
Reg. 190, Reg. 191, Reg. 192
DISHES END PLATES
Dished ends subject to external pressure
In the case of unstayed dished ends, for the coefficient 15
in equation (24) the cofficient 12 shall be substituted and
R shall be the outer radius of curvature of plate which shall
not exceed the external diameter of the shell to which it is
attached. For plates exposed to furnace flame the coefficient
shall be 10.5.
In no case shall 
R 
exceed 2.75 
T 
Reg. 191
DISHES END PLATES
Dished ends of Lancashire and Cornish Type Boilers
a) 
For dished ends
of Lancashire and Cornish boilers formed in one piece
without stays and subject to internal pressure the maximum
working pressure shall be determined by the following
formula :
W.P. = 
(T  8) x 30 x S 
Eqn.(26) 
R 
where
W.P. is the working pressure in the lbs. per square inch.
T is the thickness of the end plate in 32nds of an inch.
R is the inner radius of curvature of the end in inches
which shall not exceed one and a half times the external
diameter of the shell to which it is attached.
S is the minimum tensile breaking strength of the plate
in tons per square inch or whatever is allowed for it. 
b) 
The inside radius of curvature
at the flange shall be not less than 4 times the thickness
of the plate and in no case less than 31/2 inches 
Reg. 192
DISHES END PLATES
Dished shell and firebox crowns
a) 
In determining
the working pressure in accordance with Regulations 189
and 190 no accounts shall be taken of the influence of
the uptake tube in vertical boilers. If dished crown
plates having uptakes are fit for higher pressures, when
considered as flat plates, under Reg.197 such higher pressure
shall be allowed.

b) 
The radius Rs of the dished
part may be found as follows : 
R = 
C^{2} +
H^{2} 
Eqn.(27) 
2H 
C and H are the lengths in inches of half the base line
or chord on which H measured and the height of the dish
or camber at the middle of the chord respectively. 

