Girth Weld Joints From Long Upset Pipe Ends for Improving Fatigue Strength of Offshore Oil and Gas Pipelines

2019 ◽  
Author(s):  
Israel Marines-Garcia ◽  
Aarón Aguilar ◽  
Ramón Aguilar ◽  
Mauricio Pelcastre ◽  
Philippe Darcis
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Numerical Comparison ◽  
Entire Line ◽  
Girth Welding ◽  
Production Stages ◽  
Offshore Oil And Gas ◽  
Girth Welds

Abstract For special high dynamic loading applications, the structural integrity of the girth welds shall withstand stress levels that might be on the limits of the permissible defect tolerances for current production welding standards for plain pipe ends. In addition, unexpected loading conditions might take the stress limits out of safe operation, which can compromise the entire line. As a solution, the cross section of the girth weld may be increased for ensuring the strength and fatigue resistance under any loading circumstances, including strain cycles of reeling installation technique. The employment of pipes with upset ends is an excellent option for those cases. To propose this option as an alternative to current offshore solution for a Major O&G company, Tenaris developed a long upset pipe end with enhanced fatigue life. The challenges of this work included the manufacturing of very long upset ends from a medium wall thickness pipe, very tight mechanical properties difference between pipe and upset material properties, and finally a welding qualification program. The improvement of the fatigue strength of this product was highly expected. In order to achieve all requirements, especial arrangements were performed on the upsetter machine for achieving the target upset geometry; which was previously obtained by a design of experiments technique. Then the heat treatment of the pipes was designed for obtaining the tight mechanical properties difference between pipe body and upset sections. The main outcomes of the whole development are described within this paper; which include key information of how to overcome issues that might arise during the development and production stages of upsetted line pipes. The upset ends undertake a cylindrical machining; this process provides the advantage of achieving tight dimensional tolerances in the high-low girth welding alignment. The fatigue endurance data after full scale reeling experimental test are included, as well as the numerical comparison between the strain fields of plain pipe and upset girth weld unions. The welding procedure qualified during this work is described. The results of the whole development were very satisfactory and, as expected, the fatigue strength of upset ends was higher than the plain pipe.

Effect of Full- and Small-Scale Reeling Simulation on Mechanical Properties of Weldable 13Cr Seamless Line Pipe

2013 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Nobuyuki Hisamune
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Oil And Gas ◽  
Small Scale ◽  
Line Pipe ◽  
Offshore Pipeline ◽  
Oil And Gas Pipelines ◽  
Before And After ◽  
Offshore Oil And Gas ◽  
Offshore Oil

There are several methods currently being used to install offshore oil and gas pipelines. The reel-lay process is fast and one of the most effective offshore pipeline installation methods for seamless, ERW, and UOE line pipes with outside diameters of 18 inches or less. In the case of the reel-laying method, line pipes are subjected to plastic deformation multiplication during reel-laying. It is thus important to understand the change of the mechanical properties of line pipes before and after reel-laying. Therefore, full-scale reeling (FSR) simulations and small-scale reeling (SSR) simulations are applied as evaluation tests for reel-laying. In this study, FSR simulations were performed to investigate the effect of cyclic deformation on the mechanical properties of weldable 13Cr seamless line pipes. Furthermore, SSR simulations were performed to compare the results obtained by FSR simulations.

Corrosion Fatigue of Welded C-Mn Steel Risers for Deepwater Applications: A State of the Art Review

2005 ◽  
Author(s):  
S. J. Maddox ◽  
R. J. Pargeter ◽  
P. Woollin
Keyword(s):  
Oil And Gas ◽  
Current Knowledge ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Manganese Steel ◽  
Gas Field ◽  
Internal Surfaces ◽  
Oil And Gas Field ◽  
Offshore Oil And Gas ◽  
Girth Welds

Steel risers for deepwater offshore oil and gas field developments are subject to seawater on the external surfaces, produced fluids on the internal surfaces and to fatigue loading. This paper reviews current knowledge of the fatigue behaviour of welded carbon-manganese steel for risers in relevant environments. A substantial body of data exists relating to the performance of girth welds in seawater with cathodic protection and consequently recent attention has been turned to establishing the fatigue performance in the internal environment, which may contain water, CO2, H2S and chloride and bicarbonate ions.

