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.

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.

Global Buckling of a Pre-Pressurized Flexible Flowline

2013 ◽  
Author(s):  
Zhengmao Yang ◽  
Daniel Karunakaran
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Tensile Force ◽  
Flexible Pipe ◽  
Upheaval Buckling ◽  
Axial Tension ◽  
Lateral Resistance ◽  
Rock Cover ◽  
Global Buckling

For the protection from object drop/fishing trawl impact, flexible flowline is normally trenched or rock-dumped. And hence, upheaval buckling is promoted by the elevated temperatures and high pressures. In order to reduce the rock cover requirement for mitigation of upheaval buckling, rock-dumping or trenching while the flexible pipe are pressurized has been performed successfully in several north sea projects. The temperature and pressure induced elongation of flexible pipe are design dependent. For high pressure flexible flowline, the pressure expansion is significantly higher than conventional rigid pipelines. Due to the low bending stiffness and high pressure expansion, a flexible flowline will buckle laterally when it is pre-pressurized in hydro-test before trenching or rock-dumping. As a consequence, lateral imperfections are induced and will be kept after trenching or rock-dumping due to lateral resistance and bending stress relaxation of the flowline. In these locations, the flowline tends to deform laterally in operating. On the other hand, when the flowline is de-pressurized after trenching or rock-dumping the contraction of the flowline is restrained by the surrounding soils or rocks, and hence axial tension force can be obtained. When the flowline starts to operate, this tensile force will neutralize part of the compressive axial force, and therefore the required upheaval resistance is reduced. In this paper, global buckling of a pre-pressurized flexible flowline has been studied, and the influence on the requirement of rock covers is presented.

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 Lateral Buckling Theory and Experimental Study on Pipe-in-Pipe Structure

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 185 ◽  
Author(s):  
Zechao Zhang ◽  
Hongbo Liu ◽  
Zhihua Chen
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Thermal Loading ◽  
Oil And Gas ◽  
Critical Force ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Theoretical Derivation ◽  
Initial Imperfections ◽  
Global Buckling

With the increasing depth of marine oil and gas exploitation, more requirements have been proposed on the structure of deep-sea oil pipelines. The influencing factors of lateral buckling of a pipe-in-pipe (PIP) structure containing initial imperfections and its critical force were investigated in this study by conducting an experiment, a finite element analysis, and a theoretical derivation. The change laws on the influence of initial imperfections of the PIP structure during thermal loading were revealed through an experimental study by using imperfection amplitude and wavelength as parameters. Appropriate finite element models were established, and the influences of initial imperfections, pipe-soil interaction, and the height and the number of centralizers on the global buckling critical force of the PIP structure were analyzed. The formulas of global buckling critical force of inner and outer pipes and that under pipe-soil interaction was obtained by using a theoretical derivation method. A comparative verification with experimental and finite element (FE) models result was conducted, which provided a corresponding basis for steel pipeline design.

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.

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.

Recent Experience in the Lateral Buckling Design of Medium to Large Diameter Pipelines

2012 ◽  
Author(s):  
Maša Branković ◽  
Benjamin Anderson ◽  
Edwin Shim ◽  
Hammam Zeitoun ◽  
Eu Jeen Chin
Keyword(s):  
Large Diameter ◽  
Design Guidelines ◽  
Operating Conditions ◽  
Recent Experience ◽  
Lateral Buckling ◽  
High Pressure High Temperature ◽  
Critical Buckling Force ◽  
Global Buckling ◽  
Design Solutions ◽  
Definition Of

In the last decade and a half, the pipeline industry has gained significant experience in both the design and operation of pipeline systems exposed to lateral buckling. JIPs, design guidelines and recommended practices such as SAFEBUCK (Reference [1]), HOTPIPE (Reference [2]) and DNV RP-F110 (Reference [3]), together with operational feedback have significantly contributed to the development of comprehensive methods to determine robust lateral buckling design solutions. Most of this knowledge has been gained from understanding the behaviour of HP/HT (high pressure/ high temperature) small, light diameter systems, which buckle more predictably at operating conditions well below design conditions. Medium to large diameter, concrete coated pipelines are generally considered to be less prone to lateral buckling by comparison (due to expected milder design conditions), however the consequence of their buckling is far more severe and can prove extremely difficult to control. Fundamentally, the knowledge acquired and general lateral buckling design methodologies developed for HP/HT systems can be applied for the design of larger, heavier pipelines, however there are a number of key differences in the behaviour of both systems which warrant special considerations. Key considerations include (a), effective axial force and critical buckling force development (impacting susceptibility and initiation considerations), (b) severe post-buckle response on-seabed (impacting the acceptance of uncontrolled buckling for definition of buckle trigger spacing and extents), and (c), the consequence of introducing buckle triggers. Additional design complexity is introduced for systems installed in shallow water, which are exposed to more severe metocean conditions than deepwater HP/ HT systems. This requires heavy concrete weight coating (CWC) for stabilisation, resulting in strain localisation at field joints, concrete stiffening effects and complex interaction with hydrodynamic loading, typically ‘competing against’ intuitive global buckling design. All of the above factors result in lateral buckling design solutions for medium to large diameter, concrete coated pipelines becoming rather challenging.

