Effect of Reeling on Pipeline Structural Performance

2016 ◽  
Author(s):  
Yafei Liu ◽  
Stelios Kyriakides
Keyword(s):  
Kinematic Hardening ◽  
Element Model ◽  
External Pressure ◽  
Structural Performance ◽  
Loading History ◽  
Cross Sectional ◽  
Collapse Pressure ◽  
Comparison Of The Results ◽  
Tension Loading ◽  
D Model

The winding and unwinding of a pipeline in the reeling installation process involves repeated excursions into the plastic range of the material, which induce ovality and changes to the mechanical properties. We present two modeling schemes for simulating reeling/unreeling capable of capturing these changes and can be used to assess their impact on the structural performance of the pipeline in deeper waters. In the first model, the complete 3-D reeling process is simulated through a finite element model that includes proper treatment of contact and nonlinear kinematic hardening for plasticity. The second model includes the pipe geometric cross sectional nonlinearities, contact, and nonlinear kinematic hardening, but variations along the length of the line are neglected. Instead, an axially uniform curvature/tension loading history is applied that corresponds to that experienced by a point of the line during the process. The two models are used to simulate a set of experiments in which tubes were wound and unwound on a model reel at different values of tension. Both models are shown to reproduce the induced ovality and elongation very well. Several of the reeled tubes were subsequently tested under external pressure demonstrating the effect of the reeling cycle on structural performance. The two models are shown to also reproduce the decrease in collapse pressure as a function of the applied back tension. Comparison of the results of such simulations highlight when a fully 3-D model is required and when the simpler 2-D model is adequate for evaluating the structural performance of a reeled pipe.

Effects of Reeling on Pipe Structural Performance—Part II: Analysis

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yafei Liu ◽  
Stelios Kyriakides ◽  
Jyan-Ywan Dyau
Keyword(s):  
3D Model ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Element Model ◽  
External Pressure ◽  
Structural Performance ◽  
Collapse Pressure ◽  
Reverse Loading ◽  
Tension Loading ◽  
Different Levels

Part II presents two modeling schemes for simulating the reeling/unreeling of a pipeline, with the aim of establishing the degrading effect of the process on the structural performance of the pipeline. A three-dimensional (3D) finite element model of the winding/unwinding of a long section of pipeline onto a rigid reel is presented first. The second model applies the curvature/tension loading history experienced at a point to a section of pipe in contact with a rigid surface of variable curvature. Both models use nonlinear kinematic hardening plasticity to model the loading/reverse loading of the material. The 3D model first demonstrates how the interaction of the problem nonlinearities influences the evolution of deformation and load parameters during reeling/unreeling. The two models are subsequently used to simulate the three-reeling/unreeling cycle experiments under different levels of back tension in Part I. The ovality-tension and axial elongation-tension results are reproduced by both models with accuracy for the first cycle, adequately for the second cycle, and are overpredicted for the third cycle. The two models are also used to simulate the reeling/unreeling followed by collapse of the tubes under external pressure experiments. Both models reproduce the measured ovality-tension results and the corresponding collapse pressures accurately. Since the two-dimensional (2D) model is computationally much more efficient, it is an attractive tool for estimating the effect of reeling on collapse pressure. Questions that require exact tracking of the winding/unwinding history and the interaction of the pipe with the reel are best answered using the 3D model.

Effects of Reeling on Pipe Structural Performance—Part I: Experiments

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Stelios Kyriakides
Keyword(s):  
Mechanical Properties ◽  
Local Buckling ◽  
External Pressure ◽  
Structural Performance ◽  
Plastic Range ◽  
Cross Sectional ◽  
Collapse Pressure ◽  
Bending Strain ◽  
Testing Facility ◽  
Different Levels

