Optimization of a Weld Overlay on a Plate Structure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
John Goldak ◽  
Mahyar Asadi ◽  
Jianguo Zhou ◽  
Stanislav Tchernov ◽  
Dan Downey
Keyword(s):  
Welding Process ◽  
Francis Turbine ◽  
Transient Temperature ◽  
Weld Repair ◽  
Weld Overlay ◽  
Hydroelectric Project ◽  
Repair Procedure ◽  
Strain Stress ◽  
Welding Direction ◽  
Interpass Temperature

An overlay weld repair procedure on a 1066.8×1066.8 mm2 square plate 25.4 mm thick was simulated to compute the 3D transient temperature, microstructure, strain, stress, and displacement of the overlay weld repair procedure. The application for the overlay was the repair of cavitation erosion damage on a large Francis turbine used in a hydroelectric project. The overlay weld consisted of a 4×6 pattern of 100×100 mm2 squares. Each square was covered by 15 weld passes. Each weld pass was 100 mm long. The total length of weld in the six squares was 36 m. The welds in each square were oriented either front-to-back or left-to-right. The welding process was shielded metal arc. The analysis shows that alternating the welding direction in each square produces the least distortion. A delay time of 950 s between the end of one weld pass and the start of the next weld pass was imposed to meet the requirement of a maximum interpass temperature to 50°C.

Weld Repair for Pressure Vessels Made From Cr-Mo Steels

2010 ◽  
Author(s):  
Rinzo Kayano ◽  
Eiichi Yamamoto ◽  
Takayasu Tahara
Keyword(s):  
Temper Embrittlement ◽  
Welding Process ◽  
Pressure Vessels ◽  
Research Committee ◽  
Weld Repair ◽  
Repair Welding ◽  
Term Operation ◽  
Repair Procedure ◽  
Past Experiences

Pressure vessels made from Cr-Mo steels are utilized for high temperature and high pressure services including hot hydrogen services. After long term operation, there are several past experiences of damages and/or degradation of materials such as temper embrittlement, creep embrittlement, hydrogen attack and hydrogen embrittlement. This paper summarizes typical damages/degradation and examples of weld repairs including special attention to development of weld repair procedure. The subject equipments are heavy wall petroleum pressure vessels made from Cr-Mo steel with austenitic stainless steel overlay cladding. Cracking could be prevented by controlling the repair welding process to reduce the hydrogen content at the interface. After repair welding, adequate post weld heat treatment (PWHT) has to be executed. Recently, repair welding has become an important aspect as part of post construction codes for pressure equipment to keep safe and long term continuous operation of the process plants because many of the plants have been operated for more than thirty years in Japan. Responding to the needs of petroleum and chemical industries, The Chemical Plant Welding Research Committee (CPWRC) of The Japan Welding Engineering Society (JWES) established the Pressure Equipment Repair Welding Subcommittee (PERW S/C) [1]. The S/C has developed optimum repair welding methods and procedures in the guideline on November 2009, with reference to the above investigation results. This paper also introduces the repair welding guideline for the pressure vessels made from Cr-Mo steels.

Assessment of the Influence of the Use of Weld Overlay As a Repair Method on the Stress Level of Bulged Sections of Coke Drums

2017 ◽  
Author(s):  
Gabriel A. Vivas ◽  
Armando J. Moret ◽  
Roberto E. Bello ◽  
Luis M. Melian ◽  
Egler D. Araque
Keyword(s):  
Low Cycle Fatigue ◽  
Mechanical Analysis ◽  
Deformation Pattern ◽  
Cycle Fatigue ◽  
Weld Repair ◽  
Element Analysis ◽  
Weld Overlay ◽  
Repair Method ◽  
External Reinforcement ◽  
Repair Procedure

Several studies recognized that cracks in delayed coke drums resulted from low cycle fatigue induced by cyclic thermal stress [1], [2], [3]. According to a coke drum survey coordinated by API in 1996 [1], there are two different areas where cracks are produced. The first zone is located at the shell to skirt weld, and the second at the bulged areas found in the cylindrical section. In the second case, from 145 coke drums 57% reported that had shell bulging problems. Of the drums that bulged, 87 % also showed cracks. Recently, it has been reported the use of a novel weld repair procedure on bulged sections of a drum. In this repair, the bulge is overlaid with weld metal on the inside or outside on the bulge depending on the bulge shape. It has been reported that this repair procedure can stop further bulging on the shell, but detailed information about its influence has not yet been published. Finite element analysis of several bulged patterns that were identified from some laser mappings are used to compare the level of the stress after a weld overlay repair is made. The study was carried out running a sequentially-coupled thermo-mechanical analysis. The assessment shows the influence of the thickness and the extent of the weld overlay on the level of stress on bulged coke drums. The results indicated that depending on the initial bulged shape this repair method either reduces or increases the level of the stress. When an inward deformation pattern is observed, an external reinforcement is recommended; however, when an outward deformation pattern is developed in a coke drum, an external weld overlay repair is not recommended.

