Computational Simulation of Line-Pipe Fabrication Processes

2006 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong ◽  
B. N. Leis ◽  
P. S. Lopez ◽  
R. G. Chavela ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Welding Parameters ◽  
Radial Expansion ◽  
Split Ring ◽  
Line Pipe ◽  
Seam Welding ◽  
Ring Testing

Line pipe fabrication involves plate forming and seam welding, for which the forming process is continuous for some processes. Residual stresses that are important in line pipe performance, particularly for sour service, reflect the interaction between the plate forming, radial expansion, and welding-induced thermal and local plastic deformation. These mechanisms interact to produce a complex three-dimensional residual stress field. This paper uses an advanced computational simulation procedure to simulate the detailed forming and welding interactions and their combined effects on thermal and residual stress development. Such technology can be used to guide fabrication procedures and optimize radial expansion as well as welding parameters, which more typically reflect trial and error type decisions. The simulation process is first outlined and then applied to a specific pipe diameter and wall thickness ratio. Detailed three-dimensional finite-element-based simulations of the spiral seam welding process are then presented considering both plate forming/radial expansion effects and their interactions with seam welding. Validation experiments are presented whereby simulation outputs are directly compared to measured data. Finally, use of pipe split-ring testing is simulated to evaluate its ability to quantify the residual stresses. Not surprisingly, such results show steep through-wall gradients in the hoop and axial components, with levels for some components well above the yield stress. Cold expansion is shown to be beneficial in terms of relief of the hoop component, but potentially detrimental for the longitudinal weld component. Pipe parameters like diameter to thickness and grade are considered. The utility of split-ring testing is evaluated analytically, and compared to typical results for expanded line pipe.

scholarly journals EFFECTS OF WELDING CURRENT AND SPEED ON RESIDUAL STRESS AND DISTORTION OF JOINING ST52 ROLLED PLATE IN DIFFERENT WELDING SEQUENCES

2020 ◽  
Vol 3 (2) ◽  
pp. 40-45
Author(s):  
Ali Aminifar ◽  
Alireza M. Haghighi
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Welding Current ◽  
Element Model ◽  
Rolled Plate ◽  
Main Step ◽  
Welding Parameters ◽  
Effective Parameters ◽  
Welding Sequences

Welding is a process of permanent joining parts by different welding methods. Residual stress and distortion are the most common phenomena of this process. Reduction of the residual stresses, distortion and improving the quality of welding are the important subjects of this field. Determining and analyzing the residual stresses and distortion is the main step for these purposes. Welding sequences, speed and current are the most effective parameters of this process. In this study, effects of welding parameters such as welding speed and current, in order to reduce residual stress and distortion of welding ST52 rolled plate in different welding sequences have been studied with three-dimensional thermo-mechanical finite element model by means of ANSYS APDL. By comparing different considered situations, the most efficient welding methods with the least residual stress and distortion by considering different welding sequences have been suggested. It obtains that welding the ST52 rolled plate from edge to edge with higher current and lower speed is the best option in fatigue and load-bearing situations, and welding from the center to both sides simultaneously with lower current and higher speed is the best option for assembly problems.

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model

2012 ◽  
Author(s):  
Abul Fazal M. Arif ◽  
Ahmad S. Al-Omari ◽  
Anwar K. Sheikh ◽  
Yagoub Al-Nassar ◽  
M. Anis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Role ◽  
Large Diameter ◽  
Element Model ◽  
Regression Equation ◽  
Field Analysis ◽  
Welding Parameters ◽  
Splitting Test ◽  
Welded Pipe

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.

scholarly journals Study on Residual Stress of Welded Hoop Structure

2020 ◽  
Vol 10 (8) ◽  
pp. 2838
Author(s):  
Wenbo Ma ◽  
Heng Zhang ◽  
Wei Zhu ◽  
Fu Xu ◽  
Caiqian Yang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Welding Speed ◽  
Weld Seam ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Welding Residual Stress ◽  
Welding Parameters ◽  
Forming Process ◽  
Maximum Residual Stress

Residual stress is inevitable during welding, which will greatly affect the reliability of the structure. The purpose of this paper was to study the residual stress of the hoop structure caused by the cooling shrinkage of the weld when the outer cylinder was wrapped and welded under the condition of the existing inner cylinder. In this paper, the “method of killing activating elements” of ANSYS was used to simulate the three-dimensional finite element of the hoop structure. In the case of applying interlayer friction, the welding-forming process and welding circumferential residual stress of the hoop structure were analyzed. The blind hole method was used to test the residual stress distribution of the hoop structure, and the test results were compared with the finite element simulation results to verify the reliability of the simulation calculation method and the reliability of the calculation results. Then, the influence factors of the maximum welding residual stress of the hoop structure were studied. The results show that the maximum residual stress of the outer plate surface of the hoop structure decreases with the increase of the welding energy, the thickness of the laminate, the width of the weld seam, the welding speed, and the radius of the container. Based on the results of numerical simulation, the ternary first-order equations of the maximum residual stress of the hoop structure with respect to the welding speed, the thickness of the laminate, and the width of the weld seam were established. Then, the optimal welding parameters were obtained by optimizing the equations, which provided an important basis for the safe use and optimal design of the welding hoop structure.

