Deepwater Flexible Risers and Pipelines

Yong Bai, PhD, is the president of Offshore Pipelines & Risers Inc. in Houston, and is a professor and the director of the Offshore Engineering Research Center at Zhejiang University. He has previously taught at Stavanger University in Norway where he was a professor of offshore structures and has also worked with ABS as manager of the Offshore Technology Department, DNV as the JIP project manager and has also worked for Shell International E & P, JP Kenny, and MCS, where he was vice president of engineering. He is the co-author of two books on pipelines and over 100 papers on the design and installation of subsea pipelines and risers.

• Preface xixAcknowledgment xxiAbout the Author xxiiiPart 1: Local Analysis 11 Introduction 31.1 Flexible Pipelines Overview 31.2 Environmental Conditions 41.3 Flexible Pipeline Geometry 71.4 Base Case-Failure Modes and Design Criteria 91.5 Reinforcements 101.6 Project and Objectives 12References 122 Structural Design of Flexible Pipes in Different Water Depth 152.1 Introduction 152.2 Theoretical Models 152.3 Comparison and Discussion 242.4 Conclusions 34References 343 Structural Design of High Pressure Flexible Pipes of Different Internal Diameter 353.1 Introduction References 353.2 Analytical Models 373.2.1 Cylindrical Layers 373.2.2 Helix Layers 393.2.3 The Stiffness Matrix of Pipe as a Whole Helix Layers 403.2.4 Blasting Failure Criterion 413.3 FEA Modeling Description 423.4 Result and Discussion 463.5 Design 503.6 Conclusions 54References 554 Tensile Behavior of Flexible Pipes 574.1 Introduction 574.2 Theoretical Models 584.2.1 Mechanical Model of Pressure Armor Layer 584.2.2 Mechanical Behavior of Tensile Armor Layer 614.2.3 Overall Mechanical Behavior 634.3 Numerical Model 644.3.1 Pressure Armor Stiffness 644.3.2 Full Pipe 694.4 Comparison and Discussion 714.5 Parametric Study 774.6 Conclusions 79References 805 Design Case Study for Deep Water Risers 835.1 Abstract 835.2 Introduction 835.3 Cross-Sectional Design 855.4 Case Study 875.5 Design Result 945.6 Finite Elements Analysis 975.7 Conclusion 100References 1016 Unbonded Flexible Pipe Under Bending 1036.1 Introduction 1036.2 Helical Layer Within No-Slip Range 1046.2.1 Geometry of Helical Layer 1046.2.2 Bending Stiffness of Helical Layer 1086.3 Helical Layer Within Slip Range 1096.3.1 Critical Curvature 1096.3.2 Axial Force in Helical Wire Within Slip Range 1116.3.3 Axial Force in Helical Wire Within No-Slip Range 1126.3.4 Bending Stiffness of Helical Layer 114References 1167 Coiling of Flexible Pipes 1177.1 Introduction 1177.2 Local Analysis 1207.2.1 Dimensions and Material Characteristics 1207.2.2 Tension Test 1207.2.3 Bending Test 1237.2.4 Summary 1247.3 Global Analysis 1267.3.1 Modeling 1267.3.2 Interaction and Mesh 1277.3.3 Load and Boundary Conditions 1287.3.4 Discussion of the Results 1287.4 Parametric Study 1347.4.1 Diameter of the Coiling Drum 1347.4.2 Sinking Distance of the Coiling Drum 1357.4.3 Reeling Length 1387.4.4 The Location of the Bearing Plate 1397.5 Conclusions 142References 143Part 2: Riser Engineering 1458 Flexible Risers and Flowlines 1478.1 Introduction 1478.2 Flexible Pipe Cross-Section 1478.2.1 