Flexible Pipes

Qiang Bai, PhD, has more than 20 years of experience in subsea and offshore engineering. He has taught at Kyushu University in Japan, UCLA in the USA, and he has worked at OPE, JP Kenny, and Technip. He is also the coauthor of three influential books on pipelines, which are standard in the industry.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 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. Weidong Ruan, PhD, is the author of numerous papers in the field of flexible pipelines and has co-authored chapters of books on pipelines and risers.

• Preface xxiAbout the Authors xxiiiPart I Design and Analysis1 Flexible Pipes and Limit-States Design 31.1 I ntroduction 31.2 Applications of Flexible Pipe 31.2.1 Metal-Based Flexible Pipes 51.2.2 Composite-Based Flexible Pipes 71.2.3 D esign Codes and Specifications 101.3 Comparison between Flexible Pipes and Rigid Pipes 121.3.1 Unbonded Flexible Riser vs. Rigid Steel Riser 121.3.2 Flexible Jumper vs. Rigid Steel Jumper 121.3.3 Flexible Composite Pipe vs. Rigid Pipe 131.3.3.1 Material Costs 141.3.3.2 I nstallation Costs 141.3.3.3 Operational Costs 151.3.3.4 Comparison Example 151.4 Failure Mode and Design Criteria 151.4.1 Unbonded Flexible Pipe 151.4.1.1 Failure Modes 151.4.1.2 D esign Criteria 171.4.2 Flexible Composite Pipe 201.4.2.1 Failure Modes 201.4.2.2 D esign Criteria 201.5 L imit State Design 241.5.1 L imit States 241.5.2 Reliability-Based Methods 25References 262 Materials and Aging 292.1 I ntroduction 292.1.1 Unbonded Flexible Pipes 302.1.2 Flexible Composite Pipes 34vi Contents2.2 Metallic Material 352.2.1 Stainless Steel 352.2.2 Carbon Steel 362.3 Polymer Material 362.3.1 Annulus 362.3.2 Chemical Resistance 392.3.3 Permeation and Permeation Control Systems 412.3.3.1 Theory of Gas Permeation 412.3.3.2 Permeation Calculation 422.3.4 Anti H2S Layer 442.4 Aging 452.4.1 N onmetallic Material 462.4.2 Metallic Material 48References 493 Ancillary Equipment and End Fitting Design 513.1 I ntroduction 513.1.1 D esign Criteria 513.2 Bend Stiffeners and Bellmouths 533.2.1 I ntroduction 533.2.2 D esign Criteria and Failure Modes 553.2.3 D esign Considerations 563.2.4 Bellmouths 573.3 Bend Restrictor 583.4 Buoyancy Modules 593.5 Cathodic Protection 603.6 Annulus Venting System 613.7 E nd Fittings 633.7.1 Unbonded Flexible Pipes 643.7.1.1 D esign Criteria 643.7.1.2 Metallic Materials 663.7.1.3 E nd Fittings by Different Manufacturers 663.7.2 Flexible Composite Pipes 683.7.2.1 D esign Criteria 703.7.2.2 Materials 703.7.2.3 E nd Fitting Types 713.7.2.4 I nstallation 72References 744 Reliability-Based Design Factors 754.1 Introduction 754.2 Failure Probability 764.2.1 L imit State and Failure Mode 764.2.2 Failure Probability 764.3 Safety Factor Based on Reliability 774.3.1 Uncertainties of Resistance and Load Effect 784.3.2 L RFD Formulation 794.3.3 D esign Process 79Contents vii4.4 D esign Example 824.4.1 L imit State Function 834.4.1.1 Resistance Model for Inner Pressure Load 834.4.1.2 L imit State Function 834.4.2 Probability Model of Resistance 834.4.2.1 Probability Distribution of Resistance Parameters 834.4.2.2 Probability Model of Resistance 844.4.3 Probability Model of Load Effect 854.4.4 Target Reliability 854.4.5 Safety Factor Design Results 85References 87Part II Unbonded Flexible Pipes5 Unbonded Flexible Pipe Design 915.1 I ntroduction 915.2 Applications of Flexible Pipe 925.2.1 