Finite Element Analysis of Flexible Pipe Tension Loads Due to Iceberg Interaction

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.

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Finite Element Analysis of Flexible Pipes Under Compression

Volume 6A: Pipeline and Riser Technology ◽

10.1115/omae2014-23192 ◽

2014 ◽

Cited By ~ 3

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.

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Upheaval Creep of Rock Dumped Flexible Flowline

Volume 6A: Pipeline and Riser Technology ◽

10.1115/omae2014-23673 ◽

2014 ◽

Author(s):

Yang Zhengmao ◽

Kristian Norland ◽

Neil Brown ◽

Daniel Karunakaran

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

High Pressures ◽

Elevated Temperatures ◽

Water Injection ◽

Analysis Model ◽

Flexible Pipe ◽

Element Analysis ◽

Nonlinear Bending ◽

Start Up

For the protection from dropped object/fishing trawl impact, flexible flowlines are normally trenched or rock-dumped. And hence, upheaval buckling and lateral buckling may be promoted by the elevated temperatures and high pressures. Due to the unique properties of un-bonded flexible flowline, the flexible flowline may creep in the trench or rock berm when it is subjected to cyclic pressure and temperature changes due to start-up and shut-down of flowline in service. In this paper, a finite element analysis model for the global buckling and upheaval creep of flexible flowline is proposed. In this model the effect of bending stiffness hysteresis are considered in addition to the temperature and pressure changes in each start-up/ shut-down cycle. A case study of a 10″ water injection flowline is performed by using finite element analysis software package ANSYS. The nonlinear general beam section is used to simulate the specific flexible pipe behavior, nonlinear bending behavior but linear axial behavior.

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Study on 3d Flexible Pipe FEM Analysis by Spangler Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.850-851.821 ◽

2013 ◽

Vol 850-851 ◽

pp. 821-824 ◽

Cited By ~ 1

Author(s):

Jun Xiao ◽

Xiao Yu Zhang ◽

Jian Zhong Chen ◽

Zhuo Qiu Li

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Three Dimensional ◽

Earth Pressure ◽

Fem Analysis ◽

Flexible Pipe ◽

Element Analysis ◽

Element Simulation ◽

Complicated Process ◽

Vertical Earth Pressure

Earth pressure can be divided into three kinds of load form by Spangler theory: vertical earth pressure, bed reaction and horizontal lateral pressure. According to Spangler theory, the level of static earth pressure presents a parabolic distribution in central angle bon both sides of the tubes. Used the glass steel pipe as the specific research object, Spangler theory applied to the three-dimensional buried tube model for finite element analysis, the analysis is divided into two situations: (1) the same soil, finite element analysis of different pipe diameter; (2) the same tube diameter, finite element analysis of different soil. This method can reasonably reflect the interaction of soil and structure, it is feasible. The complicated process of the finite element simulation of tube soil interaction can be avoided.

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Periodic and Fixed Boundary Conditions for Multi-Scale Finite Element Analysis of Flexible Risers

Volume 5: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2016-54360 ◽

2016 ◽

Cited By ~ 1

Author(s):

M. T. Rahmati ◽

G. Alfano ◽

H. Bahai

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Boundary Conditions ◽

Three Dimensional ◽

Element Model ◽

Small Scale ◽

Flexible Pipe ◽

Element Analysis ◽

Time Saving ◽

Flexible Risers

In this paper the implementation of two types of boundaries, periodic and fixed in-plane boundaries, for a detailed finite-element model of flexible risers is discussed. By using three-dimensional elements, all layer components are individually modelled and a surface-to-surface frictional contact model is used to simulate their interaction. The approach is applied on several riser models with various lengths and layers. It is shown that the model with periodic boundaries can be effectively employed in a fully-nested (FE2) multiscale analysis based on computational homogenization. In fact, in this model only a small fraction of a flexible pipe is needed for a detailed nonlinear finite-element analysis at the small scale. The advantage of applying periodic boundary conditions in capturing the detailed nonlinear effects and the efficiencies in terms of significant CPU time saving are demonstrated.

