| 1) |
Where branches or saddles are secured to the shell
by riveting or by studs, the minimum thickness of the
flange adjoining the shell shall be in accordance with
the following table:-
TABLE
| Thickness of shell plate Inch |
Minimum thickness of flange Inch |
| 3/8 to 3/4 |
1/2 |
| above 3/4 to 1 |
5/8 |
| above 1 to 2 |
3/4 |
| above 2 |
1 |
The actual dimensions of the flanges shall
be governed by the requirements of compensation for
the opening.
The dimensions of flanges of branches remote from the
shell for ordinary bolted joints and those of bolts
of all pads and saddles shall be in accordance with
the appropriate table given in Appendix E for the working
pressure and temperature corresponding to the design
pressure and temperature of the shell. The dimensions
of the flanges for special joints shall be subject to
approval of the Chief Inspector of Boilers concerned.
The working pressure for the body of the branch shall
be determined by the equation as given in sub-regulation
(a) above, subject to the requirements of compensation
for the opening.
Notwithstanding the result obtained from the equation
the minimum thickness of the body of the branches shall
be such that in no case does the total stress, resulting
from the combination of the stress due to internal pressure
and to all externally applied load, exceed the permissible
stress corresponding to the design temperature. The
method of calculating the total stress shall be subject
to the approval of the Chief Inspector of Boilers concerned.
Where the magnitude of the externally applied load cannot
be determined, the minimum thickness of the body of
the branch shall be as given in the following table:-
Minimum thickness of Branches Where External Loads
Are Not Known
| Nominal bore of branch |
Thickness of cylindrical
part of shell |
Minimum body thickness |
| In. |
In. |
In. |
In. |
Upto and including 2
½
Over 2 ½ upto and including 4 ¼ |
3/4 and above
7/8 and above |
3/8
7/16 |
For thinner shells not
less than one half the thickness of the cylindrical
part of the shell. |
Over 4 ¼ upto
and including 8
Over 8 upto and including 10 |
1 and above
1 ¼ and above |
1/2
5/8 |
| Over 10 |
1 ¼ and above |
|
Subject to approval of
the Chief Inspector of Boilers concerned. |
|
