The Interaction of Free Span and Lateral Buckling Problems

2004 ◽  
Author(s):  
Nelson Szilard Galgoul ◽  
Julia Carla Paulino de Barros ◽  
Rony Peterson Ferreira
Keyword(s):  
Vortex Shedding ◽  
Lateral Buckling ◽  
Buckling Mode ◽  
Upheaval Buckling ◽  
Axial Forces ◽  
Traditional Design ◽  
Engineering Problems ◽  
Global Buckling ◽  
Present Design ◽  
Pipeline Vibration

The traditional design approach for most engineering problems, of which pipelines are no exception, is to segment the project and to present design solutions for each of these design items. When setting up a pipeline schedule, therefore, one will find an item called free span analyses and another called global buckling, which covers both lateral and upheaval buckling problems. This has been justifiable so far, because freespan vibrations have traditionally been treated totally dissociated from the axial force on the pipe, while lateral buckling is a problem to which, only recently, the industry has turned its attention. DNV has a tradition of being the regulatory agency, which has a lead on vortex shedding problems. This tradition has recently been confirmed, when they issued a new freespan vibration guideline [1], in which they are now considering the interaction of axial forces in the calculation of the pipeline vibration frequency. Shortly after this code was issued, the authors undertook three large pipeline projects, in which the use of the aforementioned code was a contractual requirement. If on one hand, however, the owner insisted upon the use of the new DNV code, on the other he was not willing to accept the very short free span limits, which were resulting from the calculations. Because of this, the authors were forced to look at the problem in further depth, thus resulting interesting conclusions, which will be presented in this paper. These point out some conservative aspects of the code, and make suggestions as to how this conservatism can be overcome, in order to use the DNV safety approach and still produce larger spans, by properly focusing on the freespan buckling problem. In addition to this, the authors have concluded that the freespan buckling problem cannot be dissociated from global buckling, because, in general, it was found that the pipe not seldom moves from a local span buckling mode to a global lateral buckling mode, thus giving the free span problem a completely different emphasis. The experience gained during these projects will be shared in this paper.

Upheaval Buckling Analysis of Partially Buried Pipeline Subjected to High Pressure and High Temperature

2011 ◽  
Author(s):  
Jason Sun ◽  
Han Shi ◽  
Paul Jukes
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Soil Cover ◽  
Resistance Force ◽  
Soil Resistance ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Lateral Buckling ◽  
Upheaval Buckling ◽  
Global Buckling

Offshore industry is now pushing into the deepwater and starting to face the much higher energy reservoir with high pressure and high temperature. Besides the significant impacts on the material, strength, and reliability of the wellhead, tree, and manifold valve; high Pressure (HP) also leads to thicker pipe wall that increases manufacturing and installation cost. High Temperature (HT) can have much wider impact on operation since the whole subsea system has to be operated over a greater temperature range between the non-producing situations such as installation, and long term shut down, and the maximum production flow. It is more concerned for fact that thicker wall pipe results in much greater thermal load so to make the pipeline strength and tie-in designs more challenging. Burying sections of a HPHT pipeline can provide the advantages of thermal insulation by using the soil cover to retain the cool-down time. Burial can also help to achieve high confidence anchoring and additional resistance to the pipeline axial expansion and walking. Upheaval buckling is a major concern for the buried pipelines because it can generate a high level of strain when happens. Excessive yielding can cause the pipeline to fail prematurely. Partial burial can have less concern although it may complicate the pipeline global buckling behavior and impose challenges on the design and analysis. This paper presents the studies on the upheaval buckling of partially buried pipelines, typical example of an annulus flooded pipe-in-pipe (PIP) configuration. The full-scale FE models were created to simulate the pipeline thermal expansion / upheaval / lateral buckling responses. The pipe-soil interaction (PSI) elements were utilized to model the relationship between the soil resistance (force) and the pipe displacement for the buried sections. The effects of soil cover height, vertical prop size, and soil resistance on the upheaval and lateral buckling response of a partially buried pipeline were investigated. This paper presents the latest techniques, allows an understanding in the global buckling, upheaval or lateral, of partially buried pipeline under the HPHT, and assists the industry to pursue safer but cost effective design.

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.

Global Buckling Mitigation of Buried Pipelines: Lateral Resistance Assessment

2015 ◽  
Author(s):  
Martin Gallegillo ◽  
Guillaume Hardouin
Keyword(s):  
Design Guidelines ◽  
Buried Pipelines ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Upheaval Buckling ◽  
Lateral Resistance ◽  
Rock Cover ◽  
Global Buckling ◽  
Cover Design ◽  
Analytical Tools

This paper presents an approach to rock cover design for un-trenched pipelines installed on the seabed and rock-dumped for protection against dropped objects, anchor chain impact and fishing/trawling activities. This is found in some North Sea locations which present challenging conditions for trenching while protection is necessary due to intensive fishing activities. Under these circumstances the pipeline must remain within the rock berm and, hence, it must be designed against global buckling. Whereas there are clear design guidelines addressing upheaval buckling behaviour, the resistance to lateral buckling to maintain a pipeline within the rock berm has received less attention in the literature. The aim of this paper is to present a method to design a rock berm to mitigate against lateral buckling of rock-dumped pipelines based on the horizontal out-of-straightness survey data provided to the designer. The main challenges associated with this activity at different design phases are also introduced, including the use of analytical tools as well as detailed finite element analysis.

