Overview

This publication provides information and guidance on good practice to assist with the planning, design, operations, maintenance and inspection of multi-buoy moorings.

Multi Buoy Moorings (MBM) are common in the oil industry and are generally used in areas where the environmental conditions are moderate.

While the information provided is primarily geared towards the initial planning, design and operation of new facilities, it may also be useful for reference when upgrading or evaluating existing berths or when replacing individual components.

The scope of this publication embraces mooring and oil transfer equipment within the multi buoy berth, up to and including the Pipeline End Manifold (PLEM). Information regarding the subsea pipelines serving the PLEM is considered to be outside the scope and may be readily found in other publications.

Content

Introduction

List of Figures 

List of Tables 

Glossary of Terms and Abbreviations

Bibliography

Section 1

Description of Multi Buoy Moorings 

1.1    General 

1.1.1    Conventional Buoy Moorings (CBMs) 

1.1.2    All Buoy Moorings (ABMs) 

1.1.3    Mooring Leg Components 

1.1.4    Cargo Transfer System 

1.2    Design Limitations of MBMs

1.3    Comparisons with Fixed Berths (Piers and Sea Islands)

1.4    Comparisons with SPMs 

1.5    Required Support Facilities 

Section 2

Design of Multi Buoy Moorings 

2.1    Preliminary Design Considerations

2.1.1    Conceptual Assessment of Proposed Terminal 

2.1.2    General Considerations 

2.1.3    Selection of MBM Configuration 

2.1.4    Products to be Handled

2.1.5    Design Tankers 

2.1.6    Environmental Data 

2.1.7    Hydrographic, Geotechnical and Geophysical Surveys 

 2.2    Site Selection, MBM Orientation and Layout 14

 2.2.1   General 

2.2.2    Use of Ship’s Anchors 

2.2.2.1  Holding Power of Ship’s Anchors 

2.2.2.2   Minimum Length of Anchor Chain for Ship’s Anchors 

2.2.3    Provision of Adequate Manoeuvring Room 

2.2.4    Provision of Adequate Water Depth 

2.2.4.1    Transit UKC 

2.2.4.2    Berth UKC 

2.2.4.3    Seabed Obstructions   

2.2.4.4    Current Effects 

2.2.4.5    Regulatory Requirements 

2.3    Mooring Load Analysis

2.3.1    Factors Effecting Mooring Loads 

2.3.2    Ship Response to Waves 

2.3.3    Effect of Wind and Current 

2.3.3.1    Wind Loads on the Ship 

2.3.3.2    Current Loads on the Ship 

2.3.4    Ship Movement 

2.3.5    Selection of Design Safe Working Load 

 2.3.6    Analysis Methodology 

 2.4    Mooring Buoy and Hook Design

2.4.1    General Buoy Requirements 

2.4.2    Buoyancy Requirements 

2.4.3    Description of Buoys for MBMs 

2.4.3.1    Structural Buoys 

2.4.3.2    Trunk Buoys 

 2.4.4    Mooring Hooks 

2.4.4.1    Quick Release Hooks 

2.5    Anchor Chain Leg Design

2.5.1    General 

2.5.2    Design of Chain Leg 

2.5.2.1    Type and Grade of Chain 

2.5.2.2    Joining Shackles 

2.5.2.3    Swivels 

2.5.2.4    Sinker Blocks at MBM Berths 

2.5.3    Safety Factors 

2.5.4    Allowances for Corrosion, Abrasion and Wear 

2.5.5    Load Transfer to Anchor Points 

2.6    Anchor Point Design

2.6.1    General 

2.6.1.1    Anchor Point Safety Factors 

2.6.2    Drag Embedment Anchors 

2.6.2.1    Holding Power of Drag Embedment Anchors 

2.6.3    Plate Anchors 

2.6.4    Gravity Anchors 

2.6.5    Pile Anchors 

2.6.6    Holding Power of Chain on Sea Floor 

2.6.7    Advantages and Disadvantages of Different Types of Anchor  34

2.7    Hose System Design

2.7.1    General 

2.7.2    Number of Hose Strings 

2.7.3    Hose Characteristics 

2.7.3.1   Flow Rates 

2.7.3.2   Lifting Considerations 

2.7.3.3   Presentation Flange 

2.7.4    Length of Hose String 

2.7.5    Hose String Configuration 

2.7.5.1   Electrical Isolation 

2.8    Pipeline End Manifold (PLEM)

2.8.1    General Requirements 

2.8.2    PLEM Location 

2.8.3    PLEM Design 

2.8.3.1  PLEM Structure 

2.8.3.2  PLEM Piping 

 2.9    Ancillary Equipment

2.9.1    Marker Buoys 

2.9.2    Pick-up Buoys 

