design and installation of marine pipelines
TRANSCRIPT
Design and Installationof Marine Pipelines
Mikael W. Braestrup (Editor)
Jan Bohl Andersen
Lars Wahl Andersen
Mads Bryndum
Curt John Christensen
Niels-Jørgen Rishøj Nielsen
BlackwellScience
DAIA01 2/12/04, 10:36 AM1
© 2005 by Blackwell Science Ltd, a Blackwell Publishing company
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First published 2005
Library of Congress Cataloging-in-Publication DataDesign and installation of marine pipelines / M.W. Braestrup . . . [et al.]. – 1st ed.
p. cm.Includes bibliographical references and index.ISBN 0-632-05984-2 (hardback : alk. paper)1. Underwater pipelines. I. Bræstrup, Mikael W. II. Title.
TJ930.D378 2005621.8’672’09162—dc22
2004017651
ISBN-10: 0-632-05984-2ISBN-13: 978-0632-05984-3
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Contents
Preface xiiAbout the authors xivGlossary and notation xvi
Chapter 1 Introduction 1
Chapter 2 Bases for design 52.1 Introduction 52.2 Basic requirements 6
2.2.1 Functional requirements 62.2.2 Authorities’ requirements 62.2.3 Environmental impact 7
2.3 Flow calculations 82.3.1 General 82.3.2 Operational parameters 92.3.3 Pipeline size determination 102.3.4 Flow simulations 10
2.4 Site investigations 132.4.1 General 132.4.2 Geophysical survey 142.4.3 Geotechnical survey 152.4.4 Soil sampling and in situ testing 162.4.5 Laboratory testing 17
2.5 Meteo-marine data 172.5.1 General 172.5.2 Wind, waves and current 182.5.3 Collection of wave data 192.5.4 Design parameters 20
2.6 Route selection 212.6.1 General 212.6.2 Alignment sheets 23
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Chapter 3 Materials 243.1 Introduction 243.2 Soil materials 25
3.2.1 General 253.2.2 Seabed soil classification 253.2.3 Backfill materials 27
3.3 Linepipe materials 273.3.1 General 273.3.2 Strength, toughness and weldability 293.3.3 Sour service resistance 323.3.4 Steel microstructure and corrosion resistance 34
3.4 Sacrificial anodes 363.4.1 General 363.4.2 Zinc alloy 363.4.3 Aluminium alloy 37
3.5 Pipeline component materials 373.5.1 General 373.5.2 Component materials for sour service 38
3.6 Coating and insulation materials 383.6.1 General 383.6.2 Material properties 39
Chapter 4 Loads 404.1 Introduction 404.2 Functional loads 40
4.2.1 General 404.2.2 Internal pressure 414.2.3 Pressure control systems 414.2.4 Temperature 45
4.3 Environmental loads 454.3.1 General 454.3.2 Hydrodynamic forces 454.3.3 Hydrodynamic force coefficients 49
4.4 Accidental loads 524.4.1 General 524.4.2 Dropped object loads 524.4.3 Trawl loads 53
4.5 Installation loads 55
Chapter 5 Risk and safety 565.1 Introduction 565.2 Safety policy and philosophy 575.3 Risk management 58
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5.3.1 General 585.3.2 Hazard identification 60
5.4 Risk acceptance criteria 615.4.1 General 615.4.2 Cost benefit analysis 63
5.5 Risk assessment 645.5.1 General 645.5.2 Risk reducing measures 655.5.3 Example: Risk of anchor damage 65
5.6 Special risk aspects 705.6.1 Subsea isolation valves 705.6.2 Welded or flanged connections 715.6.3 Corrosion in HP/HT pipelines 71
5.7 Statistical data 72
Chapter 6 Design 736.1 Design conditions 73
6.1.1 Codes and standards 736.1.2 Serviceability limit states (SLS) 746.1.3 Ultimate limit states (ULS) 756.1.4 Partial safety coefficients 75
6.2 Wall thickness determination 766.2.1 General 766.2.2 Design methods 776.2.3 Location class definition 786.2.4 Wall thickness according to DNV OS-F101 796.2.5 Code comparison and national wall thickness regulations 826.2.6 Trawling and hydrostatic pressure 866.2.7 Wall thickness design example 91
6.3 Hydrodynamic stability 926.3.1 General 926.3.2 Design activities 946.3.3 Design conditions and requirements 1006.3.4 Static stability design format 1026.3.5 Dynamic stability design format 1036.3.6 Pipe–soil interaction 103
6.4 Free span evaluation 1106.4.1 General 1106.4.2 Free span classification 1116.4.3 Pipeline and free span data 1126.4.4 Static analysis 1136.4.5 Dynamic analysis 1166.4.6 Fatigue analysis 117
Contents v
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6.5 Expansion and global buckling 1206.5.1 General 1206.5.2 Pipeline expansion 1216.5.3 Pipeline buckling 1256.5.4 Upheaval buckling 126
6.6 Corrosion prevention and insulation 1326.6.1 General 1326.6.2 Corrosion of steel in seawater 1336.6.3 Internal corrosion prevention 1346.6.4 External barrier coating 1376.6.5 Thermal insulation 138
