Section 2 Static load components
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, July 2022 - Part 10 Ship Units - Chapter 2 Loads and Load Combinations - Section 2 Static load components

Section 2 Static load components

Parent topic: Chapter 2 Loads and Load Combinations

2.1 Symbols

2.1.1 For the purposes of this Section, the following symbols apply:

L = Rule length, in metres, as defined in Pt 4, Ch 1, 5 Definitions
B = moulded breadth, in metres, as defined in Pt 4, Ch 1, 5 Definitions
D = moulded depth, in metres, as defined in Pt 4, Ch 1, 5 Definitions
= wave coefficient, as defined in Pt 10, Ch 2, 3.1 Symbols
= block coefficient, as defined in Pt 4, Ch 1, 5 Definitions
ρ = density, tonnes/m3, as defined in Pt 10, Ch 2, 1.2 Definitions 1.2.3
g = acceleration due to gravity, 9,81 m/s2
= permissible hull girder hogging and sagging still water bending moment envelopes for transit condition, in kNm
= permissible hull girder hogging and sagging still water bending moment envelopes for operational condition, in kNm
= permissible hull girder hogging and sagging still water bending moment envelopes for inspection/maintenance condition, in kNm
= permissible hull girder positive and negative still water shear force limits for transit condition, in kN
= permissible hull girder positive and negative still water shear force limits for operational condition, in kN
= permissible hull girder positive and negative still water shear force limits for inspection/maintenance condition, in kN
= length of cargo tank under consideration, in metres
= deep load draught, in metres, is the maximum draught on which the scantlings are based
= volume of centreline cargo tank under consideration, in m3
= volume of side cargo tank under consideration, in m3

2.2 Static hull girder loads

2.2.1  Permissible hull girder still water bending moment and shear force.
  1. The designer is to provide the permissible hull girder hogging and sagging still water bending moment limits for the transit condition, , operational condition, , and inspection/maintenance condition, .
  2. The designer is to provide the permissible hull girder positive and negative still water shear force limits for the transit condition, , operational condition, , and inspection/maintenance condition, .
  3. The permissible hull girder still water bending moment and shear force limits are to be given at each transverse bulkhead in the cargo area, at the middle of cargo tanks and at significant structural discontinuities, including internal turrets.
  4. The permissible hull girder still water bending moment envelope is given by linear interpolation between values at the longitudinal position given in Pt 10, Ch 2, 2.2 Static hull girder loads 2.2.1.(c).
  5. The permissible hull girder still water bending moment and shear force envelopes are to be included in the loading manual as required in Pt 4, Ch 3, 1.1 Application 1.1.3 and Pt 4, Ch 3, 1.1 Application 1.1.4.
2.2.2  New build.
  1. Loadings patterns representative of the loading conditions for all modes of operation are to be assessed considering those cases which will induce the largest forces in the hull structure.
  2. The static loading conditions to be used in combinations with the applicable dynamic loads in Section 6 should be appropriate for the intended operation of the unit. In general, they should include:
    • homogeneous full load;
    • emergency ballast;
    • ‘chequer-board’ loading;
    • all cargo tanks full with any two adjacent cargo tanks empty (this is to allow repair of any tank boundary whilst in service); and
    • all cargo tanks empty with any one cargo tank full;
    • most onerous partial loading conditions as applicable.
2.2.3  Conversions and redeployments.
  1. The loading conditions should be as for new build units, see Pt 10, Ch 2, 2.2 Static hull girder loads 2.2.2, suitably modified to take account of the following:
    • Loading limitations previously assigned prior to conversion/redeployment.
    • Where the loading conditions defined for new build units are too restrictive or too onerous.

2.3 Local static loads

2.3.1  General.
  1. The following static loads are to be considered, as appropriate:
    1. static sea pressure;
    2. static tank pressure;
    3. tank overpressure, in addition to the static tank pressure when appropriate;
    4. static deck load;
    5. accidental pressure.
2.3.2 Static pressure.
  1. The static pressures for the static loads defined in Pt 10, Ch 2, 2.3 Local static loads 2.3.1.(a) are given in Table 2.2.1 Static load pressures.
2.3.3  Static deck loads from heavy units.
  1. The scantlings of structure in way of heavy units of cargo and equipment are to consider gravity forces acting on the mass. The load acting on supporting structures and securing systems for heavy units of cargo, equipment or structural components, , is to be taken as:

    = kN

    where

    = mass of unit, in tonnes.

