Mechanics of Offshore Pipelines, Volume 2

Mechanics of Offshore Pipelines: Volume 2 Buckle Propagation and Arrest

Buckle propagation is a problem unique to offshore pipelines, in which the local collapse of a locally weakened section of the pipe initiates a collapse that propagates at high speed catastrophically flattening the line by kilometers. The lowest pressure that can sustain the propagation of the collapse, the propagation pressure, is only a small fraction of the collapse pressure of the intact pipe. The large difference between these two pressures requires that pipelines be designed on the collapse pressure, and the extent of the potential catastrophic damage suffered is limited by the periodic introduction of buckle arrestors to the line.

Volume 2 of the book series Mechanics of Offshore Pipelines addresses the major aspects of buckle propagation including its initiation, establishment of the propagation pressure, and the dynamics of buckle propagation. Buckle propagation under tension, in pipe-in-pipe pipeline systems, and confined buckle propagation in tubulars such as grouted casing are examined in dedicated chapters. Three chapters deal with the performance of the most commonly used buckle arrestors under both quasi-static and dynamic buckle propagation. Each of these problems is studied through experiments, analyses, and large-scale numerical simulations. The results are used to provide empirical design equations and design guidelines on how to mitigate the effects of buckle propagation.

Key Features

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  Buckle propagation and arrest approached from both fundamental and applied points of view

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  Provides data, empirical design formulae, and design guidelines

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  Teaches how to analyze buckle propagation and mitigate its effects through experiment and modeling

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  Based on the 40-year research and practice of the most eminent researcher in the subject

About the Authors

Stelios Kyriakides, Director, Center for Mechanics of Solids, Structures and Materials, The University of Texas at Austin, USA

Stelios Kyriakides holds the John Webb Jennings Chair in Engineering, and is Professor of Aerospace Engineering and Engineering Mechanics at The University of Texas at Austin. He serves as coeditor of Elsevier's International Journal of Solids and Structures. He has had over 40 years’ involvement with the offshore oil and gas exploration and production industry worldwide and has served the industry as a researcher and consultant.  He earned a BSc (1st Class Honors) in Aeronautical Engineering at the University of Bristol, a MS and PhD, both in Aeronautics from the California Institute of Technology. Among other recognitions he is a member of the US National Academy of Engineering.

Liang-Hai Lee, Sr. Principal Specialist, Genesis/Technip USA, Inc.

Liang-Hai Lee is currently a Sr. Principal Specialist with Genesis/Technip specializing in solid mechanics, experimental and computational mechanics, and structural design. Previously, he was a postdoctoral fellow at the University of Texas at Austin. He is a member of ASME, active in journals including Elsevier’s Engineering Structures and International Journal of Solids and Structures. He earned a MS in Structural Engineering from Chung Hua University in Taiwan, and a PhD in Engineering Mechanics from the University at Texas in Austin.

Click the below links to view the supporting videos.

Chapter 02

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  Video 2.1 (opens in new tab/window)Simulation of initiation and steady-state propagation of collapse in a tube that evaluates the propagation pressure.

  Video 2.1 shows results from a 3-D numerical simulation of the initiation of collapse, its localization, and quasi-static propagation for a tube with D/t =25.33. The tube is pressurized under volume control, and the pressure is plotted vs. the change in volume. Collapse initiates at the plane of symmetry on the left using a local imperfection. The pressure maximum recorded is governed by the amplitude of the imperfection. Collapse localizes and the pressure drops until the walls of the collapsed section come into contact. Subsequently, collapse propagates down the length of the tube. The pressure plateau traced is the propagation pressure of the tube.

Chapter 03

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  Video 3.1(opens in new tab/window) Simulation of initiation and steady-state propagation of collapse in a tube that shows the reduction in propagation pressure when tension is applied.  

  Video 3.1 shows results from a 3-D numerical simulation of the quasi-static propagation of collapse in a tube with D/t =25.3 in the presence of axial tension. The tube is pressurized under volume control first in the absence of tension. Collapse initiates at the plane of symmetry due to a local imperfection. Collapse localizes and the pressure drops until the walls of the collapsed section come into contact. Subsequently, collapse propagates down the length of the tube at the propagation pressure. When tension is applied the pressure drops and starts tracing a new pressure plateau, which constitutes the propagation pressure at the applied level of tension.

Chapter 04

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  Video 4.1(opens in new tab/window) Simulation of initiation and steady-state propagation of collapse in a confined tube.