The winding and unwinding of a pipeline in the reeling installation process involve repeated excursions into the plastic range of the material, which induce ovality, elongation, and changes to the mechanical properties. The reeling/unreeling process involves some back tension required to safeguard the pipe from local buckling. This study examines the effects of winding/unwinding a pipe on a reel at different values of tension on the induced ovality and elongation and the resulting degradation in collapse pressure. In Part I, a model testing facility is used to simulate the reeling/unreeling process in the presence of tension. The combination of reel and tube diameters used induces a bending strain of 1.89%. A set of experiments involving three reeling/unreeling cycles at different levels of tension is performed on tubes with diameter-to-thickness ratios (D/t) of 20 and 15.5 in which the progressive changes in cross-sectional geometry and elongation are recorded. Both ovalization and elongation are shown to increase significantly as the back tension increases. A second set of experiments on the same two tube D/ts is performed in which following a reeling/unreeling cycle at a chosen level of tension, the tubes are collapsed under external pressure. The collapse pressure is shown to decrease significantly with tension, which is primarily caused by the reeling/unreeling-induced ovality. Part II presents models for simulating reeling and the induced structural degradation. The experimental results in Part I are used to evaluate the performance of the models.

Flexible Riser Top Connection Analysis With I-Tube Interface and Bending Hysteresis Effect

2019 ◽  
Author(s):  
Yangye He ◽  
Hailong Lu ◽  
Murilo Augusto Vaz ◽  
Marcelo Caire
Keyword(s):  
Kinematic Hardening ◽  
Bending Moment ◽  
Element Model ◽  
Beam Model ◽  
Flexible Riser ◽  
Nonlinear Bending ◽  
Cross Sectional ◽  
Irregular Wave ◽  
Global Dynamic ◽  
Curvature Distribution

Abstract The flexible riser top connection to the floating production platform is a critical region for fatigue lifetime (re)assessment. The interface with the I-tube and its curved sleeve combined with the gap between the riser and bend stiffener may lead to different curvature distribution when compared to the traditional modeling approach that considers the bend stiffener attached to the pipe. For a more accurate top connection assessment, the flexible riser bending hysteresis can also be directly incorporated in the global dynamic analysis helping to reduce curvature amplitude and lifetime prediction conservatism. This work investigates a 7” flexible riser-bend stiffener top connection with I-tube interface by performing irregular wave global dynamic analyses with the OrcaFlex package and considering a nonlinear bending moment vs curvature riser behavior obtained from a detailed cross sectional model developed in Abaqus. OrcaFlex curvature distribution results are also compared with a quasi-static finite element model that uses an elasto-plastic formulation with kinematic hardening to represent riser hysteresis through an equivalent beam model. A good curvature distribution correlation is observed for both top connection models (OrcaFlex x Abaqus) in the bend stiffener area with reduced amplitudes when riser bending hysteresis is considered.

Effect of Steel Properties on Buckling Pressure of Corroded Pipelines

2017 ◽  
Vol 898 ◽  
pp. 741-748 ◽  
Author(s):  
Meng Li ◽  
Hong Zhang ◽  
Meng Ying Xia ◽  
Kai Wu ◽  
Jing Tian Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Strain Hardening ◽  
Corrosion Damage ◽  
Element Model ◽  
External Pressure ◽  
Strain Hardening Exponent ◽  
The Finite Element Method ◽  
Collapse Pressure ◽  
Steel Properties

Due to the harsh environment for submarine pipelines, corrosion damage of the pipeline steels is inevitable. After the corrosion damage, pipelines are prone to failure and may cause serious consequences. The analysis of the effects of different steel properties on the collapse pressure of pipelines with corrosion defects is of importance for the option of appropriate pipeline and avoiding accidents. Based on the finite element method, the finite element model of the pipeline with defects under external pressure was built. Firstly, the accuracy of the numerical model was validated by comparing with previous experimental results. The effects of yield strength and strain hardening exponent on collapse pressure of pipelines with different sizes of defect were discussed in detail. Results showed that the yield strength and strain hardening exponent have different influences on collapse pressure: the collapse pressure increases with the increasing yield strength, and the collapse pressure decreases with the increasing strain hardening exponent.

Reeling Effect on the Ultimate Strength of Sandwich Pipes

2005 ◽  
Author(s):  
Xavier Castello ◽  
Segen F. Estefen
Keyword(s):  
Ultimate Strength ◽  
Numerical Models ◽  
Kinematic Hardening ◽  
External Pressure ◽  
Combined Loading ◽  
Collapse Pressure ◽  
Finite Element Software ◽  
Structural Resistance ◽  
Longitudinal Bending ◽  
Full Scale Tests

