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SCHEDULE 3
STRUCTURAL STEELS FOR CATEGORY SHIPS
1. Interpretation
1.1 The following definitions apply in this schedule:
"structural member" means a part of a ship's structure listed in the table and includes any contiguous member inboard from the moulded line for a distance of 750 millimetres.
"exposed" means in contact with the outside air or water.
"steel grade" means a steel of a grade set out in a recognized standard that complies with the minimum requirements of that standard for that grade.
2. Steel grades ^
2.1 The steel grade of a structural member must not be lower than that set out for that member in the table. The steel grade indicated, applies for the item in the table, and for the supporting structure for a distance of 750 mm from the moulded line.
3. Plate orientation ^
3.1 All plates fitted in areas of the vessel shown in the table that are between 0.3L forward of amidships and 0.2L aft of amidships must be fitted such that the mill rolling direction is fore and aft.
4. Welding ^
4.1 The welding processes, procedures, quality control, inspection and testing must be in accordance with Recognized Standards without the exercise of any optional easement or optional reduction of extent that may be allowed therein.
5. Properties of the weld metal and heat affected zone ^
5.1 For all items, including the relevant supporting structure, mentioned in the table, the properties for material toughness and yield, in the weld metal and the heat affected zones, are to be not less than those for the minimum design requirement of the parent metal indicated in the table.
Table 1 ^
|
Area of vessel |
Steel Grade |
Item |
Column 1 |
Column 2 |
Column 3 |
Column 4 |
Column 5 |
1 |
Structural member including any attached
structure for a depth of 740mm |
from 0.2L aft to 0.3L forward
of amidships |
from 0.2L aft to 0.3L forward
of amidships |
outside 0.2L aft to 0.3L forward
of amidships |
outside 0.2L aft to 0.3L forward
of amidships |
2 |
Thickness |
< 25mm |
> 25mm |
< 25mm |
>25mm |
3 |
Sheerstrake at strength deck |
E |
F¹ |
DH |
E |
4 |
Strength deck plating exposed or in unheated
deckhouses |
E |
EH |
DH |
E |
5 |
Strength deck plating in heated deckhouses |
B |
B |
B |
B |
6 |
Side shell plating from lower edge of sheerstrake
to water-line 1m below the lightest Arctic operating draught |
E |
E |
E |
E |
7 |
Remainder of side shell to flat of bottom |
DH |
DH |
DH |
DH |
8 |
Flat of bottom and keel |
B |
B |
B |
B |
9 |
Exposed non-strength deck plating |
B |
B |
B |
B |
10 |
Continuous longitudinal members above strength
deck |
E |
EH |
DH |
E |
11 |
Upper strake of longitudinal bulkhead at
strength deck |
E |
E |
DH |
E |
12 |
Upper strake of top wing tank longitudinal
bulkhead |
E |
E |
DH |
E |
13 |
Lower strake of longitudinal bulkhead at
bottom shell |
DH |
DH |
DH |
DH |
14 |
Stern-frames, rudder horns, rudders, ice
horns, shaft brackets, bossings |
- |
- |
DH |
DH |
15. |
In ships which by the nature of their trade,
have their cargo hold hatches open in ambient temperatures below ‑20° degrees
Celsius, tank top and lower strakes of hold bulkheads |
D |
D |
D |
D |
¹ Steel of grade F, may also be known as LT steel.
Figure 1 ^
Hull steel grade areas
ENLARGE IMAGE
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