6.7 Cathodic protection 1406.7.1 General 1406.7.2 Protective potential and current requirements 1416.7.3 Hydrogen embrittlement 1426.7.4 Sacrificial anode design 1436.7.5 Impressed current 1506.7.6 Electrical isolation 1526.7.7 Stray current interference 152
6.8 Bends, components and structures 1536.8.1 General 1536.8.2 Fittings 1536.8.3 Valves and other components 1546.8.4 Structures 155
Chapter 7 Fabrication 1567.1 Introduction 1567.2 Linepipe production 157
7.2.1 General 1577.2.2 Standardisation 1587.2.3 Seamless pipe 1597.2.4 Welded pipes 1607.2.5 Specified properties of linepipe steels 1647.2.6 Hot formed bends 1677.2.7 Cladding, lining and weld-overlaying 1687.2.8 Testing during pipe manufacture 169
7.3 Internal coating 1717.3.1 General 1717.3.2 Surface preparation 1727.3.3 Fusion bonded epoxy (FBE) 1737.3.4 Epoxy paint 1737.3.5 Inspection and testing of epoxy paint 173
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7.4 External anti-corrosion coating 1747.4.1 General 1747.4.2 Surface preparation 1757.4.3 Asphalt enamel 1767.4.4 Three-layer polyolefin coatings (PE/ PU/PP) 1787.4.5 Fusion bonded epoxy (FBE) 1797.4.6 Elastomer coating (Neoprene) 1807.4.7 Thermal insulation 1817.4.8 Inspection and testing 1827.4.9 Other coating systems 184
7.5 Anode manufacture 1867.5.1 General 1867.5.2 Reinforcement insert 1877.5.3 Alloy materials 1887.5.4 Casting 1887.5.5 Anode defects 1897.5.6 Electrical connections 1917.5.7 Painting and marking 1927.5.8 Inspection and testing 192
7.6 Anode installation 1937.6.1 General 1937.6.2 Anode mounting 1937.6.3 Electrical connection 1947.6.4 Finishing 195
7.7 Concrete coating 1957.7.1 General 1957.7.2 Concrete mix design 1967.7.3 Reinforcement 1967.7.4 Impingement 1967.7.5 Extrusion 1987.7.6 Slipforming 1987.7.7 Concrete curing 1987.7.8 Inspection and testing 1997.7.9 Anode joints 202
7.8 Marking, handling and repair 2037.8.1 General 2037.8.2 Marking 2037.8.3 Handling, transport and storage 2047.8.4 Repair 205
7.9 Components and fittings 2057.9.1 General 2057.9.2 Component manufacture 206
Contents vii
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7.9.3 Risers and expansion offsets 2067.9.4 Tees and valve assemblies 2087.9.5 Pig launchers and receivers 209
Chapter 8 Installation 2108.1 Introduction 2108.2 Seabed intervention 211
8.2.1 General 2118.2.2 Pre-trenching 2118.2.3 Pipeline supports 2128.2.4 Crossings 212
8.3 Pipe assembly 2138.3.1 General 2138.3.2 Girth welding 2148.3.3 Engineering criticality assessment (ECA) 2188.3.4 Field joint coating 2248.3.5 Mechanical connections 228
8.4 Pipelaying 2288.4.1 General 2288.4.2 S-lay 2298.4.3 J-lay 2318.4.4 Reeling 2318.4.5 Piggy-back installation 2328.4.6 In-line components 2338.4.7 Abandonment and recovery 233
8.5 Towing, pulling and directional drilling 2358.5.1 General 2358.5.2 On-bottom towing and pulling 2368.5.3 Off-bottom, surface and controlled depth towing 2378.5.4 Pipeline bundles 2378.5.5 Directional drilling 238
8.6 Risers, shore approaches and tie-ins 2408.6.1 General 2408.6.2 Riser installation 2408.6.3 Shore approach construction 2418.6.4 Tie-in 2448.6.5 Branch line connection 246
8.7 Trenching and backfilling 2468.7.1 General 2468.7.2 Jetting and cutting 2478.7.3 Ploughing 2488.7.4 Artificial backfilling 2498.7.5 Protective covers 250
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8.8 Pre-commissioning 2508.8.1 General 2508.8.2 Flooding and hydrotesting 2518.8.3 Gauging 2538.8.4 Cleaning 2548.8.5 De-watering 2568.8.6 Drying 2578.8.7 Nitrogen purging 258
Chapter 9 Control and documentation 2599.1 Introduction 2599.2 General requirements 259
9.2.1 General 2599.2.2 Quality management 2609.2.3 Document formats 2609.2.4 Communication 2609.2.5 Document register 2619.2.6 Document review and acceptance 2619.2.7 Nonconforming items 262
9.3 Design 2629.3.1 Design basis 2629.3.2 Design documentation 2639.3.3 Design drawings 263
9.4 Supply and fabrication 2649.4.1 General 2649.4.2 Pipe production 2649.4.3 Anode manufacture 2669.4.4 Pipe coating 2689.4.5 Other supplies 269
9.5 Installation 2709.5.1 General 2709.5.2 Installation manuals 2709.5.3 Contractor’s engineering and management 2709.5.4 Installation procedures 2719.5.5 Construction reporting 274
9.6 As-built documentation 2769.6.1 General 2769.6.2 Pipeline management systems 276
Chapter 10 Flexible pipes 27810.1 Introduction 278
10.1.1 General 27810.1.2 The world’s first subsea flexible pipes 28010.1.3 Unbonded flexible pipe specification 280
Contents ix
