The Essential Welding Variable Methodology and its Application in Welding Procedure Development for Mechanized Girth Welds of X100 Line Pipes

2014 ◽  
Author(s):  
Scott Funderburk ◽  
Paul Spielbauer ◽  
Yaoshan Chen ◽  
Marie Quintana
Keyword(s):  
Mechanical Properties ◽  
Welding Parameters ◽  
Practical Case ◽  
Analysis Tool ◽  
Thermal Cycles ◽  
Pipe Welding ◽  
Weld Properties ◽  
Girth Welds ◽  
Welding Procedure ◽  
Procedure Development

The mechanical properties of X100 pipeline girth welds are quite sensitive to welding parameters and the design range for a viable welding procedure is narrower compared to pipeline steels of lower grades. The use of a high-productivity welding process, such as dual-torch gas metal arc welding (GMAW), further compounds the dependency of weld properties on welding parameters. Consequently, for X100 pipe welding procedure development, the path to achieve the required weld performance can be a time-consuming and costly process. Developed in a recently completed project, the essential welding variable methodology provides an effective approach to optimize the development process for X100 pipe welding, with the benefits of reducing development time and saving cost. The present paper presents a practical case study of the methodology for girth welds. The present paper focuses on the information needed and the analyses performed in the application of the methodology to the process of welding procedure development for a dual-torch pulsed GMAW (GMAW-P) procedure. Using an analysis tool that can predict the thermal cycles from welding parameters and the available knowledge of microstructure and mechanical responses of both pipe materials and weld metals to welding thermal cycles (cooling rate), several candidates of dual-torch pulsed GMAW procedures were evaluated first for cooling times to help the determination of the final welding procedures. The finalized welding procedures used for the production of the qualification welds were evaluated to estimate the mechanical properties of the girth welds. The estimated weld properties will be compared to those from the test results when they become available.

Application of Thermal Analysis Tool for Girth Welding Procedure Qualification

2016 ◽  
Author(s):  
Aditya Dekhane ◽  
Alex Wang ◽  
Yong-Yi Wang ◽  
Marie Quintana
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Parameters ◽  
Analysis Tool ◽  
Thermal Cycles ◽  
Cooling Rates ◽  
Metal Arc Welding ◽  
Girth Welding ◽  
Welding Procedure

The mechanical properties of welds are governed by the final microstructure that develops as an interaction between the chemical composition and cooling rates produced by welding thermal cycles. For welds in modern microalloyed thermomechanically controlled processed (TMCP) pipeline steels, the microstructure and mechanical properties can be extremely sensitive to cooling rates. The development and qualification of welding procedures to achieve targeted mechanical properties is often an iterative process. Accurate knowledge of welding thermal cycles and cooling rates as a function of welding parameters is valuable for optimization of welding process development. This paper covers the development, validation, and application of a girth welding thermal analysis tool. The core of the tool is a numerical model that has a two-dimensional, axi-symmetrical finite element procedure to simulate the transient heat transfer processes both in the weld metal and the heat affected zone (HAZ). The tool takes welding parameters, pipe and bevel geometry, and thermal properties as inputs and predicts thermal cycles and cooling rates in weld metal and HAZ. The comparison of thermal cycles between experimental measurements and the model predictions show the tool was robust and accurate. This tool is particularly effective in understanding the thermal history and resulting microstructure and mechanical properties of welds produced with high-productivity gas metal arc welding (GMAW), such as mechanized dual-torch pulsed gas metal arc welding (DT GMAW-P). The tool was used in optimization of development and qualification of welding procedures of a DT GMAW-P process under a tight time schedule. The actual welds were fabricated according to the optimized welding procedures followed by the mechanical testing of welds. Good agreement was found between the predicted tensile properties and those from experimental tests. The welding procedures were qualified within the tight time schedule by avoiding iterative trials, and reducing the cost associated with the making of trial welds and mechanical testing by approximately 50%. This tool has also been applied in the application of essential welding variables methodology (EWVM) for X80 and X70 linepipe steels [1, 2]. Future applications of the tools include the revamp of the approach to essential variables in welding procedure qualification. In particular, the parameters affecting cooling rates may be “bundled” together towards the one critical factor affecting weld properties, i.e., cooling rate. The individual parameters may be varied beyond the limits in the current codes and standards as long as their combined effects make the cooling rate stay within a narrow band. It is expected that the same framework of approaches to GMAW processes can be extended other welding processes, such as FCAW and SMAW.

