Section 1 Materials of construction

1.1.1 These Rules relate, in general, to the construction of steel ships, although consideration will be given to the use of other materials, when permitted by the Regulations of National and/or International Authorities for the type of ship.

1.1.2 The materials used in the construction of the ship are to be manufactured and tested in accordance with the requirements of Lloyd’s Register’s (hereinafter referred to as LR) Rules for the Manufacture, Testing and Certification of Materials, July 2022. Materials for which provision is not made in LR’s Rules for the Manufacture, Testing and Certification of Materials, July 2022 may be accepted, provided that they comply with an approved specification and such tests as may be considered necessary.

1.1.3 Where steel castings or forgings are used for sternframes, rudder frames, rudder stocks, propeller shaft brackets and other major structural items, they are to comply with LR’s Rules for the Manufacture, Testing and Certification of Materials, July 2022, Pt 3, Ch 4 Longitudinal Strength or Pt 3, Ch 5 Fore End and Aft End Structure, as appropriate.

1.1.4 Where aluminium alloy is used for superstructures, deckhouses, hatch covers or other structural components, equivalent scantlings are to be derived in accordance with Pt 3, Ch 2, 1.4 Aluminium.

1.2.1 The ships covered by these Rules are generally to be constructed of Grade ‘A’ or 'AH' steel. In highly stressed areas, however, grades of steel with higher levels of notch toughness (Grades ‘B’, ‘D’, 'DH', ‘E’ or 'EH') may be required, dependent on the thickness of the material and the stress pattern associated with its location.

1.3.1 Steel having a specified minimum yield stress of 235 N/mm² is regarded as mild steel. Steel having a higher specified minimum yield stress is regarded as higher tensile steel.

1.3.2 For the determination of the hull girder section modulus, where higher tensile steel is used, a higher tensile steel factor, k_L, is given in Table 2.1.1 Values of K_L.

or 0,66 whichever is the greater.

1.4.1 The use of aluminium alloy is permitted for superstructures, deckhouses, hatch covers, helicopter platforms or other local components on board ships.

1.4.3 In general, for welded structures, the maximum value of sa to be used in the scantlings derivation is that of the aluminium in the welded condition. However, consideration will be given to using unwelded values depending upon the weld line location and other heat affected zones, in relation to the maximum applied stress on the member (e.g. extruded sections).

1.4.4 A comparison of the mechanical properties for selected welded and unwelded alloys is given in Ch 13, 8.3 Fabrication and welding 8.3.2 of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.