  Video 4.1 shows results from a 3-D numerical simulation of the confined buckle propagation of a tube with D/t =25.6. The tube is pressurized under volume control, and the pressure is plotted vs. the change in volume. Collapse is initiated outside the confinement. The buckle propagates and, as it engages the rigid confinement, it gradually folds up into a U-mode and starts propagating inside the confinement. The pressure plateau traced is the confined propagation pressure of the tube.

Chapter 05

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  Video 5.1(opens in new tab/window) Simulation of initiation and steady-state propagation of collapse in P-I-P collapsing both tubes.

  Video 5.1 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse in a pipe-in-pipe system. The dimensions of the two tubes appear in the inserted pressure-change in volume response. The system is pressurized under volume control. Collapse initiates at the plane of symmetry on the left using a local imperfection in the outer tube. The outer tube collapses locally, comes into contact with the inner tube causing it to collapse also. The pressure drops until the inner walls of the collapsed sections come into contact. Subsequently, collapse propagates down the length, collapsing both tubes. The pressure plateau traced is the propagation pressure of the pipe-in-pipe system.

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  Video 5.2(opens in new tab/window) Buckle propagation in P-I-P collapsing first the outer tube and subsequently the inner one at higher pressure.

  Video 5.2 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse in a pipe-in-pipe system. The dimensions of the two tubes appear in the inserted pressure-change in volume response. The system is pressurized under volume control. Collapse initiates in the outer tube at the plane of symmetry on the left. Collapse propagates in a steady-state manner leaving the inner tube intact. With continued volume-controlled pressurization the inner tube collapses on the left and the collapse propagates again this time collapsing both tubes.

Chapter 06

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  Video 6.1(opens in new tab/window) Dynamic buckle propagating at a speed of 189 m/s in water at 53.4 bar external pressure.

  Video 6.1 shows a sequence of images captured by high-speed photography from a dynamic propagation experiment conducted in the experimental facility shown in Figs. 6.3 and 6.4 on a tube with D/t = 35.62. The tube is under constant pressure of 53.4 bar in water. Local collapse initiates on the right. The buckle accelerates and enters the field of view propagating at a constant velocity of 189 m/s leaving behind the tube severely fattened.

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  Video 6.2(opens in new tab/window) Dynamic buckle propagation in water at 64.2 bar external pressure in which the buckle flips by 90 degrees.

  Video 6.2 shows a sequence of high-speed photography images from a dynamic propagation experiment conducted on a tube with D/t = 35.42. The tube is under constant pressure of 64.2 bar in water. Local collapse initiates on the right. The buckle accelerates and enters the field of view propagating at a high speed. The induced reverse ovality ahead of it causes the collapse mode to flip at 90 degrees and continue to propagate downstream.

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  Video 6.3(opens in new tab/window) Simulation of dynamic buckle propagation in vacuum at 141.1 bar external pressure in which the mode of collapse flips twice.

  Video 6.3 shows a sequence of deformed images from a 3-D numerical simulation of a buckle propagating dynamically in a tube with D/t =26.8 at a constant pressure of 141.4 bar. Collapse initiates at the symmetry plane on the left, propagates at high speed, and the mode of collapse flips twice at 90 degrees.

Chapter 07

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  Video 7.1 (opens in new tab/window)Quasi-static buckle propagation, arrest by an integral arrestor, and crossover via the flattening mode.

  Video 7.1 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse toward an integral arrestor. The tube has D/t =20.83 and the arrestor h/t = 1.898, and the structure is pressurized under volume control. Collapse initiates at the plane of symmetry on the left, it localizes, and subsequently propagates at the propagation pressure toward the arrestor, where it is temporarily arrested. As the pressure increases, some ovality is passed to the downstream tube causing its collapse via the flattening mode. The maximum pressure of 189.8 bar reached constitutes the crossover pressure of this buckle arrestor.

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  Video 7.2(opens in new tab/window) Quasi-static buckle propagation, arrest by an integral arrestor, and crossover via the flipping mode.

  Video 7.2 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse toward an integral arrestor. The tube has D/t =21.01 and the arrestor h/t = 2.411, and the structure is pressurized under volume control. Collapse initiates at the plane of symmetry on the left, it localizes, and subsequently propagates at the propagation pressure toward the arrestor where it is temporarily arrested. As the pressure increases, some reverse ovality is passed to the downstream tube causing its collapse via the flipping mode. The maximum pressure of 226.6 bar reached constitutes the crossover pressure of this buckle arrestor.