The Essential Welding Variable Approach and its Application to the Welding of X80 Line Pipe Steels

2014 ◽  
Author(s):  
Yaoshan Chen ◽  
Jim Gianetto ◽  
Fateh Fazeli ◽  
Yongli Sui ◽  
Haicheng Jin
Keyword(s):  
Welding Parameters ◽  
Pipe Steels ◽  
Thermal Cycles ◽  
Pipeline Steels ◽  
Variable Approach ◽  
Weld Properties ◽  
Girth Welds ◽  
Welding Consumables ◽  
Pipe Materials ◽  
Selection Of

A weld quality control approach developed for the welding of high-strength pipeline steels has demonstrated its effectiveness in achieving reliability and consistency in the mechanical performance of girth welds. Using a predictive tool that can relate cooling times of welding thermal cycles with welding parameters and with the knowledge of microstructure responses of both pipe materials and weld metals to welding thermal cycles, the approach can evaluate the effects of welding parameters on weld properties and identify the essential welding variables. As a result, the essential welding variable approach can be used to optimize and help shorten the process of welding procedure development. The current paper presents the application of the essential welding variable approach to the girth welding of X80 pipeline steels. The application started with the selection of pipe materials, welding consumables, and candidate welding procedures. The selection of actual weld procedures and a welding matrix were made after the candidate welding procedures were analyzed in terms of cooling times. Girth welds for two X80 pipes of different chemical compositions, outside diameters, and wall thicknesses were made with single and dual torch GMAW-P processes and a range of welding consumables. The welding parameters were monitored and recorded for all welds; and the thermal cycles of selected welds were measured by thermocouples. Small-scale testing, including all-weld-metal tensile test, Charpy impact toughness and CTOD fracture toughness tests, were evaluated and correlated with microstructures formed in the HAZ of the girth welds. The material responses of heat-affected zone (HAZ) to thermal cycles of typical GMAW-P single and dual torch processes were experimentally simulated (Gleeble®). Detailed welding thermal cycle analyses were conducted based on the measured welding parameters. Cooling times of welding thermal cycles for the girth welds were calculated and correlated with the material responses, of X80 pipe steels to welding thermal cycles. The correlation demonstrated very good consistency between the cooling times, the results of the Gleeble simulation, and the mechanical properties of the girth welds. The dependency of the weld properties on welding parameters was analyzed in terms of cooling times, and the optimization strategy for development of welding procedures that offer more balanced welding properties between strength and toughness was evaluated by adjusting the essential welding variables. In summary, the process of applying the essential welding variable approach and the results from the tests and the analyses showed that the approach is capable of evaluating the effects of welding parameters on weld properties, identifying the essential welding variables, and ultimately optimizing welding procedures.

Simulation of Microstructure Evolution and Its Experimental Verifications for Girth Welds in High-Strength Pipelines

2010 ◽  
Author(s):  
Yaoshan Chen ◽  
Yong-Yi Wang ◽  
James Gianetto ◽  
Vaidyanath Rajan ◽  
Marie Quintana
Keyword(s):  
Mechanical Properties ◽  
Microstructure Evolution ◽  
Thermal Model ◽  
Measurement Data ◽  
High Strength ◽  
Welding Parameters ◽  
Thermal Cycles ◽  
Microstructure Model ◽  
Girth Welds ◽  
Welding Processes