Residual Stresses in Steel and Zirconium Weldments

1997 ◽  
Vol 119 (2) ◽  
pp. 137-141 ◽  
Author(s):  
J. H. Root ◽  
C. E. Coleman ◽  
J. W. Bowden ◽  
M. Hayashi
Keyword(s):  
Residual Stress ◽  
Electron Beam ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Prolonged Exposure ◽  
Electron Beam Welding ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Outer Diameter ◽  
Stress Relieving

Three-dimensional scans of residual stress within intact weldments provide insight into the consequences of various welding techniques and stress-relieving procedures. The neutron diffraction method for nondestructive evaluation of residual stresses has been applied to a circumferential weld in a ferritic steel pipe of outer diameter 114 mm and thickness 8.6 mm. The maximum tensile stresses, 250 MPa in the hoop direction, are found at mid-thickness of the fusion zone. The residual stresses approach zero within 20 mm from the weld center. The residual stresses caused by welding zirconium alloy components are partially to blame for failures due to delayed hydride cracking. Neutron diffraction measurements in a GTA-welded Zr-2.5Nb plate have shown that heat treatment at 530°C for 1 h reduces the longitudinal residual strain by 60 percent. Neutron diffraction has also been used to scan the residual stresses near circumferential electron beam welds in irradiated and unirradiated Zr-2.5Nb pressure tubes. The residual stresses due to electron beam welding appear to be lower than 130 MPa, even in the as-welded state. No significant changes occur in the residual stress pattern of the electron-beam welded tube, during a prolonged exposure to thermal neutrons and the temperatures typical of an operating nuclear reactor.

Fast Three-Dimensional Finite Element Analysis of Weld Overlay Application on a Formed Feeder Elbow

2011 ◽  
Author(s):  
Francis H. Ku ◽  
Pete C. Riccardella
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fe Method ◽  
Element Analysis ◽  
Weld Overlay ◽  
Welding Processes

This paper presents a fast finite element analysis (FEA) model to efficiently predict the residual stresses in a feeder elbow in a CANDU nuclear reactor coolant system throughout the various stages of the manufacturing and welding processes, including elbow forming, Grayloc hub weld, and weld overlay application. The finite element (FE) method employs optimized FEA procedure along with three-dimensional (3-D) elastic-plastic technology and large deformation capability to predict the residual stresses due to the feeder forming and various welding processes. The results demonstrate that the fast FEA method captures the residual stress trends with acceptable accuracy and, hence, provides an efficient and practical tool for performing complicated parametric 3-D weld residual stress studies.

scholarly journals Crack Growth Behavior in a Residual Stress Field for Vessel Type Structures

2003 ◽  
Author(s):  
P. Dong ◽  
G. Rawls
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Surface Crack ◽  
Growth Behavior ◽  
Welding Parameters ◽  
Crack Growth Behavior ◽  
Butt Weld ◽  
Small Surface ◽  
Longitudinal Residual Stress

Detailed residual stress analysis was performed for a multi-pass butt weld, representing the middle butt-girth weld of a storage tank. The analysis procedures addressed welding parameters, joint detail, weld pass deposition sequence, and temperature-dependent properties. The predicted residual stresses were then considered in stress intensity factor calculations using a three-dimensional finite element alternating model (FEAM) for investigating crack growth behavior for both small elliptical surface and through-wall cracks. Two crack orientations were considered: one is parallel to the vessel girth weld and the other is perpendicular to the girth weld. Since the longitudinal (parallel to weld) and transverse (perpendicular to weld) residual stresses exhibit drastically different distributions, a different crack growth behavior is predicted. For a small surface crack parallel to the weld, the crack tends to grow more quickly at the surface along the weld rather than into the thickness. The self-equilibrating nature of the transverse residual stress distribution suggests that a through-wall crack parallel to crack cannot be fully developed solely due to residual stress actions. For a crack that is perpendicular to the weld, a small surface crack exhibit a rapid increase in K at the deepest position, suggesting that a small surface crack has the propensity to become a through-wall crack. Once the through crack is fully developed, a significant re-distribution in longitudinal residual stress can be seen. As a result, in the absence of external loads there exists a limiting crack length beyond which further crack growth is deemed unlikely.