Flexible Risers 925.2.2 Flexible Flowlines 945.2.3 L oading and Offloading Hoses 945.2.4 Jumper Lines 965.2.5 D rilling Risers 975.3 Flexible Pipe System and Components 975.3.1 I nterlocked Steel Carcass 985.3.2 I nternal Polymer Sheath 995.3.3 Armor Layers 995.3.3.1 Pressure Armor 995.3.3.2 Tensile Armor 1005.3.3.3 Composite Armor 1005.3.4 E xternal Polymer Sheath 1025.3.5 Other Layers and Configurations 1025.3.6 Main Ancillaries 1035.3.6.1 E nd Fittings 1035.3.6.2 Bend Stiffener and Bellmouths 1045.3.6.3 Bend Restrictor 1055.3.6.4 Buoyancy Modules 1065.3.6.5 Annulus Venting System 106References 1066 Design and Analyses of Unbonded Flexible Pipe 1096.1 I ntroduction 1096.2 Flexible Pipe Guidelines 1106.2.1 API Specification 17K 1106.2.2 API Specification 17J 1116.2.2.1 Safety Against Collapse 1126.2.2.2 D esign Criteria 1126.2.3 API RP 17B 112viii Contents6.3 Material and Mechanical Properties 1136.3.1 Properties of Sealing Components 1146.3.1.1 Polymer 1146.3.1.2 Steel 1146.3.1.3 Fibres 1156.3.2 Properties of Armor Components 1156.3.2.1 Submerged Weight 1166.3.2.2 Bending Stiffness and Curvature Radius 1166.3.2.3 Axial Stiffness and Tension Capacity 1166.3.2.4 Torque Stiffness and Torque Capacity 1176.4 Analytical Solutions in Flexible Pipe Design 1176.4.1 Overview 1176.4.2 Analytical Modeling of Flexible Pipes 1176.4.3 Analytical Method of Unbonded Flexible Pipes 1186.4.4 Axis-Symmetric Behavior 1206.4.4.1 Kinematic Restraint 1206.4.4.2 Governing Equations 1216.4.5 Bending Behavior 1226.5 FE Analysis of Unbonded Flexible Pipe 1236.5.1 Static Analysis 1236.5.2 Fatigue Analysis 124References 1267 Unbonded Flexible Pipe Under Internal Pressure 1297.1 I ntroduction 1297.2 Analytical Solution 1307.2.1 Polymeric Layer 1317.2.2 Helically Wound Steel Layer 1327.2.3 Assembly of Layers 1347.3 FE Analysis 1347.4 Results and Discussion 1377.4.1 General 1377.4.2 Axial Tension and End Displacement 1387.4.3 Hoop Stress 1387.4.4 Axial Stress 1417.4.4.1 Axial Stress of Model A and Model B 1417.4.4.2 Axial Stresses of Model C and Model D_1417.4.5 Comparison of Mises Stress 1447.5 Conclusions 145References 1468 Unbonded Flexible Pipe Under External Pressure 1498.1 I ntroduction 1498.2 Finite Element Analysis 1518.2.1 Simplification 1528.2.2 Modeling Description 1528.2.3 Models with Different Stiffness Ratios 1538.2.4 Models with Different D/t Ratios 154Contents ix8.3 FEM Results and Discussion 1558.3.1 Prediction of Confined External Pressure 1558.3.1.1 Same D/t Ratio with Different Stiffness Ratios 1558.3.1.2 D ifferent D/t Ratios with Different Stiffness Ratios 1578.3.2 Confined Post-Buckling Behavior 1588.4 Analytical Solution 1588.5 Test Study 1618.5.1 Material Characteristics 1628.5.2 Confined Collapse Tests 1638.5.3 Test Results 1658.6 Comparison of Three Methods 1678.7 Conclusions 168References 1699 Unbonded Flexible Pipe Under Tension 1719.1 I ntroduction 1719.2 Tension Load 1729.2.1 Helical Layer 1729.2.2 Tube Layer 1759.2.3 Principle of Virtual Work 1759.3 Results and Discussion 1779.4 Parametric Study 1809.4.1 L ay Angle 1819.4.2 D iameter-to-Thickness 1839.5 Conclusions 184References 18510 Unbonded Flexible Pipe Under Bending 18710.1 I ntroduction 18710.2 Helical Layer within No-Slip Range 18810.2.1 Geometry of Helical Layer 18810.2.2 Bending Stiffness of Helical Layer 19110.3 Helical Layer within Slip Range 19210.3.1 Critical Curvature 19210.3.2 Axial Force