Section 7 Longitudinal bulkheads

7.1.1 The requirements for longitudinal oiltight bulkheads given in Pt 4, Ch 9, 6 Inner hull, inner bottom and longitudinal oiltight bulkheads and Pt 4, Ch 9, 9 Primary members supporting longitudinal framing are to be applied, together with the additional requirements of this Section.

7.1.2 Longitudinal bulkhead scantlings are to be additionally assessed against ore loading in accordance with Table 11.7.1 Longitudinal and transverse bulkhead scantlings for ore loading.

Table 11.7.1 Longitudinal and transverse bulkhead scantlings for ore loading

Item	Longitudinal and transverse bulkhead
Plate thickness including corrugations (mm)
Modulus of rolled and built stiffeners, and symmetrical corrugations (cm3)
Symbols
= s, S, k, l as defined in Pt 4, Ch 1, 1.5 Symbols and definitions 1.5.1 f = 1,1 – s/2500S but not to be taken greater than 1,0 le = effective length of stiffening member, in metres, and for bulkhead stiffeners, to be taken as l – e 1 – e 2 γ = 1,4 for rolled or built sections and double plate bulkheads = 1,6 for flat bars = 1,1 for symmetrical corrugations of deep tank bulkheads = 1,0 for symmetrical corrugations of watertight bulkheads ω, e = as defined in Table 1.9.3 Bulkhead end constraint factors in Chapter 1, see also Figure 1.9.1 End connections. Where applicable the value of M 2 is to be taken as = K c = ore pressure coefficient, to be taken as cos2 α+ (1 – sin ψ) sin2 α for inner side (hopper tank, transverse and longitudinal bulkheads, lower stool, vertical upper stool, etc.), and where: K c = 0 for top side tank, upper deck and sloped upper stool α = angle, in degrees, between panel considered and the horizontal plane ψ = assumed angle of repose, in degrees, of bulk cargo (considered drained and removed); in the absence of more precise evaluation to be taken as ψ = 35° for iron ore H = height, from position under consideration to deck at side amidships, in metres C = stowage rate, in m3/tonne, as defined in Pt 3, Ch 3, 5.2 Symbols. For vessels where Pt 4, Ch 11, 1.1 Application 1.1.5 is applicable, C is to include the cargo overshoot specified in Pt 4, Ch 11, 13.4 Cargo loading conditions for design assessment 13.4.1.(e)

7.1.3 Longitudinal bulkheads on ore carriers are to be plane with rolled or fabricated longitudinal stiffeners. The bulkhead may be sloped to form a hopper shape in the lower part of the hold or over its full depth.

7.1.4 Where the upper part of the bulkhead is vertical and the lower part sloped to form a hopper shape, the thickness of the bulkhead plating in way of the knuckle may be required to be increased to resist transverse compressive buckling stresses. The knuckle is to be arranged in way of a longitudinal.

7.1.5 The thickness of the lowest strake of sloped bulkhead plating is also to comply with inner bottom requirements as given in Pt 4, Ch 11, 6.1 General 6.1.3. Where this provision results in an increase in thickness, the latter may be gradually tapered above the lowest strake to the required longitudinal bulkhead thickness at the position of the knuckle, or at a point one third of the depth of the bulkhead above the inner bottom, whichever is the lower.