Scribd is the worlds largest social reading and publishing site. Heat treatment conference american welding society. Application of narrow gap welding process with high speed. The weld seams with the typical constant seam structure meet the highest quality demands.
The migmag narrow gap technology offers a particular economic efficiency for welding thickwalled component parts. In comparison to the conventional weld seam preparation, the. Development of swing arc narrow gap vertical welding process. Narrow gap tig welding and development of filler wires of rafms for welding free download as powerpoint presentation.
Due to an easy handling and quick interchangeable single components a productive workflow guaranteed. Narrowgap improved electroslag welding ngi esw is an updated version of an old process, optimized to provide better toughness and fewer defects while increasing productivity. Ironworkers from local 377 san francisco and local 378 oakland completed the 20 welds in june and july 2011. Narrowgap improved electroslag welding ngiesw practices and procedures will be allowed on federalaid projects for electroslag welding for joining nonfracture critical tension andor reversal stress loading members in zones 1 and 2 with material up to 3 inches thick. Electroslag welding on the new san franciscooakland bay bridge. Top recent developments in welding kemplon engineering. Mo and nb that produce long living radioactive isotopes in the reactor environment are replaced with. An electric arc is initially struck by wire that is fed into the desired weld location and then flux is added. Welding with 30 mm or 60 mm electroslag strip electroslag cladding gmawfcaw. Feasibility of narrow gap welding using the coldwire gas.
Laser welding is exhibiting greater application for connecting thin steel sheets. The experimental result using 600mm outer diameter pipes with 200mm wall thickness revealed that the shrinkage of gap at the beginning of the welding process of 174 pass. Traditional vertical welding processes cover the big groove arc welding, electrogas welding 1 and electroslag welding, 2 which are either of low production efficiency owing to multilayer and multipass welding, or unsuitable for high strength steels because of great welding heat input. Fwha started a research project to improve esw and the narrowgap improved electroslag welding ngiesw was developed. Compared 10 conventional electoslag, welding, the eswng process is characterized by. Narrow gap electroslag welding welding time approx. It gives excellent slag removal and bead appearance also for nballoyed strip electrodes. Us8816238b2 electroslag welding with variable balance. The cwgmaw process is characterized by the introduction of a continuously fed nonenergized wire coldwire into the electric arcweld pool region.
A dc balanced square wave power source, controlled in a constant voltage mode, for esw and eswng welding systems and methods can be matched with variable speed wire electrode feeders, multiple guide tubes, articulated aircooled cooper welding shoes, and multiple pass esw welding systems, thus gaining the following advantages, namely, controlling weld bead shape, reducing base metal dilution. It was found out, that the narrow gap arc welding of thick copper sections is fairly cumbersome. It is consisted of welding walking tractor, height adjuster, slag masher. Narrowgap electroslag welding for bridges, march 20, 2000. Another feature of the narrow gap gmaw welding machine is the arc monitor. Narrow gap improved electroslag welding ngiesw is permitted in the aws code. A narrow gap tig welding tool including two cascade welding nozzles was developed for the study. Experimental investigation of narrow gap improved electroslag welding for hps 70w highperformance steel a thesis submitted in partial fulfillment of the requirements for the degree of master of science at george mason university by andrei denes bachelor of science technical university of clujnapoca, 2005. Fwha started a research project to improve esw and the narrow gap improved electroslag welding ngiesw was developed. Since the federal highway administration fhwa lifted its moratorium on electroslag welding for bridge welding in 2000, the american welding society has. At present, the narrow gap submerged arc welding is an advanced welding technology. The lincoln electric narrow gap welding process is designed to meet the quality, mechanical properties and overall cost requirements of heavy wall fabrication. Process variations in current use and an outline is given of the equipment and consumable requirements associated with this technique are outlined. Fatigue resistance of hps485 w 70 w welded buttsplice connections using narrow gap improved electroslag welding article pdf available in journal of bridge engineering 146 november 2009.
