Underwater Inspection and Repair for Offshore Structures

John V. Sharp is a Visiting Professor at Cranfield University, UK. His main research interests include the ageing and life extension of structures and their inspection and repair. Formerly he was responsible for the UK Health & Safety Executive’s offshore research programme.Gerhard Ersdal is a Professor in the Department of Mechanical and Structural Engineering and Material science at the University of Stavanger, Norway. His main research interests include structural integrity management, life extension of structures, and risk management.

• Preface xiiiDefinitions and abbreviations xv1 Introduction to Underwater Inspection and Repair 11.1 Background 11.2 Why Do We Inspect and Repair Structures 31.3 Types of Offshore Structures 61.3.1 Fixed Steel Structures 61.3.2 Floating Structures 81.3.3 Concrete Platforms 91.4 Overview of this Book 101.5 Bibliographic Notes 11References 112 Statutory Requirements for Inspection and Repair of Offshore Structures 132.1 Introduction 132.2 Examples of Country Statutory Requirements 142.2.1 Introduction 142.2.2 Regulation in the US Offshore Industry 152.2.3 Regulation in the UK Offshore Industry 162.2.4 Regulation in the Norwegian Offshore Industry 172.3 Standards and Recommended Practices for Steel Structures 172.3.1 Introduction 172.3.2 API RP-2A and API RP-2SIM (Structural Integrity Management) 182.3.3 API RP-2FSIM (Floating Systems Integrity Management) 212.3.4 ISO 19902 222.3.5 ISO 19901-9 232.3.6 NORSOK N-005 232.4 Standards and Recommended Practices for Mooring Systems 242.4.1 Introduction 242.4.2 API RP-2MIM (Mooring Integrity Management) 252.4.3 IACS Guideline for Survey of Offshore Moorings 262.5 Standards and Guidance Notes for Concrete Structures 272.5.1 Introduction 272.5.2 ISO 19903—Concrete Structures 272.5.3 Department of Energy Guidance Notes 312.5.4 NORSOK N-005—Concrete Structures 322.6 Discussion and Summary 33References 343 Damage Types in Offshore Structures 373.1 Introduction 373.1.1 General 373.1.2 Corrosion 383.1.3 Cracking Due to Fatigue 403.1.4 Dents, Bows and Gouges Due to Impact 413.1.5 Cracking Due to Hydrogen Embrittlement 423.1.6 Erosion, Wear and Tear 423.1.7 Brittle Fracture 433.1.8 Grout Crushing and Slippage 433.2 Previous Studies on Damage to Offshore Structures 433.3 Previous Studies on Damage to Fixed Steel Structures 443.3.1 MTD Underwater Inspection of Steel Offshore Structures 443.3.2 MTD Review of Repairs to Offshore Structures and Pipelines 463.3.3 PMB AIM Project for MMS 473.3.4 HSE Study on Causes of Damage to Fixed Steel Structures 503.3.5 Single-Sided Closure Welds 513.3.6 MSL Rationalization and Optimisation of Underwater Inspection Planning Report 523.3.7 Studies on Hurricane and Storm Damage 543.4 Previous Studies on Damage to Floating Steel Structures 573.4.1 D.En. Studies on Semi-Submersibles 573.4.2 SSC Review of Damage Types to Ship-Shaped Structures 573.4.3 Defect Type for Tanker Structure Components 593.4.4 Semi-Submersible Flooding Incident Data 593.5 Previous Studies on Damage Types to Mooring Lines and Anchors 613.5.1 Introduction and Damage Statistics for Moorings 613.5.2 API RP-2MIM Overview of Damage Types to Mooring Lines 623.5.3 HSE Studies on Mooring Systems 633.5.4 Studies on Corrosion of Mooring Systems 643.5.5 Studies on Fatigue of Mooring Systems 643.6 Previous Studies on Concrete Structures 663.6.1 Concrete in the Oceans Project 663.6.2 Durability of Offshore Concrete Structures 673.6.3 PSA Study on Damage to Offshore Concrete Structures 683.7 Previous Studies on Marine Growth (Marine Fouling) 703.8 Summary of Damage and Anomalies to Offshore Structures 723.8.1 General 723.8.2 Damage Types Specific to Steel Structures 723.8.3 Damage Types Specific to Concrete Structures 753.8.4 Summary Table of Damage to Different Types of Structures 753.9 Bibliographic Notes 76References 764 Inspection Methods for Offshore Structures Underwater 794.1 Introduction to Underwater Inspection 794.2 Previous Studies on Inspection 814.2.1 Introduction 814.2.2 