Lateral Buckling Response of Subsea HTHP Pipelines Using Finite Element Methods

2013 ◽  
Author(s):  
M. Masood Haq ◽  
S. Kenny
Keyword(s):  
Internal Pressure ◽  
Operating Temperature ◽  
Complex Function ◽  
External Pressure ◽  
Parameter Study ◽  
Embedment Depth ◽  
Lateral Buckling ◽  
Structural Support ◽  
Global Buckling ◽  
Subsea Pipelines

Subsea pipelines are subject to load effects from external hydrostatic pressure, internal pressure, operating temperature, ambient temperature and external reactions (e.g. seabed, structural support). These parameters influence the effective axial force that governs the pipeline global buckling response. Other factors, including installation stress, seabed slope, soil type, and embedment depth, can influence the pipe effective force. Pipelines laid on the seabed surface or with limited embedment may experience lateral buckling. The resultant mode response is a complex function related to the spatial variation in these parameters and kinematic boundary conditions. In this paper, results from a parameter study, using calibrated numerical modelling procedures, on lateral buckling of subsea pipelines are presented. The parameters included pipe diameter to wall thickness (D/t) ratio, pipe out of straightness (OOS), operating temperature and internal pressure, external pressure associated with the installation depth, and seabed lateral and axial friction properties.

Assessment of Parameters Influencing Lateral Buckling of Deep Subsea Pipe-in-Pipe Pipeline System Using Finite Element Modeling

2014 ◽  
Author(s):  
M. Masood Haq ◽  
S. Kenny
Keyword(s):  
Boundary Conditions ◽  
Load Capacity ◽  
External Pressure ◽  
Design Parameters ◽  
Parameter Study ◽  
Pipeline System ◽  
Limit States ◽  
Lateral Buckling ◽  
Global Buckling ◽  
External Forces

The operational requirements for subsea pipeline systems have progressed towards higher design temperatures and pressures (HTHP). To address flow assurance requirements, pipe-in-pipe systems have been developed. For pipelines laid on the seabed, or with partial embedment, the potential for lateral buckling; in response to operational loads, external forces and boundary conditions, has become a major factor in engineering design. The effective axial force is a key factor governing the global lateral buckling response that is influenced by parameters such as internal and external pressure, and operating and ambient temperature. Other design parameters that influence lateral buckling include global imperfections or out-of-straightness, pipe/soil interaction characteristics and installation conditions. Global buckling reduces the axial load capacity of the pipeline that may impair operations and exceed serviceability limit states. Results from a numerical parameter study on lateral buckling response of a subsea pipe-in-pipe (PIP) pipeline are presented. The parameters examined include pipe embedment, pipe out-of-straightness (OOS), soil shear strength, soil peak and residual forces and displacements, variation in soil properties distributed along the pipeline route, and external pressure associated with the installation depth. The observed pipe response was a complex relationship with these parameters and kinematic boundary conditions.

Evaluation of Design Premises and Uncertainties on the Thermo-Mechanical Behavior of a Subsea Pipeline

2014 ◽  
Author(s):  
Bruno Reis Antunes ◽  
Rafael Familiar Solano ◽  
Alexandre Hansen
Keyword(s):  
Formation Process ◽  
Mechanical Design ◽  
Design Stage ◽  
Stress And Strain ◽  
Lateral Buckling ◽  
Friction Factors ◽  
Global Buckling ◽  
Pipeline Route ◽  
Seabed Bathymetry ◽  
Subsea Pipelines

Buckle formation process is a key subject for the design of subsea pipelines laid on the seabed and operating under high pressure and high temperature (HP/HT) conditions. When the controlled lateral buckling methodology is adopted triggers are placed along pipeline route in order to increase the buckle formation probability in specific locations, sharing pipeline expansion between these sites and reducing the level of stress and strain in each buckle. Despite of its importance, buckle formation process is influenced by several parameters such as the seabed bathymetry, engineered triggers, lateral out-of-straightness (OOS) and pipe-soil interaction. While the first two items above can be defined with reasonable accuracy at previous stages of design, lateral OOS will only be known with tolerable confidence after pipeline installation. The level of uncertainty related to pipe-soil interaction is also considerable since pipeline embedment and friction factors are estimated using equations that include empirical correlations and field collected data. In addition these parameters are influenced by the installation process. Due to these uncertainties, conservative premises are usually assumed in order to obtain a robust pipeline thermo-mechanical design. After pipeline installation and/or start of operation an investigation can be performed in order to confirm the assumptions considered in the design. This paper presents a comparison of premises adopted during design stage of a pipeline based on the controlled lateral buckling methodology and the feedback obtained with the post-lay survey performed. After a brief introduction, pipeline embedment, global buckling at crossings, lateral OOS and sleepers’ height are some of the subjects addressed. Finally, conclusions and recommendations are presented in order to support future similar projects.