in Helical Wire within Slip Range 19410.3.3 Axial Force in Helical Wire within No-Slip Range 19410.3.4 Bending Stiffness of Helical Layer 196References 19711 Unbonded Flexible Pipe Under Tension and Internal Pressure 19911.1 I ntroduction 19911.2 Analytical Solution 20011.3 FE Analysis 20011.3.1 Case 1: Tension Only 20111.3.2 Case 2: Internal Pressure Only 20211.3.3 Case 3: Combined Tension and Internal Pressure 202x Contents11.4 Results and Discussion 20211.5 Conclusions 208References 20812 Cross-Sectional Design and Case Study for Unbonded Flexible Pipes 21112.1 I ntroduction 21112.2 Cross-Sectional Design 21212.2.1 General Design Requirements 21212.2.2 Manufacturing Configuration and Material Qualification 21312.2.2.1 Carcass 21312.2.2.2 Pressure Sheath 21312.2.2.3 Pressure Armor 21312.2.2.4 Tensile Armor 21412.2.2.5 Tape 21412.2.2.6 Shield 21412.3 Case Study 21412.3.1 D esign Procedure 21412.3.2 D esign Requirement 21412.3.3 D esign Method 21512.3.3.1 Strength Design for Axisymmetric Loads 21512.3.3.2 Collapse Resistance Design 21612.3.4 D esign Results 21612.3.5 L oad Analysis 21712.3.6 FE Analysis 21812.4 Conclusions 219References 22013 Fatigue Analysis of Unbonded Flexible Pipe 22313.1 I ntroduction 22313.2 Theoretical Approach 22413.2.1 Assumptions 22413.2.2 E nvironment Conditions 22413.2.3 Transposition of Forces and Bending Moments 22513.2.4 Fatigue Design Criteria 22513.2.4.1 S-N Curves 22513.2.4.2 Miner’s rule 22513.3 Case Study 22613.3.1 I ntroduction 22613.3.2 Base Case 22713.4 Conclusions 230References 230Contents xiPart III Steel Reinforced Flexible Pipes14 Steel Reinforced Flexible Pipe Under Internal Pressure 23514.1 I ntroduction 23514.2 Applications 23514.2.1 Offshore 23614.2.2 Onshore 23614.2.3 Rehabilitation 23714.3 D esign and Manufacturing 23714.3.1 D esign Codes 23714.3.2 Manufacturing 23714.3.2.1 I ntroduction 23714.3.2.2 I nner and Outer Layers 23814.3.2.3 Steel Strip Reinforcement Layers 23814.3.2.4 E nd Fitting 23814.4 Analytical Solution 24014.4.1 Mechanical Properties 24014.4.2 Assumptions 24214.4.3 Stress Analysis 24214.4.3.1 L ayer Properties 24414.4.3.2 Stress-Strain Relations of HDPE Layers 24614.4.3.3 Stress-Strain Relations of Steel Strip Layers 24714.4.4 Boundary Condition 24814.4.4.1 Stress Boundary Condition 24814.4.4.2 I nterface Condition 24814.4.4.3 E quilibrium Equation of Axial Force 24814.4.4.4 Torsion Balance Equation 24814.5 FE Analysis 24914.6 Results and Discussion 24914.6.1 Stress Analysis on Layer 2 24914.6.2 Stress Analysis Between Layers 25214.7 Conclusions 253References 25415 Steel Reinforced Flexible Pipe Under External Pressure 25515.1 I ntroduction 25515.2 E xperimental Tests 25615.2.1 Material Characteristics 25615.2.2 Collapse Experiment 25615.2.3 E xperimental Results 25815.3 FE Analysis 25815.4 Simplified Estimation for Collapse Pressure 26215.5 Parametric Study 26415.6 Conclusions 266References 267xii Contents16 Steel Reinforced Flexible Pipe Under Pure Tension 26916.1 I ntroduction 26916.2 E xperimental Tests 27016.2.1 Test Processes 27016.2.2 Test Results and Discussions 27016.3 FE Analysis 27316.3.1 E lements and Interactions 27316.3.2 L oad and Boundary Conditions 27416.3.3 Material Properties 27416.4 Comparison and Discussions 27516.4.1 Comparison between Test and FE Analysis 27516.4.2 Mechanical Response of PE Layers 27616.4.3 Mechanical Response of Steel Strips 27916.5 Conclusions 