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Reg. 274, Reg. 275
Intermediate Boiler Drum Supports
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a boiler drum is supported at intermediate points in its
length at a distance greater than one internal diameter
from the end of the parallel portion of the drum shell,
the shell shall be thickened locally to the support or
so designed that when the local stress set up by the supports
in the drum shell are added, algebraically to those caused
by the internal steam pressure and supported loads, the
maximum resultant stress does not exceed the permissible
working stress at the working metal temperature. |
Reg. 275
END PLATES
Shape of Dished End Plate
When
the end plate is dished to semi ellipsodial, partial-spherical
or hemispherical form, it shall comply with the following
(see Figure 23A,
23B, 23C)
| a) |
hemispherical heads without
limitation; |
| b) |
elliptical heads sufficiently
dished so that H ³
0.2 D; |
| c) |
partial spherical heads
satisfying all the following requirements:
| r ³
0.1 D |
| r ³
3 T |
| R £
D |
| H ³
0.18D |
A value of R< 1.2 D is permitted for ends in
which the ratio H/D falls between 0.18 - 0.2.In accordance with Figs. 23A,
23B, 23C, 23D,
23E,
23F.
D = outside diameter of the head;
H = height of the head measured on its outside surface
from the junction of the dished part with the cylindrical
shell;
R = inside radius of the spherical part of partial
spherical heads;
r = inside knuckle radius of partial spherical heads.
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