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.

Global Buckling of Frames with Laced Compression Members

2016 ◽  
Vol 837 ◽  
pp. 103-108 ◽  
Author(s):  
Michal Kovac ◽  
Zsuzsanna Vanik
Keyword(s):  
Order Theory ◽  
Second Order ◽  
Order Effects ◽  
Engineering Practice ◽  
Buckling Mode ◽  
Column Method ◽  
Global Buckling ◽  
Second Order Effects ◽  
Buckling Length ◽  
Simplified Procedure

The planar frames whose members consist of a laced built-up members are often used in civil engineering practice. For chords of these structures the 1st order theory internal forces and the assessment by equivalent column method are mostly used. In the equivalent column method the buckling length according to the global buckling mode of the structures should be used. If the distance between neighboring nodes is used as the buckling length of the chord, which is the common case, the second order effects with only the bow imperfections between nodes are taken into account in the equivalent column method. For frames sensitive to buckling in a sway mode the second order effects on structures with initial sway imperfection should be taken into account. Therefore, also in frames with the laced compression columns, where the effects of additional sway deformation cause additional normal forces in the chords, the sway imperfection should be applied and the second order in frame analysis should be performed to check these additive forces. This paper deals with the simplified procedure how to evaluate additive forces due to second order effects on the structure with the global sway imperfection.

On Pipeline Lateral Buckling: Lessons Learned and Current Design Challenges

2012 ◽  
Author(s):  
Emil A. Maschner ◽  
Basel Abdalla
Keyword(s):  
Cost Effective ◽  
Lessons Learned ◽  
Operating Conditions ◽  
Design Solution ◽  
Lateral Buckling ◽  
Diverse Range ◽  
Applied Loading ◽  
Direct Design ◽  
Safety Margins ◽  
Global Buckling

The subject of lateral buckling design in recent years has by necessity become increasingly more involved as pipeline projects have moved into more difficult environments where there is a need for optimized economic solutions with assured through-life reliability. The authors have had direct design responsibility and specialist involvement with a large number of projects covering a diverse range of environments, single or PIP systems, variable product characteristics and operating conditions, external applied loading type, and geographical installation limitations. These include shallow and deep water, large thin walled and small thick walled diameter pipes, flat to undulating hard to soft seabed, variable cohesive and non-cohesive surficial soil types and various other project considerations which have impacted on the chosen design solution. The purpose of this paper will be to highlight aspects of global buckling design associated with reliable in place systems and conversely those aspects associated with integrity risks to the as-laid operational pipelines. A review of past project challenges along with a commentary as to the state of the art at the time gives an opportunity to evaluate risks and challenges being faced on current projects. Particularly, as it seeks to develop ever more cost effective designs with proven robustness but optimized safety margins for the installation and operation of HT/HP pipelines in marginal fields.

Nonlinear Stability Analysis of Sandwich Wide Panels—Part II: Postbuckling Response

2018 ◽  
Vol 85 (8) ◽  
Author(s):  
Zhangxian Yuan ◽  
George A. Kardomateas
Keyword(s):  
Continuation Method ◽  
Weak Form ◽  
Arc Length ◽  
Nonlinear Stability Analysis ◽  
Governing Equations ◽  
Buckling Mode ◽  
The Core ◽  
Global Buckling ◽  
Post Buckling ◽  
Branch Switching

The nonlinear post-buckling response of sandwich panels based on the extended high-order sandwich panel theory (EHSAPT) is presented. The model includes the transverse compressibility, the axial rigidity, and the shear effect of the core. Both faces and core are considered undergoing large displacements with moderate rotations. Based on the nonlinear weak form governing equations, the post-buckling response is obtained by the arc-length continuation method together with the branch switching technique. Also, the post-buckling response with imperfections is studied. The numerical examples discuss the post-buckling response corresponding to global buckling and wrinkling. It is found that due to the interaction between faces and core, localized effects may be easily initiated by imperfections after the sandwich structure has buckled globally. Furthermore, this could destabilize the post-buckling response. The post-buckling response verifies the critical load and buckling mode given by the buckling analysis in part I. The axial rigidity of the core, although it is very small compared to that of the faces, has a significant effect on the post-buckling response.

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