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10.2 Flexible pipe structure 28210.2.1 General 28210.2.2 Internal carcass 28310.2.3 Inner liner 28310.2.4 Pressure armour 28410.2.5 Tensile armour 28510.2.6 Holding bandage 28610.2.7 Outer sheath 28610.2.8 Additional layers 287
10.3 Flexible pipe design 28710.3.1 General 28710.3.2 Load conditions 28910.3.3 Cross-sectional design 29110.3.4 End fitting 29310.3.5 System design 29410.3.6 Service life analysis 298
10.4 Material qualification 30310.4.1 General 30310.4.2 Metallic materials 30410.4.3 Polymeric materials 30510.4.4 Epoxy resin 30510.4.5 Fibre-reinforced polymers 305
10.5 Fabrication 30610.5.1 General 30610.5.2 Pipe 30610.5.3 End fitting 30710.5.4 Factory acceptance test 30710.5.5 Packing and load out 308
10.6 Installation and pipe qualification 30910.6.1 Installation 30910.6.2 Flexible pipe qualification 31110.6.3 Prototype testing 311
Chapter 11 Operation 31611.1 Introduction 31611.2 Flow assurance 317
11.2.1 General 31711.2.2 Mitigation of flow blockage 317
11.3 Operation, maintenance and abandonment 31811.3.1 General 31811.3.2 Commissioning and operation 31811.3.3 Maintenance 32011.3.4 Changes to the design condition 320
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11.3.5 Decommissioning and abandonment 32111.3.6 Pipeline pigging 321
11.4 In-service inspection 32211.4.1 General 32211.4.2 Start-up inspection 32211.4.3 Periodical inspection 323
11.5 Repair assessment 32511.5.1 General 32511.5.2 Pipe defects 325
Bibliography and references 327Introduction 327Guidance documents 327Books and papers 331
Author index 335
Subject index 337
Contents xi
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Preface
The construction of marine pipelines is a relatively new field of engineering,having developed in the course of the last five decades. Yet, with more than100 000 km of subsea lines installed worldwide it must be regarded as a maturetechnology, although advances continue in extending the limits as regards pipedimensions, pressures, flow regimes, products, installation methods, water depthsand climatic environments. It is therefore surprising that there is a shortage ofbooks that cover the entire process of marine pipeline design and installation,from project planning through to system operation.
Marine pipelines are generally designed, fabricated and installed in accordancewith guidelines issued by various certifying agencies and regulatory bodies, aswell as national and international codes. Ideally, however, a code should be afairly slim volume, based upon functional performance criteria. The choice ofdesign methods and construction procedures should be left to the engineersresponsible, relying on a general consensus of good engineering practice, backedup by shared literature and education experience. However, this is precisely thematerial that is generally lacking in the marine pipeline field.
The aim of this publication is therefore to complement the existing codes andrecommendations with an engineering book, serving as a guide to the professionwith the objective of ensuring a reasonable standard of design and application.The book is primarily aimed at engineers who are fairly new to the field ofmarine pipelines, and want a comprehensive overview of the subject. The bookshould also provide background reading to students on specialised offshore courses,and to professionals in related fields. To experienced pipeline engineers it wouldconstitute a reference work to be consulted for fact and figures.
The origins of the work go back to 1987, when it was felt that there was a needfor a Danish national code for marine pipelines, and a code-drafting workingparty was established, eventually comprising most of the authors of the presentbook, chaired by the editor. The Danish marine pipeline code never materialised,but the working party identified the need explained above, and began collatingsupporting documentation, which eventually evolved into the present textbook.The result constitutes a set of comprehensive guidelines for the design and
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installation of marine pipeline systems, but the authors take no responsibility forthe use of the recommendations given.
The authors acknowledge the valuable comments to the draft manuscriptoffered by Robert Inglis of J P Kenny. It should be stressed, however, that theresponsibility for any errors or omissions rests with the authors alone. Finally,the authors would like to thank Dansk Olie og Naturgas A/S (DONG A/S) forpermission to use photographs from the 1998–99 installation of the South Arneto Nybro 24-inch Offshore Gas Pipeline.