Girth Welding of high strength steels such as X80 or X100 poses a number of challenges because of the sensitivity of weld mechanical properties to variations in welding parameters and material properties. This dependency is further complicated by the application of alternative welding processes with multiple wires, tandem wire or dual torch welding, for example. In order to correlate the relation between weld mechanical properties and the welding conditions, an integrated thermal and microstructure model has been developed. Given the welding conditions, the thermal model is able to simulate the local thermal cycles for a girth weld with multiple passes and multiple electrode wires. In the mean time, a microstructure model, using the thermal cycles obtained from the thermal model as input, simulates the microstructure evolution both in the weld metal and the HAZ as the welding progresses. This paper presents the latest development of this microstructure model and its verification against metallurgical measurement data from X100 girth welds. These welds included girth welds made under practical welding conditions and experimental welds made with X100 plates. The measured hardness was compared to the predicted by the microstructure model. The comparison indicated that the microstructure was able to predict the hardness profiles in a multi-pass girth weld and the general trend of variation as a function of welding conditions. In order to improve the accuracy of hardness prediction, the areas of improvement in the microstructure model have been identified.

scholarly journals Effect of welding sequence and welding current on distortion, mechanical properties and metallurgical observations of orbital pipe welding on SS 316L

2021 ◽  
Vol 2 (12 (110)) ◽  
pp. 22-31
Author(s):  
Agus Widyianto ◽  
Ario Sunar Baskoro ◽  
Gandjar Kiswanto ◽  
Muhamad Fathin Ginanjar Ganeswara
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Welding Process ◽  
Welding Current ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Depth Of Penetration ◽  
Welding Sequence ◽  
Pipe Welding

Orbital pipe welding was often used to manufacture piping systems. In orbital pipe welding, a major challenge is the welding torch’s position during the welding process, so that additional methods are needed to overcome these challenges. This paper discusses the influence of welding sequence and welding current on distortion, mechanical properties and metallurgical observations in orbital pipe welding with SS 316L pipe square butt joints. The variation of the orbital pipe welding parameters used is welding current and welding sequence. The welding current used is 100 A, 110 A, and 120 A, while the welding sequence used is one sequence, two sequences, three sequences, and four sequences. The welding results will be analyzed from distortion measurement, mechanical properties test and metallurgical observations. Distortion measurements are made on the pipe before welding and after welding. Testing of mechanical properties includes tensile tests and microhardness tests, while metallurgical observations include macrostructure and microstructural observations. The results show that maximum axial distortion, transverse distortion, ovality, and taper occurred at a welding current of 120 A with four sequences of 445 µm, 300 µm, 195 µm, and 275 µm, respectively. The decrease in ultimate tensile strength is 51 % compared to the base metal’s ultimate tensile strength. Horizontal and vertical microhardness tests show that welding with one sequence produces the greatest microhardness value, but there is a decrease in the microhardness value using welding with two to four sequences. Orbital pipe welding results in different depths of penetration at each pipe position. The largest and smallest depth of penetration was 4.11 mm and 1.60 mm, respectively

Evolution of Linepipe Manufacturing and its Implications on Weld Properties and Pipeline Service

2016 ◽  
Author(s):  
Yong-Yi Wang ◽  
David Horsley ◽  
Steve Rapp
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Negative Impact ◽  
Critical Role ◽  
Microalloyed Steels ◽  
Thermal Cycles ◽  
Girth Welding ◽  
Girth Welds ◽  
Longitudinal Strains ◽  
Design Construction