Lateral Buckling and Walking Design of a Pipeline Subjected to a High Number of Operational Cycles on Very Uneven Seabed

2014 ◽  
Author(s):  
Rafael F. Solano ◽  
Bruno R. Antunes ◽  
Alexandre S. Hansen ◽  
T. Sriskandarajah ◽  
Carlos R. Charnaux ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Structural Integrity ◽  
Mechanical Design ◽  
Lateral Buckling ◽  
Element Analysis ◽  
Control Approach ◽  
Temperature Conditions ◽  
Oil Export ◽  
Global Buckling

Global buckling is a behavior observed on subsea pipelines operating under high pressure and high temperature conditions which can jeopardize its structural integrity if not properly controlled. The thermo-mechanical design of such pipelines shall be robust in order to manage some uncertainties, such as: out-of-straightness and pipe-soil interaction. Pipeline walking is another phenomenon observed in those pipelines which can lead to accumulated displacement and overstress on jumpers and spools. In addition, global buckling and pipeline walking can have strong interaction along the route of a pipeline on uneven and sloped seabed, increasing the challenges of thermo-mechanical design. The P-55 oil export pipeline has approximately 42km length and was designed to work under severe high pressure and high temperature conditions, on a very uneven seabed, including different soil types and wall thicknesses along the length and a significant number of crossings. Additionally, the pipeline is expected to have a high amount of partial and full shutdowns during operation, resulting in an increase in design complexity. During design, many challenges arose in order to “control” the lateral buckling behavior and excessive walking displacements, and finite element analysis was used to understand and assess the pipeline behavior in detail. This paper aims to provide an overview of the lateral buckling and walking design of the P-55 oil export pipeline and to present the solutions related to technical challenges faced during design due to high number of operational cycles. Long pipelines are usually characterized as having a low tendency to walking; however in this case, due to the seabed slope and the buckle sites interaction, a strong walking tendency has been identified. Thus, the main items of the design are discussed in this paper, as follows: lateral buckling triggering and “control” approach, walking in long pipelines and mitigate anchoring system, span correction and its impact on thermo-mechanical behavior.

scholarly journals Development of Simulation Based p-Multipliers for Laterally Loaded Pile Groups in Granular Soil Using 3D Nonlinear Finite Element Model

2020 ◽  
Vol 11 (1) ◽  
pp. 26
Author(s):  
Muhammad Bilal Adeel ◽  
Muhammad Asad Jan ◽  
Muhammad Aaqib ◽  
Duhee Park
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Design Guidelines ◽  
American Petroleum Institute ◽  
Winkler Foundation ◽  
Group Effect ◽  
Pile Groups ◽  
Element Analysis ◽  
Laterally Loaded Pile ◽  
Laterally Loaded

The behavior of laterally loaded pile groups is usually accessed by beam-on-nonlinear-Winkler-foundation (BNWF) approach employing various forms of empirically derived p-y curves and p-multipliers. Averaged p-multiplier for a particular pile group is termed as the group effect parameter. In practice, the p-y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. In this study, we performed 3D finite element analysis to develop p-multipliers and group effect parameters for 3 × 3 to 5 × 5 vertically squared pile groups. The effect of the ratio of spacing to pile diameter (S/D), number of group piles, varying friction angle (φ), and pile fixity conditions on p-multipliers and group effect parameters are evaluated and quantified. Based on the simulation outcomes, a new functional form to calculate p-multipliers is proposed for pile groups. Extensive comparisons with the experimental measurements reveal that the calculated p-multipliers and group effect parameters are within the recorded range. Comparisons with two design guidelines which do not account for the pile fixity condition demonstrate that they overestimate the p-multipliers for fixed-head condition.

scholarly journals A Finite Element Study on Compressive Resistance Degradation of Square and Circular Steel Braces under Axial Cyclic Loading

2021 ◽  
Vol 11 (13) ◽  
pp. 6094
Author(s):  
Hubdar Hussain ◽  
Xiangyu Gao ◽  
Anqi Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cyclic Loading ◽  
Slenderness Ratio ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Section Shape ◽  
Axial Cyclic Loading ◽  
Global Buckling ◽  
Parametric Studies

In this study, detailed finite element analysis was conducted to examine the seismic performance of square and circular hollow steel braces under axial cyclic loading. Finite element models of braces were constructed using ABAQUS finite element analysis (FEA) software and validated with experimental results from previous papers to expand the specimen’s matrix. The influences of cross-section shape, slenderness ratio, and width/diameter-to-thickness ratio on hysteretic behavior and compressive-tensile strength degradation were studied. Simulation results of parametric studies show that both square and circular hollow braces have a better cyclic performance with smaller slenderness and width/diameter-to-thickness ratios, and their compressive-tensile resistances ratio significantly decreases from cycle to cycle after the occurrence of the global buckling of braces.

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