Guidelines for the Design, Operation and Maintenance of Multi Buoy Moorings (MBM)

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Published Date

June 2010

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Guidelines for the Design, Operation and Maintenance of Multi Buoy Moorings (MBM)

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

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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.


List of Figures 

List of Tables 

Glossary of Terms and Abbreviations


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  Holding Power of Ship’s Anchors   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    Transit UKC    Berth UKC    Seabed Obstructions    Current Effects    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    Wind Loads on the Ship    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    Structural Buoys    Trunk Buoys 

 2.4.4    Mooring Hooks    Quick Release Hooks 

2.5    Anchor Chain Leg Design

2.5.1    General 

2.5.2    Design of Chain Leg    Type and Grade of Chain    Joining Shackles    Swivels    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    Anchor Point Safety Factors 

2.6.2    Drag Embedment Anchors    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   Flow Rates   Lifting Considerations   Presentation Flange 

2.7.4    Length of Hose String 

2.7.5    Hose String Configuration   Electrical Isolation 

2.8    Pipeline End Manifold (PLEM)

2.8.1    General Requirements 

2.8.2    PLEM Location 

2.8.3    PLEM Design  PLEM Structure  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 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 Ship/Shore Safety Check-List Communications Agreed Transfer Procedures 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 Mooring Buoy Position    Connections on Buoy for Chain and Hooks    Mooring Buoy Body 

4.3.2..4    Leak Test    Mooring Buoy Freeboard    Coating    Cathodic Protection    Mooring Hooks    Shore Moorings    Fenders 

4.4    Anchor Chains 

4.4.1    General Description 

4.4.2    Inspection and Maintenance    Anchor Chains    Concrete Sinker Blocks 

4.5    Anchors Points 

4.5.1    General Description 

4.5.2    Inspection and Maintenance    Visual Inspection    Anchor Proof Test 

4.6    Hose Systems 

4.6.1    General Description 

4.6.2    Inspection    Hydrostatic Pressure Test    Vacuum Test    Electrical Test    Marine Breakaway Couplings 

4.7    Pipeline End Manifold (PLEM) 

4.7.1    General Description 

4.7.2    Inspection    PLEM Piping    Subsea Valves and Actuators    PLEM Structure 

4.8    Ancillary Equipment 

4.9    Spare Parts 

Appendices 1 and 2 

1    Example Hose Lifting Method 
2    Example Hose Lowering Method 

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.

OCIMF was formed in April 1970 in response to the growing public concern about marine pollution, particularly by oil, after the Torrey Canyon incident in 1967. In the early 1970s, a variety of anti-pollution initiatives were starting to emerge nationally, regionally and internationally, but with little coordination. Through OCIMF, the oil industry was able to play a stronger, coordinating role in response to these initiatives, making its professional expertise widely available through cooperation with governments and intergovernmental bodies.

OCIMF was granted consultative status at the IMO in 1971 and continues to present oil industry views at IMO meetings. Since then, its role has broadened to take account the changing maritime activities of its membership. Its remit now covers tankers, barges, offshore support vessels and terminals and its advice extends to issues like shipping in ice and large-scale piracy, which rarely troubled the oil industry when OCIMF was first created in the 1970s.

The current membership of OCIMF comprises 112 companies worldwide.

Today, OCIMF is widely recognised as the voice of the oil industry providing expertise in the safe and environmentally responsible transport and handling of hydrocarbons in ships and terminals and setting standards for continuous improvement. Membership is extensive and includes every oil major in the world along with the majority of National Oil Companies.

OCIMF has much to be proud of. Not only has it contributed to a substantial quantity of regulation at the IMO aimed at improving the safety of tankers and protecting the environment, but it has introduced important new guidance on pressing current issues such as piracy and Arctic shipping. With the process of introducing new Internationally-accepted regulation necessarily slow as it crosses many individual countries and jurisdictions, OCIMF is in the unique position of being able to leverage the expertise of its membership to press ahead with much needed guidance on important industry issues. This provides the means to improve practices in the membership and in the wider industry, and serves as a valuable reference for developing regulation.

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

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