Development of Repair Technologies for J-Groove Welds of Drain and Instrument Nozzle in Steam Generator

2009 ◽  
Author(s):  
Kwang Soo Park ◽  
Chang Sig Kong ◽  
Seon Ho Lee ◽  
Woo Sung Kim
Keyword(s):  
Steam Generator ◽  
Welding Process ◽  
Outer Wall ◽  
Field Application ◽  
Repair System ◽  
Monitoring Tool ◽  
Welding Equipment ◽  
Gas Tungsten Arc ◽  
Primary Water ◽  
Remote Welding

SG drain & instrument nozzles and their welds fabricated with alloy 600 and alloy 82/182 is susceptible to Primary Water Stress Corrosion Cracking (PWSCC). In Korea, the cracks due to PWSCC were discovered in the drain nozzle of Yongkwang units 3 & 4. Doosan has developed a system for steam generator to repair damaged drain nozzle & welds and to prevent further damage on the instrument nozzle & welds. The repair system consists of machining, welding equipment and installation tool for this equipment. The machining equipment is used to remove the nozzle and J-groove welds. The process is called mechanical machining and the main equipment is installed on steam generator’s outer wall. The welding equipment is designed for the machined J-groove welds and overlay. The auto welding equipment consists of welding head, controller, monitoring tool and Gas Tungsten Arc Welding (GTAW) power supply. Doosan has developed remote welding process using the monitoring tool. The installation tool consists of automatic installment tool for instrument nozzle and manual installment tool for drain nozzle. Doosan successfully completed a mockup test and field application for Yongkwang unit 3.

scholarly journals Design and Fabrication of Remote Welding Equipment in a Hot-Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Soosung Kim ◽  
Kihwan Kim ◽  
Jungwon Lee ◽  
Jinhyun Koh
Keyword(s):  
Nuclear Fuel ◽  
Performance Test ◽  
Preliminary Investigation ◽  
Welding Process ◽  
Resistance Welding ◽  
Welding Equipment ◽  
End Plate ◽  
Fuel Fabrication ◽  
Fuel Bundle ◽  
Remote Welding

The remote welding equipment for nuclear fuel bundle fabrication in a hot-cell was designed and developed. To achieve this, a preliminary investigation of hands-on fuel fabrication outside a hot-cell was conducted with a consideration of the constraints caused by the welding in a hot-cell. Some basic experiments were also carried out to improve the end-plate welding process for nuclear fuel bundle fabrication. The resistance welding equipment using end-plate welding was also improved. It was found that the remote resistance welding was more suitable for joining an end-plate to end caps in a hot-cell. This paper presents an outline of the developed welding equipment for nuclear fuel bundle fabrication and reviews a conceptual design of remote welding equipment using a master-slave manipulator. Furthermore, the mechanical considerations and a mock-up simulation test were described. Finally, its performance test results were presented for a mock-up of the remote resistance welding equipment for nuclear fuel bundle fabrication.

Multifactor mathematical model of criticality of welding process of products from aluminum- magnesium alloys

2020 ◽  
pp. 12-18
Author(s):  
F.A. Urazbahtin ◽  
A.YU. Urazbahtina
Keyword(s):  
Mathematical Model ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Welding Process ◽  
Welding Equipment ◽  
Equipment Operation ◽  
Aluminum Magnesium Alloys ◽  
Aluminum Magnesium Alloy ◽  
Welding Materials

A multifactor mathematical model of the welding process of products from aluminum-magnesium alloys, consisting of 71 indicators that assess the quality of the weld, the welding process, costs, equipment operation and quality of the welded material. The model can be used to control and optimize the welding process of products from aluminum-magnesium alloys. Keywords welding, products, aluminum-magnesium alloy, indicators, process parameters, welding equipment, welding materials, electrode sharpening, lining [email protected]

scholarly journals Multi-Objective Optimization of Resistance Welding Process of GF/PP Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2560
Author(s):  
Guowei Zhang ◽  
Ting Lin ◽  
Ling Luo ◽  
Boming Zhang ◽  
Yuao Qu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Welding Process ◽  
Welding Current ◽  
Resistance Welding ◽  
Thermoplastic Composites ◽  
Current Time ◽  
Process Factor ◽  
Welding Equipment ◽  
Lap Shear ◽  
Adhesive Connections

Thermoplastic composites (TPCs) are promising materials for aerospace, transportation, shipbuilding, and civil use owing to their lightweight, rapid prototyping, reprocessing, and environmental recycling advantages. The connection assemblies of TPCs components are crucial to their application; compared with traditional mechanical joints and adhesive connections, fusion connections are more promising, particularly resistance welding. This study aims to investigate the effects of process control parameters, including welding current, time, and pressure, for optimization of resistance welding based on glass fiber-reinforced polypropylene (GF/PP) TPCs and a stainless-steel mesh heating element. A self-designed resistance-welding equipment suitable for the resistance welding process of GF/PP TPCs was manufactured. GF/PP laminates are fabricated using a hot press, and their mechanical properties were evaluated. The resistance distribution of the heating elements was assessed to conform with a normal distribution. Tensile shear experiments were designed and conducted using the Taguchi method to evaluate and predict process factor effects on the lap shear strength (LSS) of GF/PP based on signal-to-noise ratio (S/N) and analysis of variance. The results show that current is the main factor affecting resistance welding quality. The optimal process parameters are a current of 12.5 A, pressure of 2.5 MPa, and time of 540 s. The experimental LSS under the optimized parameters is 12.186 MPa, which has a 6.76% error compared with the result predicted based on the S/N.

