had Multi-phase matrix (Acicular ferrite + Banite + Martensite) that could fill up both fracture toughness and strength as reported previously. Also, the weld metal exhibited 859MPa YS (Yield strength), 108J impact toughness at $-40^{\circ}C$ and 0.52mm CTOD (Crack Tip Open Displacement) at $-10^{\circ}C$. These results can be satisfied with the requirement of API SBD X100 girth weldment and Alaska pipe line project.

Behavior of girth-welded buried steel pipes under external pressure (원주 용접된 압력 매설강관의 거동 분석)

  • Jeon, Juntai;Lee, Chinhyung;Chang, Kyongho
    • Journal of the Society of Disaster Information
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    • v.11 no.1
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    • pp.1-8
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    • 2015
  • This paper presents finite element (FE) analyses to clarify the effects of external pressure on the residual stresses in a girth-welded steel pipe. At first, FE simulation of the girth welding process is carried out to obtain the weld-induced residual stresses employing sequentially coupled three-dimensional (3-D) thermo-mechanical FE formulation. Then, 3-D elastic-plastic FE analyses incorporating the residual stresses and plastic strains obtained from the preceding FE simulation are performed to investigate the residual stress behavior in the girth-welded pipe under external pressure. The FE analysis results show that the hoop compressive stresses induced by the external pressure significantly alter the hoop residual stresses in the course of the mechanical loading.

A Study on Structural Integrity Assessment of Pipeline using Weight Function Solution (가중함수법을 적용한 파이프라인 구조건전성평가에 관한 연구)

  • Noh, Ki-Sup;Oh, Dong-Jin;Kim, Myun-Hyun
    • Journal of Welding and Joining
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    • v.35 no.1
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    • pp.55-60
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    • 2017
  • There are many Industry Code and Standard (ICS) for Structural Integrity Assessment (SIA) on welded structure with defect. The general ICSs, such as R6, BS 7910 and API 579-1/ASME FFS-1, provide equations to determine the upper bound residual stress profiles based on collections from many literatures. However, these residual stress profiles used in the SIA cause the conservative design for welded structures. In this study, the structural integrity assessment for girth weld in pipeline has been conducted based on fracture mechanics. In addition, thermo-elastic plastic FE analysis was performed for evaluating the residual stress of girth weld in pipeline. The weight function solution is used to determine the stress intensity factor using the residual stress profile obtained by the FE analysis. This approach can account for redistribution and relaxation of residual stress as the defects grow. In order to the evaluate quantitative comparison between BS 7910 and weight function solution, structural integrity assessment determining allowable crack size on cracked pipe was performed with failure assessment diagram.

Influence of ultrasonic impact treatment on microstructure and mechanical properties of nickel-based alloy overlayer on austenitic stainless steel pipe butt girth joint

  • Xilong Zhao;Kangming Ren;Xinhong Lu;Feng He;Yuekai Jiang
    • Nuclear Engineering and Technology
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    • v.54 no.11
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    • pp.4072-4083
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    • 2022
  • Ultrasonic impact treatment (UIT) is carried out on the Ni-based alloy stainless steel pipe gas tungsten arc welding (GTAW) girth weld, the differences of microstructure, microhardness and shear strength distribution of the joint before and after ultrasonic shock are studied by microhardness test and shear punch test. The results show that after UIT, the plastic deformation layer is formed on the outside surface of the Ni-based alloy overlayer, single-phase austenite and γ type precipitates are formed in the overlayer, and a large number of columnar crystals are formed on the bottom side of the overlayer. The average microhardness of the overlayer increased from 221 H V to 254 H V by 14.9%, the shear strength increased from 696 MPa to 882 MPa with an increase of 26.7% and the transverse average residual stress decreased from 102.71 MPa (tensile stress) to -18.33 MPa (compressive stress), the longitudinal average residual stress decreased from 114.87 MPa (tensile stress) to -84.64 MPa (compressive stress). The fracture surface has been appeared obvious shear lip marks and a few dimples. The element migrates at the fusion boundary between the Ni-based alloy overlayer and the austenitic stainless steel joint, which is leaded to form a local martensite zone and appear hot cracks. The welded joint is cooled by FA solidification mode, which is forming a large number of late and skeleton ferrite phase with an average microhardness of 190 H V and no obvious change in shear strength. The base metal is all austenitic phase with an average microhardness of 206 H V and shear strength of 696 MPa.

Welding process for manufacturing of Nuclear power main components (원자력 발전 주기기 제작에 적용되는 용접공정)

  • Jung, In-Chul;Kim, Yong-Jae;Shim, Deog-Nam
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.43-46
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    • 2010
  • As the nuclear power plant has been constructed continuously for several decades in Korea, the welding technology for components manufacturing and installation has been improved largely. Standardization for weld test and qualification was also established systematically according to the concerned code. The welding for the main components requires the high reliability to keep the constant quality level, which means the repeatability of weld quality. Therefore the weld process qualified by thorough test and evaluation is able to be applied for manufacturing. Narrow gap SAW and GTAW process are usually applied for girth seam welding of pressure vessel like Reactor vessel, steam generator, and etc. For the surface cladding with stainless steel and Inconel material, strip welding process is mainly used. Inside cladding of nozzles is additionally applied with Hot wire GTAW and semi-auto welding process. Especially the weld joint having elliptical weld line on curved surface needs a specialized weld system which is automatically rotating with adjusting position of the head torch. The small sized pipe, tube, and internal parts of reactor vessel requests precise weld processes like an automatic GTAW and electron beam welding. Welding of dissimilar materials including Inconel690 material has high possibility of weld defects like a lack of fusion, various types of crack. To avoid these kinds of problem, optimum weld parameters and sequence should be set up through the many tests. As the life extension of nuclear power plant is general trend, weld technologies having higher reliability is required gradually. More development of specialized welding systems, weld part analysis and evaluation, and life prediction for main components should be taken into a consideration extensively.

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