281References 28217 Steel Reinforced Flexible Pipe Under Bending 28317.1 I ntroduction 28317.2 FE Analysis 28417.2.1 Model and Material Properties 28417.2.2 L oads and Boundary Conditions 28517.2.3 Analysis Results 28517.3 Mechanical Behaviors and Discussions 28717.3.1 I nner PE Layer 28717.3.2 Outer PE Layer 28917.3.3 Steel Strip Layers 29017.4 Conclusions 291References 29118 Steel Reinforced Flexible Pipe Under Combined InternalPressure and Tension 29318.1 I ntroduction 29318.2 Analytical Solution 29318.2.1 Strain Analysis 29318.2.2 Stress Analysis 29418.2.3 Boundary Conditions 29718.3 I nner HDPE layer 29718.3.1 Reinforcement Layers 29818.3.2 Outer HDPE Layer 29818.3.3 E quilibrium Equation 29918.3.4 Solution Chart 29918.4 Finite Element Analysis 30018.4.1 I ntroduction 30018.4.2 Material Properties 30018.4.3 FE Model 30118.4.4 Boundary Conditions 304Contents xiii18.5 Results and Discussion 30418.5.1 Comparison of Methods 30418.5.2 L oad Steps 30518.5.3 Axial Tension Followed by Internal Pressure 30618.5.3.1 Stress Response 30618.5.3.2 Failure Behavior 30618.5.4 I nternal Pressure Followed by Axial Tension 30718.6 Conclusions 309References 31019 Steel Reinforced Flexible Pipe Under CombinedInternal Pressure and Bending 31119.1 I ntroduction 31119.2 Analytical Solution 31219.3 FE Analysis 31619.3.1 Finite Element Model 31619.3.2 Boundary Conditions 31619.3.3 Analysis Results 31719.4 Summary 319References 32120 Steel Reinforced Flexible Pipe Under CombinedBending and External Pressure 32320.1 I ntroduction 32320.2 E xperimental Tests 32420.2.1 Test Procedure 32420.2.2 Test Results and Discussions 32520.3 FE Analysis 32620.3.1 Finite Element Modeling 32720.3.2 Comparison of Test and Analysis Results 32720.4 Analysis Results and Discussions 32920.5 Conclusions 330References 33121 Cross-Sectional Design and Case Study for Steel Reinforced Flexible Pipe 33321.1 I ntroduction 33321.2 Mechanical Behaviors 33421.3 Cross-Sectional Design 33521.3.1 D esign Requirement 33521.3.2 Strength Capacity 33621.4 Case Study 33821.4.1 General 33821.4.2 D esign Analysis 33921.4.2.1 Preliminary Analysis 33921.4.2.2 FE Analysis 33921.5 Conclusions 340References 34022 Damage Assessment for Steel Reinforced Flexible Pipe 34322.1 I ntroduction 34322.2 D amage Analysis of Outer Layer 34422.2.1 General 34422.2.2 FE Analysis 34422.2.3 Material Parameters 34522.2.4 Modeling of Damage Analysis 34622.2.5 Analysis Results 34722.3 I nfluence of Different Intervals 35122.4 E ffects of Insufficient Strength in Steel Strip 352References 354Part IV Bonded Flexible Pipes23 Bonded Flexible Rubber Pipes 35723.1 I ntroduction 35723.1.1 Constructions of Bonded Flexible Pipe 35823.1.2 Types of Bonded Flexible Pipe 35923.2 D esign and Applications 36023.2.1 I ntroduction 36023.2.2 D esign Criteria 36123.2.3 Hose Design Activities 36123.2.4 Bonded Flexible Hose Design 36323.2.5 E nd Fittings 36523.2.6 Materials 36623.2.7 Applications 36923.3 Failure Modes 37123.3.1 E arly Failures 37223.3.2 Random Failures 37323.3.3 Wear-Down Failures 37323.3.4 E xamples of Hose Failures 37323.4 I ntegrity Management 37423.4.1 Risk Analysis 37423.4.2 Risk Evaluation Process 37423.4.3 Actions Following Risk Assessment 375References 37624 Nonmetallic Bonded Flexible Pipe Under Internal Pressure 37724.1 I ntroduction 37724.1.1 N omenclature 37824.2 E xperimental Tests 37924.2.1 Material Properties 37924.2.2 Burst