Section 5 Accidental loads

5.1 Flooded condition

5.1.1 Global loads.

The still water bending moments and the still water shear forces in flooded condition are to be determined for each flooding scenario, considering the damaged compartments flooded up to the equilibrium waterline.

5.1.2 Local pressure.

The pressure in compartments and tanks in flooded condition or damaged condition is to be taken as , see Pt 10, Ch 2, 2.3 Local static loads 2.3.2.

5.1.3 Assessment.

Flooding strength calculations are to be carried out to determine the effects of accidental flooding on the hull strength. Flooding calculations are to be undertaken for all flooding scenarios required by National Regulations. When considering the static and dynamic loads acting simultaneously (S+D), credit may be given to agreed documented mitigation measures where permitted by the National Regulations.

5.2.1 Global loads.

The blast condition is to be assessed for the following load combinations of blast pressure and global loads:
1. Blast pressure + Permissible still water hogging bending moment for the operational condition.
2. Blast pressure + Permissible still water sagging bending moment for the operational condition. Loading conditions where there is no risk of blast loads need not be included in the calculation of the permissible still water bending moments for the blast assessment.
Environmental loads need not be considered. See also Pt 4, Ch 3, 4.16 Accidental loads.

5.2.2 Pressure.

Generally, the blast pressure is a rapidly propagating pressure or shock-wave in the atmosphere, with high pressure, high density and high particle velocity.
The design blast pressures are to be defined by the Owners/designers and are to comply with National Regulations.
Design calculations are to be submitted which may be based on elastic analysis or elastoplastic design methods.

5.2.3 Assessment.

Assessment of the potential fire loadings and blast pressures are to be based on the specific hazards associated with the general layout of the unit, production and process activities and operational constraints. For assessment of the post accident condition, the static loads may be reduced if damage control or recovery measures are implemented, see Pt 4, Ch 3, 4.3 Load combinations 4.3.1.
The blast load case is applicable primarily to the upper deck, deck-house and turret boundary. The pressures acting on the opposite side of these structures to the blast load (ballast water pressure, inert gas pressure, etc.) may be ignored when assessing the local scantlings but the hull girder stresses (due to shear and bending) are to be included. The amount of damage to the structure following a blast is to be considered in the assessment.

5.2.4 Boundary bulkheads and main decks.

Particular consideration is to be given to the potential effects of fire and blast impinging on exposed boundary bulkheads of accommodation spaces and main decks. Where boundary bulkheads and main decks can be subjected to blast loading, the scantlings are to comply with Pt 4, Ch 3, 4.16 Accidental loads 4.16.9.

5.3.1 General.

Collision loads are to be considered in the design of the unit as applicable to the function of the unit. In general, the loads described in Pt 4, Ch 3 Structural Design are to be considered.