1、 ABSGUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS .2010 1 GUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS JUNE 2010 NOTICE NO. 3 September 2012 The following Rule Changes become EFFECTIVE AS OF 1 SEPTEMBR 2012. (See http:/www.eagle.org for the co
2、nsolidated version of the Guide for Building and Classing Floating Offshore Liquefied Gas Terminals, 2010, with all Notices and Corrigenda incorporated.) Notes - The date in the parentheses means the date that the Rule becomes effective for new construction based on the contract date for constructio
3、n. (See 1-1-4/3.3 of the ABS Rules for Conditions of Classification Offshore Units and Structures (Part 1).) CHAPTER 2 DESIGN CONSIDERATIONS SECTION 1 CLASSIFICATION OF FLOATING OFFSHORE LIQUEFIED GAS TERMINALS 3 Additional Class Notations (Revise Paragraph 2-1/3.1, as follows.) 3.1 Disconnectable S
4、ystem (1 September 2012) A floating terminal that has a propulsion system and a means of disengaging the terminal from its mooring and riser systems to allow the floating terminal to ride out severe weather or seek refuge under its own power for a specified design environmental condition will be cla
5、ssed with the appropriate class notation in 2-1/1.1 above and with the notations (Disconnectable), null AMS at the end. One example of such class designation is: null A1, Offshore Liquefied Gas Terminal, F(LNG) ORS (Disconnectable), null AMS If a Disconnectable floating terminal is restricted to a s
6、pecific service area in proximity to its operating site location, a restricted service notation Disconnectable-R (from site to designated port) or (from site to geographic area bounded by Lat. X1, Long. Y1; Lat. X2, Long. Y2; Lat. X3, Long. Y3; Lat. X4, Long. Y4), may be assigned where permitted by
7、local authorities or regulations. Notice No. 3 September 2012 2 ABSGUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS .2010 (Revise Paragraph 2-1/3.7, as follows.) 3.7 Dynamic Loading Approach (1 September 2012) Where requested, the ABS Dynamic Loading Approach and notation DL
8、A may be applied to assess the adequacy of the floating steel structure of liquefied gas terminals. In such cases, the floating terminal will be classed and distinguished in the Record by the notation DLA. The DLA notation will be placed after the appropriate hull classification notation. The applic
9、ation of the dynamic loading approach is optional. The dynamic load components considered in the evaluation of the hull structure are to include the external hydrodynamic pressure loads, internal dynamic loads (fluids stored onboard, ballast, major equipment items, etc.) and inertial loads of the hu
10、ll structure. The magnitude of the load components and their combinations are to be determined from appropriate ship motion response calculations for loading conditions that represent the envelope of maximum dynamically-induced stresses in the floating terminal. The adequacy of the hull structure fo
11、r all combinations of the dynamic loadings is to be evaluated using an acceptable finite element analysis method. In no case are the structural scantlings to be less than those obtained from other requirements in this Guide. In addition, the design of the containment system of independent tanks is t
12、o be assessed and analyzed in accordance with Part 5C, Chapter 8 of the Steel Vessel Rules. The basic notation DLA is applied when the hydrodynamic loads have been determined using the wave environment of the North Atlantic with a 20-year service life. If the wave environment of the intended site is
13、 used during the analysis, the notation will include an S qualifier, followed by the design return period at the defined site. For example, if the 100-year return period was used, the following may apply: DLA (S100). Transit conditions to the intended site are also to be included in the DLA evaluati
14、on. (Revise Paragraph 2-1/3.9, as follows.) 3.9 Design Life and Design Fatigue Life (1 September 2012) 3.9.1 Design Life Floating terminals designed and built to the requirements in this Guide and maintained in accordance with the applicable ABS requirements are intended to have a structural design
15、life of not less than 20 years for a new build hull structure. Where the structural design life is greater than 20 years and the floating terminal is designed for uninterrupted operation on-site without any drydocking, the nominal design corrosion values (NDCV) of the hull structure are to be increa
16、sed in accordance with 3-2/3.3. When the design life is greater than 20 years (in 5-year increments) the increased life will be identified in the Record by the notation HL (number of years). The (number of years) refers to the design life greater than 20 years as reflected by the increase in nominal
17、 design corrosion values. 3.9.2 Design Fatigue Life Where a floating terminals design calls for a minimum design fatigue life of 20 years or in excess of the minimum design life of 20 years, the design fatigue life is to be verified to be in compliance with the fatigue criteria in this Guide. The “d