Mikael W. BraestrupJan Bohl Andersen
Lars Wahl AndersenMads B. BryndumCurt J. Christensen
Niels J. Rishøj Nielsen
Preface xiii
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About the authors
Editor
Mikael W. Braestrup, MSc, PhDBorn in 1945, Dr Braestrup obtained his PhD in structural engineering from theTechnical University of Denmark in 1970. After spending two years as a volun-teer in charge of low-cost road construction in Peru he was engaged in structuralconcrete research and teaching in Copenhagen, Denmark, and Cambridge, UK.He joined the consulting company RAMBOLL in 1979, and worked for fiveyears on the design and construction of the offshore pipelines of the DanishNatural Gas Transmission System. Subsequently he has headed the RAMBOLLdepartments of Marine Pipelines and Underwater Technology, and of Knowledgeand Development.
Since 1992 Dr Braestrup has been attached to the RAMBOLL Department ofBridges, but is also active in the field of marine pipelines. Recent assignmentsinclude coating design for the 24″ Danish North Sea gas trunkline and the 30″BalticPipe between Denmark and Poland, feasibility studies for a 42″ gas trans-mission pipeline across the Baltic Sea from Russia to Germany, and secondmentto the Statoil engineering team for the export pipelines of the Kristin HP/HTsubsea development. Dr Braestrup is an active member of a number of interna-tional associations ( fib (CEB-FIP), IABSE, ACI), has served on several Danishcode committees, and is the author of a substantial number of papers and reportson civil engineering subjects, including marine pipelines.
Co-authors
Jan Bohl Andersen, MSc, started his professional career at the RAMBOLLpipeline department, and then spent some years as an independent consultant,mostly in Norway. Since 1993 he has been back with RAMBOLL, specialisingin design, contracting, and project management of marine pipelines.
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Lars Wahl Andersen, MSc, worked in the RAMBOLL pipeline departmentuntil 1992, when he transferred to the Department of Risk and Reliability. Hisexpertise on safety and risk studies is widely applied to offshore projects, plat-forms as well as pipelines.
Mads Bryndum, MSc, is chief engineer in the Ports and Offshore Department atDHI Water and Environment. Mads Bryndum has a background in structuralengineering and worked for several years at C G DORIS on the design of con-crete gravity platforms. He joined DHI in 1980 and has specialised in hydraulicand hydrodynamic problems in relation to marine pipelines and risers.
Curt John Christensen, BSc, has been employed by FORCE Technology(formerly the Danish Welding and Corrosion Institute) since 1976 as a corrosionand metallurgy specialist. He started in the marine engineering sector and, from1980, he has been deeply involved in oil and gas industry and pipeline industryrelated jobs. From 1985 to 2000 he was in charge of the full scale pipeline testingactivities at FORCE Technology.
Niels-Jørgen Rishøj Nielsen, MSc, PhD, heads the Engineering and R&DDepartment of NKT Flexibles I/S. Following a PhD in structural optimisation ofship structures, he began his professional offshore career in 1984 at the DanishMaritime Institute. He then moved to Maersk Olie og Gas A/S, working in theirpipeline department, and spent some years at the DNV Copenhagen office beforejoining NKT Flexibles in 1995.
About the authors xv
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Glossary and notation
Introduction
Like most other specialised fields the jargon of the offshore pipeline world is rifewith acronyms and terms whose specific meaning is not obvious to the uninitiated.The sections below list the employed abbreviations and explain the frequentlyused symbols and special terms.
SI units are used throughout, with a few exceptions, such as bar to indicatepressures and inch (″) to designate pipe sizes. However, all equations are dimen-sionally correct, unless specifically noted.
Symbols
Specific symbols are defined in the text, and a comprehensive, global listing wouldhave little value as the meaning often depends on the context. However, the listbelow contains the most common notations as they are used in this book, with orwithout descriptive indices. A few symbols (m, α, β) are also used to designatesundry constants, in addition to the specific meanings given below.
A area, amplitude, elongation (material property)D pipe diameter, grain size, diffusion coefficient (material property)E modulus of elasticity (material property)F forcef strength, skin friction factor (material properties), frequency of occurrenceg acceleration of gravityH heighth water levelk thermal conductivity, roughness (material properties)L lengthl lengthm mass
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N axial forceP probability, permeability (material property)p pressure, loadR reaction force, anodic resistance, steel strength (material property)r radiusT timet pipe wall thickness, timeU water particle velocityv velocityW weight
α coefficient of thermal expansion (material property)β reliability index (or safety index)∆ deformation, increment or variationε strainφ angle of friction (material property)γ safety factorη usage factorµ coefficient of friction (material property)ν Poisson’s ratio, viscosity (material properties)θ temperatureρ density, specific ohmic resistivity (material properties)σ stress
Abbreviations
This list defines the acronyms used in this book. Sections giving further explana-tions are referenced in brackets, if relevant. Chemical elements, units or notationsare not included.