Virtual Optimization of Regulating and Controlling on Welding Residual Stress of Francis Turbine Runner

2011 ◽  
Vol 704-705 ◽  
pp. 762-769
Author(s):  
Shu De Ji ◽  
Xue Song Liu ◽  
Jian Guo Yang ◽  
Zhen Lei Liu
Keyword(s):  
Residual Stress ◽  
Heating Temperature ◽  
Local Heating ◽  
Welding Process ◽  
Heating Time ◽  
Welding Residual Stress ◽  
Francis Turbine ◽  
Turbine Runner ◽  
Welding Direction ◽  
Heating Technology

In order to solve the problem of crack appeared in Francis turbine runner, the welding residual stress of Francis turbine runner is regulated and controlled by means of numerical simulation from the view of subsection welding, local heating and local peening. The results show that the length of welding section of blade outlet and the welding direction in the subsection welding process influence the residual stress of the turbine blade. For the local heating technology, the decreasing effect on residual stress increases with the increase of heating time, heating temperature and heating area. The welding residual stress of dangerous region decreases and then increases with the increase of heating distance. Moreover, the peening effect is very clear when the temperature of material in the peening region reaches its own plastic temperature.

Post Weld Overlay Residual Stresses in Dissimilar Metal Welds Considering Various Butt Weld and Weld Repair Fabrication Sequences

2009 ◽  
Author(s):  
Francis H. Ku ◽  
Christopher S. Lohse ◽  
David G. Dijamco ◽  
Charles J. Fourcade ◽  
Richard L. Bax ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Welding Process ◽  
Reasonable Assumption ◽  
Weld Repair ◽  
Pressurized Water ◽  
Butt Weld ◽  
Weld Overlay ◽  
Water Reactor ◽  
Dissimilar Metal ◽  
Pipe Size

Weld overlays have been used to repair or mitigate stress corrosion cracking (SCC) in both boiling water reactor (BWR) and pressurized water reactor (PWR) nozzle-to-pipe dissimilar metal welds (DMW). One of the contributing factors to SCC is the high tensile residual stresses produced during the fabrication of the original butt weld, especially when local weld repairs were present during the welding process. In analytical simulations to determine the post weld overlay residual stresses, complete simulation of the original butt weld, weld repair and the overlay is desired. However, to reduce the computational effort, it is commonly assumed that the weld repair stresses overwhelm the original butt weld residual stresses such that the original butt weld need not be simulated and only the weld repair is simulated before the application of the overlay. Questions have also been raised as to why the butt weld and/or the weld repair need to be simulated since it is assumed that both of these fabrication processes would be overcome by the weld overlay process. This paper investigates three fabrication sequences in order to determine their effect on the post weld overlay residual stresses: (1) the butt weld is simulated followed by a weld repair and then the weld overlay is applied; (2) the butt weld is simulated followed by the weld overlay with no consideration of a weld repair; (3) the butt weld is not simulated but a weld repair is assumed and the weld overlay is applied. Five different nozzle-to-pipe size configurations were used in the study to determine the effect of pipe size on the three fabrication sequences described above. The investigation indicates that the post weld overlay residual stresses for Cases 1 and 3 are similar and hence simulation of the weld repair alone (without the butt weld simulation) prior to simulating the weld overlay is a reasonable assumption. However, not simulating the weld repair (corresponding to Case 2) may provide different residual stress distribution.

G-30 FILLER METAL

Alloy Digest ◽  
1993 ◽  
Vol 42 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Filler Metal ◽  
Weld Repair ◽  
Weld Overlay ◽  
High Chromium ◽  
Cast Products

Abstract Hastelloy Alloy G-30 filler metal is used as matching composition filler metal for fabrication of Hastelloy G-30 wrought and cast products and as filler metal for fabrication of G/G-3 alloy wrought products. It is also used for weld repair of high chromium castings and for weld overlay cladding. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as joining. Filing Code: Ni-432. Producer or source: Haynes International Inc.

scholarly journals Capability of Advanced Ultrasonic Inspection Technologies for Hydraulic Turbine Runners

2021 ◽  
Vol 11 (10) ◽  
pp. 4681
Author(s):  
Mohammad Ebrahim Bajgholi ◽  
Gilles Rousseau ◽  
Martin Viens ◽  
Denis Thibault
Keyword(s):  
Ultrasonic Inspection ◽  
High Stress ◽  
Welding Process ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Detection Rates ◽  
Critical Range ◽  
Area Of Interest ◽  
Ambitious Program ◽  
Pulse Echo

This paper presents the results of a project aimed at evaluating the performance of ultrasonic techniques for detecting flaws in Francis turbine runners. This work is the first phase of a more ambitious program aimed at improving the reliability of inspection of critical areas in turbine runners. Francis runners may be utilized to supply power during peak periods, which means that they experience additional load stress associated with start and stop sequences. Inspection during manufacturing is then of paramount importance to remove as much as feasible all flaw initiation sites before the heat treatment. This phase one objective is to collect initial data on a simplified mock-up and then to compare the experimental ultrasonic data with the results of simulations performed by CIVA, a computer simulation package. The area of interest is the region with the highest stress between the blade and the web. A welded T-joint coupon made of UNS S41500 was manufactured to represent this high-stress area. During the FCAW welding process, ceramic beads were embedded in the weld to create discontinuities whose size is in the critical range to initiate a crack. Inspection of the material was carried out by various nondestructive testing (NDT) methods namely conventional pulse-echo, phased array, total focusing method (TFM). With these results, detection rates were obtained in order to compare the effectiveness of each method.