scholarly journals Subsea FRP pipeline performance in external pressure: Failure and external pressure-induced buckling

2021 ◽  
Vol 1201 (1) ◽  
pp. 012040
Author(s):  
Dimitrios Pavlou
Keyword(s):  
Hydrostatic Pressure ◽  
Internal Pressure ◽  
External Pressure ◽  
Compressive Stresses ◽  
Analytical Formulae ◽  
Hoop Stresses ◽  
Subsea Pipelines ◽  
Pressure Failure

Abstract The Subsea pipelines are subjected to high hoop stresses due to the hydrostatic pressure. When the internal pressure of the liquid has a higher value than the external hydrostatic one, there is a balance of the tensile and compressive stresses. However, during the offshore installation, the subsea pipelines are empty and the compression due to the hydrostatic pressure of the sea is predominant. High compressive stresses in FRP pipelines can cause failure or buckling. In the present work, an investigation of the external pressure-induced failure and buckling is carried out. Analytical formulae and results are provided and discussed.

Overview of the Lateral Buckling and Walking Designs of Deepwater Pipelines in Offshore Brazil

2019 ◽  
Author(s):  
Rafael F. Solano ◽  
Carlos O. Cardoso ◽  
Bruno R. Antunes
Keyword(s):  
Oil And Gas ◽  
Design Guidelines ◽  
Mitigation Measures ◽  
Design Parameters ◽  
Clayey Soils ◽  
Lateral Buckling ◽  
Buckling Behavior ◽  
The World ◽  
Global Buckling ◽  
Subsea Pipelines

Abstract Last two decades have been marked by a significant evolution on the design of HP/HT subsea pipelines around the world. The HotPipe and SAFEBUCK JIPs can be seen as the first deepened developments in order to obtain safe design guidelines for subsea pipelines systems subjected to global buckling and walking behaviors. The adopted design approach have been to allow exposed pipeline buckles globally on seabed in a safe and controlled manner. Otherwise, the walking phenomenon has been in general mitigated constraining axial displacements by means of anchoring systems. After several design and installation challenges concerning lateral buckling and pipeline walking behaviors, nowadays there is a significant amount of deepwater pipelines operating with buckle initiators (triggers) as well as walking mitigation devices in offshore Brazil. Oil and gas pipelines, short gathering lines and long export lines, installed by reeling and J-lay methods, in other words different kinds of subsea pipelines have operated on very soft clayey soils and have formed planned lateral buckles as well as rogue buckles. This paper presents the main characteristics and design challenges of the deepwater pipelines subjected to the lateral buckling behavior, also highlighting mitigation measures to constrain the walking phenomenon of some pipelines. The relevant design results are highlighted as type and number of buckle triggers, buckle spacing, type and locations of walking mitigations. Envelopment of the main design parameters are mapped in order to identify some trends. Finally, survey images of operating pipelines are presented confirming behaviors predicted in the design phase.

Interaction between Upheaval/Lateral and Propagation Buckling in Subsea Pipelines

2014 ◽  
Vol 553 ◽  
pp. 434-438
Author(s):  
Hassan Karampour ◽  
Faris Albermani
Keyword(s):  
Horizontal Plane ◽  
Oil And Gas ◽  
Vertical Plane ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Upheaval Buckling ◽  
Oil And Gas Pipelines ◽  
Global Buckling ◽  
Internal Pressures ◽  
Subsea Pipelines

Due to high service temperatures and internal pressures in oil and gas pipelines, axial compression forces are induced in the pipe due to seabed friction. Slender trenched pipelines can experience global buckling in the vertical plane (upheaval buckling) while untrenched pipelines buckle in the horizontal plane (lateral buckling). Furthermore, deep subsea pipelines subjected to high external hydrostatics pressures can undergo catastrophic propagation buckling. In this study, the possible interaction between upheaval/lateral buckling and propagation buckling is numerically investigated using finite element analysis. A new concept is proposed for subsea pipelines design that gives higher capacity than conventional pipelines.

scholarly journals Buckle Interaction in Deep Subsea Pipelines

2013 ◽  
Author(s):  
Hassan Karampour ◽  
Faris Albermani
Keyword(s):  
Deep Water ◽  
Numerical Study ◽  
Local Mode ◽  
Imperfection Sensitivity ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Design Capacity ◽  
Global Buckling ◽  
Subsea Pipelines

The paper investigates the interaction between propagation buckling and lateral buckling in deep subsea pipelines. Lateral buckling is a possible global buckling mode in long pipelines while the propagation buckling is a local mode that can quickly propagate and damage a long segment of a pipeline in deep water. A numerical study is conducted to simulate buckle interaction in deep subsea pipelines. The interaction produces a significant reduction in the buckle design capacity of the pipeline. This is further exasperated due to the inherent imperfection sensitivity of the problem.

