Additional tests before rejection
Should either a tensile or bend test fail, two further
tests of the type which failed may be made on test pieces
cut from the same test rings. If the results obtained
from these re-tests are satisfactory, the drum shall
be accepted, provided that in other respects it fulfils
the conditions of this Chapter. If these re-tests do
not give satisfactory results the drum represented may
be re-heat-treated together with the remainder of the
test rings, and presented for further testing.
In all cases where final re-tests do not give satisfactory
results, the drum represented by the test pieces which
fail shall be rejected.
Sufficient discard shall be made from the top and bottom
of each ingot to ensure soundness in the portion for
forging shall be made from a solid cast ingot, punched,
bored or trepanned, or alternatively, hollow, cast
ingots may be used.
The resultant wall in the case of the solid cast
ingot, or the wall of hollow ingot as cast shall be
reduced in thickness by at least one-half in the process
deviation from circularity in any section shall, in the
case of normalised drums, not exceed 2% and in case of
stress relieved drum 1%. The deviation from a straight
line shall not exceed 0.3% of the cylindrical length.
order to determine the deviation from circularity of the
drums the maximum and minimum internal diameter at one
cross section shall be measured. From these measured values
the percentage deviation from circularity shall be calculated
according to the following formula:-
C = percentage deviation from circularity of the drums.
d = internal diameter at one cross section.
In order to determine the deviation from a straight line,
a stretched line should be placed longitudinally against
the sides and its largest distance from the shell line
concerned shall be measured. From this distance, and from
the cylindrical shell, the deviation from the straight
line shall be calculated.