3-RF 3-Roller Forming (7.2.4)ADCP Acoustic Doppler Current Profiler (2.5.3)AGA American Gas Association (4.3.3)AISI American Iron and Steel Institute (10.2.2)ALARP As Low As Reasonably Practicable (5.4.1)ALS Accidental Limit State or Accidental Load Situation (5.2)API American Petroleum InstituteASD Allowable Stress Design (6.1.1)ASM American Society of Metals (7.2.1)ASME American Society of Mechanical EngineersASTM American Society for Testing and MaterialsBOP Blow Out Preventer (4.4.2)
Abbreviations xvii
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BS British StandardCAPEX Capital Cost (2.3.3)CBV Cost Benefit Value (5.4.1)CEN Centre Européen de NormalisationCEV Carbon Equivalent (7.2.5)CIV Corrected Inherent ViscosityCOE C-bending, O-pressing, Expansion (7.2.4)CP Centre Point (2.6.2), Cathodic ProtectionCPT Cone Penetrometer Testing (2.4.4)CRA Corrosion Resistant Alloy (3.3.1)CTOD Crack Tip Opening DisplacementCSA Canadian Standards AssociationDEH Direct Electrical Heating (6.6.5)DFI Design, Fabrication and Installation (9.6.1)DFO Documents For Operation (9.1)DFT Dry Film Thickness (7.3.4)DIN Deutscher Institut für NormungDNV Det Norske VeritasDONG Dansk Olie og NaturgasDP Dynamic Positioning (8.4.1)DS Dansk StandardDWT Dead Weight TonnageDWTT Drop Weight Tear Test (7.2.5)ECA Engineering Criticality Assessment (8.3.3)EEZ Exclusive Economic Zone (2.2.3)EFC European Federation of CorrosionEIA Environmental Impact Assessment (2.2.3)EN Euro NormENV European Pre-Standard (draft EN)ESD Emergency Shut Down (valve) (4.2.3)EU European UnionFAR Fatal Accident Rate (5.4.1)FBE Fusion Bonded Epoxy (7.3.3)FEM Finite Element MethodFLS Fatigue Limit State (6.1.1)FMEA Failure Mode Effect AnalysisFPS Floating Production System (10.1.1)FPSO Floating Production, Storage and Offloading (10.3.5)FRP Fibre Reinforced PolymerGA General Arrangement (drawing)GIS Geographical Information System (9.6.2)GL Germanischer LloydGMAW Gas Metal Arc Welding (8.3.2)
xviii Glossary and notation
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GPS Global Positioning SystemGPTC Gas Piping Technology Committee (4.2.3)HAZ Heat Affected ZoneHAZID Hazard Identification (5.3.2)HAZOP Hazard and Operability (study) (5.3.2)HD- High Density (e.g. HDPE, HDPU)HDD Horizontal Directional Drilling (8.5.5)HFW High Frequency Welding (7.2.4)HIC Hydrogen Induced Cracking (3.3.3)HIP Hot Isostatic Pressing (7.2.7)HIPPS High Integrity Pressure Protection System (4.2.3)HP/HT High Pressure/High TemperatureHSE Health, Safety and Environmental Protection (9.2.2)ID Internal Diameter (pipe bore)IEC International Electrotechnical Commission (4.2.3)IP Intersection Point (2.6.2)ISO International Standardisation OrganisationISO/DIS Draft International (ISO) StandardKP Kilometre Post (2.6.2)LAT Lowest Astronomical TideLCI Life Cycle Information (9.1)LI Liquidity Index (3.3.2)LL Liquid Limit (3.3.2)LRFD Load and Resistance Factor DesignMAIP Maximum Allowable Incidental Pressure (4.2.3)MAOP Maximum Allowable Operating Pressure (4.2.3)MBR Minimum Bending Radius (10.3.3)MD- Medium Density (e.g. MDPE)MEG Methyl Ethyl Glycol/Mono Ethylene GlycolMPI Magnetic Particle InspectionMSL Mean Sea LevelMTO Material Take-OffNACE National Association of Corrosion Engineers (USA)NDE/NDT Non-Destructive Examination/Non-Destructive TestingNGL Natural Gas LiquidsNKT Nordisk Kabel og Tråd (10.1.2)NORSOK Norsk Sokkels konkuranseposisjon (competitive standing of the
Norwegian offshore sector)NPV Net Present Value (2.3.3)OD Outer DiameterOPEX Operational Cost (2.3.3)OREDA Offshore Reliability Data (5.7)OS Offshore Standard
Abbreviations xix
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P&ID Process and Instrumentation DiagramPA PolyamidePD Published Document (6.1.1)PE PolyethylenePI Plasticity Index (3.3.2)PL Plastic Limit (3.3.2)PP PolypropylenePRCI Pipeline Research Council International, Inc. (4.3.3)prEN European Pre-StandardPSD Process Shut Down (valve) (4.2.3)PSV Pressure Safety (relief) Valve (4.2.3)PU PolyurethanePVC Poly Vinyl ChloridePVDF Polyvinylidene FluorideQA/QC Quality Assurance/Quality ControlQRA Quantified Risk Analysis (5.3.2)REM Rare Earth Materials (3.3.2)RFO Ready For Operation (8.8.1)ROV Remotely Operated VehicleRP Recommended PracticeRTS ROV-operated Tie-in System (8.6.4)S Seamless (pipe) (7.2.2)SAR Synthetic Aperture Radar (2.5.3)SAW Submerged-Arc WeldingSAWH Submerged-Arc Welding HelicalSAWL Submerged-Arc Welding LongitudinalSCADA Supervision, Control and Data Acquisition (4.2.3)SCF Stress Concentration FactorSI Système Internationale/International System of Units of