Carcass 1498.2.2 Internal Polymer Sheath 1508.2.3 Pressure Armor 1508.2.4 Tensile Armor 1518.2.5 External Polymer Sheath 1518.2.6 Other Layers and Configurations 1528.3 End Fitting and Annulus Venting Design 1528.3.1 End Fitting Design and Top Stiffener (or Bellmouth) 1528.3.2 Annulus Venting System 1538.4 Flexible Riser Design 1548.4.1 Design Analysis 1548.4.2 Riser System Interface Design 1558.4.3 Current Design Limitations 156References 1589 Lazy-Wave Static Analysis 1599.1 Introduction 1599.2 Fundamental Assumptions 1629.3 Configuration Calculation 1629.3.1 Cable Segment 1639.3.1.1 Hang-Off Section 1639.3.1.2 Buoyancy Section 1669.3.1.3 Decline Section 1669.3.2 Boundary-Layer Segment 1679.3.3 Touchdown Segment 1689.3.4 Boundary Conditions 1709.4 Numerical Solution 1719.5 Finite Element Model 1749.5.1 Environment 1759.5.2 Riser 1759.5.3 Boundary Conditions 1759.6 Comparison and Discussion 1759.7 Parameter Analysis 1809.7.1 Effect of Seabed Stiffness 1809.7.2 Effect of Hang-Off Inclination Angle 1829.7.3 Effect of Buoyancy Section Length 1859.8 Conclusions 187References 18810 Steep-Wave Static Configuration 18910.1 Introduction 18910.2 Configuration Calculation 19010.2.1 Touch-Down Segment 19110.2.2 Buoyancy Segment 19410.2.3 Hang-Off Segment 19510.2.4 Boundary Conditions 19510.3 Numerical Solution 19610.4 Comparison and Discussion 19810.5 Parametric Analysis 20310.5.1 Effect of Buoyancy Segment’s Equivalent Outer Diameter 20310.5.2 Effect of Buoyancy Segment Length 20510.5.3 Effect of Buoyancy Segment Location 20710.5.4 Effect of Current Velocity 20910.6 Conclusions 212References 212Contents ix11 3D Rod Theory for Static and Dynamic Analysis 21311.1 Introduction 21311.2 Nomenclature 21511.3 Mathematical Model 21611.3.1 Governing Equations 21611.3.2 Bending Hysteretic Behavior 22011.3.3 Bend Stiffener Constraint 22211.3.4 Pipe-Soil Interaction 22411.4 Case Study 22511.5 Results and Discussion 22711.5.1 Static Analysis 22711.5.2 Dynamic Analysis 23111.5.2.1 Top-End Region 23111.5.2.2 Touchdown Zone 23311.5.3 Effect of Bend Stiffener Constraint 23611.5.4 Effect of Bending Hysteretic Behavior 23811.5.5 Effect of Top Angle Constraint 24011.6 Conclusions 242References 24312 Dynamic Analysis of the Cable-Body of the Deep Underwater Towed System 24712.1 Introduction 24712.2 Establishment of Towed System Dynamic Model 24812.3 Numerical Simulation and Analysis of Calculation Results 25112.3.1 The Effect of Different Turning Radius 25212.3.2 The Effect of Different Turning Speeds 25312.3.3 Dynamic Analysis of the Towed System with the Change of the Parameters of the Cable 25412.3.4 The Effect of the Diameters of the Towed Cable 25712.3.5 The Effect of the Drag Coefficients of the Towed Cable 25712.3.6 The Effect of the Added Mass Coefficient of the Towed Cable 26112.4 Conclusions 263Acknowledgments 264References 26413 Dynamic Analysis of Umbilical Cable Under Interference 26713.1 Introduction 26713.2 Dynamic Model of Umbilical Cable 26913.2.1 Establishment of Mathematical Model 26913.2.2 The Discrete Numerical Method for Solving the Lumped Mass Method 27113.2.3 Calculation of the Clashing Force of Umbilical Cable 27713.3 The Establishment of Dynamic