Pipe grade is a dominant parameter in a pipeline’s service life. Critical decisions on the design, construction, and maintenance of pipelines are made on the basis of pipe grade. The implied assumptions or expectations are that pipes of the same grade would behave similarly and the experiences with a particular grade can be applied to all pipelines of the same grade. This simplification does not adequately take into account the other characteristics that are not represented by pipe grade, but can play a critical role in the safe and economical operation of pipelines. For instance, the evolution of steel-making processes and advancements in field welding practice can lead to significant differences in weld behavior among pipes of the same nominal grade. Most of the design, construction, and maintenance practices in the pipeline industry were established before the extensive use of modern control-rolled and microalloyed steels. With the exception of a few isolated research projects, the impacts of the fundamental changes in the steel metallurgy in modern microalloyed steels have not been systematically examined and understood. For instance, these steels may have very low strain-hardening capacity as a result of the TMCP process and may be subject to high levels of heat-affected zone (HAZ) softening due to their ultra-low carbon low-hardenability steel chemistry. HAZ softening reduces the longitudinal pipe strain capacity of girth welds, and low strain-hardening can potentially have a negative impact on tolerance to anomalies such as corrosion or mechanical damage. This paper starts with a brief review of linepipe manufacturing history with a focus on the chemical composition and rolling practices that directly affect the mechanical properties and the response to welding thermal cycles. The characteristics of linepipes made from modern microalloyed steels are contrasted with those made from vintage hot-rolled and normalized steels. The resulting mechanical properties of these two types of materials in the presence of welding thermal cycles are presented, and compared in terms of their behavior. The consequence of the weld characteristics is shown using examples of girth welds subjected to longitudinal strains. The implications of the pipe and weld characteristics on the design, field girth welding, and maintenance of pipelines are highlighted. Future directions and best practices in linepipe alloying and manufacturing strategies, linepipe specifications, field girth welding, and building strain-resistance girth welds are briefly described. It is emphasized that assessing the performance of pipelines based on their grades has fundamental shortfalls, and that gaps in codes and standards can lead to unexpected outcomes in pipeline integrity. In the long-run, revising relevant codes and standards is necessary to ensure consistent and reliable applications of new materials in the entire industry.

Examinations Regarding the Sour Gas Resistance of Girth Welds Carried Out on API Grade X80 Seamless Pipe Steel (Heavy Wall)

2014 ◽  
Author(s):  
Diana Toma ◽  
Jörg Wiebe ◽  
Dorothee Niklasch ◽  
Ashraf Koka
Keyword(s):  
High Strength ◽  
Mechanical Tests ◽  
Carbon Equivalent ◽  
Welding Parameters ◽  
Line Pipe ◽  
Sea Bed ◽  
Steel Grades ◽  
Girth Welds ◽  
Welding Procedure ◽  
Sour Gas

Various accessories such as buckle arrestors and J-lay collars are needed in some cases to successfully lay and secure an offshore pipeline on the sea bed. For such applications the using of high strength seamless pipes in Grade X70 and X80 with heavy wall are necessary. However, there is only small information regarding the welding procedure for such grades in heavy wall dimensions. In comparison to steels used for lower strength level, the chemistry of high strength steel pipes includes higher amounts of micro-alloying elements as well as requires a more complex heat treatment. Due to the higher carbon equivalent these steel grades react more sensitive on heat input during welding. Consequently, the range of welding parameters which ensure suitable mechanical properties has to be adapted. This article presents the results of weldability trials carried out on seamless API X80 heavy wall (> 50mm) line pipe. The welding trials were performed using different preheating temperatures and heat inputs followed by microstructure investigations and mechanical tests of the multilayer welds. The sour gas resistance has to be demonstrated by SSC-tests because it stays challenging to guarantee values below 250 HV10.

Thermal Simulation and Its Experimental Verifications for Girth Welds in High-Strength Pipelines

2010 ◽  
Author(s):  
Yaoshan Chen ◽  
Yong-Yi Wang ◽  
Vaidyanath Rajan ◽  
Marie Quintana
Keyword(s):  
Thermal Model ◽  
Gas Metal Arc Welding ◽  
Superposition Principle ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Parameters ◽  
Transfer Model ◽  
Thermal Cycles ◽  
Girth Welds ◽  
Welding Processes