Sandwich pipes composed of two steel layers separated by a polypropylene annulus can be used for the transport of oil&gas in deepwaters, combining high structural resistance with thermal insulation in order to prevent blockage by paraffin and hydrates. In this work, sandwich pipes with typical inner diameters of those employed in the offshore production are analyzed numerically to evaluate the ultimate strength under external pressure and longitudinal bending as well as the effect of the reeling installation method on the collapse pressure. Numerical models were developed using the commercial finite element software ABAQUS. The validation was based on experimental results. The analyses for combined loading were performed using symmetry conditions and the pipe was reduced to a ring with unitary length. The analysis of bending under a rigid surface was simulated numerically according to the experiments performed using a bending apparatus especially built for full scale tests. Symmetry conditions were employed in order to reduce the analysis to a quarter of a pipe. Mesh sensitivity studies were performed to obtain an adequate mesh refinement in both analyses. The collapse pressure was simulated numerically either for the pre or post reeling process. Bauschinger effect was included by using kinematic hardening plasticity models. The influences of plasticity and out-of-roundness on the collapse pressure have been confirmed.

The Effect of the Reeling Laying Method on the Collapse Pressure of Steel Pipes for Deepwater

2004 ◽  
Author(s):  
Ilson P. Pasqualino ◽  
Silvia L. Silva ◽  
Segen F. Estefen
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Element Model ◽  
External Pressure ◽  
Test Facility ◽  
Collapse Pressure ◽  
Steel Pipes ◽  
Custom Made ◽  
Nonlinear Finite Element Model

This work deals with a numerical and experimental investigation on the effect of the reeling installation process on the collapse pressure of API X steel pipes. A three-dimensional nonlinear finite element model was first developed to simulate the bending and straightening process as it occurs during installation. The model is then used to determine the collapse pressures of both intact and plastically strained pipes. In addition, experimental tests on full-scale models were carried out in order to calibrate the numerical model. Pipe specimens are bent on a rigid circular die and then straightened with the aid of a custom-made test facility. Subsequently, the specimens are tested quasi-statically under external pressure until collapse in a pressure vessel. Unreeled specimens were also tested to complete the database for calibrating the numerical model. The numerical model is finally used to generate collapse envelopes of reeled and unreeled pipes with different geometry and material.

Modeling of the Collapse and Propagation Behavior of UOE SAW Pipes Under External Pressure: Influence of Thermal Treatments for Typical Coating Applications

2012 ◽  
Author(s):  
Luciano O. Mantovano ◽  
Santiago Serebrinsky ◽  
Hugo A. Ernst ◽  
Teresa Perez ◽  
Martin Valdez ◽  
...  
Keyword(s):  
Finite Element ◽  
Experimental Testing ◽  
Large Diameter ◽  
Model Development ◽  
External Pressure ◽  
Sensitivity Analyses ◽  
Thermal Treatments ◽  
Collapse Pressure ◽  
Collapse Resistance ◽  
Comparison Of The Results

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. Since oil discoveries are moving towards ultra deep water areas, collapse resistance is a key factor in the design of the pipelines. It has been demonstrated in previous works that the application of typical coating thermal treatments increases the collapse resistance of the pipes recovering the original strength of the plate. To improve the understanding of these effects, the Tenaris has embarked on a program of both, experimental testing and finite element modeling. Previous phases of this work formulated the basis for model development and described the 2D approach taken to model the various stages of manufacture, from the plate to the final pipe and the collapse test. More recent developments included some modeling enhancements, sensitivity analyses, and comparison of predictions to the results of full scale collapse testing. In the present work, 3D finite element analyses of collapse were performed and compared with the latest collapse and propagation tests performed by Tenaris, where the effect of typical coating thermal treatments was studied and significant increments in the collapse pressure of pipes were obtained. The numerical results show a good agreement with the experimental ones and could predict the increment produced in the collapse pressure by the effect of the thermal treatments. Comparison of the results with the predictions from API RP 1111 and DNV OS-F101 equations was also performed. The outcomes of this study will be employed to further optimize the collapse resistance of subsea linepipe in order to reduce material and offshore installation costs through the increment of the fabrication factor as stated in the DNV OSF101 standard.