Chapter 08

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  Video 8.1 (opens in new tab/window)Simulation of dynamic buckle propagation at a pressure of 108.4 bar, and arrest by an integral arrestor.

  Video 8.1 shows a sequence of deformed images from a 3-D numerical simulation of a dynamic buckle propagating toward an integral arrestor at a constant pressure of 108.4 bar. The tube has D/t =28.27 and the arrestor h/t = 2.387. Collapse initiates at the symmetry plane on the left, propagates at high speed, engages the arrestor, deforms it somewhat, but is arrested.

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  Video 8.2(opens in new tab/window) Simulation of dynamic buckle propagation at a pressure of 116.6 bar, and crossover of an integral arrestor via the flipping mode.

  Video 8.2 shows a sequence of deformed images from a 3-D numerical simulation of a dynamic buckle propagating toward an integral arrestor at a constant pressure of 116.6 bar. The tube and arrestor have the same dimensions as those of Video 8.1: D/t =28.27 and h/t = 2.387. Collapse initiates at the symmetry plane on the left, propagates at high speed, engages the arrestor, deforms it somewhat and crosses it via the flipping mode.

Chapter 09

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  Video 9.1(opens in new tab/window) Quasi-static buckle propagation, arrest by a slip-on arrestor, and crossover via the U-mode.

  Video 9.1 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse toward a slip-on arrestor. The tube has a D/t =25.4 and the arrestor h/t = 2.87, and the structure is pressurized under volume control. Collapse initiates at the plane of symmetry on the left, it localizes and subsequently propagates at the propagation pressure toward the arrestor where it is temporarily arrested. As the pressure increases, the buckle gradually folds up into a U-mode and penetrates the ring arrestor. The maximum pressure of 1104.9 bar reached constitutes the crossover pressure of this slip-on buckle arrestor.

Chapter 10

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  Video 10.1 (opens in new tab/window)Quasi-static buckle propagation, arrest by an IRA arrestor, and crossover via the flipping mode.

  Video 10.1 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse in a pipe-in-pipe system toward an internal ring arrestor. The dimensions of the tubes and arrestor appear in the inserted pressure-change in volume response. The structure is pressurized under volume control. Collapse initiates at the plane of symmetry on the left, it localizes, and subsequently propagates toward the arrestor flattening both tubes, where it is temporarily arrested. The pressure plateau traced represents the propagation pressure of the P-I-P system. As the pressure increases, some reverse ovality is passed to the downstream tube causing its collapse via the flipping mode. The maximum pressure of 214.6 bar reached constitutes the crossover pressure of this P-I-P and internal ring buckle arrestor system.

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  Video 10.2(opens in new tab/window) Quasi-static buckle propagation, arrest by an IRA arrestor, and crossover via the flattening mode.

  Video 10.2 shows results from a 3-D numerical simulation of the quasi-static initiation and propagation of collapse in a pipe-in-pipe system toward an internal ring arrestor. The dimensions of the tubes and arrestor appear in the inserted pressure-change in volume response. The structure is pressurized under volume control. Collapse initiates at the plane of symmetry on the left, it localizes, and subsequently propagates toward the arrestor flattening both tubes, where it is temporarily arrested. The pressure plateau traced represents the propagation pressure of the P-I-P system. As the pressure increases, some ovality is passed to the downstream tube causing its collapse via the flattening mode. The maximum pressure of 200 bar reached constitutes the crossover pressure of this P-I-P and internal ring buckle arrestor system.

Appendix A

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  Video A1(opens in new tab/window) Inflation of a rubber tube leads to localized bulging that grows and subsequently propagates along the length at its propagation pressure.

  Video A1 shows the pressure-time history recorded in a volume-controlled inflation experiment on a latex rubber tube and a sequence of photographic images of the deforming tube. The tube initially expands uniformly and the pressure reaches a maximum value following which a local bulge forms. The bulge grows in size with the pressure dropping. At some stage, radial expansion is no longer possible so the bulge starts propagating along the length, tracing a pressure plateau in the process.

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  Video A2(opens in new tab/window) Numerical simulation of bulge localization and steady-state propagation.

  Video A2 shows the pressure-time history and a sequence of deformed tube images from the axisymmetric membrane solution of the inflation of a latex rubber tube. The tube initially expands uniformly, the pressure reaches a maximum when a local bulge starts to form. The bulge grows in size with the pressure dropping and then propagates in a steady-state fashion along the length.