Simulation Model in OrcaFlex 27913.3.1 The Equivalent Calculation of the Stiffness of the Umbilical Cable 27913.3.2 RAO of the Platform 28113.3.3 The Choice of Wave Theory 28113.3.4 Establishment of Model in OrcaFlex 28213.4 The Calculation Results 28313.4.1 The Clashing Force of Interference 28313.4.2 The Variation of the Effective Tension Under Interference 28513.4.3 The Variation of Bending Under Interference 28713.5 Conclusion 291References 29414 Fatigue Analysis of Flexible Riser 29514.1 Introduction 29514.2 Fatigue Failure Mode of Flexible Riser 29614.3 Global Model of Flexible Risers 29714.3.1 Pipe Element 29714.3.2 Bending Stiffener 29814.3.3 Sea Condition 29914.3.4 Platform Motion Response 30014.3.5 Time Domain Simulation Analysis 30114.4 Failure Mode and Design Criteria 30214.4.1 Axisymmetric Load Model 30214.4.2 Bending Load Model 30314.5 Calculation Method of Fatigue Life of Flexible Riser 30514.5.1 Rainflow Counting Method 30514.5.2 S-N Curve 30514.5.3 Miner’s Linear Cumulative Damage Theory 30714.5.4 Modification of Average Stress on Fatigue Damage 30814.6 Example of Fatigue Life Analysis of Flexible Riser 309References 31415 Steel Tube Umbilical and Control Systems 31715.1 Introduction 31715.1.1 General 31715.1.2 Feasibility Study 31815.1.3 Detailed Design and Installation 31915.1.4 Qualification Tests 32015.2 Control Systems 32015.2.1 General 32015.2.2 Control Systems 32115.2.3 Elements of Control System 32215.2.4 Umbilical Technological Challenges and Solutions 32315.3 Cross-Sectional Design of the Umbilical 32615.4 Steel Tube Design Capacity Verification 32715.4.1 Pressure Containment 32815.4.2 Allowable Bending Radius 32815.5 Extreme Wave Analysis 32915.6 Manufacturing Fatigue Analysis 33015.6.1 Accumulated Plastic Strain 33015.6.2 Low Cycle Fatigue 33115.7 In-Place Fatigue Analysis 33115.7.1 Selection of Sea State Data From Wave Scatter Diagram 33215.7.2 Analysis of Finite Element Static Model 33215.8 Installation Analysis 33215.9 Required On-Seabed Length for Stability 333References 33416 Stress and Fatigue of Umbilicals 33716.1 Introduction 33716.2 STU Fatigue Models 33816.2.1 Simplified Model 33916.2.1.1 Axial and Bending Stresses 33916.2.1.2 Friction Stress 34016.2.1.3 Simplified Approach: Combining Stresses 34216.2.1.4 Simplified (Combining Stresses) Fatigue Damage 34216.2.1.5 Simplified Model Assumptions 34316.2.2 Enhanced Non-Linear Time Domain Fatigue Model 34316.2.2.1 Friction Stresses 34416.2.2.2 Effect of Multiple Tube Layers 34416.2.2.3 Combined Friction Stresses 34516.2.2.4 Axial and Bending Stresses 34516.2.2.5 Combining Stresses 34616.2.2.6 Fatigue Life 34616.2.2.7 Benefits of Enhanced Non-Linear Time Domain Fatigue Model 34716.3 Worked Example 34816.3.1 Time Domain vs. Simplified Approaches 35016.3.2 Effect of Friction on STU Fatigue 35116.3.2.1 Influence of High Tube Friction on Umbilical Fatigue 35216.3.2.2 Influence of Low Tube Friction on Umbilical Fatigue 35216.3.2.3 Influence of Metal-to-Metal Friction vs. Metal-to-Plastic Contact on Umbilical Fatigue 35216.3.3 Effect of Increasing Water Depth 35316.3.4 Effect of Increasing the Tube Layer Radius 35416.4 Conclusions 35516.5 Recommendations 356References 35717 