THE STORAGE OF GAS 635
(It will be noticed that this gives the cross-sectional area at the base, i.e. where the greatest stresses have to be withstood. The cross-sectional area may, of course, be reduced towards the top.)
In designing a column the total area required must be taken {i.e. formulæ A+B).
rr, , , , /24I? + D2 , BI?x
The total area =----------4---------).
k 10,000 N 3240?//
{Note.—The valne for / has been taken as 6 tons per square inch. Cripps, in order to allow a margin o wing to the faet that the standard is acting as a column, takes a value of 4 tons per square inch.)
The method of calculation will be readily understood by the oonsideration of a simple example.
Take a holder of such design as that seen in Fig. 388, having a capacity of about 750,000 cubic feet. Let the diameter of the bottom lift be 110 feet, and the total height of the beil (which is the same as the effeetive heiglit of the standards) 80 feet. The standards will be conveniently spaced at a pitch of about 16 feet; or, as the tank circle will measure approximately 352 feet, it can be assumed that the standards will be 22 in number.
The total area required for each flange at the base of the standards
_24L2+D2 bl2 10,000 N + 3240?/'
In the example under consideration.—
L = 80 feet
D = 110 „
N= 22
B = 16 feet
y — half depth of cross-section in inches.
rn, t /(24 x 80 x 80) + (110 x 110) . 16 X 80 X 80\
More area = (-------------10;000 -----------+ 3240 X >
„ „ =0-75+^±°
y
18
Assuming a depth of 18 inches for the cross-section, y = —- =9, therefore area
31*60
of each flange = 0-75 +-------= 4-26 sq. inches,
9
or, total area of flanges = 8-52 sq. inches.