Section 6 Hull envelope framing – Combination system

6.1.1 This Section covers the arrangements and requirements for the hull framing of the midship region of flush deck and trunk deck tankers according to the combination system (shell transverse and bottom and deck longitudinal framing).

6.1.2 The scantlings are based on end connections in accordance with Pt 3, Ch 10, 3 Secondary member end connections. Where brackets having arm lengths differing from the standard are fitted, the modulus of stiffening members is to be corrected in accordance with Pt 3, Ch 10, 3.7 Correction of stiffening member modulus in relation to end connections.

6.1.3 Outside the midship region the structure is to be scarfed into the fore end and aft end structure as provided for in Pt 3, Ch 5 Fore End and Aft End Structure and Pt 3, Ch 6 Machinery Spaces so far as applicable.

6.1.4 It is recommended that the bottom of ships regularly resting aground be additionally strengthened to withstand the stresses to which it may be subjected.

6.2.1 A bottom centreline girder is to be fitted if required by Pt 4, Ch 6, 5.2 Bottom centreline girder 5.2.1.

6.3.1 Longitudinals are to comply with the relevant requirements of Pt 4, Ch 6, 5.1 General and Pt 4, Ch 6, 5.3 Longitudinal framing.

6.4.1 Transverses are to comply with the relevant requirements of Pt 4, Ch 6, 5.4 Primary structure. In single hull ships they are to be connected to reinforced side frames, see Pt 4, Ch 6, 6.5 Side frames, stringers and web frames 6.5.3. If the shell and longitudinal bulkhead(s) are fitted with a system of stringers and webs, they are to be connected to webframes, see Pt 4, Ch 6, 6.5 Side frames, stringers and web frames 6.5.1.

6.5.1 Side frames, stringers and web frames are to comply with the relevant requirements of Pt 4, Ch 6, 4.5 Side frames, stringers and web frames. Their scantlings are to be in accordance with Table 6.4.1 Hull framing - Transversely framed ships.

6.5.2 Side frames are to be fitted with end brackets connected to the outboard longitudinals. When, however, the frames are carried through the bilge radius they may be directly connected to the outboard bottom longitudinal.

6.5.3 In single hull ships, the section modulus of side frames in way of bottom and deck transverses is to be increased by 100 per cent.

6.5.4 If a system of stringers and web frames is fitted, the web frames are to be located in way of, and connected to, bottom and deck transverses.

6.6.1 The arrangements and scantlings of the double skin are to be in accordance with Pt 4, Ch 6, 4.8 Double skin arrangement or Pt 4, Ch 6, 5.5 Double skin arrangements, as applicable.

6.7.1 The arrangements and scantlings of the double bottom are to be in accordance with Pt 4, Ch 6, 4.9 Double bottom arrangements or Pt 4, Ch 6, 5.6 Double bottom arrangements, as applicable. The brackets required to be fitted by Pt 4, Ch 6, 5.6 Double bottom arrangements 5.6.3 at the margins may require to be fitted at every frame.