Cross-Sectional Stiffness for Umbilicals 35917.1 Introduction 35917.2 Theoretical Model of Umbilicals 36117.3 Bending Stiffness of Umbilicals 36217.4 Tensile Stiffness of Umbilicals 36617.5 Torsional Stiffness of Umbilicals 36817.6 Ultimate Capacity of Umbilicals 36817.6.1 Minimum Bending Curvature 36817.6.2 Minimum Tensile Load 36917.6.3 Tensile Capacity Curve 369References 37218 Umbilical Cross-Section Design 37518.1 Introduction 37518.1.1 General 37518.1.2 Sectional Composition of the Umbilical Cable 37518.1.3 Umbilical Cable Structure Features 37618.2 Umbilicals Cross-Section Design Overview 37718.2.1 Umbilical Cross-Section Design Flowchart 37718.2.2 Load Analysis 37818.3 Umbilical Cable Cross-Section Design 38018.3.1 Umbilical Cable Cross-Section Layout Design 38018.3.2 Tensile Performance Design 38118.3.3 Bending Performance Design 382References 384Part 3: Fiber Glass Reinforced Deep Water Risers 38519 Collapse Strength of Fiber Glass Reinforced Riser 38719.1 Introduction 38719.2 External Pressure Test 38819.2.1 Testing Specimen 38819.2.2 Testing System 38919.2.3 Testing Results 38919.3 Theoretical Analysis 39019.3.1 Fundamental Assumptions 39019.3.2 Constitutive Model of Materials 39119.3.3 Establish the Equations of Motion 39319.3.4 Establish Virtual Work Equations 39419.4 Numerical Analysis 39419.5 Finite Element Analysis 39519.5.1 Establish the Finite Element Model 39619.5.2 The Results of the Finite Element Analysis 39719.6 Conclusion 401References 40220 Burst Strength of Fiber Glass Reinforced Riser 40520.1 Introduction 40520.2 Experiment 40620.2.1 Dimensions and Material Properties of FGRFP 40620.2.2 Experiment Device 40720.2.3 Experiment Results 40720.3 Numerical Simulations 40720.3.1 Mesh and Interaction 40720.3.2 Load and Boundary Conditions 40820.3.3 Numerical Results 40920.4 Analytical Solution 40920.4.1 Basic Assumptions 40920.4.2 Stress Analysis 41120.4.3 Boundary Condition 41420.5 Results and Discussion 41620.6 Parametric Analysis 41720.6.1 Winding Angle of Fiber Glass 41720.6.2 Diameter-Thickness Ratio 41820.7 Conclusions 419References 41921 Structural Analysis of Fiberglass Reinforced Bonded Flexible Pipe Subjected to Tension 42121.1 Introduction 42121.2 Experiment 42321.2.1 Basic Assumptions 42321.2.2 Material Characteristics 42521.2.3 Experimental Results 42621.3 Theoretical Solution 42721.3.1 Basic Assumptions 42921.3.2 Cross-Section Simplification 42921.3.3 Fiber Deformation 43021.3.4 Cross-Section Deformation 43121.3.5 Equilibrium Equations 43421.4 Finite Element Model 43421.5 Comparison and Discussion 43621.5.1 Tension-Extension Relation 43621.5.2 Cross-Section Deformation 43721.5.3 Fiberglass Stress 43921.5.4 Contribution of Each Material 43921.5.5 Summary 44021.6 Parametric Study 44221.6.1 Winding Angle 44221.6.2 Fiberglass Amount 44321.6.3 Diameter-Thickness Ratio 44421.7 Conclusions 445Acknowledgement 446References 44622 Fiberglass Reinforced Flexible Pipes Under Bending 44922.1 Introduction 44922.2 Experiment 45122.2.1 Experimental Facility 45122.2.2 Specimen 45322.2.3 Experiment Process 45322.2.4 Experimental Results 45522.3 Analytical Solution 45722.3.1 Fundamental Assumption 45722.3.2 Kinematic Equation 45722.3.3 