MeasurementsSLOR Single Line Offset Riser (10.3.5)SLS Serviceability Limit State (6.1.2)SMAW Shielded Metal Arc Welding (8.3.2)SMSS Super Martensitic Stainless SteelSML Seamless (pipe) (7.2.2)SMTS Specified Minimum Tensile StrengthSMYS Specified Minimum Yield StressSOHIC Stress Oriented Hydrogen Induced Cracking (3.3.3)SRB Sulphate Reducing Bacteria (8.8.2)SSC Sulphide Stress Cracking (3.3.3)SSIV Subsea Safety Isolation ValveSWC Stepwise Cracking (3.3.3)SZC Soft Zone Cracking (3.3.3)
xx Glossary and notation
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TEG Tri-Ethylene GlycolTLP Tension Leg PlatformTFL Through FlowlineTMCP Thermo-Mechanical Controlled Processing (3.3.1)TP Tangent Point (2.6.2)TÜV Technische Überwachungs VereinULS Ultimate Limit State (6.1.3)UNECE United Nations Economic Commission for Europe (2.2.3)UNS Unified Numbering SystemUOE U-shaping, O-pressing, Expansion (7.2.4)UTC Unit Transportation Cost (2.3.3)UV Ultraviolet (radiation)VIV Vortex Induced Vibrations (6.4.6)WBC Wet Buckle Contingency (8.4.6)WBS Work Breakdown StructureWC Water Content (3.3.2)WT Wall Thickness (steel)XLPE Cross-linked Polyethylene (10.4.3)
Terms
The list explains the most common specialised terms, in the sense in which theyare employed in this book, as well as a few other terms in common usage.
Acid washChemical treatment of steel substrate by means of diluted mineral acid (usuallyphosphoric acid) in combination with detergency systems.
ActuatorSee Ball valve.
Added massAdditional mass is assigned to a body to reflect the fact that the force requiredto accelerate a submerged body is larger than the force required to acceleratethe same body in vacuum. The reason for this is that part of the surround-ing water is accelerated together with the body. The added mass is typicallydescribed by a coefficient and the mass of the volume of water displaced bythe body.
Alignment sheetDrawing showing a section of pipeline (in plan and profile), incorporating seabedfeatures as well as physical pipeline properties and installation parameters.
Terms xxi
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AnodeElectrode from which electric current flows to an electrolyte (water, soil). On thesurface an oxidation process takes place, e.g. metal to metal ions or hydroxylions to oxygen and water.
Anode assemblyAlso referred to as anode bank. A cluster of anodes delivering current, e.g.to provide cathodic protection. Anodes placed in (onshore) soil are normallysurrounded by low resistance material (e.g. coke), and are referred to as anodebeds.
Anode padSee Doubler plate.
AsphaltSee Bitumen.
AsphalteneNon-volatile, high molecular weight fraction of petroleum that is insoluble inlight alkanes such as n-pentane and n-heptane.
Atterberg LimitsLimiting water contents between which soil behaviour is characterised as a plasticsolid (as opposed to a semisolid or a viscous liquid).
AusteniteSee Steel microstructure.
BackfillingCovering of trenched pipeline, which may be natural (by sedimentation) or artificial(by rock dumping or by mechanically returning the seabed material removedduring trenching).
BainiteSee Steel microstructure.
Ball valveValve where the valve body is built around a ball provided with through hole, thesize of the pipe bore. The valve is closed by rotation of the ball manually or bymeans of a hydraulic actuator, which may be diver, ROV or remotely operated.
Barrier coatingBlockage against oxygen and other gases, as well as water and dissolved salts.
xxii Glossary and notation
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BendCurved piece of pipe, for offshore use either hot formed from induction bentlinepipe joints (motherpipe) or forged items. Bends with small bending radius(1.5 × ID or less) are also referred to as elbows, and will normally be forged. Tofacilitate the welding into the pipeline, bends are normally provide with short,straight sections (tangent lengths).
BellmouthPart of a guide tube, formed in the shape of a bellmouth, to control the bendingcurvature of the flexible pipe in dynamic or static applications.
Bending restrictorA mechanical device that functions as a mechanical stop to limit the bendingcurvature of a flexible pipe in static applications.
