An Experimental Investigation on the Bending Behaviour of Flexible Pipes

2003 ◽  
Author(s):  
Le´a M. B. Troina ◽  
Lui´z F. L. Rosa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Production Systems ◽  
Global Analysis ◽  
High Capacity ◽  
Experimental Tests ◽  
External Pressure ◽  
Analytical Models ◽  
Internal Diameter ◽  
Flexible Pipe ◽  
Low Tension

A flexible pipe is a composite structure, built up of several steel and plastic layers, which has been increasingly used in floating offshore petroleum production systems. It is characterized by presenting low bending stiffness and high capacity with regard to internal and external pressure and tension. In order to determine some physical properties of a flexible pipe specimen, which is useful for a global analysis, and to better understand the behaviour of its tensile armour layers, when the pipe is submitted to low tension loads, a series of experimental tests were performed by COPPE/UFRJ and CENPES/PETROBRAS. In this context, bending tests, with internal pressure variation, were carried out on a 4” internal diameter flexible pipe. In some specific cross sections, the outer plastic sheath of the specimen was removed to enable the installation of electrical extensometers in the tensile armour layer. Some experimental results were compared to those obtained through analytical models, and the discrepancies are discussed.

Improvements on the Numerical Analysis of the Coupled Extensional–Torsional Response of a Flexible Pipe

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Héctor E. M. Muñoz ◽  
José R. M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Axial Rotation ◽  
Nonlinear Finite Element ◽  
Analytical Models ◽  
Fe Model ◽  
Flexible Pipe ◽  
Torsional Response ◽  
Axial Twist

In this paper, the coupled extensional–torsional behavior of a 4 in. flexible pipe is studied. The pipe is subjected to pure tension and two different boundary conditions are considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist induced by the applied tension. Moreover, the cross sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

On the Coupled Extensional–Torsional Response of Flexible Pipes

2009 ◽  
Author(s):  
He´ctor E. M. Merino ◽  
Jose´ R. M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Axial Rotation ◽  
Analytical Models ◽  
Fe Model ◽  
Flexible Pipe ◽  
Torsional Response ◽  
Flexible Pipes ◽  
Axial Twist

In this paper, the coupled extensional-torsional behavior of a 4″ flexible pipe is studied. The pipe was subjected to pure tension and two different boundary conditions were considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as: the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests performed at COPPE/UFRJ. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist or torque led by the applied tension. Moreover, the cross-sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

Lateral Buckling of Armor Wires in Flexible Pipes: Reaching 3000m Water Depth

2011 ◽  
Author(s):  
Philippe Secher ◽  
Fabrice Bectarte ◽  
Antoine Felix-Henry
Keyword(s):  
Deep Water ◽  
Failure Modes ◽  
External Pressure ◽  
Internal Diameter ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Flexible Pipes ◽  
Valid Solution ◽  
Sour Service ◽  
Water Depths

This paper presents the latest progress on the armor wires lateral buckling phenomena with the qualification of flexible pipes for water depths up to 3,000m. The design challenges specific to ultra deep water are governed by the effect of the external pressure: Armor wires lateral buckling is one of the failure modes that needs to be addressed when the flexible pipe is empty and subject to dynamic curvature cycling. As a first step, the lateral buckling mechanism is described and driving parameters are discussed. Then, the program objective is presented together with flexible pipe designs: - Subsea dynamic Jumpers applications; - Sweet and Sour Service; - Internal diameters up to 11″. Dedicated flexible pipe components were selected to address the severe loading conditions encountered in water depths up to 3,000m. Hydrostatic collapse resistance was addressed by a thick inner carcass layer and a PSI pressure vault. Armor wires lateral buckling was addressed by the design and industrialization of new tensile armor wires. The pipe samples were manufactured using industrial production process in the factories in France and Brazil. The available testing protocols are then presented discussing their advantages and drawbacks. For this campaign, a combination of Deep Immersion Performances (DIP) tests and tests in hyperbaric chambers was selected. The DIP test campaign was performed End 2009 beginning 2010 in the Gulf of Mexico using one of Technip Installation Vessel. These tests replicated the actual design conditions to which a flexible pipe would be subjected during installation and operation. The results clearly demonstrated the suitability of flexible pipes as a valid solution for ultra deep water applications. In addition, the DIP tests results were compared to the tests in hyperbaric chambers giving consistent results. This campaign provided design limitations of the new designs for both 9″ and 11″ internal diameter flexible pipes, in sweet and sour service in water depths up to 3,000m.

