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Cleveland, OH, United States

Lee K.Y.,Lincoln Electrical Company | Sadurski K.,Lincoln Electrical Bester S.A.
Welding International | Year: 2012

The paper presents new possibilities related to quality assessment of girth welds. Global trends in oil and gas pipeline construction point to the growing application of methods where fracture mechanics and crack tip opening displacement tests are used for critical defect size determination. This approach can precisely determine pipeline wear levels under given conditions. The most important benefit of this lies in the dependence of critical defect size on the quality of pipe material and the welding consumables' mechanical properties. © 2012 Copyright Taylor and Francis Group, LLC. Source

Narayanan B.K.,Lincoln Electrical Company | Brady N.,Lincoln Electrical Company | Wang Y.-Y.,Center for Reliable Energy Systems | Ogborn J.,Lincoln Electrical Company
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2010

Ferritic weld metal was deposited with gas shielded flux cored arc welding (FCAW-G) process. The nitrogen level in the deposited weld metal varies typically between 20 to100 ppm. Nitrogen is a fast diffusing solute element that is known to cause strain ageing affecting both strength and toughness. Weld metal was produced with intentional additions of two strong nitride formers, titanium and vanadium. All-weld metal tensile samples were subjected to varying levels of strain, aged at 170°C for 20 minutes and reloaded to failure. Both the yield and tensile strength increased with increase in pre-strain confirming the presence of strain ageing. The strain hardening rate is also seen to change with strain ageing. There is also a corresponding decrease in the uniform elongation with increase in nitrogen and prestrain. The effect of strain ageing treatment on weld metal toughness was also evaluated. A nominal 2%-3% strain was imposed on the weld metal by straining it in the direction of welding and Charpy V-Notch toughness of the weld was measured. The ductile to brittle transition temperature (DBTT) of the weld metal was estimated by measuring the percent shear and the weld metal toughness at different temperatures. The DBTT of the weld metal is seen to shift slightly to higher temperatures with increase in pre-strain. However there was a dramatic drop in the upper shelf energy and a consistent decrease in the average toughness of the weld metal at all temperatures. The as-welded and reheat microstructure of the weld metal was characterized using optical and electron microscopy techniques. The possible implications of strain ageing on pipeline girth weld procedure qualification and inservice integrity are discussed. Copyright © 2010 by ASME. Source

Funderburk S.,CRC Evans Pipeline International Inc. | Spielbauer P.,CRC Evans Pipeline International Inc. | Chen Y.,Center for Reliable Energy Systems | Quintana M.,Lincoln Electrical Company
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

The mechanical properties of X100 pipeline girth welds are quite sensitive to welding parameters and the design range for a viable welding procedure is narrower compared to pipeline steels of lower grades. The use of a high-productivity welding process, such as dual-torch gas metal arc welding (GMAW), further compounds the dependency of weld properties on welding parameters. Consequently, for X100 pipe welding procedure development, the path to achieve the required weld performance can be a time-consuming and costly process. Developed in a recently completed project, the essential welding variable methodology provides an effective approach to optimize the development process for X100 pipe welding, with the benefits of reducing development time and saving cost. The present paper presents a practical case study of the methodology for girth welds. The present paper focuses on the information needed and the analyses performed in the application of the methodology to the process of welding procedure development for a dualtorch pulsed GMAW(GMAW-P) procedure. Using an analysis tool that can predict the thermal cycles from welding parameters and the available knowledge of microstructure and mechanical responses of both pipe materials and weld metals to welding thermal cycles (cooling rate), several candidates of dual-torch pulsed GMAW procedures were evaluated first for cooling times to help the determination of the final welding procedures. The finalized welding procedures used for the production of the qualification welds were evaluated to estimate the mechanical properties of the girth welds. The estimated weld properties will be compared to those from the test results when they become available. Copyright © 2014 by ASME. Source

Zhang T.,Tianjin University | Li Z.,Beijing University of Technology | Young F.,Lincoln Electrical Company | Jin Kim H.,Korea Institute of Industrial Technology | And 3 more authors.
ISIJ International | Year: 2014

This paper reviews the global progress on welding consumables for high strength low alloy steel. The numerous aspects, such as the toughness and cleanliness of weld metal, the new removal mechanisms of impurity elements and the crack resistance of weld metal, are discussed. To meet increasing environment requirements, the fumes and life cycle assessment of welding consumables are also discussed. Finally, future trends in the development of welding consumables for high strength low alloy steel are pointed out. © 2014 ISIJ. Source

Melfi T.,Lincoln Electrical Company | Daniel J.,Lincoln Electrical Company
Materials at High Temperatures | Year: 2010

Heat input is an essential variable in many codes and industry specifications due to the relationship between heat input and the mechanical properties of a weldment. However, the current and voltage values displayed by many welding power sources or traditional hand-held meters often do not reflect the energy input to a weld with pulsing or other modern welding waveforms. Modern welding waveforms are often not symmetric. They operate on inductive loads, contain high frequency harmonics and are not repetitive. Traditional methods of calculating heat input involve the measuring of either average or RMS voltage and average or RMS current. While traditional methods produce relatively consistent results with high energy processes, such as traditional spray arc, the results become less consistent or accurate with short arc and pulse modes due to the continually changing output of the machine. This work identifies modern waveforms and describes the means for accurately measuring the energy input into a weld. This measurement system lays a foundation which code bodies may use to enable a continued correlation between heat input and the mechanical properties of a weldment, and suggests a method that allows previously qualified procedures to use this measurement system. © 2010 Science Reviews 2000 Ltd. Source

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