1、 Guidance Notes on Nearshore Position Mooring GUIDANCE NOTES ON NEARSHORE POSITION MOORING OCTOBER 2017 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 2017 American Bureau of Shipping. All rights reserved. ABS Plaza 16855 Northchase Drive Houston, TX 770
2、60 USA Foreword Foreword These Guidance Notes provide direction for the design and analysis of nearshore position mooring systems used for floating structures such as Floating Offshore Liquefied Gas Terminals (FLGTs), Floating Storage and Regasification Units (FSRUs), Floating Production Storage and
3、 Offloading installations (FPSOs) and accommodation barges. Nearshore position mooring in these Guidance Notes is intended to provide long-term solutions for stationkeeping for these floating structures. These Guidance Notes are applicable to the position mooring system and mooring equipment onboard
4、 the floating structures. The design of jetties or similar bottom supported structures used for the mooring of floating structures is generally the responsibility of the Owner. These structures should be designed in accordance with related industry guidelines and standards, and they should be able t
5、o provide required holding capacity to the mooring systems. Nearshore position mooring in these Guidance Notes cover the following types of mooring configurations: i) Jetty Mooring ii) Tension Pile Mooring These Guidance Notes should be used in conjunction with the ABS Rules for Building and Classin
6、g Floating Production Installations (FPI Rules), ABS Guide for Building and Classing Floating Offshore Liquefied Gas Terminals (FLGT Guide) and ABS Guide for Building and Classing LNG Regasification Vessels. These Guidance Notes become effective on the first day of the month of publication. Users ar
7、e advised to check periodically on the ABS website www.eagle.org to verify that this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be sent electronically by email to rsdeagle.org. Terms of Use The information presented herein is intended s
8、olely to assist the reader in the methodologies and/or techniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the responsibility of the reader to perform their own assessment and obtain professional advice. Information conta
9、ined herein is considered to be pertinent at the time of publication, but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information and the reader assumes full responsibility for compliance. This publication may not be copied or redis
10、tributed in part or in whole without prior written consent from ABS. ii ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 Table of Contents GUIDANCE NOTES ON NEARSHORE POSITION MOORING CONTENTS SECTION 1 Introduction 1 1 General . 1 3 Overview of Nearshore Position Mooring Systems 1 3.1 Jetty Mo
11、oring . 2 3.3 Tension Pile Mooring . 2 3.5 Other Alternative Mooring Systems . 2 3.7 Mooring Arrangement for Loading/Unloading Operations . 3 3.9 Comparison with other Mooring Systems 3 TABLE 1 Comparison of Mooring Systems 4 SECTION 2 Design Considerations 5 1 Design Life 5 3 Operational Considerat
12、ions 5 5 Mooring Design Conditions . 5 5.1 Survival Condition . 5 5.3 Operation Condition 6 5.5 One Component Damage Condition . 6 5.7 Disconnecting Condition 6 7 Environmental Conditions . 6 7.1 Wind, Waves and Current . 7 7.3 Water Depth 8 7.5 Directions of Wind, Wave and Current 8 7.7 Site Specif
13、ic Environmental Data 8 9 Environmental Loads 8 9.1 Wind Loads . 8 9.3 Current Loads 9 9.5 Wave Loads 9 9.7 Passing Vessel Effects 9 9.9 Effect of Piers 10 9.11 Multi-Body Dynamics . 10 11 Mooring Line and Fender Design Assessment . 11 11.1 Mooring Line and Fender Load for Strength Analysis . 11 11.
