6.1.1 Administrations should
take appropriate steps to ensure uniformity in the implementation
and application of the provisions of this chapterfootnote
6.1.2 This chapter gives the
requirements for plates, sections, pipes, forgings, castings and weldments
used in the construction of cargo tanks, cargo process pressure vessels,
cargo and process piping, secondary barriers and contiguous hull structures
associated with the transportation of the products. The requirements
for rolled materials, forgings and castings are given in 6.2 and tables 6.1, 6.2, 6.3, 6.4 and 6.5.
The requirements for weldments are given in 6.3.
6.1.3 The manufacture, testing,
inspection and documentation should be in accordance with Recognized
Standards and the specific requirements given in this Code
6.1.4.1 Acceptance tests
should include Charpy V-notch toughness tests unless otherwise specified
by the Administration. The specified Charpy V-notch requirements are
minimum average energy values for three full size (10 mm x 10 mm)
specimens and minimum single energy values for individual specimens.
Dimensions and tolerances of Charpy V-notch specimens should be in
accordance with Recognized Standards. The testing and requirements
for specimens smaller than 5.0 mm size should be in accordance with
Recognized Standards. Minimum average values for subsized specimens
should be:
Minimum average energy values
| Charpy
V-notch specimen size (mm)
|
Minimum
energy average of three specimens
|
| 10 x
10
|
E
|
| 10 x
7.5
|
5/6
E
|
| 10 x
5.0
|
2/3
E
|
Only one individual value may be below the specified average
value provided it is not less than 70% of that value.
6.1.4.2 In all cases, the
largest size Charpy specimens possible for the material thickness
should be machined with the specimens located as near as practicable
to a point midway between the surface and the centre of the thickness
and the length of the notch perpendicular to the surface (see figure
6.1). If the average value of the three initial Charpy V-notch specimens
fails to meet the stated requirements, or the value for more than
one specimen is below the required average value, or when the value
for one specimen is below the minimum value permitted for a single
specimen, three additional specimens from the same material may be
tested and the results combined with those previously obtained to
form a new average. If this new average complies with the requirements
and if no more than two individual results are lower than the required
average and no more than one result is lower than the required value
for a single specimen, the piece or batch may be accepted. At the
discretion of the Administration other types of toughness tests, such
as a drop weight test, may be used. This may be in addition to or
in lieu of the Charpy V-notch test.
6.1.5 Tensile strength, yield
stress and elongation should be to the satisfaction of the Administration.
For carbon-manganese steel and other materials with definitive yield
points, consideration should be given to the limitation of the yield
to tensile ratio.
6.1.6 The bend test may be
omitted as a material acceptance test, but is required for weld tests.
6.1.7 Materials with alternative
chemical composition or mechanical properties may be accepted by the
Administration.
6.1.8 Where post-weld heat
treatment is specified or required, the properties of the base material
should be determined in the heat treated condition in accordance with
the applicable table of this chapter and the weld properties should
be determined in the heat treated condition in accordance with 6.3. In cases where a post-weld heat treatment
is applied, the test requirements may be modified at the discretion
of the Administration.
6.1.9 Where reference is made
in this chapter to A, B, D, E, AH, DH and EH hull structural steels,
these steel grades are hull structural steels according to Recognized
Standards.