3 Pressures and Forces due to Dry Cargoes in Flooded Conditions

3.1 Vertically corrugated transverse watertight bulkheads

3.1.1 Application

The pressure defined in this sub-article applies to vertically corrugated transverse watertight bulkheads of the cargo holds of bulk carriers for the assessment in flooded conditions.

Each cargo hold is to be considered individually flooded, see Figure 5, Figure 6 and Figure 7.

3.1.2 General

The loads to be considered as acting on each bulkhead are those given by the combination of loads induced by cargo loads with those induced by the flooded loads of one hold adjacent to the bulkhead under examination. In any case, the pressure due to the flooded loads without cargo is also to be considered.

The most severe combinations of cargo induced loads and flooded loads are to be used for the check of the scantlings of each bulkhead, depending on the loading conditions included in the loading manual considering the individual flooded condition of both loaded and empty holds:

Homogeneous loading conditions;
Non-homogeneous loading conditions;

For the purpose of this article, the following items are defined as:

Design load limits:
- The specified design load limits for the cargo holds are to be represented by loading conditions defined by the designer in the loading manual.
Maximum cargo mass to consider:
- Unless the ship is intended to carry, in non-homogeneous conditions, only iron ore or cargo having bulk density equal to or greater than 1.78 t/m³, the maximum mass of cargo which may be carried in the hold is also to be considered to fill that hold up to the top of the hatch coaming.
Homogeneous loading conditions:
- Homogeneous loading condition means a loading condition in which the ratio between the highest and the lowest filling level, evaluated for each hold, does not exceed 1.20, to be corrected for different cargo densities.
Packed cargoes:
- Holds carrying packed cargoes (such as steel mill products) are to be considered as empty.
Unconsidered loading conditions:
- Non-homogeneous part loading conditions associated with multi-port loading and unloading operations for homogeneous loading conditions do not need to be considered for the verification of these requirements.

3.1.3 Flooded level

The flooded level z_F is the distance, in m, measured vertically from the baseline with the ship in the upright position, and obtained from Table 4.

**Table 4 : Flooded level z_F, in m, for vertically corrugated transverse bulkheads**

Bulk carrier type	Loading condition	Vertically corrugated transverse bulkhead position
Bulk carrier type	Loading condition	Foremost	Others
Bulk carriers less than 50,000 t deadweight with Type B freeboard	Non-homogeneous loading conditions with cargo density less than 1.78 t/m³	z_F = 0.9 D₁	z_F = 0.8 D₁
	Other cases	z_F = 0.95 D₁	z_F = 0.85 D₁
Other bulk carriers	Non-homogeneous loading conditions with cargo density less than1.78t/m³	z_F = 0.95 D₁	z_F = 0.85 D₁
Other bulk carriers	Other cases	z_F = D₁	z_F = 0.9 D₁

3.1.4 Flooded patterns

Three different flooded patterns are to be considered:

The flooded level is below the upper surface of the cargo, (see Figure 5: z_C > z_F)
The flooded level is above the upper surface of the cargo, (see Figure 6: z_C ≤ z_F)
The flooded hold is empty, (see Figure 7: z_C = h_DB)

Figure 5 : Flooded level below upper surface of bulk cargo

Figure 6 : Flooded level above upper surface of bulk cargo

Figure 7 : Flooded cargo hold without cargo

3.1.5 Pressures and forces on vertically corrugated transverse bulkheads of flooded cargo holds

The static pressure P_bf-s, in kN/m², at any point of the vertically corrugated transverse bulkhead located at a level z from the baseline is given in Table 5 for each flooded pattern defined in [3.1.4].

The force F_bf-s, in kN, acting on a corrugation of a transverse bulkhead is given by Table 6 for each flooded pattern defined in [3.1.4].

where:

P_bf-s-LE : Static pressure calculated according to Table 5 for z = h_LS + h_DB.