    Table 2.2.1 Static load pressures

    Load cases Static pressure, in kN/m2
    (a) Static sea pressure
    (b) Static tank pressure
    (c) Static tank pressure + overpressure

    see Note 2

    (d) Static deck pressure
    (e) Accidental pressure
    Symbols
    z = vertical coordinate of load point, in metres, and is not to be greater than , see Figure 2.2.1 Static sea pressure, pressure-heads and distances of static tank pressure
    = density of sea-water, 1,025 tonnes/m3 see Note 2
    = draught in the loading condition being considered, in metres
    = vertical distance from highest point of tank, excluding small hatchways, to the load point, see Figure 2.2.1 Static sea pressure, pressure-heads and distances of static tank pressure, in metres
    = vertical distance from top of air pipe or overflow pipe to the load point, whichever is the lesser, see Figure 2.2.1 Static sea pressure, pressure-heads and distances of static tank pressure, in metres
    =
    = height of air pipe or overflow pipe, in metres, is not to be taken less than 0,76 m above highest point of tank, excluding small hatchways. For tanks with tank top below the weather deck, the height of air pipe or overflow pipe is not to be taken less than 0,76 m above deck at side, unless a lesser height is approved by the Flag Administration. See also Figure 2.2.1 Static sea pressure, pressure-heads and distances of static tank pressure
    = vertical distance from the load point to the deepest equilibrium waterline in damaged condition obtained from applicable damage stability calculations or to freeboard deck if the damage waterline is not given, in metres
    = vertical distance to the load point is to be taken as defined in Table 2.2.2 Testing load height
    = setting of pressure relief valve, if fitted, is not to be taken less than 25 kN/m2
    = uniformly distributed pressure on lower decks and decks within superstructures, including platform decks in the main engine room and for other spaces with heavy machinery components, in kN/m2. is not to be taken less than 16 kN/m2
    NOTE
    1. The added overpressure due to sustained liquid through the air pipe or overflow pipe in the case of overfilling, , is to be taken as 25 kN/m2. Additional calculations may be required where piping arrangements may lead to a higher pressure drop, e.g. long pipes or arrangements such as bends and valves.
    2. The density ρtank is not to be taken greater than the value defined in Table 2.1.1 Minimum density of liquid for strength and fatigue assessment. For example, where a tank is not designed to be filled or tank-tested with sea water e.g. liquefied gas tanks, the greater of the density of the testing liquid and the actual liquid to be stored is to be used to assess the tank.

    Figure 2.2.1 Static sea pressure, pressure-heads and distances of static tank pressure

    Table 2.2.2 Testing load height

    Compartment or structure to be tested Testing load height, in metres
    Cargo tanks and other tanks designed for liquid filling, including double bottom tanks, hopper side tanks, topside tanks, double side tanks, deep tanks, fuel oil bunkers, slop tanks, fresh water tanks, lube oil tanks, fore and after peaks used as tanks and/or fitted with air pipe. Cofferdams The greater of the following:
    =
    =
    =
    Fore and aft peaks not used as tanks and not fitted with air pipe To be tested for tightness, see Note
    Watertight doors below freeboard deck To be tested for tightness, see Note
    Chain locker =
    Ballast ducts Testing load height corresponding to ballast pump maximum pressure
    Symbols are as defined in Table 2.2.1 Static load pressures
    = equivalent head of pressure safety valve, in metres
    =
    = setting pressure, in bar, of pressure safety valve where applicable
    NOTE
    When hose testing cannot be performed without damaging possible outfittings already installed, it may be replaced by a careful visual inspection of all the crossings and welded joints. Where necessary, dye penetrant test or ultrasonic leak test may be required.
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