Reliability of Lateral Buckling Formation From Planned and Unplanned Buckle Sites

2008 ◽  
Author(s):  
Andrew Rathbone ◽  
Mahmoud Abdel-Hakim ◽  
Gary Cumming ◽  
Knut To̸rnes
Keyword(s):  
Risk Assessment ◽  
High Pressure ◽  
Quantitative Risk Assessment ◽  
Design Solution ◽  
Lateral Buckling ◽  
Detailed Design ◽  
High Pressure High Temperature ◽  
Global Buckling ◽  
Subsea Pipelines ◽  
Design Stress

Global buckling for exposed HPHT (High Pressure / High Temperature) subsea pipelines is an important feature that needs to be assessed during detailed design. By safely triggering controlled buckles at predetermined locations and considering the potential for rogue buckles to be triggered by seabed or pipelay out-of-straightness features, a robust design solution can be obtained. This paper presents a methodology whereby quantitative risk assessment may be carried out on the reliability of lateral buckling initiation systems, considering the pipeline in its entirety, rather than considering each intended buckle individually. This method accounts for buckle interaction when calculating the post-buckle loads, and allows simple incorporation of potential rogue sites through vertical and/or horizontal out-of-straightness. The results of the risk assessment can be defined in terms of buckle formation reliability, and design stress/strain criteria.

Fitness for Service Assessments of Bulging and Out-of-Round Structures

2004 ◽  
Author(s):  
Peter Carter ◽  
D. L. Marriott ◽  
M. J. Swindeman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Structural Model ◽  
External Pressure ◽  
Element Analysis ◽  
Structural Imperfection ◽  
Level 2

This paper examines techniques for the evaluation of two kinds of structural imperfection, namely bulging subject to internal pressure, and out-of-round imperfections subject to external pressure, with and without creep. Comparisons between comprehensive finite element analysis and API 579 Level 2 techniques are made. It is recommended that structural, as opposed to material, failures such as these should be assessed with a structural model that explicitly represents the defect.

Lateral buckling of subsea pipelines triggered by dual sleepers

2021 ◽  
Vol 116 ◽  
pp. 102863
Author(s):  
Zhenkui Wang ◽  
Yougang Tang ◽  
Nuo Duan
Keyword(s):  
Lateral Buckling ◽  
Subsea Pipelines

A Theoretical and Experimental Analysis of the Bending Behavior of Unbonded Flexible Pipes

2014 ◽  
Author(s):  
Tatiana Vargas-Londoño ◽  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Internal Pressure ◽  
Cross Section ◽  
Structural Response ◽  
Experimental Tests ◽  
Theoretical Models ◽  
External Pressure ◽  
Local Behavior ◽  
Flexible Pipes ◽  
Floating System ◽  
Bending Loads

Due to its compound cross-section, the prediction of the structural response of flexible pipes to loads such as their self-weight, internal and external pressure, movements imposed by the floating system and environmental loads such as currents, waves and wind is quite complex. All these loads generate stresses and strains in the cross section of the pipe that have to be properly evaluated in order to ensure integrity of the line. Research has been done on the local behavior of flexible pipes under combined axisymmetric loads as well as under bending loads. However, there is a lack of research combining both axisymmetric and bending loads, as also in the study of the strains in the tensile amour layers of the pipes, aspects which are important for the calibration of theoretical models to predict such behavior. Based on that, this study aims to evaluate the local behavior of flexible pipes under combinations of axisymmetric (tension, and internal pressure) and bending loads via a series of experimental tests in a 9.13″ I.D pipe. In the experimental tests, the behavior of the pipe was studied for three load combinations: i) bending combined with tension; ii) bending combined with internal pressure; and iii) bending combined with tension and internal pressure. Based on these tests, the authors obtained the strains in the tensile armor layer, axial elongation due to tension, axial reaction forces due to internal pressure, and deflection due to bending. These measurements were used to calibrate a theoretical model devoted to simulate the pipe’s response, getting accurate results for stiffness and stresses of the pipe in each scenario.

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