Tests 38024.3 Analytical Solution 38124.3.1 I ntroduction 38124.3.2 Assumptions 381xiv ContentsContents xv24.3.3 Coordinate Systems 38224.3.4 I nner Layer and Outer Layer 38324.3.5 Reinforced Layers 38524.3.6 Boundary Conditions 38724.3.7 Failure Criterion 38824.3.8 Burst Pressure Calculation 38824.4 Finite Element Analysis 38924.5 Results and Comparison 391References 39225 Nonmetallic Bonded Flexible Pipe Under External Pressure 39325.1 I ntroduction 39325.2 Analytical Solution of Collapse 39425.2.1 Kinematics 39425.2.2 Materials of Each Layer 39525.2.2.1 PE_39525.2.2.2 Reinforced Layer 39525.2.2.3 The Material Plasticity 39625.2.3 Principle of Virtual Work 39725.2.4 Amendment of Radius and Wall Thickness 39825.2.5 Analytical Method 39925.3 FE Analysis 40025.3.1 I ntroduction 40025.3.2 FE Modeling 40125.4 E xample of Collapse Analysis 40125.4.1 I ntroduction 40125.4.2 I nput Data 40125.4.3 Pressure-Ovality Curves 40225.5 Sensitivity Analysis 40325.5.1 E ffect of Initial Imperfections 40425.5.2 E ffect of Shear Deformation 40425.5.3 E ffect of Pre-Buckling Deformation 405References 40626 Nonmetallic Bonded Flexible Pipe Under Bending 40726.1 I ntroduction 40726.2 Analytical Solution 40926.2.1 Assumptions 40926.2.2 Kinematics 40926.2.3 Models of Material 41026.2.3.1 Mechanical Behaviors of HDPE_41026.2.3.2 Mechanical Behaviors of Fiber Reinforced Layer 41226.2.4 Constitutive Model for RTP 41526.2.5 Principle of Virtual Work 41526.3 FE Analysis 41626.4 E xperiment Test 418xvi Contents26.5 Results and Discussion 41926.6 Parametric Studies 42126.6.1 Wall-Thickness 42126.6.2 D iameter of Pipe 42226.6.3 D /t Ratio 42226.6.4 I nitial Ovality 42326.7 Conclusions 424References 424Appendix 42627 Nonmetallic Bonded Flexible Pipe Under CombinedTension and Internal Pressure 42927.1 I ntroduction 42927.2 N onlinear Analytical Solution 43127.2.1 Fundamental Assumptions 43127.2.2 Simplification of Reinforcement Layers 43227.2.3 Kinematics of a Single Wire 43327.2.4 D eformation of Cross Section 43427.2.5 E quilibrium Equation 44027.2.6 Constitutive Model 44227.2.7 Solution Method 44227.3 Finite Element Model 44227.3.1 Model Design and Meshing 44327.3.2 Materials 44427.3.3 Constraints 44427.3.4 Boundary Conditions and Loadings 44527.4 Results and Discussion 44527.4.1 Tension-Extension Relation 44527.4.2 Stress in Kevlar Wires 44627.4.3 Radial Deformation 44627.4.4 D iscussion 44627.5 Parametric Study 44827.5.1 I nternal Pressure 44927.5.2 L ay Angle 45027.5.3 D /t Ratio 45027.5.4 Amount of Kevlar Wires 45127.6 Conclusions 452References 45328 Nonmetallic Bonded Flexible Pipe Under CombinedExternal Pressure and Bending 45528.1 General 45528.2 I ntroduction 45528.3 Analytical Solution 45728.3.1 Kinematics 45728.3.2 Material Simplification 45828.3.3 Constitutive Model 462Contents xvii28.3.4 Principle of Virtual Work 46228.3.5 Amendment of Radius and Wall Thickness 46328.3.6 Solution Method 46328.4 Finite Element Model 46428.5 Results and Discussions 46528.5.1 Collapse of RTP Under External Pressure 46528.5.2 Collapse of RTP Under Pure Bending 46828.5.3 Collapse of RTP Under Combined Bendingand External Pressure 47128.6 Conclusions 473References 47429 Fibre Glass Reinforced Flexible Pipes Under Internal Pressure 47529.1 I ntroduction 47529.2 Analytical Solution 47629.2.1 Assumptions 47629.2.2 Stress Analysis 47629.2.3 Boundary Conditions 47929.3 Finite Element Analysis 48029.4 