SSC Survey of Non-Destructive Test Methods 814.2.3 Underwater Inspection / Testing / Monitoring of Offshore Structures 844.2.4 HSE Handbook for Underwater Inspectors 854.2.5 MTD Underwater Inspection of Steel Offshore Structures 854.2.6 Department of Energy Fourth Edition Guidance Notes on Surveys 864.2.7 HSE Detection of Damage to Underwater Tubulars and Its Effect on Strength 874.2.8 MSL Rationalization and Optimisation of Underwater Inspection Planning Report 894.2.9 Projects on Testing of Inspection Methods and Their Reliability 934.2.10 Concrete in the Oceans Programme 964.3 Inspection and Inspection Methods 1004.3.1 Introduction 1004.3.2 Visual Inspection 1004.3.3 Ultrasonic Testing Methods 1034.3.4 Electromagnetic Methods 1044.3.5 Radiographic Testing 1064.3.6 Flooded Member Detection 1064.3.7 Rebound Hammer 1084.3.8 Chloride Ingress Test 1084.3.9 Electro-Potential Mapping 1094.3.10 Cathodic Protection Inspection 1114.4 Deployment Methods 1124.4.1 Introduction 1124.4.2 Divers 1134.4.3 ROV and AUV 1144.4.4 Splash Zone Access 1164.4.5 Summary of Inspection Methods and Their Deployment 1174.5 Competency of Inspection Personnel and Organisations 1174.5.1 Introduction 1174.5.2 Regulatory Requirements on Competency 1194.5.3 Requirements on Competency in Standards 1194.5.4 Certification and Training of Inspectors 1214.5.5 Trials to Study Inspector Competency 1214.5.6 Organisational Competency 1224.6 Reliability of Different Inspection Methods Underwater 1244.7 Inspection of Fixed Steel Structures 1264.8 Inspection of Concrete Structures 1284.9 Inspection of Floating Structures and Mooring Systems 133References 1375 Structural Monitoring Methods 1415.1 Introduction 1415.1.1 General 1415.1.2 Historical Background 1425.1.3 Requirements for Monitoring in Standards 1455.2 Previous Studies on Structural Monitoring Methods 1465.2.1 MTD Underwater Inspection of Steel Offshore Installations 1465.2.2 HSE Review of Structural Monitoring 1465.2.3 HSE Updated Review of Structural Monitoring 1485.2.4 SIMoNET 1505.3 Structural Monitoring Techniques 1515.3.1 Introduction 1515.3.2 Acoustic Emission Technique 1515.3.3 Leak Detection 1525.3.4 Global Positioning Systems and Radar 1525.3.5 Fatigue Gauge 1535.3.6 Continuous Flooded Member Detection 1535.3.7 Natural Frequency Monitoring 1535.3.8 Strain Monitoring 1545.3.9 Riser and Anchor Chain Monitoring 1555.3.10 Acoustic Fingerprinting 1555.3.11 Monitoring with Guided Waves 1555.4 Structural Monitoring Case Study 1555.5 Summary on Structural Monitoring 1575.6 Bibliographic Notes 159References 1596 Inspection Planning, Programme and Data Management 1616.1 Introduction 1616.1.1 General 1616.1.2 Long-Term Inspection Plan 1626.1.3 Approaches for Long-Term Inspection Planning 1636.1.4 Inspection Programme 1676.1.5 Integrity Data Management 1706.1.6 Key Performance Indicators 1736.2 Previous Studies on Long-Term Planning of Inspections 1736.2.1 PMB AIM Project for MMS 1736.2.2 MSL Rationalization and Optimisation of Underwater Inspection Planning Report 1746.2.3 HSE Study on the Effects of Local Joint Flexibility 1756.2.4 HSE Ageing Plant Report 1766.2.5 Studies on Risk-Based and Probabilistic Inspection Planning 1766.2.6 EI Guide to Risk-Based Inspection Planning 1806.3 Summary on Inspection Planning and Programme 1806.3.1 Introduction 1806.3.2 Fixed Steel Platforms 1816.3.3 Floating Steel Structures 1826.3.4 Concrete Platforms 1836.4 Bibliographic Notes 184References 1847 Evaluation of Damage and Assessment of Structures 1877.1 Introduction 1877.2 Previous Studies on Evaluation of Damaged Tubulars 1897.2.1 Remaining Fatigue Life of Cracked Tubular Structures 1897.2.2 Static Strength of Cracked Tubular Structures 1957.2.3 Effect of Multiple Member Failure 1997.2.4 Corroded Tubular Members 2017.2.5 Dent and Bow Damage to Underwater Tubulars and Their Effect on Strength 2057.2.6 Studies on Assessment of System Strength 2087.2.7 PMB AIM Project for MMS 2097.2.8 MSL Significant JIP for MMS 2117.2.9 MSL Assessment of Repair Techniques for Ageing or Damaged Structures 