14、3 Mooring Line Fatigue Load Analysis . 13 11.5 Mooring Line Fatigue Capacity 14 11.7 Design Life and Replacement . 15 ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 iii 13 Other Design Considerations 15 13.1 Clearance 15 13.3 Mooring Supporting Structure 15 13.5 Mooring Holding Foundation 15
15、13.7 Corrosion, Wear and Rope Creep . 16 13.9 Safety Considerations 16 13.11 Bend Radius and Bending Fatigue of Mooring Line. 16 13.13 Axial Compression Fatigue of Fiber Rope . 17 13.15 Mooring Load Monitoring . 17 13.17 Mooring Equipment 17 13.19 Inspection and Replacement . 17 TABLE 1 Factor of Sa
16、fety for Anchoring Lines . 11 SECTION 3 Documentation . 18 1 Mooring Arrangement and Equipment 18 3 Analysis Reports . 18 5 Operations Manual 19 APPENDIX 1 Abbreviations . 20 1 Abbreviations 20 APPENDIX 2 Reference Standards and Guidelines . 21 1 ABS Rules, Guides and Guidance Notes . 21 3 Industry
17、Standards and Guidelines . 21 iv ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 Section 1: Introduction SECTION 1 Introduction 1 General These Guidance Notes provide direction for the design and analysis for nearshore position mooring systems used for floating structures such as Floating Offs
18、hore Liquefied Gas Terminals (FLGTs), Floating Storage and Regasification Units (FSRUs), Floating Production Storage and Offloading installations (FPSOs) and accommodation barges. The nearshore mooring system in this document is intended to provide a long-term permanent stationkeeping solution, in t
19、hat it is designed to keep the floating structure on position throughout its design life. Position mooring systems should be designed in accordance with applicable rules or guides with a level of safety that matches the intended service. The requirements for mooring systems are in ABS Rules for Buil
20、ding and Classing Floating Production Installations (FPI Rules). Industry guidelines, such as Mooring Equipment Guidelines, 3rdEdition (MEG3), published by Oil Companies International Marine Forum (OCIMF), may be used for nearshore position mooring systems where applicable. Nearshore position moorin
21、g systems have special characteristics in comparison with offshore mooring systems and nearshore temporary berthing covered by OCIMF MEG3. Comparisons of those mooring systems are shown in 1/3.9. These Guidance Notes primarily focus on: i) Jetty mooring or tension pile mooring ii) Design environment
22、 considerations iii) Operating conditions iv) Survival conditions of mooring systems vi) Environmental Loads and bearing capacity of the mooring systems vii) Emergency release of the mooring system viii) Mooring equipment qualification ix) Maintenance, monitoring and inspection The design of bottom
23、fixed structures, such as a jetty, a pier, quay, sea island, wharf, or dolphins, which serve as holding foundations for the mooring systems, is generally the responsibility of the owner. Those structures should be designed in accordance with relevant industry guidelines and standards, and they shoul
24、d be able to provide the required holding capacity for the mooring systems. 3 Overview of Nearshore Position Mooring Systems Nearshore position mooring systems have close proximity to the shoreline, and the access to the mooring system is relatively simple. In most cases, they can be accessed direct
25、ly from structures that are connected to shore. They are normally located in areas where currents and wave motions are influenced by sea bed bathymetry. Similar to the position mooring systems defined in the ABS FPI Rules and ABS Guide for Building and Classing Floating Offshore Liquefied Gas Termin
26、als (FLGT Guide), a nearshore position mooring system can be designed based on one of the following two options: ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 1 Section 1 Introduction i) Non-disconnectable. Floating structure stays at the location, even in severe weather. The mooring system
27、is designed for extreme events with the floating structure connected. ii) Disconnectable. Floating structure departs ahead of severe weather. The mooring system is disconnected from the floating structure. The mooring system alone is designed for extreme events if applicable. Nearshore position moor
28、ing in these Guidance Notes cover the following types of mooring configurations: i) Jetty Mooring (see 1/3.1) ii) Tension Pile Mooring (See 1/3.3) iii) Other Alternative Mooring Systems (See 1/3.5) 3.1 Jetty Mooring Jetty mooring is a mooring system to affix the floating structure alongside a jetty
29、structure. In a jetty mooring system, the anchoring points of the mooring system are either connected to onshore structures or nearshore structures such as a jetty (or a pier, quay, sea island, wharf, dolphins). A jetty mooring system consists of: Mooring lines (fiber ropes, chain, and/or wire ropes
30、) Mooring end fitting and accessories (thimbles, shackles) Fenders Quick release hooks Mooring equipment onboard the floating structure (mooring winch, fairlead, chain stoper, chocks, bitts, rollers, and etc.) Jetty structure (mooring bollards, cleats, and/or other mooring equipment) 3.3 Tension Pil
31、e Mooring A tension pile mooring system is similar to the tendon system used for a Tension Leg Platform (TLP). In such a system, the position of the floating structure is maintained by the tension of several vertical piles fixed to the seabed. The floating structure is connected at the piles through
32、 pins and hooks or other connection hardware. The piles are uplifted in tension with the buoyancy of the floating structure. A tension pile mooring system consists of: Piles and foundation of the piles Hooks on the top of piles Pins/extended pins on the hull of the floating structure Tension piles a
33、re within the scope of ABS classification, and should comply with the requirements in Section 6-1-2 of the FPI Rules. 3.5 Other Alternative Mooring Systems There are other alternative mooring systems such as: Guide pile mooring Hinged stiff leg restraint mooring Unconventional mooring equipment is e
34、ither in-use or proposed at a small number of terminals. Examples are: Vacuum pads ITB-style (Integrated Tug/Barge) hydraulic pins and matching slot 2 ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 Section 1 Introduction Nearshore position mooring technology is currently evolving. For innovat
35、ive designs, reference can be made to ABS Guidance Notes on Review and Approval of Novel Concepts and the principles contained in these guidance notes. 3.7 Mooring Arrangement for Loading/Unloading Operations For FLGT or FSRU, an LNGC is usually used to load/unload cargoes from the FLGT or FSRU. The
36、 arrangement of FLGT/FRSU, LNGC and sometimes a jetty structure can be one of the following configurations: i) Side-by-side Mooring. The LNGC alongside FLGT/FSRU, and FLGT/FSRU may be moored alongside a jetty structure in the case of jetty mooring, or with other types of mooring. ii) Tandem Mooring.