The narrow gap improved electroslag welding process was used to make 20 welds in the new san franciscooakland bay bridge tower base. May 22, 1979 a method of electroslag, narrow gap welding of metallic work pieces comprising the steps of aligning the work pieces in spaced relation upon a starting plate, inserting a starting material on the starting plate between the work pieces, positioning a consumable, stationary guide plate having a filler wire electrode extending therethrough between. Oct 05, 2015 the migmag narrow gap technology offers a particular economic efficiency for welding thickwalled component parts. It is a submerged arc process designed to weld thick walled steel plate from 2 in. Ewl electroslag welding lines steel mec welding equipments. Structural steel design, fabrication, and construction. Two narrowgap welding variations with a rotating arc movement are shown in fig. This memorandum supersedes and cancels a previous memo. Flux for electroslag welding sandvik 37s se811 81 sandviken sweden march 2005 general description sandvik 37s is a highly basic, agglomerated flux for electroslag strip surfacing. Narrow gap improved electroslag welding ngiesw practices and procedures will be allowed on federalaid projects for electroslag welding for joining nonfracture critical tension andor reversal stress loading members in zones 1 and 2 with material up to 3 inches thick. A better electroslag welding process was developed, called narrow gap improved electroslag welding ngiesw that demonstrated that higher weld properties could be achieved and guaranteed. As one of the practical issues for narrow gap tungsten inert gas welding, the mechanism of gap width shrinkage in multipass circumferential butt welding of thickwalled pipes was examined experimentally and numerically. Electroslag welding is a nontraditional welding process in which molten metal pool is created. Narrow gap welding also called narrow groove welding was developed to weld thick sections more economically.
Narrow gap welding, high heat input, and automatic welding are boosting the efficiency of arc welding. Today we will learn about electroslag welding principle, working, application, advantages and disadvantages with its diagram. Electroslag welding on the new san franciscooakland bay. The relatively low energy supply during narrow gap welding provides special. Esab cab 460c submerged arc narrow gap welding sawng depth up to 350 mm with a minimum width of 18 mm mounted on a rotating column 2. Narrowgap improved electroslag welding how is narrowgap. The narrow gap welding torch of claim 1 wherein a shielding gas space is defined between said first and second gas bars, and further including means for.
This method is combination of both arc welding and resistance welding because at starting, heat is generated by establishes. Two narrow gap welding variations with a rotating arc movement are shown in fig. Electroslag welding esw applications are similar to electrogas welding. Nov 05, 2014 the migmag narrow gap technology offers a particular economic efficiency for welding thickwalled component parts. Electroslag welding esw is a highly productive, single pass welding process for thick greater than 25 mm up to about 300 mm materials in a vertical or close to vertical position. Narrow gap submerged arc welding of steel 2331984 twi. Welding power sources gas tungsten arc gta welding plasma welding and cutting manual metal arc mma welding gas metal arc gma welding submergedarc welding saw narrow gap welding electroslag welding esw high power density welding surfacing solid phase processes the metallurgical effects of fusion welding introduction. Narrow gap electroslag welding for bridges, march 20, 2000. Narrow gap tig welding and development of filler wires of.
The experimental result using 600mm outer diameter pipes with 200mm wall thickness revealed that the shrinkage of gap at the beginning of the welding process of 174. Design on cleaning device for slag of narrow gap submerged. However, manual fine tuning of the welding speed in response to changes in the groove width is necessary. Narrow gap welding of pressure vessels a manufacturers.
Flux is added, which then melts by the heat of the arc. It was published that electroslag welding was going to be approved in the new edition of aws d1. This scope is focused on the welding tip at the end of the welding torch and magnifies the arc region 5x while shielding the arc light so that the operator does not need a welding shield. This welding procedure uses joint preparations with small, included angles, typically in the range 220, which require less weld metal and less welding time to fill. Electroslagwelding was derived from a metal manufacturing process called electroslag remelting or refining esr. Submerged arc narrow gap welding sawng depth up to 350 mm with a minimum width of 18 mm mounted on a rotating column 2. This detail needs to be incorporated into projects that. The narrow gap welding torch of claim 3 wherein said contact tip is screwthreaded into said bore in said center bar.
However, cvn testing of the heataffected zone is currently not covered in aws and is supplemented by special provision. In comparison to the conventional weld seam preparation, the weld seam volume. The basis of the narrow gap technology is the rectangular narrow gap blade with a length of up to 300 mm, which guides the wire electrode, the shielding gas and the water coolant. Because of the success of this method, the moratorium was rescinded in 2000. By comparison, narrow gap gas metal arc gma vertical.