18、esign fatigue life” refers to the target value set by the owner or designer, not the value calculated in the analysis. The required fatigue strength analysis of critical details and welded joints in floating terminals is to be in accordance with 3-5/7.1 and 3-5/7.3, and Chapter 3, Appendix 1. Only o
19、ne design fatigue life notation is to be assigned and published in the Record for the hull, hull interface structure, position mooring system and components. The hull interface structural requirements are described in Chapter 3, Section 7 of this Guide and the position mooring system requirements in
20、 Part 6 of the FPI Guide. When only the required fatigue analysis of 3-5/7.1 and 3-5/7.3 is performed, the class notation FL (number of years) and the Year of maturation of fatigue life in the defined site location is assigned. The fatigue life will be identified in the Record by the notation FL (nu
21、mber of years), Year; for example, FL(30), 2041 for a floating terminal built in 2011 if the minimum design fatigue life specified is 30 years. Notice No. 3 September 2012 ABSGUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS .2010 3 If in addition, spectral fatigue analysis (
22、see 2-1/3.11 and 3-5/7.5) is requested by the owner or designer, only the design fatigue life notation, SFA (number of years), Year will be assigned and published in the Record for the hull and hull interface structural system. Although only the SFA notation is assigned, and not the FL notation, the
23、 required fatigue analysis of 3-5/7.1 and 3-5/7.3 and Chapter 3, Appendix 1 is to be performed and the calculated fatigue life is to satisfy the design fatigue life. The (number of years) refers to the design fatigue life equal to 20 years or more (in 5-year increments), as specified by the owner or
24、 designer. Where different design fatigue life values are specified for different structural elements within the terminal, such as hull structure components, hull interface structures and position mooring system components, the (number of years) refers to the least of the target values. In the case
25、when spectral fatigue analysis is also applied the least of the fatigue life values calculated by the required fatigue strength analysis according to 3-5/7.1 and 3-5/7.3 and spectral fatigue analysis must satisfy the design fatigue life. For example if the design fatigue life is specified as 25 year
26、s, the fatigue calculations of hull structural components must satisfy a fatigue life of 25 years. The fatigue calculations of the position mooring hull interface structures and hull mounted equipment interface structures, and position mooring system must also satisfy fatigue lives of (25 FDF) years
27、, where FDF are the fatigue safety factors specified in 3-7/Table 1 for hull interface structures and in 6-1-1/Table 1 of the FPI Guide for mooring lines. (Add new Paragraph 2-1/3.11, as follows.) 3.11 Spectral Fatigue Analysis Notation (1 September 2012) The fatigue strength criteria require the fa
28、tigue strength evaluation of structural details, which might also rely on spectral analysis methods to demonstrate the adequacy of fatigue strength. Where Spectral Fatigue Analysis is performed in accordance with the ABS Guide for the Fatigue Assessment of Offshore Structures, the floating terminal
29、will be identified in the Record by the notation SFA (number of years) followed by the specific site of the terminal. The (number of years) refers to the design fatigue life equal to 20 years or more (in 5-year increments), as specified by the applicant (e.g., SFA (30). Only one minimum design fatig
30、ue life value is applied to the entire structural system a described in 2-1/3.9. This notation is optional. (Renumber existing Paragraph 2-1/3.11 as 2-1/3.13.) (Add new Paragraph 2-1/3.15, as follows.) 3.15 Additional Corrosion Margin (1 September 2012) Where the floating terminal incorporates addit
31、ional plate thicknesses above the required scantlings, the terminal will be identified in the Record by the notation AT, followed by the description of the major hull girder component(s) that has the additional thickness. This notation will also include a number to indicate the magnitude of the addi
32、tional thickness (rounded down to the nearest 0.5 mm) that has been applied (i.e., AT(DK+0.5). In order to apply the notation AT, the additional thickness must be applied to the complete structural element throughout the tank area of the floating terminal. This notation documents major areas of the
33、structure that have an additional “as-built” margin on thickness to address areas subject to significant corrosion or areas where it may be desirable to increase normal corrosion margins to extend a structural members anticipated service life. This notation is optional and is only available to new c
