|Reg. 153, Reg. 154
BOILER AND SUPER-HEATER TUBES SUBJECT TO INTERNAL
Copper tubes upto one inch in external diameter may be used
for small boilers; such tubes shall be not less than 12 s.w.g.
HEADERS, MUD BOXES, ETC., OF WATER TUBE BOILERS
||(i) Headers and Mud Boxes,
etc., of water tube boiler may be of seamless or welded
steel, or of cast steel complying with the requirements
of the provisions contained in regulations
73 to 80. Where
welded, the welding shall be stress relieved, radiographed
or ultrasonically examined and in all respects shall be
to the satisfaction of the Inspecting Authority.
(ii) Open ends of seamless steel tube headers may be
closed by forging or the ends may be secured by bolting,
screwing or welding in an approved manner. Bolting shall
not be used where the bolts are exposed to or are swept
by gases of combustion.
(iii) The method of attachment of the ends shall be
subject to the approval of the Inspecting Authority.
||Each piece prior to being fitted
in place shall be subjected to hydraulic test to one-and-a-half
times the permissible working pressure of the boiler into
which it is fitted.
||(i) The sighting hole doors
and header caps shall be substantial and be capable of
being removed or replaced from time to time without loss
of efficiency or safety. They must be held in position
either by means of bolts or by seal welding.
(ii) The bolts by which they are held in place shall
be fitted to them in such a way as to satisfy the above
(iii) The doors shall be so designed that they will
not blow out in the event of breakage of the bolt.
(iv) Circular holes also may be provided in addition
to the elliptical holes, if provision is made to prevent
the door bolts from turning, while securing the joint.
||All flanges shall have a fillet
with a radius of curvature at least equal to the thickness
of the necks to which they are attached.