Common Structural Rules - Common Structural Rules for Bulk Carriers and Oil Tankers, January 2019 - Part 1 General Hull Requirements - Chapter 4 Loads - Section 6 Internal Loads - 4 Steel Coil Loads in Cargo Holds of Bulk Carriers
4 Steel Coil Loads in Cargo Holds of Bulk Carriers
4.1 General
4.1.1 Application
The provision is determined by assuming Figure 8 as the standard means of securing steel coils loaded on wooden dunnage.
It is assumed that all the steel coils have the same characteristics.
In cases where steel coils are lined up in two or more tiers, formulae in [4.1.3] and [4.2] can be applied assuming that only the lowest tier of steel coils is in contact with hopper sloping plate or inner side plate. In other cases, scantling requirements are to be determined on a case-by-case basis.
Figure 8 : Inner bottom loaded by steel coils
4.1.2 Arrangement of steel coils on inner bottom
- The steel coils are positioned without respect to the location of the inner bottom floors, as shown in Figure 9.
- The steel coils are positioned with respect to the location of the inner bottom floors, as shown in Figure 10.
Figure 9 : Steel coils loaded independently of inner bottom floors locations
Figure 10 : Steel coils loaded between inner bottom floors
4.1.3 Arrangement of steel coils independently of the floor locations
For steel coils loaded without respect to the location of floors in the inner bottom, see Figure 9:
The number n2 of load point dunnages per elementary plate panels is to be found in comply with Table 9.
The distance ℓlp, in m, between outermost load point dunnages per elementary plate panel is to be found in comply with Table 10.
Table 9 : Number n2 of load point dunnages per elementary plate panel
| n2 | n3 | |||
| 2 | 3 | 4 | 5 | |
| 1 | 
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| 2 | 
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| 3 | 
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| 4 | 
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| 5 | 
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6 |
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| 7 | 
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| 8 | 
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| 9 | 
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| 10 | 
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Table 10 : Distance between outermost load point dunnages per elementary plate
panel, 
, in m
| n2 | n3 | |||
| 2 | 3 | 4 | 5 | |
| 1 | Actual breadth of dunnages | |||
| 2 | 0.5ℓst | 0.33ℓst | 0.25ℓst | 0.2ℓst |
| 3 | 1.2ℓst | 0.67ℓst | 0.50ℓst | 0.4ℓst |
| 4 | 1.7ℓst | 1.20ℓst | 0.75ℓst | 0.6ℓst |
| 5 | 2.4ℓst | 1.53ℓst | 1.20ℓst | 0.8ℓst |
| 6 | 2.9ℓst | 1.87ℓst | 1.45ℓst | 1.2ℓst |
| 7 | 3.6ℓst | 2.40ℓst | 1.70ℓst | 1.4ℓst |
| 8 | 4.1ℓst | 2.73ℓst | 1.95ℓst | 1.6ℓst |
| 9 | 4.8ℓst | 3.07ℓst | 2.40ℓst | 1.8ℓst |
| 10 | 5.3ℓst | 3.60ℓst | 2.65ℓst | 2.0ℓst |
4.1.4 Arrangement of steel coils between floors
- The number n2 of load point dunnages per elementary plate panels is to be taken as: n2 = n3
- The distance ℓlp between outermost load point dunnages per elementary plate panel is to be taken as the distance between the outermost dunnage supporting one row of steel coils.
4.1.5 Centre of gravity of steel coil cargo
- a) Longitudinal position
- xGsc is the X coordinate, in m, of the volumetric centre of gravity of the considered cargo hold with respect to the reference coordinate system defined in Ch 4, Sec 1, [1.2.1].
- b) Transverse position
- c) Vertical position
where:
- ε = 1.0 when a port side structural member is assessed.
- ε = -1.0 when a starboard side structural member is assessed.
4.2 Total loads
4.2.1 Total load on the inner bottom
The total load Fsc-ib, in kN, due to steel coil cargoes on the inner bottom is to be taken as:
Fsc – ib = cos(CXG ϕ) cos(CYG θ) Fsc – ib – s + Fsc – ib – d but not less than 0
where:
Fsc-ib-s : Static load, in kN, on the inner bottom, given in [4.3.1].
Fsc-ib-d : Dynamic load, in kN, on the inner bottom, given in [4.4.2].
CXG, CYG : Load combination factors, as defined in Ch 4, Sec 2, [2.2].
4.2.2 Total load on the hopper side
The total load Fsc-hs, in kN, due to steel coil cargoes on the hopper side is to be taken as:
but not less than 0
where:
Fsc-hs-s : Static load, in kN, on the hopper side, given in [4.3.2].
Fsc-hs-d : Dynamic load, in kN, on the hopper, given in [4.4.3].
CXG, CYG : Load combination factors, as defined in Ch 4, Sec 2, [2.2].
4.3 Static loads
4.3.1 Static loads on the inner bottom
The static load Fsc-ib-s, in kN, on the inner bottom due to steel coils is to be taken as:
Fsc – ib – s = Msc – ibg
where:
for n2 ≤ 10 and n3 ≤ 5
for n2 > 10 and n3 > 5
- KS = 1.4 when steel coils are lined up in one tier with a key coil.
- KS= 1.0 in other cases.
4.3.2 Static load on the hopper side
The static load Fsc-hs-s, in kN, on the hopper side due to steel coils is to be taken as:
Fsc – hs – s = cosθhMsc – hs ⋅ g
where:
for n2 ≤ 10 and n3 ≤ 5
for n2 > 10 and n3 > 5
- Ck = 3.2 when steel coils are lined up two or more tiers, or when steel coils are lined up one tier and key coil is located second or 3rd from hopper sloping plate or inner hull plate.
- Ck = 2.0 for other cases.
4.4 Dynamic loads
4.4.1 Tangential roll acceleration
The tangential roll acceleration aR, in m/s2, is to be taken as:
where:
yGsc : Y coordinate, in m, of the centre of gravity of the steel coil cargo of the considered cargo hold, given in [4.1.5].
zGsc : Z coordinate, in m, of the centre of gravity of the steel coil cargo of the considered cargo hold, given in [4.1.5].
4.4.2 Dynamic load on the inner bottom
The dynamic load Fsc-ib-d, in kN, on the inner bottom due to steel coils is to be taken as:
Fsc – ib – d = Msc – ib az
where:
az : Vertical acceleration, in m/s2, as defined in Ch 4, Sec 3, [3.2.4], calculated at the centre of gravity of the steel coil cargo of the considered cargo hold, given in [4.1.5].
4.4.3 Dynamic load on the hopper side
The dynamic load Fsc-hs-d, in kN, on the hopper side due to steel coils is to be taken as:
where:
CYS, CYR : Load combination factors, defined in Ch 4, Sec 2, [2.2].
asway : Sway acceleration, in m/s2, as defined in Ch 4, Sec 3, [2.2.2].
aR : Tangential acceleration, in m/s2, as defined in [4.4.1].
yGsc : Y coordinate, in m, of the centre of gravity of the steel coil cargo of the considered cargo hold, given in [4.1.5].
zGsc : Z coordinate, in m, of the centre of gravity of the steel coil cargo of the considered cargo hold, given in [4.1.5].
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