Narrow gap improved electroslag welding of bridge steels. 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. Flux is added, which then melts by the heat of the arc. 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. Ngiesw is defined as narrowgap improved electroslag welding national bridge research organization rarely. 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. Joining copper to steel this is a real question we got from one of our correspondents. Use of electroslag welding in highway bridges and 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 weld seams with the typical constant seam structure meet the highest quality demands. This yields a weld with a high ratio of depth to width. In comparison to the conventional weld seam preparation, the weld seam volume. Fracture strength of electroslag welding joint with high. Ironworkers from local 377 san francisco and local 378 oakland completed the 20 welds in june and july 2011. The gap decreases the load, and the power supply draws less amperage. Ewl electroslag welding lines steel mec welding equipments. Ngiesw stands for narrowgap improved electroslag welding national bridge research organization. The method allows using lowerpowered lasers, which is more economically feasible. Laser welding is exhibiting greater application for connecting thin steel sheets.
Electroslag welding on the new san franciscooakland bay. Krishna verma in the bridge division hng32 at 202 3664601 by january 15, 1999 with your recommendations. Use of electroslag welding in highway bridges and structures fhwa. Jstartm welding12, which is a type of co2 arc welding, is one such effort. Preprogrammed number of beads at different joint width. It is a submerged arc process designed to weld thick walled steel plate from 2 in. Ngiesw narrowgap improved electroslag welding national. Electroslag welding esw is a highly productive, single pass welding process for thick greater.
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. May 22, 1979 the embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows. 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. Two narrow gap welding variations with a rotating arc movement are shown in fig. Electroslag welding esw applications are similar to electrogas welding. Under this brand, itw welding now brings together a wealth of submerged arc welding expertise and consumables with unequalled welding performance. 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. A better electroslagwelding process was developed, called narrow gap improved electroslagwelding ngiesw that demonstrated that higher weld properties could be achieved and guaranteed. A bandpass filter in which the band of frequencies transmitted by the filter has a bandwidth which is small compared to the average frequency of the band explanation of narrowbandpass filter. Two narrowgap welding variations with a rotating arc movement are shown in fig. Eswng is a variation of electroslag welding character. A parametric study of the electroslag welding process citeseerx. Fwha started a research project to improve esw and the narrow gap improved electroslag welding ngiesw was developed. 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.
Eagar a formulation is presented to calculate, in three dimensions, the important process parameters such as the voltage profiles, heat generation patterns and temperature profiles in the slag and metal phases for an electroslag welding system. Narrow gap welding, high heat input, and automatic welding are boosting the efficiency of arc welding. Experimental investigation of narrow gap improved electroslag. Verma is a welding engineer in the fhwas bridge division. The migmag narrow gap technology offers a particular economic efficiency for welding thickwalled component parts.
Feasibility of narrow gap welding using the coldwire gas. Narrow gap arc welding experiments of thick copper sections. Jun 01, 2015 the art of narrowgroove welding june 1, 2015 narrowgroove ng welding is defined, in part, by the american welding society aws as a variation of a multiplepass welding process with filler metal, using a small root opening and a vgroove with a small groove angle. Narrowgap improved electroslag welding for bridges. Nov 26, 2015 electroslag welding is capable of welding plates with thicknesses ranging from 50 mm to more than 900 mm and welding is done in one pass. Narrow gap submerged arc welding of steel 2331984 twi. After the molten slag reaches the tip of the electrode, the arc is extinguished. The travel speed of the weld is in the range from 12 to 36 mmmin. He has been responsible for overseeing the bridge weld program, pertaining to the nations steel bridges, since 1984. Esw is similar to electrogas welding, but the main difference is the arc starts in a different location. An electric arc is initially struck by wire that is fed. It was published that electroslagwelding was going to be approved in the new edition of aws d1.
