Flat Crown plates of Vertical Boilers
||For the flat crown plates of
vertical boilers either with or without bolt stays,
Equation(35) shall be used in determining the working pressure
with C = 80, when the plates are not exposed to flame,
and 70 when they are exposed to flame. In this case D
is the diameter of the largest circle in inches that can
be drawn passing through the centres of the rivets or
bolt stays when fitted, or the commencement of the curvature
of the flanging, whichever is applicable. Where bolt stays
are fitted with washers of the same thickness as the plate
securely riveted thereto, the circle shall pass through
the centre of the washer rivets but where the washers
are not riveted or where none are fitted the circle shall
pass through the centre of stays.
||Where the crown plate is flanged
the inside radius of curvature of the flange shall not
be less than 4 times the thickness of the end plate, but
in no case less than 2-1/2".
|| The thickness of flat crown
plates shall in no case be less than the thickness of
the cylindrical portion to which it is attached.