Electro-thermal-mechanical Coupled Analysis on Two High-Current Composite Umbilical Cable Cross-sections

2021 ◽  
pp. 1-32
Author(s):  
Jun Yan ◽  
Qi Su ◽  
Yufeng Bu ◽  
Zhixun Yang ◽  
Qingzhen Lu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Heat Dissipation ◽  
Production Systems ◽  
Mechanical Analysis ◽  
External Pressure ◽  
Field Analysis ◽  
Coupled Analysis ◽  
Cross Sectional ◽  
The Cross ◽  
Umbilical Cable

Abstract A new type of umbilical cable named ‘strong-electricity composite umbilical cable’ is composed of electronic cables, optical cables, steel tubes and structural strengthening components. It can be regarded as a key piece of industrial equipment in subsea production systems that provide control functions, strong electric and hydraulic remote transmission. when it is oriented at a power supply with a relatively high rated voltage, power transmission will produce a lot of heat. Then, the cross-sectional temperature increases, which affects the performances of its material and mechanical responses. Therefore, electro–thermal–mechanical coupled analysis is critical for the cross-sectional design of the strong-electricity composite umbilical cable. Accordingly, a multi-physics coupled analysis was performed based on two typical umbilical cable cross-sections. Finite element models were established and subjected to electro–thermal analysis to obtain a temperature distribution of the two sections at different current capacities. Based on results of temperature field analysis, the section models were subjected to thermal–mechanical analysis. The results of the two types of analyses are compared and differences are discussed, which illustrate the multi-physics coupled effect cannot be neglected. The armored layers will relatively reduce the heat dissipation performance, but compared with the umbilical cable model without the armored layers, the model with double-armored layers is less affected by temperature, so its capacity of resistance external pressure is relatively better. The proposed coupled analysis methodology provides a new guidance for the design of the strong-electricity composite umbilical cables.

A Comparative Buckling Study for the Carcass Layer of Flexible Pipes

2009 ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clo´vis de Arruda Martins
Keyword(s):  
Numerical Models ◽  
External Pressure ◽  
Plastic Layer ◽  
Internal Diameter ◽  
Flexible Pipe ◽  
Equivalent Thickness ◽  
Flexible Pipes ◽  
Buckling Behavior ◽  
Numerical Finite Element ◽  
Ring Approximation

When there are some failures on the external plastic layer of a flexible pipe, a high value of hydrostatic pressure can be transferred to its interlocked carcass layer, maybe causing a collapse. So it is necessary to predict on the design of a flexible pipe the maximum value of pressure that would be acceptable to avoid collapse of the carcass layer. That value depends on the imperfections on the internal diameter due to fabrication uncertainties. To study that problem, two numerical finite element models were created and used to simulate external pressure loading condition. The first model is a full 3D approximation, composed by solid elements. The second one is a 3D ring approximation, still made by solids. An analytical model using an equivalent thickness approach for carcass was done. A good correlation between analytical and numerical models was achieved for pre-buckling behavior, but analytical buckling behavior was not the same as numerical values predictions. Discussions about these differences are done.

Numerical and Experimental Study of a Flexible Pipe Under Torsion

2010 ◽  
Author(s):  
He´ctor E. M. Merino ◽  
Jose´ Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Nonlinear Finite Element ◽  
Analytical Models ◽  
Fe Model ◽  
Pure Torsion ◽  
Flexible Pipe ◽  
Torsional Loads

The torsional behavior of a 4″ flexible pipe is here studied. The pipe was subjected to clockwise and anticlockwise torsion and also to torsion combined with tension. For pure torsion, two different boundary conditions were considered: ends free to elongate and prevented from elongating. When tensional and torsional loads are imposed to the pipe, only analyses with ends prevented from elongating are carried out. In all cases, the response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model and with a classical analytical model. Experimental tests performed at COPPE/UFRJ are also employed to validate the theoretical estimations. The obtained results point out that the pipe is torque balanced for clockwise torsion, but it is not balanced for anti-clockwise torsion. Moreover, analytical models for axissymetric analyses assume that the layers of a flexible pipe are subjected to the same twist and elongation, but the FE results state that this hypothesis holds only for anti-clockwise torsion. Therefore, some differences were found between the FE and analytical models mainly when clockwise torsion is considered. Finally, due to its ability to deal with friction and adhesion between layers, the FE estimations agreed quite well with the experimental measures.

