scholarly journals Stability of filament-wound hyperbolic flexible pipes under internal pressure based on non-geodesic winding

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guo-min Xu ◽  
Chang-geng Shuai
Keyword(s):  
Internal Pressure ◽  
Vibration Suppression ◽  
Tensile Modulus ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Design And Optimization ◽  
Filament Wound ◽  
Flexible Pipes ◽  
The Stability ◽  
Winding Angle

AbstractFilament-wound flexible pipes are widely used to transport fluid in pipeline systems, proved extremely useful in marine engineering. The hyperbolic flexible pipes have good vibration suppression performance, but they are easily deformed under internal pressure. This paper focuses on the stability of hyperbolic flexible pipes based on the composite Reissner shell theory and the transfer-matrix method. The nonlinear stretch of the reinforced filament and the fiber bridge effect are considered in the model. The calculation results show that a large winding angle reduces the deformation and the meridional stress. The available initial winding angle is limited by the geometry and the slippage coefficient of flexible pipe. The reinforced filament of high tensile modulus will reduce the deformation of the pipe. Compared with the geodesic winding trajectory, non-geodesic winding trajectories improves the stability of the pipe. The theoretical result is verified by the finite element analysis. The investigation method and results present in this paper will guide the design and optimization of more novel flexible pipes in the future.

scholarly journals Burst pressure prediction of fiber-reinforced flexible pipes with arbitrary generatrix

2021 ◽  
Vol 16 ◽  
pp. 155892502199081
Author(s):  
Guo-min Xu ◽  
Chang-geng Shuai
Keyword(s):  
Transfer Matrix ◽  
Linear Equations ◽  
Burst Pressure ◽  
Fiber Reinforced ◽  
Flexible Pipe ◽  
Theoretical Derivation ◽  
Design And Optimization ◽  
Flexible Pipes ◽  
Novel Method ◽  
Winding Angle

Fiber-reinforced flexible pipes are widely used to transport the fluid at locations requiring flexible connection in pipeline systems. It is important to predict the burst pressure to guarantee the reliability of the flexible pipes. Based on the composite shell theory and the transfer-matrix method, the burst pressure of flexible pipes with arbitrary generatrix under internal pressure is investigated. Firstly, a novel method is proposed to simplify the theoretical derivation of the transfer matrix by solving symbolic linear equations. The method is accurate and much faster than the manual derivation of the transfer matrix. The anisotropy dependency on the circumferential radius of the pipe is considered in the theoretical approach, along with the nonlinear stretch of the unidirectional fabric in the reinforced layer. Secondly, the burst pressure is predicted with the Tsai-Hill failure criterion and verified by burst tests of six different prototypes of the flexible pipe. It is found that the burst pressure is increased significantly with an optimal winding angle of the unidirectional fabric. The optimal result is determined by the geometric parameters of the pipe. The investigation method and results presented in this paper will guide the design and optimization of novel fiber-reinforced flexible pipes.

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Sample Length

2015 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
The Stability

In order to study the compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape and a rigid inner nucleus. Using this model, several studies are being conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered one of these parameters and its variation causes significant change at the stability response of the tensile layers. This article includes a detailed description of the finite element model itself and a case study where the length of the pipe is changed. The procedure of this analysis is here described, along with the results.

The Impact of Flexbarrier Ingress on Flexlok Stress

2009 ◽  
Author(s):  
Jing Lu ◽  
Frank Ma ◽  
Zhimin Tan ◽  
Terry Sheldrake
Keyword(s):  
Internal Pressure ◽  
Structural Function ◽  
Analysis Model ◽  
Flexible Pipe ◽  
Case Scenario ◽  
Element Analysis ◽  
Worst Case ◽  
Ongoing Research ◽  
Nominal Size ◽  
The Impact

An unbonded flexible pipe typically consists of multiple metallic and thermoplastic layers, where each layer is designed to provide a specific structural function. The burst resistance against the internal pressure in an unbonded flexible pipe is provided mainly by its Flexlok layer. The Flexlok is made by helically-wound steel wires, with neighbouring wires interlocking each other. Beneath the Flexlok is the Flexbarrier, a polymer layer, acting as the boundary for conveyed fluids. The internal pressure is passed onto the Flexlok through the Flexbarrier layer. Under internal pressure, the Flexbarrier can creep into the gaps between Flexlok wires. Theoretically, the polymer material ingress could reduce the flexibility of the Flexlok due to premature lock-up between Flexlok wires and subsequently increase the stress levels. This study presents a 3D finite element analysis model developed to quantify the stress elevation in the Flexlok wire, caused by the Flexbarrier layer ingress. In terms of Flexlok gap size distribution, both nominal and worst case scenarios are studied. In the nominal scenario, the Flexlok gap sizes are evenly distributed. In the worst case scenario, the Flexlok gap is assumed to be completely closed at one position while the gaps at the neighbouring positions are twice the nominal size. Flexbarrier ingress with different temperatures is also studied. Conclusions are obtained by analyzing the simulation results. The work presented is part of an ongoing research and development project.