Welding: Particulate and Gaseous Emissions

2019 ◽  
Author(s):  
Cole Homer ◽  
Epstein Seymour ◽  
Peace Jon
Keyword(s):  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Pure Metal ◽  
Gaseous Emissions ◽  
Hazard Communication ◽  
Gas Tungsten Arc ◽  
Metal Arc Welding ◽  
Electric Arc Welding ◽  
And Control

Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.

scholarly journals Contributions Regarding the Use of Mechanical Vibrations in Order to Improve the Properties of Steels and Welded Joints Used in Metal Constructions

2020 ◽  
Vol 21 (2) ◽  
pp. 67-71
Author(s):  
Gheorghe Novac ◽  
Bogdan Novac
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Significant Contribution ◽  
Welding Process ◽  
Internal Stresses ◽  
Welding Equipment ◽  
Welding Technology ◽  
Submerged Arc ◽  
Very High

The paper presents aspects regarding the influence of vibrations on the mechanical properties of welded joints, made with basic materials of Spanish and Romanian origin. In this research is presented the practical way to make the necessary assemblies for the proposed tests. The tests show that vibrations have a significant contribution to the quality of welded joints. This is explained by the appearance of several crystallization centres which makes the structure finer. By using vibrations, the atoms are rearranged in the structure, ensuring a proper de-tensioning. The stresses induced in welded metals are significantly reduced by the use of vibration during welding process. The addition materials have a significant contribution to the emergence of stresses in welded joints as well. These stresses can contribute to the appearance of microstructural constituents with significant hardness. The welding equipment and technologies used also have a significant contribution to the emergence of the remaining stresses. For example, the submerged arc welding technology (SAF) can introduce very high internal stresses. By using vibrations during the welding process, it is achieved a fine structure and a significant reduction of remaining stresses in the welded joints.

The Effect of Sub-Zero Treatment on Mechanical Properties of GTAW Welded AA6082

2016 ◽  
Vol 852 ◽  
pp. 349-354 ◽  
Author(s):  
R. Devanathan ◽  
Sanjivi Arul ◽  
T. Venkatamuni ◽  
D. Yuvarajan ◽  
D. Christopher Selvam
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Artificial Aging ◽  
Cryogenic Treatment ◽  
Welding Process ◽  
Travel Speed ◽  
Treatment Result ◽  
Gas Tungsten Arc ◽  
Shallow Cryogenic Treatment ◽  
Hardness Values

The consequence of sub-zero treatment on the mechanical properties of welded AA6082-T6 by Gas Tungsten Arc Welding (GTAW) which in turn softens the heat concentrated welded region owing to dissolution of the strengthening precipitates. The sub-zero i.e. Shallow Cryogenic Treatment (SCT) is carried out on GTAW welded plate having a thickness of 6 mm at -77°C by varying the electrode travel speed and sub-zero treatment periods. Welded region of AA6082 were tested for hardness and microstructure by adapting three different conditions such as welded, post weld artificial aging with and without sub-zero treatment. Result revealed that the amount of softening in the welded region is indirectly proportional to electrode travel speed during welding process. It is also observed that the post weld SCT with artificial aging has increased the micro hardness values on the welded region as a consequence of the reactivation in the sequence of precipitation.

A study on sustainability assessment of welding processes

2019 ◽  
Vol 234 (3) ◽  
pp. 501-512 ◽  
Author(s):  
Jaber Jamal ◽  
Basil Darras ◽  
Hossam Kishawy
Keyword(s):  
Arc Welding ◽  
Social Impact ◽  
Sustainability Assessment ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Friction Stir ◽  
Gas Tungsten Arc ◽  
Metal Arc Welding ◽  
Sustainability Assessments ◽  
Welding Processes

The concept of “sustainability” has recently risen to take the old concept of going “green” further. This article presents general methodologies for sustainability assessments. These were then adapted to measure and assess the sustainability of welding processes through building a complete framework, to determine the best welding process for a particular application. To apply this methodology, data about the welding processes would be collected and segregated into four categories: environmental impact, economic impact, social impact, and physical performance. The performance of each category would then be aggregated into a single sustainability score. To demonstrate the capability of this methodology, case studies of three different welding processes were performed. Friction stir welding obtained the highest overall sustainability score compared to gas tungsten arc welding and gas metal arc welding.

Wet Welding as a “Serious” Repair Procedure?

1998 ◽  
Vol 120 (3) ◽  
pp. 191-196 ◽  
Author(s):  
P. Szelagowski
Keyword(s):  
Welding Process ◽  
High Hardness ◽  
Field Application ◽  
Oil Field ◽  
Quality Data ◽  
Design Criteria ◽  
High Porosity ◽  
High Hydrogen ◽  
Research Activities ◽  
Welding Processes

Due to intensive and concentrated research activities during the last 10 to 15 yr, the quality of wet-welded joints has been improved to an extent that this process is currently regarded as a potential alternative to the more costly dry hyperbaric welding processes in comparable water depths. The wet welding process has matured to an interesting alternative repair process due to its high flexibility and versatility and its low investment costs with respect to achieving comparable weldment quality. However, due to the previous bad reputation of the poor weldment quality in former times, related to extremely high hardness, high porosity, high hydrogen contamination, and, in combination with this, high cracking susceptibility, the wet welding process still requires concentrated activities to improve its reputation and credibility, especially in European oil field application. New acceptance creiteria, more detailed information on the achievable weldment quality, and especially the development of life-predicting data for wet-welded components on the one hand, and new design criteria especially related to the process application in wet environment as well as excellent training of diver welders on the other hand, have been required. Advanced testing methods had to be applied, additional design criteria had to be developed, and achievable weldment quality data had to be included in acknowledged and approved standards and recommendations in training and certification standards for diver welders. All these data are now available. These results have been achieved with the financial support of the European Community through the THERMIE PROJECT FUNDING.

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