Modeling Residual Stresses in Superduplex Stainless Steel Welded Pipes Using the Finite Element Method

2013 ◽  
Vol 758 ◽  
pp. 1-10
Author(s):  
Fabiano Rezende ◽  
Luís Felipe Guimarães de Souza ◽  
Pedro Manuel Calas Lopes Pacheco
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Welding Process ◽  
Welding Parameters ◽  
Superduplex Stainless Steel ◽  
Mechanical Components ◽  
Element Method

Welding is a complex process where localized and intensive heat is imposed to a piece promoting mechanical and metallurgical changes. Phenomenological aspects of welding process involve couplings among different physical processes and its description is unusually complex. Basically, three couplings are essential: thermal, phase transformation and mechanical phenomena. Welding processes can generate residual stress due to the thermal gradient imposed to the workpiece in association to geometric restrictions. The presence of tensile residual stresses can be especially dangerous to mechanical components submitted to fatigue loadings. The present work regards on study the residual stress in welded superduplex stainless steel pipes using experimental and a numerical analysis. A parametric nonlinear elastoplastic model based on finite element method is used for the evaluation of residual stress in superduplex steel welding. The developed model takes into account the coupling between mechanical and thermal fields and the temperature dependency of the thermomechanical properties. Thermocouples are used to measure the temperature evolution during welding stages. Instrumented hole drilling technique is used for the evaluation of the residual stress after welding process. Experimental data is used to calibrate the numerical model. The methodology is applied to evaluate the behavior of two-pass girth welding (TIG for root pass and SMAW for finishing) in 4 inch diameter seamless tubes of superduplex stainless steel UNS32750. The result shows a good agreement between numerical experimental results. The proposed methodology can be used in complex geometries as a powerful tool to study and adjust welding parameters to minimize the residual stresses on welded mechanical components.

A Study of Residual Stresses and Microstructure in 2024-T3 Aluminum Friction Stir Butt Welds

2002 ◽  
Vol 124 (2) ◽  
pp. 215-221 ◽  
Author(s):  
M. A. Sutton ◽  
A. P. Reynolds ◽  
D.-Q. Wang ◽  
C. R. Hubbard
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Weld Line ◽  
Free Edge ◽  
Two Dimensions ◽  
Grain Structure ◽  
Friction Stir ◽  
Shoulder Diameter ◽  
Shoulder Region

Three-dimensional residual stress mapping of an aluminum 2024-T3 arcan specimen, butt-welded by the friction stir technique, was performed by neutron diffraction. Results indicate that the residual stress distribution profiles across the weld region are asymmetric with respect to the weld centerline, with the largest gradients in the measured residual stress components occurring on the advancing side of the weld, with the longitudinal stress, σL, oriented along the weld line, as the largest stress. Within the region inside the shoulder diameter, the through-thickness stress, σZ, is entirely compressive, with large gradients occurring along the transverse direction just beyond the shoulder region. In addition, results indicate a significant reduction in the observed residual stresses for a transverse section that was somewhat closer to the free edge of an Arcan specimen. Microstructural studies indicate that the grain size in the weld nugget, is approximately 6.4 microns, with the maximum extent of the recrystallized zone extending to 6 mm on each side of the weld centerline. Outside of this region, the plate material has an unrecrystallized grain structure that consists of pancake shaped grains ranging up to several mm in size in two dimensions and 10 microns in through-thickness dimension.

Evaluation of Residual Stresses in Small Diameter Stainless Steel Pipe Welds by Two-Dimensional and Three-Dimensional Finite Element Analyses

2014 ◽  
Author(s):  
Francis H. Ku ◽  
Trevor G. Hicks ◽  
William R. Mabe ◽  
Jason R. Miller
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Steel Pipe ◽  
3D Analysis ◽  
Two Dimensional ◽  
Finite Element Analyses ◽  
Stainless Steel Pipe

Two-dimensional (2D) and three-dimensional (3D) weld-induced residual stress finite element analyses have been performed for 2-inch Schedule 80 Type-304 stainless steel pipe sections joined by a multi-layer segmented-bead pipe weld. The analyses investigate the similarities and differences between the two modeling approaches in terms of residual stresses and axial shrinkage induced by the pipe weld. The 2D analyses are of axisymmetric behavior and evaluate two different pipe end constraints, namely fixed-fixed and fixed-free, while the 3D analysis approximates the non-axisymmetric segmented welding expected in production, with fixed-free pipe end constraints. Based on the results presented, the following conclusions can be drawn. The welding temperature contour results between the 2D and 3D analyses are very similar. Only the 3D analysis is capable of simulating the non-axisymmetric behavior of the segmented welding technique. The 2D analyses yield similar hoop residual stresses to the 3D analysis, and closely capture the maximum and minimum ID surface hoop residual stresses from the 3D analysis. The primary difference in ID surface residual stresses between the 2D fixed-fixed and 2D fixed-free constraints cases is the higher tensile axial stresses in the pipe outside of the weld region. The 2D analyses under-predict the maximum axial residual stress compared to the 3D analysis. The 2D ID surface residual stress results tend to bound the averaged 3D results. 2D axisymmetric modeling tends to significantly under-predict weld shrinkage. Axial weld shrinkage from 3D modeling is of the same magnitude as values measured in the laboratory on a prototypic mockup.

Sign in / Sign up

Export Citation Format

Share Document