Effect of Tension on Collapse Performance of Flexible Pipes

2018 ◽  
Author(s):  
Marcelo Miyazaki ◽  
Laurent Paumier ◽  
Fabien Caleyron
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
Cost Model ◽  
Negative Influence ◽  
External Pressure ◽  
Flexible Pipe ◽  
Test Protocol ◽  
Specific Test ◽  
Flexible Pipes ◽  
Finite Elements Model

This paper investigates the effect of tension on collapse performance of flexible pipes. In the design of flexible pipelines for offshore field developments, one of the failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, TechnipFMC methodology for flexible pipe collapse resistance determination ensures a robust design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations. TechnipFMC and IFP Energies nouvelles have also developed and improved over the past few years a Finite Elements Model dedicated to flexible riser studies. It takes full advantage of the structure periodicities such that a whole riser can be studied with a short length and low CPU cost model associated to specific periodicity conditions. The model is able to represent bent risers in various configurations (bending cycles, internal and external pressure, axial tension, torsion) and has been used for collapse prediction of flexible risers under tension. Additionally, a specific test protocol has been developed to be able to carry out a collapse test associated to tension. The purpose of this paper is to present the collapse test result, the specific development of the model for collapse and tension and the corresponding calculations performed with the Finite Elements Model on several structures, demonstrating that there is no negative influence of tension on collapse mode. It also gives a better understanding on the interaction between tension in the armor layers and collapse phenomenon.

Effect of Installation on Collapse Performance of Flexible Pipes

2017 ◽  
Author(s):  
Fabien Caleyron ◽  
Vincent Le Corre ◽  
Laurent Paumier
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
External Pressure ◽  
Residual Effects ◽  
Cyclic Plasticity ◽  
Flexible Pipe ◽  
Collapse Resistance ◽  
Flexible Pipes ◽  
Offshore Field ◽  
Finite Elements Model

This paper investigates the effect of installation on collapse performance of flexible pipes. In the design of flexible pipelines for offshore field developments, one of the critical failure modes being associated with external pressure and bending loadings is the hydrostatic collapse. In accordance with standards, Technip methodology for flexible pipe collapse resistance determination ensures a robust and competitive design. The model has an analytical basis, leading to a fast and straightforward use. It has been validated with more than 200 tests performed on all possible pipe constructions on straight and curved configurations. As the industry is moving to deeper and deeper water, there is a greater need to understand all factors which could affect collapse. This includes residual effects due to the high installation loads from the laying system. As a consequence, Technip has performed several collapse tests on samples previously submitted to a loading representative of installation conditions (tension and crushing). Moreover, Technip and IFP Energies Nouvelles have developed and improved over the past few years a Finite Elements model dedicated to collapse prediction. The model accounts for the detailed geometry of the wires (carcass, pressure vault, spiral), ovalization, cyclic plasticity, contacts and residual stresses due to manufacturing. It allows to evaluate the effect of installation on the ovalization and plasticity of each layer and the collapse performance of the flexible pipe. The purpose of this paper is to present the collapse tests results and the corresponding calculations performed with the Finite Elements Model on several cases representative of Technip flexible pipes portfolio.

Prediction and Qualification of Radial Birdcage and Lateral Buckling of Flexible Pipes in Deepwater Applications

2015 ◽  
Author(s):  
Linfa Zhu ◽  
Zhimin Tan ◽  
Victor Pinheiro Pupo Nogueira ◽  
Jian Liu ◽  
Judimar Clevelario
Keyword(s):  
Failure Modes ◽  
Local Buckling ◽  
External Pressure ◽  
Design Guidelines ◽  
Prediction Theory ◽  
Flexible Pipe ◽  
Lateral Buckling ◽  
Operation Conditions ◽  
Flexible Pipes ◽  
Compressive Loads

Increasing oil exploitation in deepwater regions is driving the R&D of flexible pipes which are subjected to high external pressure loads from the hydrostatic head during their installation and operation. One of the challenges of flexible pipe design for such applications is to overcome the local buckling failure modes of tensile armor layers due to the combination of high external pressure, compressive loads and pipe curvature. This paper presents the latest progress in local buckling behavior prediction theory and the qualification process of flexible pipes. First, the mechanisms of two types of buckling behaviors, radial birdcage buckling and lateral buckling, are described. For each failure mode, the analytical buckling prediction theory is presented and the driving parameters are discussed. As part of the qualification process, the ability to resist radial birdcage and lateral buckling must be demonstrated. Suitable test protocols are required to represent the installation and operation conditions for the intended applications by deep immersion performance (DIP) tests. Several flexible pipes were designed based on radial birdcage and lateral buckling prediction theory, and pipe samples were manufactured using industrial production facilities for DIP tests. The results clearly show that flexible pipes following current design guidelines are suitable for deepwater applications. An alternative in-air rig was developed to simulate the DIP tests in a controlled laboratory environment to further validate the model prediction as a continuous development.