Bending Analysis of a Flexible Pipe With Broken Tensile Armor Wires

2015 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Experimental Tests ◽  
Analytical Models ◽  
Force Distribution ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration ◽  
Bending Loads

In this work, the mechanical response of a damaged 2.5″ flexible pipe under combined tensile and bending loads is studied. A set of experimental tests was carried out either considering the pipe intact or with one up to four broken wires in its outer tensile armor. In these tests, the deflections along the pipe as well as the strains in its outer tensile armor wires were measured thus allowing estimating the bending stiffness of the pipe and the force distribution among the wires, respectively. The results obtained are compared to those provided by a previously presented finite element (FE) model and analytical models. The numerical and analytical predictions agreed well with the experimental measurements pointing to a negligible decrease in the stiffness of the pipe with the increasing number of broken wires and, furthermore, a redistribution of forces among the intact wires of the damaged layer with high stress concentration in the wires close to the damaged ones.

Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

2017 ◽  
Author(s):  
Francisco Lamas ◽  
Miguel A. M. Ramirez ◽  
Antonio Carlos Fernandes
Keyword(s):  
High Speed ◽  
Production Systems ◽  
Experimental Tests ◽  
Experimental Results ◽  
Analytical Methodology ◽  
New Approach ◽  
Laboratory Facilities ◽  
Polynomial Curve ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

Integrity Assessment of Damaged Flexible Pipe Cross-Sections

2014 ◽  
Author(s):  
Guomin Ji ◽  
Bernt J. Leira ◽  
Svein Sævik ◽  
Frank Klæbo ◽  
Gunnar Axelsson ◽  
...  
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Element Model ◽  
Computer Code ◽  
Flexible Pipe ◽  
Dynamic Stresses ◽  
Integrity Assessment ◽  
Residual Capacity ◽  
Nonlinear Finite Element Model

This paper presents results from a case study performed to evaluate the residual capacity of a 6″ flexible pipe when exposed to corrosion damages in the tensile armour. A three-dimensional nonlinear finite element model was developed using the computer code MARC to evaluate the increase in mean and dynamic stresses for a given number of damaged inner tensile armor wires. The study also includes the effect of these damages with respect to the associated stresses in the pressure spiral. Furthermore, the implications of a sequence of wire failures with respect to the accumulated time until cross-section failure in a probabilistic sense are addressed.

Optimization Applied to Buzios Flexible Riser Systems and Subsea Layout

2021 ◽  
Author(s):  
Vinicius Gasparetto ◽  
Thierry Hernalsteens ◽  
Joao Francisco Fleck Heck Britto ◽  
Joab Flavio Araujo Leao ◽  
Thiago Duarte Fonseca Dos Santos ◽  
...  
Keyword(s):  
Deep Water ◽  
Technology Use ◽  
Capital Expenditure ◽  
Lessons Learned ◽  
Internal Diameter ◽  
Flexible Riser ◽  
Flexible Pipe ◽  
Injection Wells ◽  
Gas Field ◽  
Field Development

Abstract Buzios is a super-giant ultra-deep-water pre-salt oil and gas field located in the Santos Basin off Brazil's Southeastern coast. There are four production systems already installed in the field. Designed to use flexible pipes to tie back the production and injection wells to the FPSOs (Floating Production Storage and Offloading), these systems have taken advantage from several lessons learned in the previous projects installed by Petrobras in Santos Basin pre-salt areas since 2010. This knowledge, combined with advances in flexible pipe technology, use of long-term contracts and early engagement with suppliers, made it possible to optimize the field development, minimizing the risks and reducing the capital expenditure (CAPEX) initially planned. This paper presents the first four Buzios subsea system developments, highlighting some of the technological achievements applied in the field, as the first wide application of 8" Internal Diameter (ID) flexible production pipes for ultra-deep water, leading to faster ramp-ups and higher production flowrates. It describes how the supply chain strategy provided flexibility to cover the remaining project uncertainties, and reports the optimizations carried out in flexible riser systems and subsea layouts. The flexible risers, usually installed in lazy wave configurations at such water depths, were optimized reducing the total buoyancy necessary. For water injection and service lines, the buoyancy modules were completely removed, and thus the lines were installed in a free-hanging configuration. Riser configuration optimizations promoted a drop of around 25% on total riser CAPEX and allowed the riser anchor position to be placed closer to the floating production unit, promoting opportunities for reducing the subsea tieback lengths. Standardization of pipe specifications and the riser configurations allowed the projects to exchange the lines, increasing flexibility and avoiding riser interference in a scenario with multiple suppliers. Furthermore, Buzios was the first ultra-deep-water project to install a flexible line, riser, and flowline, with fully Controlled Annulus Solution (CAS). This system, developed by TechnipFMC, allows pipe integrity management from the topside, which reduces subsea inspections. As an outcome of the technological improvements and the optimizations applied to the Buzios subsea system, a vast reduction in subsea CAPEX it was achieved, with a swift production ramp-up.

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