Page 15 - Pipelines and Risers

XI1 Contents

3.3 Pipe Capacity under Couple Load .......................................................................................................... 47
3.3.1 Combined Pressure and Axial Force .............................................................................................. 47
3.3.2 Combined External Pressure and Bending ..................................................................................... 48
3.4 Pipes under Pressure Axial Force and Bending ..................................................................................... 49
3.4.1 Case 1 -Corroded Area in Compression ....................................................................................... 49
3.4.2 The Location of the Fully Plastic Neutral Axis .............................................................................. 51
3.4.3 The Bending Moment .................................................................................................................... 5 1
3.5 Finite Element Model ............................................................................................................................. 55
3.5.1 General ........................................................................................................................................... 55
3.5.2 Analytical Solution Versus Finite Element Results ....................................................................... 56
3.5.3 Capacity of Pipes Subjected to Single Loads ................................................................................. 56
3.5.4 Capacity of Pipes Subjected to Combined Loads ........................................................................... 58
3.6 References .............................................................................................................................................. 61
Chapter 4 Limit-state based Strength Design 63
4.1 Introduction ............................................................................................................................................ 63
4.2 Out of Roundness Serviceability Limit .................................................................................................. 64
4.3 Bursting .................................................................................................................................................. 65
4.3.1 Hoop Stress vs . Equivalent Stress Criteria ..................................................................................... 65
4.3.2 Bursting Strength Criteria for Pipeline ........................................................................................... 65
4.4 Local Buckling/Collapse ........................................................................................................................ 67
4.5 Fracture .................................................................................................................................................. 70
4.5.1 PD6493 Assessment ....................................................................................................................... 70
4.5.2 Plastic Collapse Assessment .......................................................................................................... 72
4.6 Fatigue ......................................................................................................... .................................... 73
4.6.1 General ................................................................................................ .................................... 73
4.6.2 Fatigue Assessment based on S-N Curves ..................................................................................... 74
4.6.3 Fatigue Assessment based on A&-N Curves ................................................................................... 74
4.7 Ratcheting .............................................................................................................................................. 75
4.8 Dynamic Strength Criteria ..................................................................................................................... 75
4.9 Accumulated Plastic Strain .................................................................................................................... 75
4.10 Strain Concentration at Field Joints Due to Coatings .......................................
4.1 1 References .............................................................................................................................................. 76
Chapter 5 Soil and Pipe Interaction 79
5.1 General .............................................................................................................
5.2 Pipe Penetration in Soil .. ............................................................................................. 19
5.2.1 Verley and Lund Method ............................................................................................................... 79
5.2.2 Classical Method ............................................................................................................................ 80
5.2.3 Buoyancy Method .......................................................................................................................... 81
5.3 Modeling Friction and Breakout Forces ................................................................................................. 82
5.3. I Anisotropic Friction ....................................................................................................................... 82
5.3.2 Breakout Force ............................................................................................................................... 82
5.4 References .............................................................................................................................................. 83

Chapter 6 Hydrodynamics around Pipes 85
6.1 Wave Simulators .................................................................................................................................... 85
6.2 Choice of Wave Tkeory ......................................................................................................................... 85
6.3 Mathematical Formulations used in the Wave Simulators ..................................................................... 85
6.3.1 General ........................................................................................................................................... 85
6.3.2 2D Regular Long-Crested Waves .................................................................................................. 86
6.3.3 2D Random Long-Crested Waves .................................................................................................. 87
6.4 Steady Currents ...................................................................................................................................... 90