Bending stiffenerA cone-shaped ancillary component that supports the flexible pipe and thusprevents over-bending of the pipe in dynamic or static applications.
BenthicGeneric term for plant and animal life living at the seabed.
BitumenCoating material derived from distillation of hydrocarbons or extracted fromnatural deposits (asphalt).
BleedingSee Venting.
Bonded flexible pipeA flexible pipe where the steel reinforcement is integrated and bonded to avulcanised, elastomeric material.
Bottom towInstallation method whereby pipe strings are pulled in position on the seabed(see Towing).
BuckleDeformation of pipeline as a result of local actions or stability failure of thepipe section due to external pressure, possibly in combination with bending.The buckling may lead to water entering the pipeline (wet buckle) or not (drybuckle).
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Buckle arrestorSection of thick-walled linepipe introduced at regular intervals to prevent propa-gation buckling of a pipeline.
CaissonSleeve pipe housing one or several pipelines, cables, etc.
CathodeElectrode into which electric current flows from an electrolyte (water, soil). Onthe surface a reduction process takes place, e.g. water to hydrogen and hydroxylions.
Cathodic disbondingLoss of bond between barrier coating and steel substrate due to the formation ofhydroxyl ions in connection with cathodic protection.
Cathodic protectionElectrochemical method of corrosion protection of metal structures, achieved byforcing an electric current from an anode through the surrounding electrolyte intothe metal, which becomes a cathode.
ChainageDistance measured along the pipeline by accumulating the lengths of the installedpipe joints. Owing to local deviations and seabed irregularities this will be some-what higher than the kilometre post (KP) reckoning along the theoretical pipelineroute. Thus if KP numbers are used to designate chainage it should be highlighted.
Charpy V testTest method to determine impact fracture properties of steels.
Check valveNon-return valve, preventing counterflow. Swing check valves (also known asflapper or clapper valves) are built around a flapper disc, attached at the valvehouse top, which can be rotated to close the valve. During operation the disc issuspended by the fluid flow, and if there is a change in flow direction the flapperwill swing closed, providing a seal that will prevent fluid loss.
Chromate conversion coatingChemical treatment of steel substrate by wetting the surface with diluted chrom-ate acid in combination with other chemicals.
CladdingSee Sheeting.
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Clapper valveSee Check valve.
Crack arrestorDevice to be incorporated in a pipeline to prevent long running crack.
Coal tarCoating material manufactured by distillation (pyrolysis) of rock coal.
Coating yardOnshore facility for the application of pipe coatings and sacrificial anodes topipe joints.
CobblesSee Rock dumping.
Cold springingIntroduction of residual moment in a connection by elastic deformations duringtie-in.
CollapseDeformation of a pipeline due to a distributed load, particularly external pressure.
ComponentsPressure sustaining parts of a pipeline system which are not linepipe (e.g. fittings,valves, isolation couplings, pig launchers/receivers).
Concrete coatingPipe coating of reinforced concrete, applied to increase the pipeline weight and/or protect the steel pipe and its anti-corrosion coating against mechanical damage.
CondensateLiquid hydrocarbon, separated from natural gas by reduction of pressure andtemperature. Also referred to as NGL.
ContractorExecuting party in a contractual relationship, including sub-contractor or supplier.
CounteractLateral support on the seabed, guiding the pipeline during pipelaying in hori-zontal curves, also called a turnpoint.
Corrosion allowanceIncrease of the wall thickness corresponding to the expected corrosion loss, withthe objective of ensuring the required wall thickness during the service life.
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CrossingIntersection of pipeline with a previously installed (operational or abandoned)pipeline or cable.
CrushingRadial compression, which may cause a sudden collapse or significant ovalisationof the pipe cross-section.
CuttingTrenching of pipeline by means of a mechanical digging machine riding on thepipe, towed or self-propelled.
Davit liftAbove-water tie-in operation, involving lifting of the two pipe string ends bybarge-mounted cranes (davits).
Dead man anchorHigh holding anchor with corresponding chain, placed on the seabed to providetension for pipelay initiation.
DentLocal deformation of the linepipe wall, resulting in a reduction of the pipebore.
Design pressureMaximum internal pressure occurring in the pipeline during normal operation,referred to a specific reference height.
Directional drillingInstallation method whereby the pre-fabricated pipe string is pulled through ahole drilled through the soil.
DoglegSee Expansion offset.
Double jointingWelding together of two pipe joints before they are incorporated into the pipestring.
Doubler plateSteel plate welded on to the pipe joint under factory conditions, to provide alocation for structural attachment, in particular anode pads for sacrificial anodecable connection, by stick welding, pin brazing or thermite welding.
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Drop weight tear testTest method to determine fracture properties of heavy sections of steel.
Dry buckleSee Buckle.