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Vector form intrinsic finite-element analysis of static and dynamic behavior of deep-sea flexible pipe

International Journal of Naval Architecture and Ocean Engineering ◽

10.1016/j.ijnaoe.2020.04.003 ◽

2020 ◽

Vol 12 ◽

pp. 376-386

Author(s):

Han Wu ◽

Xiaohui Zeng ◽

Jianyu Xiao ◽

Yang Yu ◽

Xin Dai ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Dynamic Behavior ◽

Deep Sea ◽

Vector Form ◽

Flexible Pipe ◽

Element Analysis

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Experimental Study and Finite Element Analysis for the Installation of a Pipeline Into an Existing Pipeline

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4006764 ◽

2013 ◽

Vol 135 (1) ◽

Cited By ~ 1

Author(s):

Yong Bai ◽

Yu Binbin ◽

Cheng Peng ◽

Wang Ning

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Model Tests ◽

Sensitivity Analyses ◽

Radius Of Curvature ◽

Flexible Pipe ◽

Element Analysis ◽

Analytical Studies ◽

Plastic Pipe ◽

Major Factors

Some metallic pipelines suffer from corrosion issues due to internal and external environmental conditions. The pipe-in-pipe technology has been developed by inserting a new pipe (e.g., plastic pipe or flexible pipe) into an existing pipeline. The pipe-in-pipe approach may be applicable to the reconstruction of an existing pipeline, where the existing pipe is used as protective casing and the inserted new pipe is used to contain corrosive petrochemicals. The new pipe is installed in the long existing pipeline with several bends. The magnitude of the pull-in load and the response of the inserted pipe are the major concerns during installation. This paper presents the installation process of inserting a plastic pipe into an existing steel pipe, based on model tests, finite element analysis (FEA), and analytical investigations. First, a series of model tests are presented. In order to optimize the process of installation, sensitivity analyses based on model tests were conducted to study the influence of some key parameters, including the radius of curvature of the pipeline and diameter of the pipe. Then ABAQUS finite element models were applied to analyze the major factors. In addition, analytical studies on calculating the pull-in load are presented to make a comparison with the FEA and model test results. Since little previous work has been done about simulating the installation process of this kind of rehabilitation, the proposed finite element analysis results and the analytical studies of the installation can serve as a feasibility study for the design and evaluation of offshore pipeline rehabilitation project.

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A Three-Dimensional Finite Element Analysis of Unburied Flexible Flowline: A Case Study

21st International Conference on Offshore Mechanics and Arctic Engineering, Volume 3 ◽

10.1115/omae2002-28568 ◽

2002 ◽

Cited By ~ 2

Author(s):

Wenchao Zhang ◽

Justin Tuohy

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Three Dimensional ◽

Longitudinal Direction ◽

Flexible Pipe ◽

Element Analysis ◽

Upheaval Buckling ◽

Dimensional Finite Element ◽

Three Dimensional Finite Element

Pipelines in the service of conveying hot fluid will tend to expand due to pressure and differential temperature. However, since the flowline is generally fixed at the end terminations to rigid structures or equipment, such an expansion will be restricted in longitudinal direction. This is particularly the case for the section remote from the pipe ends, and results in an axial compression in the pipe section. In many cases, a subsea flowline has to be trenched or buried for the purposes of protection and thermal insulation. Consequently, the lateral movement of a flexible flowline is greatly limited, and an upward displacement is encouraged that may become excessive. Eventually, the flowline may lift out of the trench when the uplift resistance provided by the backfill cover and self-weight of the flowline is gradually overcome by the strain energy built up in the flowline. For flexible pipe, it is this excessive upward deformation being termed as the Upheaval Buckling, which can be prevented by employing adequate downward restraint, such as sand bag/rock dump or by designing a subsea pipe route to overcome this phenomenon. In this paper a case study of the full three-dimensional finite element analysis of a trenched but unburied 6.0-inch production flowline is presented following a description of Wellstream Finite Element Method (FEM) based methodology for Upheaval Buckling analysis of flexible pipes. The effect Bending Stiffness Hysteresis and Upheaval Creep–unique to flexible pipe characteristics, is considered in addition to the general loads such as the flowline self-weight and backfill, pretension, pressure, temperature distribution and prescribed forces (either concentrated or distributed) and displacements. The effects of environmental loads, such as the action of currents that would result in scouring off the backfill, can also be addressed. The finite element analysis program package ANSYS was chosen for this case study due to its special feature of ANSYS Parametric Design Language (APDL) and contact/target elements; and the general three-dimensional shell and solid elements were used to represent the flexible pipe and trench soil respectively.

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