Controlling Factors of Carcass Fatigue in Unbonded Flexible Pipes

2019 ◽  
Author(s):  
Upul S. Fernando ◽  
Andrew P. Roberts ◽  
Michelle Davidson
Keyword(s):  
Fatigue Failure ◽  
Failure Modes ◽  
Dynamic Stress ◽  
External Pressure ◽  
Controlling Factors ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Innermost Layer ◽  
Key Features ◽  
Unbonded Flexible Pipes

Abstract Carcass, the innermost layer of a flexible pipe structure is designed to prevent the collapse of the pressure sheath due to external pressure. Weakness, damage or failure of the carcass layer can result in collapse with associated loss of production and potentially serious risk to pipe integrity and hydrocarbon leakage to the environment. Avoiding carcass failure in service is therefore an essential consideration during the design of unbonded flexible pipes. Carcass failure is rare in service. This paper highlights the three possible failure modes and presents further analysis on the fatigue failure mode, relevant to dynamic service. Two key features of carcass manufacture are identified as causes for dynamic stress; locking of the carcass profile due to extended pitch and polymer ingress within the carcass cavity. Guidelines for the design of carcass profiles, setting safe pitch limits and appropriate barrier profile controls to mitigate carcass fatigue failure in dynamic service are presented.

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.

Simplified Finite Element Models to Study the Dry Collapse of Straight and Curved Flexible Pipes

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Eduardo Ribeiro Malta ◽  
Rafael Loureiro Tanaka ◽  
Carlos Alberto Ferreira Godinho
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Computational Cost ◽  
Three Dimensional ◽  
Element Model ◽  
External Pressure ◽  
Flexible Pipe ◽  
Flexible Pipes ◽  
Simplified Modeling ◽  
Good Agreement

Dry collapse is one of the possible failure modes of flexible pipes. It refers to the situation in which no damage occurs in the flexible pipe external sheath. In this scenario, all layers of the pipe withstand the external pressure loading in a deep-water application. Such a situation is addressed in this work, which proposes some simplified modeling techniques to represent straight and curved flexible pipes subjected to external pressure, undergoing dry collapse during simulation procedure. The results of the proposed models are compared to other reference results, from a fully three-dimensional (3D) finite element model. Good agreement has been got, even with the proposed simplifications with a large reduction in computational cost when compared to full 3D model.

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

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins
Keyword(s):  
Three Dimensional ◽  
External Pressure ◽  
Flexible Pipe ◽  
3D Fem ◽  
Collapse Pressure ◽  
Flexible Pipes ◽  
Polymeric Layer ◽  
Set Up ◽  
3D Finite Element Method ◽  
Ring Approximation

When submitted to high external pressure, flexible pipes may collapse. If the external sheath is damaged, all the external pressure is directly applied on the internal polymeric layer that transmits the loading to the carcass layer, which can fail due to this effect, leading to wet collapse. This failure mode must be taken into account in a flexible pipe design. A model can be set up neglecting the influence of the pressure armor, but this assumption may underestimate the wet collapse pressure value. This work aims to include 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 to find the wet collapse pressure in flexible pipes. A first study was done using a ring approximation three-dimensional (3D) finite element method (FEM) model. Comparisons are made with more simplified models using a 3D FEM equivalent ring approximation. The aim is to clarify the mechanical behavior of the pressure armor in the wet collapse scenario. Parametric studies of initial ovalization of carcass and initial gaps and interference between polymeric layer and pressure armor are made and discussed.

Parallelized Element-by-Element Architecture for Structural Analysis of Flexible Pipes Using Macro Finite Elements

2017 ◽  
Author(s):  
Fernando Geremias Toni ◽  
Clóvis de Arruda Martins
Keyword(s):  
Structural Analysis ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
Local Analysis ◽  
Present Moment ◽  
Flexible Pipe ◽  
Computational Performance ◽  
Flexible Pipes ◽  
Oil And Natural Gas ◽  
Global Stiffness Matrix