Duplex steelSteel with mixed microstructure. Stainless duplex steel is a chromium alloyedmixture of austenite and ferrite. Normal grade is 22 Cr, the higher grade 25 Crwith higher strength and superior corrosion resistance is also referred to as superduplex.
Dye stickSolid dye units designed to dissolve after flooding, and serve in case leak detec-tion is required. Dye sticks are easy to place in critical units such as tie-in orvalve spools. The dye can be coloured or clear but fluorescent.
Eddie current testingNon-destructive test method based on electromagnetic principles.
ElbowSee Bend.
ElboletSee Olet.
EnamelHot applied pipe coating consisting of bitumen or coal tar, reinforced with layersof fibreglass wrap.
Epoxy paintTwo-component paint consisting of epoxy resin and solvent.
Expansion bucklingLateral deformation, possibly of large displacement, of a pipeline, caused byprevented longitudinal expansion to relieve compressive forces due to increasesin pressure and/or temperature.
Expansion offsetPipe spool (in the shape of an L, Z or U) that is inserted between a pipeline anda fixed structure (e.g. a platform riser or a wellhead) to absorb longitudinaldeformations due to changes in temperature or pressure of the pipeline medium.Also referred to as an expansion loop or dogleg.
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Export pipelinePipeline transporting a treated product (gas, condensate, oil) from an offshorefacility. It may be an interfield pipeline or a transmission pipeline.
Fall pipeVertical steel pipe suspended from a surface vessel, through which rock or gravelis dumped on the seabed. See Rock dumping.
FerriteSee Steel microstructure.
Field jointConnection of two pipe joints carried out on site (offshore or at an onshore siteor construction yard). It includes the girth weld and the field joint coating,bridging the gap between the factory-applied anti-corrosion coating on the out-side, and possibly also the inside, of the pipe. Additional field joint infill may fillthe gap between insulation or concrete coating on the adjoining pipe joints.
Firing lineWork area on a laybarge where the pipe joints are welded onto the pipe string.
FishStreamlined platform or container for survey, and other, instruments; towed by asurface vessel along a specified route, used for data gathering.
FittingsPipeline components that do not have operational functions (e.g. flanges, tees,wyes, olets).
Flapper valveSee Check valve.
Flange connectionSee Mechanical connection.
Flexible pipeFactory produced pipe string characterised by a layered configuration, resultingin a bending stiffness which is orders of magnitude smaller than for steel pipe ofsimilar dimension.
FloodingFilling the pipeline with water, to perform hydrotesting or to facilitate tie-in.
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FlotationUpwards directed, vertical instability of a buried pipeline.
Flow assuranceThe prevention of production losses by ensuring unrestricted flow path in thepipe transportation system during its service life.
FlowlinePipeline transporting untreated well fluids.
Flow regimeNature of the transported medium. Normal designations are: single phase (liquidor gaseous), two-phase (e.g. oil and gas) and multi-phase (e.g. oil, gas, water andparticles).
Fracture toughnessMeasure of the ability to resist crack propagation under sustained load. See alsoImpact toughness.
Free spanSection of pipeline unsupported by the seabed.
Girth weldCircumferential weld between pipe joints. See also Field joint.
GougeLocal linepipe imperfection, affecting the pipe wall only, without resulting in areduction of the pipe bore.
GravelSee Rock dumping.
Heat affected zoneZones adjacent to welds where the heat input from welding changes the basemetal microstructure.
Heat shrink sleeveField joint anti-corrosion coating consisting of cross-linked polyolefin, whichshrinks upon the application of heat.
Hot spot stressImaginary reference stress for welded joints. Hot spot stress is established byextrapolation of stresses outside the weld notch zone into the singularity at the
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weld root or toe. Hot spot stress includes geometric stress concentration, but notthe high local stress generated by the welding process.
Hot-tappingConnection of a branch line to an existing pipeline without emptying the latter,as an alternative to using a pre-installed tee (or wye).
HubShort piece of pipe with a raised flange to engage with a remotely operated tool(e.g. for tie-in or hot-tapping).
HydratesIce-like combinations of water and natural gas, formed for certain temperatureand pressure conditions, depending on the gas composition.
Hydrogen embrittlementDamage to steel material incurred through the uptake of atomic hydrogen, e.g. inconnection with welding, galvanising, cathodic protection or corrosion.
HydrotestingShort for hydrostatic testing, whereby the strength and tightness of a pipelinesection is documented by flooding with water and pressurising.
Hyperbaric weldingWelding performed subsea in a pressurised habitat. See also Saturation diving.
Impact toughnessMeasure of the ability to resist crack initiation and propagation under high impactloads. See also Fracture toughness.
ImpingementApplication of concrete coating whereby a no-slump concrete mix is thrown atthe rotating pipe joint.
Impressed currentMethod of cathodic protection where the driving current is delivered from anexternal power source.
Incidental pressureMaximum internal pressure that can occur in the pipeline during operation, referredto the same reference height as the design pressure.
InfillField joint coating material filling the gap between the coatings on the adjacentpipe joints.
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