Use of electroslag welding in highway bridges and structures. Narrow gap arc welding experiments of thick copper sections. April 6, 2015 2 electroslag welding narrow gap eswng. The effects of welding in a deep, narrow groove on the metallurgical structure and the mechanical properties of the weld metal and heat affected zone.
Structural steel design, fabrication, and construction jamie f. Vijayan m g background rafm steels are the candidate structural materials for tbm to be installed in the iter fusion reactor. Rafm steels have a chemical composition similar to modified 9cr1mo steel. A welding torch adapted for welding deep narrow gaps wherein shielding gas diffusers fit inside the welding groove, a plastic liner is placed deep inside the torch so electric contact between the filler wire and contact tube is close to the exit, and a zirconia oxide insulation prevents torch contact with the gap walls. Experimental investigation of narrow gap improved electroslag. The writers investigated the performance of narrow gap improved electroslag weld ngiesw procedures in welded butt splices using highperformance steel grade hps485 w 70 w through comparison against similar specimens fabricated using submerged arc welding saw. Separate systems for the horizontal and the vertical joint tracking. Narrowgap improved electroslag welding how is narrow. The narrow gap welding torch of claim 1 wherein a shielding gas space is defined between said first and second gas bars, and further including means for adjusting said shielding gas space. Fluxcored welding was created and put into use in the early years of the 1950s. A narrow gap tigwelding tool including two cascade welding nozzles was developed for the study.
An electric arc is initially struck by wire that is fed. The latest version of electroslag welding, eswng the ng stands for narrow gap about 34 inch, is currently accepted by aashto for welding common types of bridge steels and is included in the bridge welding code. Electroslagwelding, cost effective vertical one pass process. Nov 26, 2015 electroslag welding esw applications are similar to electrogas welding. A copper welding station, which is an insulated cell, was also developed for the welding trials. Fatigue resistance of hps485 w 70 w welded buttsplice. Narrow gap improvedelectroslag welding ngiesw is permitted in the aws code.
Fracture strength of electroslag welding joint with high. Esw is similar to electrogas welding, but the main difference is the arc starts in a different location. Preprogrammed number of beads at different joint width. As the weld is very deep and narrow, the slag is difficult to clean and will have impact on the quality of welding seam. This article evaluates the performance of the coldwire gas metal arc welding cwgmaw process for narrow gap girth welding. Narrow gap improved electroslag welding ngi esw is an updated version of an old process, optimized to provide better toughness and fewer defects while increasing productivity. Sep 21, 2016 arc welding with conventional machinery and work practices still remains the main method of connecting heavy plates that make up large steel structures. Narrowgap improved electroslag welding how is narrowgap improved electroslag welding abbreviated. Narrow gap welding, electrogas and electroslag welding. Induction heating provides improved productivity, ease of use and lower costs compared to conventional heating on welding projects by james byrne, miller electric mfg. Arc welding with conventional machinery and work practices still remains the main method of connecting heavy plates that make up large steel structures.
Narrow gap welding, electrogas and electroslag welding 76 nique is the high crystal restructuring rate in the weld metal and in the basemetal adjacent to the fusion line an advantage that gains good toughness properties. The main difference is that the arc is started between the electrode tip and the bottom of the part to be welded. Electroslagwelding is a process providing one of the highest weld deposition rates and is therefore most costeffective for suitable applications its unique capability permits to weld in one pass groove joint of two plates, thick 1 to 12 inches 25 to 300 mm and more. Mar 24, 2017 today we will learn about electroslag welding principle, working, application, advantages and disadvantages with its diagram. Pdf fatigue resistance of hps485 w 70 w welded butt. After the molten slag reaches the tip of the electrode, the arc is extinguished. The arc is viewed during welding through an optical viewing scope. Electroslagwelding, cost effective vertical one pass. A method of electroslag, narrow gap welding of metallic work pieces comprising the steps of aligning the work pieces in spaced relation upon a starting plate, inserting a starting material on the starting plate between the work pieces, positioning a consumable, stationary guide plate having a filler wire electrode extending therethrough between. The coldwire is melted by using the surplus heat available at the arc and molten metal at the weld pool. Eswng is a variation of electroslag welding character. Performance improvements were achieved by changing the welding details. The hng multi meets the demands for a fully automatic welding process with accurate controlling of all parameters for reduced welding times and perfect weld metal when welding hightensile material.
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