Effects of Thickness and Winding Angle of the Laminate on Internal Pressure Capacity of Thermoplastic Composite Pipes

2020 ◽  
Author(s):  
H. Xia ◽  
C. Shi ◽  
J. Wang ◽  
X. Bao ◽  
H. Li ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Oil And Gas ◽  
Solid Wall ◽  
Three Dimensional ◽  
Oil And Gas Industry ◽  
Thermoplastic Composite ◽  
Critical Parameters ◽  
Element Analysis ◽  
Composite Pipes ◽  
Winding Angle

Abstract Thermoplastic composite pipes (TCPs) are increasingly used to transport hydrocarbons and water in the oil and gas industry due to their superior properties including corrosion resistance, thermal insulation, light weight, etc. The cross-section of TCPs generally consists of three layers: inner liner, composite laminate, and outer jacket. Three layers are bonded together and form a solid-wall construction. Inner liner and outer jacket made of thermoplastic polymer provide protective barriers for the laminate to against the inner fluid and outer environment. The laminate is constructed by an even number of helically wounded continuous fiber reinforced thermoplastic composite tapes. In this study, mechanical behaviors of a TCP under an internal pressure were investigated by using analytical and finite element analysis (FEA) methods. The analytical method which is based on the three-dimensional (3D) anisotropy elastic theory can take account of non-uniformly distributed stress and strain through the thickness of the pipe wall. FEA models were setup by using the software ABAQUS to predict the stress distribution of the pipe. 3D Tsai-Wu failure criterion was used to predict the maximum internal pressure of the pipe. Effects of some critical parameters, such as the winding angle of composite tapes and the number of reinforced plies, on the internal pressure capacity of TCPs were studied. Results obtained from the analytical and FEA methods were fairly agreed with each other, which showed that with the increasing of the number of reinforced plies the internal pressure capacity of a TCP gradually increases and approaches to an extreme value. In addition, the optimal winding angle which results the maximum internal pressure is not a constant value, instead, it varies with the increasing thickness of the laminate layer. This study provides useful tools and guidance for the design and analysis of TCPs, and is currently under validation through experiments.

An Experimental and Numerical Investigation of the Effect of Axial Thermal Gradients in Flexible Pipes

2017 ◽  
Author(s):  
Dag Fergestad ◽  
Frank Klæbo ◽  
Jan Muren ◽  
Pål Hylland ◽  
Tom Are Grøv ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Measurement Techniques ◽  
Full Scale ◽  
Model Complexity ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
Full Scale Testing

This paper discusses the structural challenges associated with high axial temperature gradients and the corresponding internal cross section forces. A representative flexible pipe section designed for high operational temperature has been subject to full scale testing with temperature profiles obtained by external heating and cooling. The test is providing detailed insight in onset and magnitude of relative layer movements and layer forces. As part of the full-scale testing, novel methods for temperature gradient testing of unbonded flexible pipes have been developed, along with layer force- and deflection-measurement techniques. The full-scale test set-up has been subject to numerous temperature cycles of various magnitudes, gradients, absolute temperatures, as well as tension cycling to investigate possible couplings to dynamics. Extensive use of finite element analysis has efficiently supported test planning, instrumentation and execution, as well as enabling increased understanding of the structural interaction within the unbonded flexible pipe cross section. When exploiting the problem by finite element analysis, key inputs will be correct material models for the polymeric layers, and as-built dimensions/thicknesses. Finding the balance between reasonable simplification and model complexity is also a challenge, where access to high quality full-scale tests and dissected pipes coming back from operation provides good support for these decisions. Considering the extensive full scale testing, supported by advanced finite element analysis, it is evident that increased attention will be needed to document reliable operation in the most demanding high temperature flexible pipe applications.