Mechanical Properties Characterization and Finite Element Analysis of Epoxy Grouts in Repairing Damaged Pipeline

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Lim Kar Sing ◽  
Nordin Yahaya ◽  
Alireza Valipour ◽  
Libriati Zardasti ◽  
Siti Nur Afifah Azraai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Flexural Behavior ◽  
Fe Model ◽  
Element Analysis ◽  
Structural Repair ◽  
Repair Mechanisms ◽  
Infill Material

Oil and gas pipelines are subjected to various types of deterioration and damage over long service years. These damaged pipes often experience loss of strength and structural integrity. Repair mechanisms have been developed in restoring the loading capacity of damaged pipelines, and composite repair systems have become popular over the past few years. The mechanical properties of the putty/grout are critical to their potential application as infill materials in structural repair. In this paper, the compression, tensile, and flexural behavior of four epoxy grouts was investigated through laboratory tests. The stiffness of the grouts for compression, tensile, and flexural was found to be 6 GPa to 18 GPa, 4 GPa to 15 GPa, and 4 GPa to 12 GPa, respectively. The ultimate strength for all grouts was found from 62 MPa to 87 MPa, 18 MPa to 38 MPa, and 34 MPa to 62 MPa under compression, tensile, and flexural tests, respectively. The behavior of all the tested grouts is discussed. A finite element (FE) model simulating a composite-repaired pipe was developed and compared with past studies. The FE results show a good correlation with experimental test with margin of error less than 10%. By replacing the infill properties in FE model to mimic the used of different infill material for the repair, it was found that about 4–8% increment in burst pressure can be achieved. This signifies that the role of infill material is not only limited to transferring the load, but it also has the potential to increase overall performance of composite-repaired pipe.

Effect of Reeling Simulation on the Mechanical Properties of New Duplex Stainless Steel for Line Pipe

2014 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Masayuki Sagara ◽  
Hisashi Amaya ◽  
Nobuyuki Hisamune ◽  
Daisuke Motoya ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Oil And Gas ◽  
Flow Line ◽  
Small Scale ◽  
Line Pipe ◽  
Stress Cracking ◽  
Wet Gas ◽  
Before And After ◽  
Sulfide Stress ◽  
Offshore Oil And Gas

Corrosion resistant alloys (CRAs) such as martensitic and duplex stainless steels (DSS) are used as a flow line material in corrosive wet gas environments (i.e., carbon dioxide and hydrogen sulfide environments). A new DSS which consists of 25mass%Cr - 5mass%Ni - 1mass%Mo - 2.5mass%Cu has been developed for line pipe usage in slightly sour environments. There are several methods currently being used to install offshore oil and gas pipelines. The reel-lay process is fast and one of the most effective offshore pipeline installation methods for seamless, ERW, and UOE line pipes with outside diameters of 18 inches or less. In the case of the reel-laying method, line pipes are subjected to plastic deformation multiplication during reel-laying. Thus, it is important to understand the change of the mechanical properties of line pipes before and after reel-laying. In this study, full-scale reeling (FSR) simulations and small-scale reeling (SSR) simulations were performed to investigate the effect of cyclic deformation on the mechanical properties of the new DSS for line pipe. Furthermore, investigation of the most susceptible temperature range to cracking and sulfide stress cracking (SSC) tests were performed in slightly sour conditions.

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.

Experimental study of the weld microstructure properties in assembling of natural gas transmission pipelines

2015 ◽  
Vol 231 (6) ◽  
pp. 1039-1047 ◽  
Author(s):  
M Sabokrouh ◽  
SH Hashemi ◽  
MR Farahani
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Chemical Analysis ◽  
Structural Integrity ◽  
Optical Microscope ◽  
Microalloyed Steels ◽  
Chemical Compositions ◽  
Natural Gas Pipelines ◽  
Natural Gas Transmission ◽  
Girth Welds

The coexistence of high levels of strength and toughness is necessary for the microalloyed steels used in natural gas pipelines. The welding thermal cycle can significantly change the microstructures and therefore the mechanical properties of the girth welded pipelines. Thus, the experimental investigation on the welded material properties is required for assessing the structural integrity of the pipelines. In this article, the metallurgical characteristics of the multi-pass girth welds on API X70 steel pipes with 56 in outside diameter and 0.780 in wall thickness were determined for the first time using chemical analysis and standard metallography. The chemical analysis showed different chemical compositions in different weld passes. The amount of carbon in the weldment increased in comparison with the base metal, although the microalloy elements in the weld gap decreased by increasing the pass number. The metallographic investigation by optical microscope demonstrated the different microstructures in different sub-zones of the welded joint. The images obtained from scanning electron microscope also presented the dendritic and acicular structures in the root and cap passes, respectively. The observed hard phases in the weldment, such as martensite, had direct effects on the mechanical properties of the weldment and heat-affected zone.

