Nonmetallic Bonded Flexible Pipe Under Combined Tension and Internal Pressure

2017 ◽  
pp. 429-454
Keyword(s):  
Internal Pressure ◽  
Flexible Pipe

Failure behavior analysis of steel strip–reinforced flexible pipe under combined tension and internal pressure

2018 ◽  
Vol 33 (6) ◽  
pp. 727-753
Author(s):  
Wei Chen ◽  
Haichao Xiong ◽  
Yong Bai
Keyword(s):  
Internal Pressure ◽  
Numerical Study ◽  
Steel Strip ◽  
Sensitivity Study ◽  
Failure Behavior ◽  
Load Path ◽  
Flexible Pipe ◽  
Fe Method ◽  
Axial Extension ◽  
The Relationship

The mechanical behaviors of steel strip–reinforced flexible pipe (steel strip PSP) under combined axial extension → internal pressure ( T→ P) load path were investigated. Typical failure characteristics of pipe samples under pure internal pressure and T→ P load path were identified in the full-scale experiments. A theoretical model for pipe under tension load was proposed to capture the relationship between axial extension of the pipe body and stress state of the steel strip. Numerical study based on finite element (FE) method was conducted to simulate the experiment process, and good agreement between FE data and experiment results were observed. Sensitivity study was conducted to study the effect of some key parameters on the pipe antiburst capacities in T→P load path; the effect of preloaded internal pressure on the pipe tensile capacity in P→T load path was also studied. Useful conclusions were drawn for the design and application of the steel strip PSP.

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.

Numerical Model to Simulate Tensile Wire Behavior in Unbonded Flexible Pipe During Bending

2007 ◽  
Author(s):  
Yanqiu Zhang ◽  
Lun Qiu
Keyword(s):  
Fatigue Life ◽  
Numerical Model ◽  
Internal Pressure ◽  
Flexible Pipe ◽  
Working Mechanism ◽  
Axial Strength ◽  
Strength And Stiffness ◽  
Stress Variations ◽  
Metal Layers ◽  
Pipe Bending

The tensile wires in flexible pipe play an important role for forming the axial strength and stiffness of the pipe and for supporting the pressure armoring wires to resist the internal pressure. In the meanwhile, the fatigue life of the flexible pipe is generally often limited by the tensile wire life because the stress variations in the wires are considerably greater than those in other metal layers of the pipe. Therefore, exactly understanding and evaluating tensile wire behaviors are significantly important and necessary. In other words, as long as the behaviors of tensile wires can be evaluated the working mechanism of pipe bending can be evaluated.

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.

Influence of Suspension Length on the Mechanical Response of Submarine Flexible Pipe under Internal Pressure and Transverse Load

2013 ◽  
Vol 671-674 ◽  
pp. 884-887
Author(s):  
Fan Gu ◽  
Hui Xin Wang ◽  
Dan Wang ◽  
Jia Quan Sun
Keyword(s):  
Internal Pressure ◽  
Mechanical Response ◽  
Axial Stress ◽  
Steel Wire ◽  
Element Model ◽  
Transverse Load ◽  
Submarine Pipeline ◽  
Flexible Pipe ◽  
Actual Structure ◽  
Rubber Layer

According to the actual structure of submarine flexible pipe, considering the combined effect of internal pressure and transverse load by wave-current flow that is based on 50 year return period wave statistics data of Cheng Dao sea area, ANSYS finite element model of flexible pipe is established. The influence of internal pressure and suspension length on the axial stress of steel wire reinforcement layer and the Mises stress of rubber layer was analyzed. Comparatively, suspension is the main cause for the failure of steel submarine pipeline, but could hardly lead to the failure of submarine flexible pipe, which shows that flexible pipe is stronger applicable for submarine pipeline.

A Study on the Response of a Flexible Pipe to Combined Axisymmetric Loads

2013 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
Tatiana V. Londoño ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Pressure ◽  
Reaction Force ◽  
Experimental Tests ◽  
Element Model ◽  
Tension Test ◽  
Experimental Results ◽  
Flexible Pipe ◽  
Pure Tension

In this work, the response of a 2.5″ flexible pipe to combined and pure axisymmetric loads is studied. A set of experimental tests was carried out and the results obtained are compared to those provided by a previously presented finite element model. The pipe was firstly subjected to pure tension. After that, the response to torsion superimposed with tension combined or not with internal pressure and the response to internal pressure combined with tension were investigated. In all these cases, the induced strains in the tensile armors were measured. Moreover, the axial elongation of the pipe was monitored in the pure tension test, whilst the twist of the pipe was measured when torsion was imposed and the axial reaction force was monitored when internal pressure was applied. The experimental results obtained agreed very well with the theoretical estimations indicating that the response of the pipe to tension and internal pressure is linear, whilst its response to torsion is nonlinear due to friction between layers.

Mechanical Behaviors of Reinforced Thermoplastic Pipe Under Combined Load

2019 ◽  
Author(s):  
Baodong Wang ◽  
Hong Zhang ◽  
Xiaoben Liu
Keyword(s):  
Internal Pressure ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Element Model ◽  
External Pressure ◽  
Gas Production ◽  
Aramid Fiber ◽  
Mechanical Behaviors ◽  
Flexible Pipe ◽  
Oil And Gas Production

Abstract Reinforced thermoplastic pipe (RTP) is used in the oil and gas industry for its good flexibility, corrosion resistance and wear resistance, especially in offshore oil and gas production process. However, they are subject to internal pressure, external pressure and tension loads that are important aspects affecting the integrity and security of the flexible pipe. Their reinforced layers are designed for bearing internal pressure and tension. In this paper, the mechanical behaviors of reinforced thermoplastic pipe with 3 layers, where the reinforced layer is aramid fiber braid layers, is investigated by numerical methods. The internal pressure burst test of reinforced thermoplastic pipes was carried out to determine the burst internal pressure and failure behaviors of RTP. A finite element model that considers the material nonlinearity as well as the friction interactions between layers was created using ABAQUS. The mechanical behavior of reinforced flexible pipe subjected to internal pressure and tension load as well as its failure model was investigated in detail. Effects of the braided angle of aramid fiber braid layers were elucidated. This study can be referenced for the applications of reinforced thermoplastic pipe in marine oil and gas production.

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