Section 1 Application

1.1.1 These Rules for the Application of Sandwich Panel Construction to Ship Structure, July 2022 set down the criteria for the assessment of ship structures constructed using steel sandwich panels, see Ch 1, 2.2 Steel Sandwich Panel definition, and are applied in addition to other relevant requirements of the Rules and Regulations for the Classification of Ships, July 2022.

1.1.2 These Rules are in general applicable to mono hull ships of normal form, proportions and speed constructed in whole or partly using sandwich construction.

1.1.3 Ships of unusual form, proportions, speed, or intended for the carriage of special cargoes, or for special or restricted service, not covered by Pt 3 Ship Structures (General) and Pt 4 Ship Structures (Ship Types) of the Rules and Regulations for the Classification of Ships, July 2022, will receive individual consideration based on the general standards of the Rules for the Application of Sandwich Panel Construction to Ship Structure, July 2022 (see also Ch 1, 1.5 Special application).

1.1.4 It is assumed in these Rules that the material of construction for the top and bottom plating of the sandwich panel is steel according to the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

1.1.5 Scantlings of structures constructed of aluminium are to be on the basis of equivalent scantlings as set out in Pt 3, Ch 2, 1.3 Aluminium of the Rules and Regulations for the Classification of Ships, July 2022. In general, for welded structure, the maximum value for the strength of the material, σ_a , to be used in the scantling derivation is that of the aluminium alloy in the welded condition, where σ_a is defined as the 0,2 per cent butt welded proof stress or 70 per cent of the ultimate strength of the material in the welded condition in N/mm², whichever is the lesser.

1.1.6 These Rules set down requirements for new construction that in general include a structural design as described in Ch 1, 3 Structural configuration.

1.1.7 These Rules also include requirements for overlay construction (see Ch 1, 2.1 General 2.1.5) applicable to existing ships. Overlay construction is only to be applied when the gauged thickness after diminution is equal to or greater than the rule minimum plate thickness as defined in Table 3.4.1 Thickness allowance (see also Ch 1, 1.5 Special application).

1.1.8 The core material for the sandwich construction is to be approved by Clasifications Register (hereinafter referred to as ‘LR’), see Ch 1, 6.3 Core material approval 6.3.1.

1.2.1 These Rules are framed on the understanding that ships will be properly loaded and handled; they do not, unless it is stated or implied in the class notation, provide for special distributions or concentrations of loading other than those included in the approved Loading Manual. The Committee may require additional strengthening to be fitted in any ship which, in their opinion, would otherwise be subjected to severe stresses due to particular features of the design, or where it is desired to make provision for exceptional load or ballast conditions.

1.3.1 These Rules do not cover certain technical characteristics, such as stability, trim, vibration, docking arrangements, structural fire protection, etc. The Committee cannot assume responsibility for these matters but is willing to advise upon them on request.

1.4.1 The scantling requirement for plating calculated according to the Rules and Regulations for the Classification of Ships, July 2022 includes a corrosion margin.

1.4.2 The requirements for materials of construction, fracture control and corrosion protection, as stipulated in Pt 3, Ch 2, 1 Materials of construction, Pt 3, Ch 2, 2 Fracture control and Pt 3, Ch 2, 3 Corrosion protection respectively of the Rules and Regulations for the Classification of Ships, July 2022, are to be applied.

1.5.1 Application of sandwich construction on any of the following areas whether as overlay construction or new construction will require to be specially considered:

1. Sheer strake, when longitudinal strength is a critical factor.

2. Upper deck on container ships.

3. Upper strake of longitudinal bulkheads on container ships.

4. Fore peak structure including bulbous bow.

5. Aft peak structure.

6. Stern frame, pod or rudder trunk integration.

7. Bilge plating.

8. Wash bulkheads.

9. Double bottom floors and girders.

10. Stem, bar keels, bilge keels, sternframe.

11. Perforated flats.

12. Primary structural members.

13. Corrugated bulkheads.

14. Deck transverses, girders, stringers.

15. Decks on oil tankers.

16. Any structure directly in contact with the oil cargo (e.g. longitudinal bulkhead, transverse bulkhead, inner hull and inner bottom of oil tankers).

17. Transverse webs in topside tanks of bulk carriers.

18. Upper decks of LNG carriers.

1.5.2 Where the proposed construction of any part of the hull is of novel design, or where experience, in the opinion of LR, has not sufficiently justified the principle or mode of application involved, special tests or examinations before and during service may be required.

1.6.1 The interpretation of these Rules is the sole responsibility and at the sole discretion of LR. Where there is any doubt regarding the interpretation of these Rules it is the Builder's and/or designer's responsibility to obtain clarification from LR prior to submission of plans and data for design appraisal.

1.6.2 Where applicable, these Rules take into account unified requirements established by the International Association of Classification Societies.

1.7.1 Where calculation procedures other than those available within the ‘ShipRight Procedures’ are employed, supporting documentation is to be submitted for appraisal and this is to include details of the following:

1. calculation methods, assumptions and references;

2. loading;

3. structural modelling;

4. design criteria and their derivation, e.g. permissible stresses, factors of safety against plate panel instability, etc.

1.7.2 LR will be willing to consider the use of Builders’ programs for direct calculations in the following cases:

1. Where it can be established that the program has previously been satisfactorily used to perform a direct calculation similar to that now submitted.

2. Where sufficient information and evidence of satisfactory performance is submitted to substantiate the validity of the computation performed by the program.

1.7.3 Alternative scantlings and arrangements may be accepted as equivalent to the Rule requirements. Details of such proposals are to be submitted for consideration and this is to include the following:

1. calculation methods;

2. assumptions and references;

3. loading;

4. structural modelling;

5. stress and deflection output.

1.7.4 All direct calculations are to be submitted for examination.