2.1.1 The
resistance to fracture is controlled, in part, by the notch toughness
of the steel used in the structure. Steels with different levels of
notch toughness are specified in Rules for the Manufacture, Testing and Certification of Materials, July 2022.
The grade of steel to be used is, in general, related to the thickness
of the material and the stress pattern associated with its location.
2.1.2 In
general for locations where the Lowest Observed Daily Mean Ambient
Temperature (LODMAT) is not less than 0°C the grade of steel used
in the construction of the primary strength members of the facility
is to comply with Table 2.2.1 Steel grades.
Table 2.2.1 Steel grades
| Thickness t
(mm)
|
Mild Steel
|
H. T. Steel
|
| t ≤ 20
|
A
|
AH
|
| 20 < t ≤ 25
|
B
|
AH
|
| 25 < t ≤ 40
|
D
|
DH
|
| t > 40
|
E
|
EH
|
2.1.3 Tee
or cruciform welded connections should be avoided wherever possible.
Where unavoidable, and the plate material is subject to significant
strains in a direction perpendicular to the rolled surfaces, it is
recommended that consideration be given to the use of special plate
material with specified through thickness properties, as detailed
in Ch 3, 8 Plates with specified through thickness properties.
2.1.4 For
facilities with sub-zero design temperatures, the material for primary
structural members is to comply with the requirements of Table 2.2.2 Grades of steel for minimum design
temperatures below 0 degrees C.
Table 2.2.2 Grades of steel for minimum design
temperatures below 0 degrees C
| Minimum design temperature, in
°C
|
Thickness, in mm
|
Grades of steel
|
| 0 to -10
|
t ≤ 12,5
|
B/AH
|
|
|
12,5 < t ≤
25,5
|
D/DH
|
|
|
t > 25,5
|
E/EH
|
|
|
|
|
| -10 to -25
|
t ≤ 12,5
|
D/DH
|
|
|
t > 12,5
|
E/EH
|