37、 The LNGC is moored behind the FLGT/FSRU, both may be moored alongside a jetty structure in the case of jetty mooring, or with other types of mooring. iii) Cross Dock Jetty Structure. The LNGC and the FLGT/FSRU are moored on either side of the jetty structure. 3.9 Comparison with other Mooring Syste
38、ms There are many commonalities between nearshore position mooring and offshore mooring in terms of environmental load analysis and strength assessment of the mooring system. Nearshore position mooring also has similarities to temporary berthing systems in terms of surrounding environment, shore acc
39、essibility and mooring system arrangements. Section 1, Table 1 provides a comparison between nearshore position mooring, offshore mooring, and temporary berthing. The list in the table highlights the differences that should be taken into consideration in the design of nearshore position mooring syst
40、ems. ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 3 Section 1 Introduction TABLE 1 Comparison of Mooring Systems Offshore Mooring for FPI Temporary Berthing Nearshore Mooring Moored Floating Structure Types Production facility/Terminal Ocean going/trading vessels Production facility/Termina
41、l Design Life 20 years or more N/A In accordance with the moored facility Distance to Shore No direct access to shore Direct access to shore Direct access to shore Water Depth In general water depth has no significant impact on wave and current load on the moored floater No specific requirement for
42、the return period for the high and low water level Water depth has impact on wave and current load, as well as clearance. Should consider 100-year high and low water level in the analysis Environmental Conditions Open ocean condition, Site specific wave statistics are normally available Site specifi
43、c wave data may be derived from the record of deep water location. Bathymetry and bottom effect may be important. Increased current load due to small bottom clearance. Similar to temporary berthing Mooring Arrangement No easy access to the mooring components. Mooring lines are submerged and relative
44、ly long. The natural period of the mooring systems is relatively long. Mooring lines are in the air. Fenders attached to the terminals contact the moored vessels. Mooring lines are short and the natural period of the mooring systems is short. For jetty mooring, similar to temporary berthing. Equipme
45、nt Mooring equipment onboard the facility and controlled on the facility Mooring equipment onboard the mooring terminals or on the vessel Similar to offshore mooring Mooring Line Adjustment and Replacement Should be avoided if possible. Replacement is expensive and not easy. Often adjusted, wear and
46、 tear could be high. The replacement is relatively easy. Jetty mooring is similar to temporary berthing, however, replacement may disrupt the operation and the cost may be high. Operational Considerations Continuous production operation for a relatively long period of time Loading/offloading in a re
47、latively short period of time Similar to offshore mooring Monitoring Systems Not often used during normal operation Often used during mooring line adjustment, and berthing/unberthing Should be used for mooring line adjustment and for disconnecting Inspection Methods Divers and ROV Easy access for vi
48、sual inspection and measurement Similar to temporary berthing Analysis Method Coupled dynamic analysis method including motions and line dynamic effects Uncoupled quasi-static method where dynamic effects are often not included Recommend the coupled dynamic analysis method Strength Assessment 100-ye
49、ar return period environment for strength assessment No specific return period. Recommend using 100-year return period environment and also include the values for maximum high water and minimum low water levels Fatigue Assessment Required Not required Required in general if the components are designed for long-term use. If the components are designed for periodical replacement, fatigue assessment may not be necessary 4 ABSGUIDANCE NOTES ON NEARSHORE POSITION MOORING .2017 Section 2 : Design Considerations SECTION 2 Design Considerations 1 Design Life The d