2.9.3    Navigational and Buoy Lights 

2.9.4    Methods of Hose Connection 

2.9.5    Marine Breakaway Couplings 

2.9.6    Use of Shore Wires and Ropes 

 2.10    Coating Systems

2.10.1   General 

2.10.2   Hardware 

Section 3

Operation of Multi Buoy Moorings 

3.1    Health, Safety and the Environment (HSE) 

3.1.1    HSE Policy 

3.1.2    Standard Operating Procedures 

3.1.2.1 Environmental Limits 

3.1.3    HSE Management System 

3.1.4    Security 

3.1.5    Risk Assessment 

3.1.6    HSE Audits 

3.1.7    Incident Reporting 

3.1.8    Exercises and Drills 

3.1.9    Terminal Manning 

3.2    Nomination and Vessel Acceptance Criteria 

 3.3    Pre-Arrival Procedures 

3.3.1    Advice to Arriving Ships 

3.3.2    Actions Prior to Ship’s Arrival 

3.3.3    Pre-Mooring Conference 

3.4    Approach to Berth and Preparations 

 3.5    Berthing and Mooring Operations 

3.5.1    Environmental Limits for Berthing 

3.5.2    Approach Speed and Anchoring 

 3.5.3   Working with Mooring Launches 

3.5.4    Berthing and Mooring at a CBM 

3.5.5    Berthing and Mooring at an ABM 

3.6    Safety While in the Berth 

3.6.1    Pre-Transfer Procedures 

3.6.1.1 Ship/Shore Safety Check-List 

3.6.1.2 Communications 

3.6.1.3 Agreed Transfer Procedures 

3.6.1.4 Emergency Shut Down Procedure 

3.6.2    Environmental Limits While in the Berth 

3.6.3    Onboard Supervision of Operations 

3.6.4    Precautions against Tanker Break-out from Berth 

3.7    Hose Connection and Disconnection 

3.7.1    Position of Hose on the Seabed 

3.7.2    Hose Handling 

3.7.3    Hose Lifting and Connection 

3.7.4    Method of Lowering the Hose to the Seabed using a Launch 

3.8    Departure from the Berth 

Section 4

Inspection and Maintenance of Multi Buoy Moorings  

4.1    General 

4.2    Methods of Inspection 

4.2.1  Pre-Berthing Visual Inspections 

4.2.2  In-Service Inspections (Time-Based inspections) 

4.2.3   Out of Water Inspections (Time-Based/ Condition-Based Inspections) 

4.3    Mooring Buoys 

4.3.1  General Description 

4.3.2  Inspection and Maintenance 

4.3.2.1 Mooring Buoy Position 

4.3.2.2    Connections on Buoy for Chain and Hooks 

4.3.2.3    Mooring Buoy Body 

4.3.2..4    Leak Test 

4.3.2.5    Mooring Buoy Freeboard 

4.3.2.6    Coating 

4.3.2.7    Cathodic Protection 

4.3.2.8    Mooring Hooks 

4.3.2.9    Shore Moorings 

4.3.2.10    Fenders 

4.4    Anchor Chains 

4.4.1    General Description 

4.4.2    Inspection and Maintenance 

4.4.2.1    Anchor Chains 

4.4.2.2    Concrete Sinker Blocks 

4.5    Anchors Points 

4.5.1    General Description 

4.5.2    Inspection and Maintenance 

4.5.2.1    Visual Inspection 

4.5.2.2    Anchor Proof Test 

4.6    Hose Systems 

4.6.1    General Description 

4.6.2    Inspection 

4.6.2.1    Hydrostatic Pressure Test 

4.6.2.2    Vacuum Test 

4.6.2.3    Electrical Test

4.6.2.4    Marine Breakaway Couplings 

4.7    Pipeline End Manifold (PLEM) 

4.7.1    General Description 

4.7.2    Inspection 

4.7.2.1    PLEM Piping 

4.7.2.2    Subsea Valves and Actuators 

4.7.2.3    PLEM Structure 

4.8    Ancillary Equipment 

4.9    Spare Parts 

Appendices 1 and 2 

1    Example Hose Lifting Method 
2    Example Hose Lowering Method 

Introduction

The objective of this publication is to provide information and recommendations on good practice to assist with the development of site-specific requirements. Terminals operators and designers are encouraged to provide feedback to OCIMF on the content, and on any aspects, that are not addressed, for proposed inclusion in subsequent editions of this publication.

Details 

Title: Guidelines for the Design, Operation and Maintenance of Multi-Buoy Moorings (MBM)
Number of Volumes: 1
Edition: First
Number of Pages: 112
Product Code: WS1249K
ISBN: ISBN 13: 978-1-85609-361-3 (9781856093613), ISBN 10: 1-85609-361-1 (1856093611)
Published Date: June 2010
Binding Format: Hardback
Book Height: 297 mm
Book Width: 210 mm
Book Spine: 10 mm
Weight: 0.70 kg
Author: Oil Companies International Marine Forum