2147.3 Previous Studies on Evaluation of Damaged Plated Structures 2157.3.1 Introduction 2157.3.2 SSC Studies on Residual Strength of Damaged Plated Marine Structures 2167.4 Previous Studies on Evaluation of Damaged Concrete Structures 2187.4.1 Department of Energy Assessment of Major Damage to the Prestressed Concrete Tower 2187.4.2 Department of Energy Review of Impact Damage Caused by Dropped Objects 2207.4.3 HSE Review of Durability of Prestressing Components 2207.4.4 HSE Review of Major Hazards to Concrete Platforms 2207.4.5 Department of Energy Review of the Effects of Temperature Gradients 2217.4.6 Concrete in the Oceans Review of Corrosion Protection of Concrete Structures 2217.4.7 Norwegian Road Administration Guideline V441 2227.5 Practice of Evaluation and Assessment of Offshore Structures 2237.5.1 General 2237.5.2 Fixed and Floating Steel Structures 2257.5.3 Concrete Structures 230References 2328 Repair and Mitigation of Offshore Structures 2398.1 Introduction to Underwater Repair 2398.2 Previous Generic Studies on Repair of Structures 2428.2.1 UEG Report on Repair to North Sea Offshore Structures 2428.2.2 MTD Study on Repairs of Offshore Structures 2428.2.3 UK Department of Energy Fourth Edition Guidance Notes 2478.2.4 DNV GL Study on Repair Methods for PSA 2488.3 Previous Studies on Repair of Tubular Structures 2508.3.1 Grout Repairs to Steel Offshore Structures 2508.3.2 UK Joint Industry Repairs Research Project 2528.3.3 UK Department of Energy and TWI Study on Repair Methods for Fixed Offshore Structures 2548.3.4 UK Department of Energy–Funded Work on Adhesive Repairs 2578.3.5 Residual and Fatigue Strength of Grout-Filled Damaged Tubular Members 2608.3.6 Fatigue Life Enhancement of Tubular Joints by Grout Injection 2618.3.7 ATLSS Projects on Repair to Dent-Damaged Tubular Members 2618.3.8 ATLSS Projects on Repair to Corrosion Damaged Tubulars 2638.3.9 MSL Strengthening, Modification and Repair of Offshore Installations 2658.3.10 MSL Underwater Structural Repairs Using Composite Materials 2668.3.11 HSE Experience from the Use of Clamps Offshore 2678.3.12 MSL Study on Neoprene-Lined Clamps 2698.3.13 MSL Repair Techniques for Ageing and Damaged Structures 2708.3.14 MMS Studies on Hurricane Damage and Repair 2738.3.15 BOEME Report on Wet Weld Repairs to US Structures 2748.4 Previous Studies on Repair of Concrete Structures 2768.4.1 Introduction 2768.4.2 Repair of Major Damage to Concrete Offshore Structures 2778.4.3 Scaling of Underwater Concrete Repairs 2788.4.4 Assessment of Materials for Repair of Damaged Concrete Underwater 2808.4.5 Effectiveness of Concrete Repairs 2858.5 Previous Studies on Repair of Plated Structures 2868.6 Repair of Steel Structures 2898.6.1 Introduction 2898.6.2 Selection of Mitigation and Repair Methods 2908.6.3 Machining Methods (Grinding) 2958.6.4 Re-Melting Methods 2978.6.5 Weld Residual Stress Improvement Methods (Peening) 2978.6.6 Stop Holes and Crack-Deflecting Holes 2988.6.7 Structural Modifications 3008.6.8 Underwater Welding 3018.6.9 Doubler Plates 3058.6.10 Removal of Structural Elements 3058.6.11 Bonded-Type Repairs 3068.6.12 Structural Clamps and Sleeves 3078.6.13 Grout Filling of Members 3108.6.14 Grout Filling of Tubular Joints 3128.6.15 Installation of New Structural Elements 3128.6.16 Summary of Steel Repairs 3138.7 Repair of Corrosion and Corrosion Protection Systems 3168.7.1 Introduction 3168.7.2 Repair of Damaged Coatings 3188.7.3 Replacement of Corroded Material 3188.7.4 Repair or Replacement of the Corrosion Protection System 3188.8 Repair of Mooring Systems 3198.9 Repair of Concrete Structures 3208.9.1 Introduction 3208.9.2 Choice of Repair Method 3228.9.3 Concrete Material Replacement 3238.9.4 Injection Methods 3258.9.5 Repair of Reinforcement and Prestressing Tendons 3268.9.6 Summary of Concrete Repairs 3278.10 Overview of Other Mitigation Methods 3288.11 Bibliographic Notes 329References 3299 Conclusions and Future Possibilities 3379.1 Overview of the Book 3379.2 Emerging Technologies 3389.3 Final Thoughts 340References 341Index 342