Microstructure and Mechanical Properties of Girth Weld HAZ in X80 Line Pipe With High Deformability for Strain Based Design Applications

2016 ◽  
Author(s):  
Yu Liu ◽  
Yezheng Li ◽  
Shuo Li ◽  
Zongbin You ◽  
Zhanghua Yin
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Heat Input ◽  
Thermal Simulation ◽  
Impact Testing ◽  
Pipe Material ◽  
Line Pipe ◽  
Microstructure And Mechanical Properties ◽  
Girth Welding ◽  
Girth Welds

X80 line pipe with high longitudinal deformability (X80HD) has been developed and applied in the Strain Based Design (SBD) of pipelines in harsh environment such as seismic areas, permafrost areas, fault zones, etc. For SBD pipelines it is critical that the pipeline girth welds overmatch the tensile properties of the pipe material to avoid local strain accumulation in the girth weld during a strain event. Also, it is important that pipeline girth welds that may experience high strains in operation have sufficient toughness to ensure adequate resistance to failure by fracture. The objective of this research was to gain a better understanding of the influence of chemical composition and essential welding variables on microstructure and properties of the HAZ regions formed in X80HD pipeline girth welds. In this study, by using the weld thermal simulation approach, the peak temperatures (Tp, representative of the distance to the fusion boundary) and the cooling times, particularly between 800 °C and 500 °C (t8/5, representative of the weld heat input), identical to those occurring in the girth weld HAZ of three different X80HD pipe steels, were artificially reproduced. It should be noted that t8/5 is influenced by both heat input and preheat temperature. The weld peak temperatures, Tp, from 500 °C to 1300 °C, in 100 °C increment, whereas the cooling times t8/5 from 5 to 30 seconds were in 5, 15, and 30 seconds, associated with the heat input range of self-shielded flux cored arc welding (FCAW-S). The thermal simulation specimens on tensile properties, Charpy impact toughness, and Vickers hardness were tested and analyzed. Microstructures of these simulated HAZ were characterized by optical microscopy (OM) and scanning electron microscopy (SEM). Finally, the actual FCAW-S girth welding experiments were carried out. These girth welds were subjected to different testing for evaluation of microstructure and mechanical properties of X80HD girth welded joints. These included transverse weld tensile testing, microhardness map of the weld joint, Charpy V-notch impact testing of weld metal and HAZ, and microstructure analysis. The results demonstrated that softening occurs in the fine grained HAZ (FGHAZ) and the inter-critical HAZ (ICHAZ) of X80HD line pipe girth welds. The severity of HAZ softening depends on the steel chemistry and the heat input applied during girth welding. The metallurgical design of the X80HD pipeline steel and the optimization of the girth welding procedures were proposed.

scholarly journals Characterization of mechanical properties in weld metal using inverse modelling

2012 ◽  
Vol 3 (1) ◽  
pp. 19-24
Author(s):  
J. Beddeleem ◽  
W. De Waele ◽  
S. Hertelé ◽  
M. Verstraete ◽  
K. Van Minnebruggen
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Accurate Determination ◽  
Simulated Data ◽  
Element Model ◽  
Inverse Modelling ◽  
Full Field ◽  
Modelling Framework

Nowadays, more oil and gas transportation pipelines are constructed in areas with permafrost and/or higherseismic activity. These pipelines can be subjected to longitudinal plastic deformations necessitating a strainbased design. Since girth- and seam welds are critical in terms of structural integrity, it is desirable to knowtheir mechanical properties. In a strain based design context, the accurate determination of yield strengthand hardening are necessary. A longitudinally extracted (is parallel to the pipe axis) specimen notched atthe weld region and loaded in tension, in combination with inverse modelling is assumed to be a valuabletool to determine these properties. This notched cross weld test ensures that the largest deformations willoccur at the weld, thereby allowing to fully determine the stress-strain behaviour of the weld metal. Inversemodelling combines experimental full-field strain data with numerical simulations to determine theconstitutive parameters. Strains will be measured experimentally and compared with simulated data. Byminimizing their difference, i.e. a certain cost function, a correspondence is found and the desiredparameters are determined. This paper focuses on one aspect of the inverse modelling framework, thedevelopment of the parametric finite element model.

scholarly journals Re-Evaluation of Fatigue Thickness Effect Based on Fatigue Test Database

2020 ◽  
Vol 8 (11) ◽  
pp. 895 ◽  
Author(s):  
Wangwen Zhao ◽  
Wei-Ting Hsu
Keyword(s):  
Fatigue Strength ◽  
Oil And Gas ◽  
Offshore Wind ◽  
Thickness Effect ◽  
Research Programmes ◽  
Offshore Oil And Gas ◽  
Corrosive Environments ◽  
Steel Joints ◽  
Test Database ◽  
Current Standards

This paper reassesses the detrimental effect on fatigue performance of welded structural steel joints due to thicker sections based on an extensive fatigue strength test database, taken from research programmes worldwide over the past half century, mostly from the offshore oil and gas and marine industries. The data entries in the database were evaluated to ensure its data integrity. Statistical analyses on these S-N data were performed with or without the thickness correction at different exposure levels to a corrosive environment, in order to re-evaluate the suitability of current standards in regard to the thickness effect. The study concentrated on T-joints, transverse butt-welded joints and tubular joints, as these are the most commonly used joint types in the offshore wind industry. The analysis indicates a general agreement of fatigue strength with the thickness effects in current standards for in-air conditions, but great conservatism for corrosive environments. In addition, the statistical models determined in this study can be used for a broader range of studies, such as probabilistic fatigue analysis.

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