IMPROVEMENTS IN THE CONSTRUCTION OF BOILERS FOR HEATING LIQUIDS AND GENERATING STEAM
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Reuben Marriott at the Office
of the Commissioners of Patents, with his Petition, on the 25th
September 1874.
I, REUBEN MARRIOTT, of the Firm of "Marriott & Graham," of Govan,
in the County of Renfrew, North Britain, Boiler Maker, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE
CONSTRUCTION OF BOILERS FOR HEATING LIQUIDS AND GENERATING STEAM," to be
as follows:-
This Invention has reference to the improved construction of vertical
boilers with the top end of the shell and fire-box domed or rounded, all
without rivets or joints, so that they are lighter, stronger, and more
uniform in thickness throughout, thereby giving equal expansion and
contraction and greater durability than has been possible with such
boilers as hitherto constructed; and the nature and novelty of this said
Invention (or improvements) consist in forming the whole fire-box, cross
tubes, lower part of central chimney flue, domed crown, and outer
main shell, all of solid welded wrought sheet iron without a rivetted or
calked joint.

page_text: This new or improved construction of domed fire-box and domed
crown shaped vertical boilers (for heating water or other liquids, or for
the generation of steam), is effected by first forming the cylindrical part of
the fire-box out of one large plate and welding it in a butt or lap joint at
the ends in vertical line, and cutting the hole out of it near the bottom
for the furnace door, and bending its lip outwards all round ready to insert
into a corresponding hole in the outer shell of the boiler so as to be
welded thereto. The lower edge of the fire-box is then kneed or flanged
out so as to overlap the lower end edge of the outer shell and be welded
thereto. Before this, however, holes are cut out near the top for the
large cross tubes which are inserted and welded after its top or domed
upper end has been shaped out of a large plate, and butt welded all round
to the upper edge of the fire-box so formed, and which at this part is
rounded at the same time to complete the dome shape at this part,
the curved or domed plate having previously had a hole formed in the
middle to fit and be welded to the lowest end of the central funnel fluc,
which passes up through the water and steam space of the boiler, so as
to have its upper end passed through and welded to a corresponding hole
in the middle of the domed crown of the outer shell. The cylindrical
body part of the outer shell is previously and separately made, and
welded out of one or more plates welded in vertical joints at their edges,
and having the upper domed end or crown shaped out of one plate, or it
may be two plates, according to size, welded across a central joint, and
which is then butt welded all round to the upper edge of the cylindrical
shell, and rounded at the welded corner at the same time to complete its
dome shape. The outer shell thus completed, with its man-hole and
sludge holes previously cut in it, has the shell of the fire-box (previously
completed as described) inserted into it so as to have the bottom flange
and lip of the fire hole and upper end of central flue all welded to
the main outer shell, when the whole will be completed, and solidly
welded in one piece without a single rivetted or other joint in the whole
body of the fire-box, tube flues, and outer shell exposed to the fluid
action or pressure, except the doors of the said man-hole and sludge holes,
and those of the usual necessary pipes and fittings; and the upper part
of the funnel, which, not being exposed to the fluid pressure is only set
on top of central flue and attached by simple screw pins or other
ordinary fastenings, as also that of the lower rim and shell part forming
the ash space or hole below the fire-box.

page_text: It is to be understood that many of these parts have before been
made with solid welded joints, such as the square or rectangular butt
joint at the ends of the tubes, chimney flue, fire hole and lower flange,
the especial new feature being the welding of the domed crown plates of
the fire-box and outer shell to the upper edges of their cylindrical
bodies by welding them before being fully domed at the edges, so as to
be able to strike and manipulate the welded joint, and then at the same
time completely round or dome these parts to their proper shape, thus
enabling the whole to be solidly welded, these joints having hitherto
required to be made by rivetting and calking them.