Electroslag and electrogas welding12 welding, brazing and. Recent trend of welding technology development and applications. Too narrow a gap may cause arcing between the electrode and the base metal. The lincoln electric narrow gap welding process is designed to meet the quality, mechanical properties and overall cost requirements of heavy wall fabrication. By comparison, narrow gap gas metal arc gma vertical. Performance improvements were achieved by changing the welding details. The objectives of dp102, narrowgap improved electroslag welding for bridges, include. Narrowgroove ng welding is defined, in part, by the american welding society aws as a variation of a multiplepass welding process with filler metal, using a small root opening and a vgroove with a small groove angle. Narrow gap tig welding and development of filler wires of.
How is narrow gap improved electroslag welding national bridge research organization abbreviated. Narrowgap improved electroslag welding how is narrowgap improved electroslag welding abbreviated. The attached flyer provides general information on the demonstration project dp102 narrow gap improved electroslag welding for bridges. Narrowgap improved electroslag welding how is narrowgap. It was published that electroslag welding was going to be approved in the new edition of aws d1. 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. This detail needs to be incorporated into projects that. A narrow gap tig welding tool including two cascade welding nozzles was developed for the study. Characteristics of welding and arc pressure in tig narrow gap. Ngiesw is defined as narrow gap improved electroslag welding national bridge research organization rarely. Todays developments are aimed at increasing a sophisticated process understanding, especially concerning the physical effect of arc behavior, which can provide many strategies to enhance weld prediction and joint quality.
Because of the success of this method, the moratorium was rescinded in 2000. The fhwa commissioned research from universities and industry and narrow gap improved electro slag welding ngiesw was developed as a replacement. 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. The latest version of electroslag welding, eswng the ng stands for narrow gap about 34 inch, is currently accepted by aashto for welding common. Training manual for narrowgap improved electroslag welding, fhwasa96. Narrow gap laser welding provides for sufficiently high performance and weld quality compared to multipass arc welding.
Initially when the process was introduced in the united states in the late 1960s, there was some obvious success. The narrow gap improved electroslag welding ngiesw process is an optimized. Pdf the aim of the work consisted in development of technology for electroslag. 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. 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. 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. Electroslag welding esw has been of interest for many. Verma 1 abstract this paper describes an ongoing comprehensive research and development effort by the federal highway administration to introduce narrowgap improved electroslag welding for bridges for production welding. Flux 37s is used together with strip electrodes of the cr. This article evaluates the performance of the coldwire gas metal arc welding cwgmaw process for narrow gap girth welding. Narrow gap improved electroslag welding process because of its high deposition rate, esw is considered the most productive of any welding process in joining thick components. Separate systems for the horizontal and the vertical joint tracking. For welding of materials with wall thickness over 20 mm, it is recommended to use multipass narrow gap laser welding with cold filler metal. Electroslag welding on the new san franciscooakland bay bridge.
Pdf fatigue resistance of hps485 w 70 w welded butt. Since the federal highway administration fhwa lifted its moratorium on electroslag welding for bridge welding in 2000, the american welding society has. When esw is used to surface machine parts, metalcored tubular wire. Fwha started a research project to improve esw and the narrowgap improved electroslag welding ngiesw was developed. In comparison to the conventional weld seam preparation, the. Multipass narrow gap of heavy gauge steel with filler wire. Process operational guide for narrowgap improved electroslag welding, fhwasa96053, february 1996. 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. Electroslag welding esw and electrogas welding egw are two related procedures. The narrow gap improved electroslag welding process was used to make 20 welds in the new san franciscooakland bay bridge tower base. Narrow gap welding, electrogas and electroslag welding. Public roads narrowgap improved electroslag welding for. Training manual for narrow gap improved electroslag welding, fhwasa96.
Narrowgap improved electroslag welding listed as ngiesw. Tungsten inert gas tig narrow gap welding using magnetic arc oscillation is one of the most important methods for joining thick components. The cwgmaw process is characterized by the introduction of a continuously fed nonenergized wire coldwire into the electric arcweld pool region. Ngiesw stands for narrow gap improved electroslag welding national bridge research organization. However, cvn testing of the heataffected zone is currently not covered in aws and is supplemented by special provision. Top recent developments in welding kemplon engineering. Nov 06, 2009 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. Arc welding with conventional machinery and work practices still remains the main method of connecting heavy plates that make up large steel structures.