Flexible Pipes: Influence of the Pressure Armor in the Wet Collapse Resistance

2011 ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clo´vis de Arruda Martins
Keyword(s):  
External Pressure ◽  
Flexible Pipe ◽  
3D Fem ◽  
Collapse Pressure ◽  
Flexible Pipes ◽  
External Pressures ◽  
Complete Study ◽  
Polymeric Layer ◽  
Equivalent Ring ◽  
Comparison Of The Results

When subjected to large valued external pressures, flexible pipes may collapse. If the external sheath is damaged, all the external pressure is directly applied to the internal polymeric layer that transmits the loading to the carcass layer. When the carcass layer fails due to this effect, the wet collapse occurs. This failure mode must be taken into account in the flexible pipe design. The study for this problem can be done neglecting the influence of the pressure armor, but this assumption may underestimate the wet collapse pressure value. This work aims to study the pressure armor effect in the numerical prediction of wet collapse. The main contribution of the pressure armor to the flexible pipe resistance to collapse is to be a constraint to the radial displacement of the carcass and the internal polymeric layers. Two models were developed and compared with the purpose of calculating the critical value of the external pressure that causes carcass layer to collapse. The first and most complete study is done using a ring 3D FEM model that takes into account both the real pressure armor and carcass real profiles. In the second model, the pressure armor is considered adopting an equivalent ring simplification. The comparison of the results of both the models clarifies how the behavior of the pressure armor in the wet collapse situation is. Parametric studies of initial ovalization of the carcass and initial gaps in manufacturing of flexible pipes are made and discussed.

Investigation on the free vibration behavior of sandwich conical shells with reinforced cores

2021 ◽  
pp. 109963622110204
Author(s):  
Mehdi Zarei ◽  
Gholamhossien Rahimi ◽  
Davoud Shahgholian-Ghahfarokhi
Keyword(s):  
Free Vibration ◽  
Orientation Angle ◽  
Element Model ◽  
Filament Winding ◽  
Vertex Angle ◽  
Sandwich Shell ◽  
Cross Sectional ◽  
Conical Shells ◽  
Vibration Behavior ◽  
Axial Forces

The free vibration behavior of sandwich conical shells with reinforced cores is investigated in the present study using experimental, analytical, and numerical methods. A new effective smeared method is employed to superimpose the stiffness contribution of skins with those of the stiffener in order to achieve equivalent stiffness of the whole structure. The stiffeners are also considered as a beam to support shear forces and bending moments in addition to the axial forces. Using Donnell’s shell theory and Galerkin method, the natural frequencies of the sandwich shell are subsequently derived. To validate analytical results, experimental modal analysis (EMA) is further conducted on the conical sandwich shell. For this purpose, a method is designed for manufacturing specimens through the filament winding process. For more validation, a finite element model (FEM) is built. The results revealed that all the validations were in good agreement with each other. Based on these analyses, the influence of the cross-sectional area of the stiffeners, the semi-vertex angle of the cone, stiffener orientation angle, and the number of stiffeners are investigated as well. The results achieved are novel and can be thus employed as a benchmark for further studies.

scholarly journals Numerical investigation of the effects of unsupported railway sleepers on train-induced environmental vibrations

2017 ◽  
Vol 36 (2) ◽  
pp. 160-176 ◽  
Author(s):  
Seyed-Ali Mosayebi ◽  
Morteza Esmaeili ◽  
Jabbar-Ali Zakeri
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Two Dimensions ◽  
Railway Track ◽  
Sensitivity Analyses ◽  
Regression Equations ◽  
The Finite Element Method ◽  
Technical Literature ◽  
Support Force ◽  
Comparison Of The Results

Review of technical literature regarding to train-induced vibrations shows that the effects of unsupported railway sleepers on this issue have been less investigated. So, the present study was devoted to numerical investigations of the mentioned issue. In this regard, first the problem of longitudinal train–track dynamic interaction was simulated in two dimensions by using the finite element method and the developed model was validated through comparison of the results with those obtained by previous researchers. In the next stage, a series of sensitivity analyses were accomplished to account for the effects of value of gap beneath the unsupported sleeper(s) and the track support stiffness on increasing the sleeper displacement and track support force. Moreover, the raised sleeper support force was introduced as applied load to a two-dimensional plane strain finite element model of track in lateral section and consequently the train-induced vibrations were assessed. As a result, a series of regression equations were established between the peak particle velocity in the surrounding environment of railway track and the sleeper support stiffness for tracks without unsupported sleepers and with one and two unsupported sleepers.

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