DISHES END PLATES
Dished ends subject to internal pressure
||For unstayed ends of steam
and water drums, tops of vertical boilers, etc., when
dished to partial spherical form the maximum working pressure
shall be determined by the following formula : -
||15 x S
x (t - 1)
W.P. is the working pressure in lbs. per square inch,
t is the thickness of end plates in 32nds of an inch.
R is the inner radius of curvature of the end in inches,
which shall not exceed the external diameter of the shell
to which it is attached,
S is the minimum tensile breaking strength of plate in
tons per square inch, or whatever is allowed for it.
||The inside radius of curvature
of the flange shall be not less than 4 times the thickness
of the end plate, and in no case less that 2-1/2 inches.
||When the end has a manhole
in it (t - 5), shall be substituted for (t - 1) in the
||The total depth of flange of
manhole from the outer surface in inches measured on the
minor axis shall be at least equal to -
| (T x W) 1/2
= depth of flange
T is the thickness of the plate in inches,, and
W is the minor axis of the hole in inches.
NOTE - The foregoing provisions shall not preclude the
use of dished ends in compliance with Regs.275 to
where not fitted with an up-take.