----------+-----------------------------------------
Height | DIAMETER OF BOILER IN INCHES.
from tubes+-----+-----+-----+-----+-----+-----+-----
to shell.| 36 | 42 | 48 | 54 | 60 | 66 | 72
----------+-----+-----+-----+-----+-----+-----+-----
15 | 3.5 | | | | | |
16 | 4.0 | | | | | |
17 | 4.5 | 5.0 | | | | |
18 | | 5.6 | 6.2 | 6.7 | | |
19 | | 6.2 | 6.9 | 7.5 | | |
20 | | 6.8 | 7.5 | 8.2 | 8.9 | |
21 | | | 8.2 | 9.0 | 9.6 | |
22 | | | 8.9 | 9.8 |10.5 | |
23 | | | |10.5 |11.3 |12.1 |
24 | | | |11.3 |12.2 |13.1 |
25 | | | |12.1 |13.1 |14.0 |
26 | | | |12.9 |14.0 |15.0 |15.9
27 | | | |13.7 |14.9 |16.0 |16.9
28 | | | | |15.8 |16.9 |18.0
29 | | | | |16.7 |17.9 |19.1
30 | | | | |17.6 |18.9 |20.2
31 | | | | | |19.9 |21.3
32 | | | | | |21.0 |22.4
33 | | | | | | |23.5
34 | | | | | | |24.9
----------+-----+-----+-----+-----+-----+-----+-----
In Table 2 this calculation has been made for all sizes of boilers that
are ordinarily met with. The area to be braced has been calculated
as above in each case, the two-inch strip above the tubes, and the
three-inch strip around the shell being taken into account. As an
example of its use, let us suppose that upon measuring a boiler we find
that its diameter is 54 inches, and that the distance from the upper
tubes to the top of the shell is 25 inches. Then by looking in the
table under 54″ and opposite 25″ we find 714, which is the number of
square inches that requires staying on each head.