Material Simplification 45922.3.4 Constitutive Model 46222.3.5 Principle of Virtual Work 46422.3.6 Algorithm of Analytical Solutions 46422.4 Finite Element Method 46522.5 Result and Conclusion 46622.6 Parametric Analysis 46922.6.1 D/t Ratio 46922.6.2 Initial Ovality 47022.7 Conclusions 472References 47323 Fiberglass Reinforced Flexible Pipes Under Torsion 47523.1 Introduction 47523.2 Experiments 47723.3 Experimental Results 47823.4 Analytical Solution 48123.4.1 Coordinate Systems 48123.4.2 Elastic Constants of Reinforced Layers (k = 2, 3 … (n − 1)) 48323.4.3 Reinforced Layers Stiffness Matrix k = 2, 3...(n – 1) 48423.4.4 Inner Layer and Outer Layer Stiffness Matrix (k = 1, n) 48623.4.5 Stress and Deformation Analysis 48723.4.6 Boundary Conditions 49123.4.7 Interface Conditions 49223.4.8 Geometric Nonlinearity 49323.5 Numerical Simulations 49423.6 Results and Discussions 49623.7 Parametric Analysis 49823.7.1 Effect of Winding Angle 49823.7.2 Effect of Thickness of Reinforced Layers 49823.8 Conclusions 499Acknowledgments 500References 50124 Cross-Section Design of Fiberglass Reinforced Riser 50324.1 Introduction 50324.2 Nomenclature 50324.3 Basic Structure of Pipe 50524.3.1 Overall Structure 50524.3.2 Material 50624.4 Strength Failure Design Criteria 50624.4.1 Burst Pressure 50624.4.2 Burst Pressure Under Internal Pressure Bending Moment 50824.4.3 Yield Tension 50824.5 Failure Criteria for Instability Design 51024.5.1 Minimum Bending Radius 51024.5.2 External Pressure Instability Pressure 51024.6 Design Criteria for Leakage Failure 511References 51125 Fatigue Life Assessment of Fiberglass Reinforced Flexible Pipes 51325.1 Introduction 51325.2 Global Analysis 51525.3 Rain Flow Method 51725.4 Local Analysis 51925.5 Modeling 51925.6 Result Discussion 52025.7 Sensitivity Analysis 52425.8 Fatigue Life Assessment 52725.9 Conclusion 528References 529Part 4: Ancillary Equipments for Flexibles and Umbilicals 53126 Typical Connector Design for Risers 53326.1 Introduction 53326.2 Carcass 53426.3 Typical Connector 53526.4 Seal System 53626.5 Termination of the Carcass 53726.6 Smooth Bore Pipe 53926.7 Rough Bore Pipe 54026.8 Discussion 54226.9 Conclusions 544References 54527 Bend Stiffener and Restrictor Design 54727.1 Introduction 54727.2 Response Model 54827.3 Extreme Load Description 54927.4 General Optimization Scheme 55027.5 Application Example 55227.6 Non-Dimensional Bend Stiffener Design 55327.7 Alternative Non-Dimensional Parameters 55627.8 Conclusions 558References 55828 End Termination Design for Umbilicals 56128.1 Introduction 56128.2 Umbilical Termination Assembly 56128.2.1 General 56128.2.2 UTA Design 56228.2.3 UTA Structural Design Basis 56528.3 Subsea Termination Interface 566References 56829 Mechanical Properties of Glass Fibre Reinforced Pipeline During the Laying Process 56929.1 Introduction 56929.2 Theoretical Analysis 57029.2.1 Wave Load 57029.2.2 Motion Response of the Vessel 57229.2.3 Dynamic Numerical Solution 57329.3 Static Analysis 57529.4 Dynamic Characteristic Analysis 57929.4.1 Influence of the Wave Direction 57929.4.2 Influencing of Different Lay Angle 58229.4.3 Influencing Submerged Weight 58429.5 Conclusions 584References 586Index 589