|Reg. 213, Reg. 214
Tubes plates, other than ends of vertical boilers forming
parts of outer shell
||When vertical boilers have
nest or nests of horizontal tubes so that there is direct
tension on the tube plates due to the vertical load on
the boiler ends, or to their acting as horizontal ties
across the shell the thickness of the tube plates and
the spacing of the tubes shall be such that the section
of metal taking the load is sufficient to keep the stress
within that allowed on the shell plates.
||Each alternate tube in the
outer vertical rows of tubes shall be a stay tube. The
tube plates between the stay tubes shall be of accordance
with the rules for tube plates and in addition, considered
as part shell, the maximum working pressure.
(t - 2) x (P - D) x S
|R x P
t is the thickness of the tube plate in 32nds of an inch,
P is the vertical pitch of the tubes in inches,
D is the diameter of the tube holes in inches,
S is the minimum tensile breaking strength of the tube
plates in tons per square inch, or whatever is allowed
R is the radial distance of the centre of the outer row
of tube hole from the axis of the shell in inches.
Curved tube plates of water-tube boilers
For tube plates forming part of the cylindrical drums the maximum
working pressure shall be : -
- 4) x E x S
t = thickness of tube plate in 32nds of an inch,
E = Efficiency of the longitudinal joint or the ligament between
the tube holes, whichever is less,
S = Minimum Tensile Stress of the tube plate in tons per sq.
in or whatever is allowed for it,
D = Inside diameter of the drum in inches.