Girth welds in high-strength pipeline constructions are often made with mechanized pulsed gas-metal-arc welding (P-GMAW) process. Welding of the high strength steels poses a number of challenges because of the sensitivity of weld mechanical properties to variations in welding parameters and material properties. In addition to the unique characteristics of narrow groove weld geometry and multiple weld passes, the fabrication of P-GMAW girth welds sometimes also employs alternative welding processes such as dual torch or tandem wire in order to increase pipeline construction productivity. In order to understand the dependency of weld properties on welding processes and their parameters, a transient thermal model for multi-pass girth weld had been proposed and successfully developed. The heat transfer model used the superposition principle of heat sources to handle the welding processes with multiple wires or multiple passes. This paper presents the latest development of this numerical approach and its verification against experimental measurements of thermal cycles from X100 girth welds under different welding conditions. A number of X100 pipe girth welds under different welding conditions were made for the verification purpose. The welding conditions include single torch and dual torch P-GMAW process, 1G and 5G welding. Thermocouples were placed in the heat-affected zone (HAZ) and the weld-pool for the measurements of thermal cycles. The measured thermal cycles and cooling times from 800°C to 500°C were compared to those predicted by the thermal model. Very good agreements between the measured results and the numerical prediction by the thermal model were achieved.

Dissimilar Friction Stir Welds in AA 5086-AA 2024: The Effect of Process Parameters on Microstructures and Mechanical Properties

2012 ◽  
Vol 445 ◽  
pp. 753-758 ◽  
Author(s):  
Seyed Ali Asghar Akbari Mousavi ◽  
S.H. Sham Abadi
Keyword(s):  
Mechanical Properties ◽  
Natural Aging ◽  
Age Hardening ◽  
Welding Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Friction Stir ◽  
Aa 2024 ◽  
Weld Properties ◽  
Microstructures And Mechanical Properties

The effect of tool traverse and rotation speeds on the microstructures and mechanical properties are quantified for welds between non-age-hardening Al5083 and age hardening Al2024 and compared to single alloy joints made from each of the two constituents. In this paper, we report the results of microstructural, mechanical property investigations of Al5186Al2024 friction stir welds produced using various rotations and traveling speeds of the tool to investigate the effects of the welding parameters on the joint strength. Metallographic studies by optical microscopy, electron probe microscopy, and the utilization of the X-ray diffraction technique have been conducted. It was found that the weld properties were dominated by the thermal input rather than the mechanical deformation by the tool. In particular the larger stresses under the weld tool on the AA5186 side compared to the AA2024 side are related to a transient reduction in yield stress due to dissolution of the hardening precipitates during welding prior to natural aging after welding.

scholarly journals Resarch on Mechanical Properties of Al 6061 Alloy Processed By FSW

2019 ◽  
Vol 8 (12S2) ◽  
pp. 295-297
Keyword(s):  
Mechanical Properties ◽  
Rotational Speed ◽  
Living Arrangements ◽  
Welding Parameters ◽  
Aluminum Compound ◽  
Aluminum Composite ◽  
Lightweight Structures ◽  
Making Sense ◽  
Strong State ◽  
Welding Procedure

The reason for this investigations is to improve the mechanical living arrangements of aluminum composite 6061 by means of grinding mix preparing (FSP), strong state strategies to change the microstructure utilizing the warmth of contact and blending. Aluminum compound 6061 is broadly utilized inside the assembling of lightweight structures with a proportion of power to-weight high and proper erosion opposition. Welding is the essential creation technique 6061 amalgam for assembling a repercussion of designing added substances. Erosion mix (FSW) is a solid nation welding procedure changed into as of late advanced to beat the issues experienced in combination welding. This procedure utilizes a non-admission gadget to produce frictional warmth at the outside of a fringe. Welding parameters, which incorporates stick profile apparatus, the rotational speed, the welding pace and the hub pressure, plays a main situation in making sense of the shape and microstructure of the consumption opposition of welded joints. In this work the applicable composite design with speeds, explicit cross pace and Four rigging had been utilized to limit exploratory situations.

Effects of bottom plate in friction stir welding of AA6061-T6

2020 ◽  
Vol 118 (1) ◽  
pp. 108
Author(s):  
M.A. Vinayagamoorthi ◽  
M. Prince ◽  
S. Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Axial Load ◽  
Weld Zone ◽  
Welding Process ◽  
Bottom Plate ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Friction Stir ◽  
Weld Joints ◽  
Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

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