34、onstruction FLGTs. The major structural components are defined as follows: DK Upper deck ID Inner deck SD Second deck BS Bottom shell (including bilge) IB Inner-bottom Notice No. 3 September 2012 4 ABSGUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS .2010 BG Watertight botto
35、m girder SS Side shell (including shear strake) ST Watertight side stringer IS Inner skin (including “hopper” sloping plating) CB Centerline cofferdam bulkhead TB Transverse Bulkhead (Renumber existing Paragraph 2-1/3.13 as 2-1/3.17.) CHAPTER 2 DESIGN CONSIDERATIONS SECTION 2 DESIGN OF FLOATING OFFS
36、HORE LIQUEFIED GAS TERMINALS (Revise Subsection 2-2/1, as follows.) 1 Environmental Conditions (1 September 2012) The floating terminal is to be designed for load scenarios encountered during transit and site-specific conditions. Site-specific conditions are to include both the Design Environmental
37、Condition and the Design Operating Condition. 1.1 Position Mooring System Unless the terminal is classed with the notation (Disconnectable), null AMS, floating terminals are to be capable of remaining on station under the most adverse environmental conditions specified in 2-2/1 of this Guide through
38、 a position mooring system. The position mooring system may be comprised of a conventional anchor mooring system or Single Point Mooring (SPM) systems such as: Catenary Anchor Leg Mooring (CALM), Single Anchor Leg Mooring (SALM), Turret Mooring, etc. The design, fabrication, installation, deployment
39、 and testing is to be in compliance with the requirements of this section of the FLGT Guide and Part 6 of the FPI Guide. The position mooring system of a floating terminal is to be designed to survive in the Design Environmental Condition and operate in the Design Operating Condition. For a disconne
40、ctable mooring system, the limiting condition at which the mooring system is to be disconnected or reconnected is to be specified. 1.1.1 Design Environmental Condition (DEC) The Design Environmental Condition (DEC) is defined as the extreme condition with a specific combination of wind, waves and cu
41、rrent for which the system is to be designed. The DEC is to be one of the following combinations that results in the most severe loading case: 100-year waves with associated wind and current. 100-year wind with associated waves and current. 100-year current with associated waves and wind. In areas w
42、ith high current, additional design environmental load cases may need to be considered. The 100-year waves are normally characterized by a significant wave height with a spectral shape type and a range of associated peak wave periods. A minimum return period of 100 years for the DEC is required for
43、floating terminals. A minimum return period of 50 years will be specially considered if it is accepted by the coastal state. Any environmental combinations with return periods shorter than that of the DEC which induce larger mooring load responses are also to be used in the design. Notice No. 3 Sept
44、ember 2012 ABSGUIDE FOR BUILDING AND CLASSING FLOATING OFFSHORE LIQUEFIED GAS TERMINALS .2010 5 For a floating terminal with a Disconnectable notation (see 2-1/3.1 of this Guide), the DISconnecting Environmental Condition (DISEC) of the mooring system is the limiting extreme environmental condition
45、at which the terminal is to be disconnected from the mooring system. However, the permanent mooring system, i.e., the mooring system alone (without the terminal), is to be designed to withstand an environmental condition based on a 100-year recurrence period. An acceptable monitoring system is to be
46、 provided for tracking environmental conditions or mooring line tensions in order to assist in the decision to disconnect the terminal from the mooring system. In addition to waves, wind and current, the design of the floating terminal may require investigation of the following environmental factors
47、, as appropriate to the type of terminal structure and the terminals operating site: i) Tides and storm surges ii) Air and sea temperatures iii) Ice and snow iv) Marine growth v) Seismicity vi) Sea ice Other phenomena, such as tsunamis, submarine slides, seiche, abnormal composition of air and water
48、, air humidity, salinity, ice drift, icebergs, ice scouring, etc., may require investigation depending upon the specific operating site. The required investigation of seabed and soil conditions is described in Section 3/6 of the Offshore Installations Rules. 1.1.2 Design Operating Condition (DOC) Th
49、e Design Operating Condition (DOC) is defined as the limiting environmental condition that would require suspension of normal operations. The return period associated with the DOC shall be the larger of: a) the value as specified by the Operator, or b) one year. 1.1.3 Design Installation Condition (DIC) The Design Installation Condition (DIC) is defined as the limiting environmental condition that would require suspension of terminal operations. Specific limits on environmental conditions affecting safe operation during the installation phases described in Part 3, Cha