Table 5 : Static pressure on vertically corrugated transverse bulkhead of a flooded cargo hold P_bf-s

Flooded case	Load point position	Pressure P_bf-s , in kN/m²
z_C > z_F	z > z_C	P_{bf – s} = 0
	z_C ≥ z ≥ z_F	P_{bf – s} = ρ_C g (z_C – z) K_{C – f}
	z_F > z > h_DB	P_{bf – s} = ρg (z_F – z) + [ρ_C (z_C – z) – ρ (1 – perm) (z_F – z)] gK_{C – f}
h_DB ≤ z_C ≤ z_F	z > z_F	P_{bf – s} = 0
	z_F ≥ z ≥ z_C	P_{bf – s} = ρg (z_F – z)
	z_C > z ≥ h_DB	P_{bf – s} = ρg (z_F – z) + [ρ_C – ρ (1 – perm)] g (z_C – z)] K_{C – f}

Table 6 : Force acting on a corrugation in the flooded cargo holds F_bf-s

Flooded case	Force F_bf-s,in kN
z_C > z_F
z_F ≥ z_C

3.1.6 Pressures and forces on vertically corrugated transverse bulkheads of non-flooded cargo holds

The static pressure P_bs, in kN/m², at a point of the vertically corrugated transverse bulkhead located, located at the level z from the baseline, due to dry bulk cargo of a non-flooded cargo hold acting on the intact side of the transverse bulkhead which is flooded on the other side is to be taken as:

P_bs = ρ_C g K_{C – f} (z_C – z) but not less than 0.

The resultant force F_bs, in kN, acting on a corrugation is to be taken as:

3.1.7 Resultant pressures and forces on vertically corrugated transverse bulkheads of flooded cargo holds

The resultant pressure P_R, in kN/m², at each point of the bulkhead, and the resultant force F_R, in kN, acting on a corrugation, given in Table 7, are to be considered for the assessment in flooded conditions of vertically corrugated transverse bulkhead structures, where:

P_bf-s : Pressure in the flooded cargo holds, in kN/m², as defined in [3.1.5].

P_bs : Pressure in the non-flooded cargo holds, in kN/m², as defined in [3.1.6].

F_bf-s : Force acting on a corrugation in the flooded cargo holds, in kN, as defined in [3.1.5].

F_bs : Force acting on a corrugation in the non-flooded cargo holds, in kN, as defined in [3.1.6].

**Table 7 : Resultant pressure P_R and resultant force F_R on vertically corrugated transverse bulkhead in flooded condition**

Loading condition	*Resultant pressure P_R,in kN/m²*	*Resultant force F_R, in kN*	Application
Homogeneous	P_R = P_bf-s – 0.8 P_bs	F_R = F_bf-s – 0.8 F_bs	All bulk carriers
Alternate	P_R = P_bf-s	F_R = F_bf-s	BC-A bulk carriers

3.2 Double bottom in cargo hold region of bulk carrier in flooded conditions

3.2.1 Application

Each cargo hold is to be considered individually flooded.

3.2.2 General

The loads to be considered as acting on the double bottom are those given by the external sea pressures and the combination of the cargo loads with those induced by the flooding of the hold to which the double bottom belongs.

The most severe combinations of cargo induced loads and flooded loads are to be used, depending on the loading conditions included in the loading manual:

Homogeneous loading conditions.
Non-homogeneous loading conditions.
Packed cargo conditions (such as in the case of steel mill products).

For each loading condition, the maximum dry bulk cargo density to be carried is to be considered in calculating the allowable hold loading.

3.2.3 Flooded level

The flooded level z_F is the distance, in m, measured vertically from the baseline with the ship in the upright position, and obtained from Table 8.

Table 8 : Flooded level z_F, for double bottom in cargo hold region of bulk carrier

Bulk carrier type	Cargo hold
Bulk carrier type	Foremost	Others
Bulk carriers less than 50,000 t deadweight with Type-B freeboard	z_F = 0.95D₁	z_F = 0.85D₁
Other bulk carriers	z_F = D₁	z_F = 0.9D₁

3 Pressures and Forces due to Dry Cargoes in Flooded Conditions

Table 4 : Flooded level zF, in m, for vertically corrugated transverse bulkheads

Table 5 : Static pressure on vertically corrugated transverse bulkhead of a flooded cargo hold Pbf-s

Table 6 : Force acting on a corrugation in the flooded cargo holds Fbf-s

Table 7 : Resultant pressure PR and resultant force FR on vertically corrugated transverse bulkhead in flooded condition

Table 8 : Flooded level zF, for double bottom in cargo hold region of bulk carrier

**Table 4 : Flooded level z_F, in m, for vertically corrugated transverse bulkheads**

Table 5 : Static pressure on vertically corrugated transverse bulkhead of a flooded cargo hold P_bf-s

Table 6 : Force acting on a corrugation in the flooded cargo holds F_bf-s

**Table 7 : Resultant pressure P_R and resultant force F_R on vertically corrugated transverse bulkhead in flooded condition**

Table 8 : Flooded level z_F, for double bottom in cargo hold region of bulk carrier