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Hang Li ◽  
Hongseok Choi ◽  
Chao Ma ◽  
Jingzhou Zhao ◽  
Hongrui Jiang ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Heat Generation ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Transient Temperature ◽  
Monitoring And Control ◽  
Change Rate ◽  
Flux Change ◽  
And Control

Process physics understanding, real time monitoring, and control of various manufacturing processes, such as battery manufacturing, are crucial for product quality assurance. While ultrasonic welding has been used for joining batteries in electric vehicles (EVs), the welding physics, and process attributes, such as the heat generation and heat flow during the joining process, is still not well understood leading to time-consuming trial-and-error based process optimization. This study is to investigate thermal phenomena (i.e., transient temperature and heat flux) by using micro thin-film thermocouples (TFTC) and thin-film thermopile (TFTP) arrays (referred to as microsensors in this paper) at the very vicinity of the ultrasonic welding spot during joining of three-layered battery tabs and Cu buss bars (i.e., battery interconnect) as in General Motors's (GM) Chevy Volt. Microsensors were first fabricated on the buss bars. A series of experiments were then conducted to investigate the dynamic heat generation during the welding process. Experimental results showed that TFTCs enabled the sensing of transient temperatures with much higher spatial and temporal resolutions than conventional thermocouples. It was further found that the TFTPs were more sensitive to the transient heat generation process during welding than TFTCs. More significantly, the heat flux change rate was found to be able to provide better insight for the process. It provided evidence indicating that the ultrasonic welding process involves three distinct stages, i.e., friction heating, plastic work, and diffusion bonding stages. The heat flux change rate thus has significant potential to identify the in-situ welding quality, in the context of welding process monitoring, and control of ultrasonic welding process. The weld samples were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to study the material interactions at the bonding interface as a function of weld time and have successfully validated the proposed three-stage welding theory.

Welding Robot Welding Process Research and Development of Intelligent Technology

2013 ◽  
Vol 419 ◽  
pp. 774-777
Author(s):  
Ji Ming Yi ◽  
Min Han
Keyword(s):  
Vision System ◽  
Welding Process ◽  
Depth Information ◽  
Laser Sensor ◽  
Automatic Welding ◽  
Welding Robot ◽  
Existing Problems ◽  
Intelligent Technology ◽  
Welding Direction ◽  
Binocular Vision System

The welding direction of robot and existing problems, the groove plate is difficult to realize automatic welding robot problem, methods using laser sensor and a binocular vision system combines, image and depth information extraction plate groove groove, realize accurate 3D reconstruction.

A Comparison Between Three- and Two-Dimensional Thermal Finite Element Analysis of the Gas Metal Arc Welding Process

2003 ◽  
Author(s):  
Mohammad S. Davoud ◽  
Xiaomin Deng
Keyword(s):  
Finite Element ◽  
3D Model ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Element Model ◽  
Transient Temperature ◽  
Two Dimensional ◽  
Element Analysis ◽  
Cross Sectional ◽  
2D Model

Predictions of transient temperature distributions in welding can help the selection of welding process parameters that minimize residual stresses. A three-dimensional (3D) thermal finite element model of bead-on-plate gas metal are welding (GMAW) is presented and is used to evaluate a cross-sectional, two-dimensional (2D) counterpart model. While the thermomechanical problem of welding is 3D in nature, it is shown that the 2D model can provide temperature field predictions comparable to those of the 3D model, even though the 2D model tends to predict peak temperatures higher than those of the 3D model. Both types of model predictions are compared to welding test measurements.

Plasma Arc Welding for Code Compliance Nuclear Applications

2020 ◽  
Author(s):  
Dongmei (Donna) Sun ◽  
Rob Pistor
Keyword(s):  
Arc Welding ◽  
Welding Process ◽  
Nuclear Industry ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Hot Wire ◽  
Weld Overlay ◽  
Nuclear Component ◽  
Wire Feeding ◽  
Code Compliance

Abstract Plasma Arc Welding (PAW) has been used for many critical applications due to its flexibility, reliability and high weld quality. In this paper, two code compliance plasma arc welding applications in the nuclear industry are discussed. The first application is an innovative welding process using PAW with specially designed dual hot wire feeding system, namely Dual Hot Wire Gas Metal Plasma Arc Welding (GMPAW). The GMPAW process offers unique advantages for high deposition and low dilution weld overlay application. The second application is a remote weld overlay repair from pipe inside diameter (ID) for a highly radiated nuclear component using PAW process with remote machining and NDE capability. In this paper, the benefits and advantages are provided for the aforementioned PAW applications. The versatility of plasma arc welding system configuration, as well as high quality and productivity can make plasma arc welding a good candidate for many critical code compliance applications.

Sign in / Sign up

Export Citation Format

Share Document