Finite Element Analysis of Flexible Pipes Under Compression

2014 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Strength ◽  
Element Model ◽  
Large Displacements ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes ◽  
Compressive Loads ◽  
Surface Vessel

Axial compressive loads can appear in several situations during the service life of a flexible pipe, due to pressure variations during installation or due to surface vessel heave. The tensile armor withstands well tension loads, but under compression, instability may occur. A Finite Element model is constructed using Abaqus in order to study a flexible pipe compound by external sheath, two layers of tensile armor, a high strength tape and a rigid nucleus. This model is fully tridimensional and takes into account all kinds of nonlinearities involved in this phenomenon, including contacts, gaps, friction, plasticity and large displacements. It also has no symmetry or periodical limitations, thus permitting each individual wire of the tensile armor do displace in any direction. Case studies were performed and their results discussed.

Finite Element Analysis of Flexible Pipes Under Axial Compression: Influence of the Sample Length

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Inner Core ◽  
High Sensitivity ◽  
Element Model ◽  
Sample Length ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Flexible Pipes

In order to study the axial compressive behavior of flexible pipes, a nonlinear tridimensional finite element model was developed. This model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape, and a rigid inner core. Using this model, several studies were conducted to verify the influence of key parameters on the wire instability phenomenon. The pipe sample length can be considered as one of these parameters. This paper includes a detailed description of the finite element model itself and a case study where the length of the pipe is varied. The procedure of this analysis is here described and a case study is presented which shows that the sample length itself has no practical effect on the prebuckling response of the samples and a small effect on the limit force value. The postbuckling response, however, presented high sensitivity to the changes, but its erratic behavior has made impossible to establish a pattern.

Stability of Vertically Bent Pipelines Buried in Sand

2004 ◽  
Vol 126 (3) ◽  
pp. 382-390 ◽  
Author(s):  
Sahel N. Abduljauwad ◽  
Hamdan N. Al-Ghamedy ◽  
Junaid A. Siddiqui ◽  
Ibrahim M. Asi ◽  
Naser A. Al-Shayea
Keyword(s):  
Internal Pressure ◽  
Three Dimensional ◽  
Computer Software ◽  
Specific Weight ◽  
Bend Angle ◽  
Element Analysis ◽  
Minimum Cover ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.

Prediction of Burst in Flexible Pipes

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Celso Pupo Pesce ◽  
Christiano Odir C. Meirelles ◽  
Eduardo Ribeiro Malta ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Cross Section ◽  
Plastic Material ◽  
Numerical Models ◽  
Fluid Pressure ◽  
Material Model ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Equivalent Ring ◽  
Cross Section Profile

Usually when a large internal fluid pressure acts on the inner walls of flexible pipes, the carcass layer is not loaded, as the first internal pressure resistance is given by the internal polymeric layer that transmits almost all the loading to the metallic pressure armor layer. The last one must be designed to ensure that the flexible pipe will not fail when loaded by a defined value of internal pressure. This paper presents three different numerical models and an analytical nonlinear model for determining the maximum internal pressure loading withstood by a flexible pipe without burst. The first of the numerical models is a ring approximation for the helically rolled pressure layer, considering its actual cross section profile. The second one is a full model for the same structure, considering the pressure layer laying angle and the cross section as built. The last numerical model is a two-dimensional (2D) simplified version, considering the pressure layer as an equivalent ring. The first two numerical models consider contact nonlinearities and a nonlinear elastic-plastic material model for the pressure layer. The analytical model considers the pressure armor layer as an equivalent ring, taking into account geometrical and material nonlinear behaviors. Assumptions and results for each model are compared and discussed. The failure event and the corresponding stress state are commented.

Finite Element Analysis of Flexible Pipes Under Compression: Influence of the Friction Coefficient

2016 ◽  
Author(s):  
Eduardo Ribeiro Malta ◽  
Clóvis de Arruda Martins
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
High Strength ◽  
Element Model ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Frictional Contacts ◽  
Flexible Pipes ◽  
Nonlinear Finite Element Model

In order to study the compressive behavior of flexible pipes, a nonlinear Finite Element model was developed. This fully tridimensional model recreates a five layer flexible pipe with two tensile armor layers, an external polymeric sheath, an orthotropic high strength tape and a rigid inner nucleus. The friction coefficient is known as a key parameter in determining the instability response of flexible pipes tensile armor. Since the featured model includes all nonlinear frictional contacts between the layers, it has been used to conduct several experiments in order to investigate its influence on the response. This article includes a description of the Finite Element Model itself and a case study where the friction between the layers of the pipe is changed. The procedure of this analysis is here described, along with the results.

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