Flexible pipes are employed to transport oil and natural gas from the seabed to the floating units, and vice versa. These pipes are made of concentric layers of different geometries, materials and structural functions in order to withstand a series of static and dynamic loads from its adverse operating environment. The local analysis is an important stage in the design of a flexible pipe and consists in determining the stresses and strains distributions along its layers. Multipurpose finite element packages, such as ANSYS and ABAQUS, are commonly used in this task, but present many limitations for their generic nature, varying from the absence of specific tools for model creation to heavy restrictions of the number of degrees-of-freedom to make computational processing feasible. Over the past years, several macro finite elements were formulated by PROVASI & MARTINS specifically for modeling a flexible pipe, allowing a reduction in the total number of degrees-of-freedom. However, until the present moment, there is no parallel processing software that efficiently implements these elements for large model applications. Aiming greater computational performance, the macro elements can be combined with the element-by-element (EBE) method, which is characterized by the global stiffness matrix elimination, is highly parallelizable, scalable and shows a memory consumption that grows linearly with the number of elements in the model. In this context, a parallelized architecture for structural analysis of flexible pipes that explores the EBE method and macro finite elements has been developed, being of great interest for design applications in the industry.

Flexible Pipe Curved Collapse Resistance Calculation

2009 ◽  
Author(s):  
Laurent Paumier ◽  
Daniel Averbuch ◽  
Antoine Felix-Henry
Keyword(s):  
Failure Modes ◽  
Analytical Calculation ◽  
External Pressure ◽  
Calculation Model ◽  
Third Party ◽  
Flexible Pipe ◽  
The Past ◽  
Curved Pipes ◽  
Pressure Resistance ◽  
Collapse Failure

In the design of flexible pipelines for offshore field developments, the determination of the pipe resistance while subjected to external pressure and bending is very important in deepwater and is now required by the ISO and API standards. One of the critical failure modes being associated with this type of loads is the hydrostatic collapse. The collapse value of flexible pipe is calculated with a model validated with over 200 tests performed on all possible pipe constructions. This model has an analytical basis, and has been established in the past, leading to a fast and straightforward use. In order to address the bent collapse failure mode, Technip and IFP have therefore developed and improved over the past few years an analytical calculation model, based on the collapse model for straight pipes. The purpose of this paper is to present this design methodology and its validation. The modelling principles of the collapse calculation of straight flexible pipes are firstly presented, along with the main hypotheses. The adaptation to the case of curved pipes is detailed in the sequel of the paper. Many types of flexible pipe samples have been tested up to collapse both in straight and curved configurations. The results of these tests have been used to validate this model. In the paper, several tests results will be presented and compared with the calculations. This model is effective, of straightforward use, and has been certified by a third party. It allows Technip to optimize the flexible pipe design in particular for ultra-deep water applications, where external pressure resistance is very important.

Analysis of Mechanical Properties of Pipes with Helical Reinforcement under Axial Tension

2011 ◽  
Vol 189-193 ◽  
pp. 1822-1826 ◽  
Author(s):  
Wei Huang ◽  
Zhong You
Keyword(s):  
Mechanical Properties ◽  
Contact Pressure ◽  
Pitch Angle ◽  
External Pressure ◽  
Compatibility Equation ◽  
Flexible Pipe ◽  
Axial Tension ◽  
Flexible Pipes ◽  
Marine Engineering ◽  
Deformation Compatibility

Flexible pipes with helical reinforcement are widely used in the marine engineering and tissue engineering because of their low bending stiffness. Through appropriate design, they could also meet the strength requirement. All studies on this kind of structures regard the pitch angle of helical wires, strips or fibers as a vital parameter influencing the mechanical properties. In this study, we compare the tensile property of pipes with helical reinforcements braided in different initial pitch angles. Contact pressure is taken into consideration and eliminated by using deformation compatibility equation. The pitch angle changes under axial tension which induces the geometric nonlinearity. It is noted that when the pitch angle is larger than a critical value, even if there is no internal or external pressure, helixes will contact with the core under axial tension. But the initial pitch angle can not be too large since the contact pressure will induce partial buckling of the flexible pipe.

An Experimental and Numerical Study on the Axial Compression Response of Flexible Pipes

2010 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
Paula F. Viero ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Axial Compression ◽  
Failure Modes ◽  
Mechanical Response ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Fe Model ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper deals with a nonlinear three-dimensional finite element (FE) model capable of predicting the mechanical response of flexible pipes subjected to axisymmetric loads focusing on their axial compression response. Moreover, in order to validate this model, experimental tests carried out at COPPE/UFRJ are also described. In these tests, a typical 4″ flexible pipe was subjected to axial compression until its failure is reached. Radial and axial displacements were measured and compared to the model predictions. The good agreement between all obtained results points that the proposed FE model is efficient to estimate the response of flexible pipes to axial compression and, furthermore, has potential to be employed in the identification of the failure modes related to excessive axial compression as well as in the mechanical analysis of flexible pipes under other types of loads.

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