Fluxcored welding was created and put into use in the early years of the 1950s. A copper welding station, which is an insulated cell, was also developed for the welding trials. Narrow gap improvedelectroslag welding ngiesw is permitted in the aws code. 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. Mo and nb that produce long living radioactive isotopes in the reactor environment are replaced with. This detail needs to be incorporated into projects that include the ngiesw special provision. Narrowbandpass filter article about narrowbandpass. Bestinclass submerged arc welding consumables from a trusted source since 1917, the hobart name enjoys a solid reputation for quality, innovation and knowhow. Due to an easy handling and quick interchangeable single components a productive workflow guaranteed. We will use argon gas for shielding, 2% thoriated tungsten, would you recommend a low silver 5% or a high silver 15% filler metal or something altogether different.
Fracture strength of electroslag welding joint with highperformance. It gives excellent slag removal and bead appearance also for nballoyed strip electrodes. Electroslag welding makes comeback for fabricating bridges onepass welding of 4in. This thesis presents an experimental investigation of the narrow gap improved electroslag eswng welding method when applied on hps 70w.
The coldwire is melted by using the surplus heat available at the arc and molten metal at the weld pool. Narrowgap improved electroslag welding how is narrow. An electric arc is initially struck by wire that is fed into the desired weld location and then flux is added. 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. This new process provides a higher productivity rate, improved fracture toughness both in. Process variations in current use and an outline is given of the equipment and consumable requirements associated with this technique are outlined.
It was found out, that the narrow gap arc welding of thick copper sections is fairly cumbersome. Us8816238b2 electroslag welding with variable balance. With laser welding utilizing power sources of greater capacity, lasers are also joining heavy plates. Oct 05, 2015 the migmag narrow gap technology offers a particular economic efficiency for welding thickwalled component parts. A narrow gap tigwelding tool including two cascade welding nozzles was developed for the study. The objectives of dp102, narrow gap improved electroslag welding for bridges, include. Fatigue resistance of hps485 w 70 w welded buttsplice. Narrowgroove welding techniques are wellestablished for submerged arc welding saw, gas metal arc welding. The main difference is that the arc is started between the electrode tip and the bottom of the part to be welded. However, jstartm welding realizes droplet transfer in a spray form, enabling deep penetration welding with minimal. Heat generation patterns and temperature profiles in electroslag welding t.
April 6, 2015 2 electroslag welding narrow gap eswng. This publication brings to the readers practical answers to welding problems in an informal setting designed to be helpful and informative. 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. Narrow gap improved electroslag welding for bridges demonstration project, dp102 background. Heat generation patterns and temperature profiles in. Electroslagwelding, cost effective vertical one pass. Narrow gap welding also called narrow groove welding was developed to weld thick sections more economically. Electroslag welding easily lends itself to mechanization, thus reducing the requirement for skilled manual welders. Narrow gap improved electroslag welding ngiesw is permitted in the aws code. Compared 10 conventional electoslag, welding, the eswng process is characterized by. The objective of this federal highway administration fhwa demonstration project 102 dp102 narrow gap improved electroslag welding for bridges is to introduce a modified version of a productive welding process for joining thick plates or other thickwall components. 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. The current required is about 600 a at 40 to 50 volts although higher currents are used for thick plates. Manual angle setting device for adjustable cross seam tilt of.
Characteristics of welding and arc pressure in tig narrow. Recent trend of welding technology development and. The relatively low energy supply during narrow gap welding provides special. Sep 21, 2016 narrow gap welding, high heat input, and automatic welding are boosting the efficiency of arc welding. Development of swing arc narrow gap vertical welding process. 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. Technical information guide for narrowgap improved elec.
1327 658 1293 92 961 535 1471 1010 410 1106 701 1109 82 247 207 119 93 1003 1138 166 732 1331 834 1343 88 1378 335 37 396 304 298 947 1352 1370 47 1450 715 207 665 690 711 843 602 982 461 412 449