Results and Discussions 48129.5 Winding Angle 48329.6 Conclusions 484References 48530 Fibre Glass Reinforced Flexible Pipe Under External Pressure 48730.1 I ntroduction 48730.2 FE Analysis 48830.2.1 I ntroduction 48830.2.2 Geometrical Parameters and Material Properties 48930.2.3 FE Modeling 49030.3 Results and Discussions 49130.3.1 I ntroduction 49130.3.2 I nitial Imperfection 49130.3.2.1 I nitial Ovality 49130.3.2.2 I nitial Wall Eccentricity 49230.3.3 Geometrical Configurations 49430.3.3.1 D iameter Over Thickness Ratio D1/t1 ofOuter PE Layer 49430.3.3.2 N umber of Reinforced Layers 49530.3.3.3 D iameter Over Thickness Ratio D2/t2of Inner Layer 49630.3.4 Material 49630.5 Conclusions 497References 498xviii Contents31 Steel Wire Bonded Flexible Pipe Under Internal Pressure 49931.1 I ntroduction 49931.2 Analytical Solution 50131.2.1 General 50131.2.2 Stress and Strain Analysis 50131.2.3 Simplification of Reinforced Layers 50331.3 Finite Element Analysis 50431.3.1 General 50431.3.2 ABAQUS Modeling 50431.4 Analysis Results 50631.4.1 Comparison of Strains 50631.4.2 E ffect of Winding Angle 50731.5 E xperimental Test 50831.5.1 General 50831.5.2 Test Results 50831.6 E ngineering Burst Pressure Formula 509References 51032 Steel Wire Bonded Flexible Pipe Under External Pressure 51332.1 I ntroduction 51332.2 Analytical solution 51432.2.1 Fundamental Assumptions 51432.2.2 N onlinear Ring Theory 51432.2.3 Constitutive Relation of Material 51632.2.4 Principle of Virtual Work Equation 51832.3 N umerical Simulations 52032.4 E xperimental Test 52332.5 Conclusions 525References 52533 Steel Wire Bonded Flexible Pipe Under Bending and Internal Pressure 52733.1 I ntroduction 52733.2 Analytical Solution 52833.2.1 Principle of Virtual Work 52933.2.2 Burst Pressure of PSP in Axial Direction 53133.2.3 Burst Pressure of PSP in Circumferential Direction 53133.2.4 Constitutive Model for Materials 53233.3 N umerical Simulations 53533.4 Pure Bending Experimental Test 53533.4.1 Test 53533.4.2 Results and Discussion 53733.5 Combined Internal Pressure and Bending Experimental Test 53833.5.1 Test Facilities 53933.5.2 Test Procedure 53933.5.3 Test Results 54033.6 Comparison of Results 54033.7 Conclusions 541References 542Contents xix34 Cross-Sectional Design and Case Study for Steel WireBonded Flexible Pipe 54334.1 I ntroduction 54334.2 Cross-Sectional Design 54434.2.1 D esign Procedure 54434.2.2 D esign Parameters 54434.2.3 Properties and Capacities 54634.3 Case Study 55034.4 V alidation by FE Model 55134.5 Conclusions 555References 55535 Damage Assessment for Steel Wire Bonded Flexible Pipes 55735.1 I ntroduction 55735.2 Analytical Method 55835.2.1 Basic Assumptions 55835.2.2 Stress-Strain Relationship 55835.3 Finite Element Analysis 56435.4 Comparison between Analytical Method and FEM 56535.4.1 E ffect of Steel Wire Winding Angle 56735.4.2 E ffects of Steel Wire Diameter 56835.4.3 E ffects of Missing Steel Wire 56835.4.4 E ffect of Damaged Inner and Outer PE Layers 56935.4.5 E ffects of Layer Interfacial Peeling 56935.5 Summary 572References 57336 Third-Party Damage for Steel Wire Bonded Flexible Pipe 57536.1 I ntroduction 57536.2 Pipeline, Soil and Tamper Parameters 57636.3 Finite Element Model 57736.4 L oading and Boundary Conditions 57836.5 Analysis Results 57836.5.1 D ynamic Response 57936.5.2 Tamping Velocity 58136.5.3 Buried Depth 58136.6 Summary 583References 583Index 585