CERTAIN IMPROVEMENTS IN BOILER TUBES OR FLUES."
Year: 1881

page_text: LETTERS PATENT to William Henry Wood, of Cookley, in the County of
Worcester, Engineer, for an Invention of " CERTAIN IMPROVEMENTS IN
BOILER TUBES OR FLUES."
PROVISIONAL SPECIFICATION left by the said William Henry Wood at
the Office of the Commissioners of Patents on the 23rd April 1881.
WILLIAM HENRY WOOD, of Cookley, in the County of Worcester, Engineer.
"CERTAIN IMPROVEMENTS IN BOILER TUBES OR FLUES."
This Invention primarily and chiefly consists in constructing the internal tubes
or flues of steam boilers, applicable to locomotive, stationary, marine, and other
boilers. These tubes or flues are subject to compressive strains by means of my
improvements, greater strength and heating surface is imparted, the deposition of
incrustation on the tubes is materially reduced.
"
Each section of the tubes I construct concave to the fire and convex exteriorally,
so as to greatly resist external pressure. At the one end I form a swell or flange,
in diameter approaching the tube, which at any part in cross section is circular.
The other end of the tube is also flanged, and arranged to fit in the foriner, when
two or more, as required, are connected by rivetting at the flange. By this mode
a joint is formed capable of expansion and contraction, the material being the same
as hitherto employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Henry Wood in the Great Seal Patent Office on the
22nd October 1881.
WILLIAM HENRY WOOD, of Cookley, in the County of Worcester, Engineer.
"IMPROVEMENTS IN BOILER TUBES OR FLUES."
My Invention has for its object certain improvements in boiler tubes or flues, by
which greater facilities are obtained for raising steam and for the general circu-
lation of the water in boilers, with greater strength to the flues, with facilities for
expansion and contraction.
The flues of boilers as at present constructed are built up generally of a number
of plates fastened together either by lapping their ends over each other and
rivetting, or by flanging the ends and rivetting the flanges together, or by welding
the lengths together, as is now often the case, or, as is sometimes the case, by the
intervention of (what is known as) Bowling expansion rings. Now my Invention
consists in the combination of a concave plate in conjunction with the old Bowling
expansion joint, but made in one piece or from one plate, i.e., each single plate
which forms a part of the boiler flue is welded up into a cylinder, and is then passed
through a suitable machine or rolls to give to each particular length a concave
shape, the ends of the plate being also turned up, so as when two plates. come
together the said curve, which is similar to the old Bowling expansion joint, may
be formed at each junction. Plates bent concave to the fire are most favourable
for the purpose of raising steam, because they receive the radient heat, and the
concave shape facilitates the access of fresh supplies of water to replace the heated
particles which promotes the circulation and of boiling off the matter deposited from
the water, thus preventing incrustation to a greater or less extent. The concave shape
has the further advantage of imparting great strength to the flue to resist external
pressure, ie, the pressure of the water upon its external surface, and thus the flues
may be made lighter than when straight. The unequal strain between the flue
and shell of the boiler is provided for by the curved ends of the plates, which is
really equivalent to a double flanged expansion and contraction joint; or the
concave plates may be flanged up and rivetted together to answer the purpose
almost equally well.
I will now proceed to explain my Invention by referring to the accompanying
Sheet of Drawings, which will enable any practical man to carry my Invention into
practice.
Figure 1 is an elevational section of a double flued boiler, showing the shell and
the flues in section.
Figure 2 is a longitudinal section and part elevation of the same boiler broken
through, so as to show the front end A and the back end B.
Figure 3 is a front elevation and part section of one plate welded up.
Figure 4 illustrates a plate after passing through the machine, ready for either
joining up by welding or rivetting.
The plates are first welded together in the usual way, as shown by Figure 3. If
to be rivetted together to form the flues, as shown at c; c, at the A end of Figure 2,
one end would be formed a little larger than the other, so as to lap inside and
outside, as shown; but if the lengths are to be welded together, as shown by d, d,
at the B end of Figure 2, the ring, Figure 3, would then be made parallel. Thus
the concave shape of the plate e, f, g, forms an arch to the pressure applied in the
direction of the arrows, while the expansion joints c, c, and d, d, form convenient
junctions for the plate, and they give a certain amount of elasticity to the tube
lengthwise, which relieves the pressure on the ends H and K of the outer shell,
thus bringing the various parts into greater sympathy one with the other.

page_text: Having now described my said Invention of certain improvements in boiler tubes
or flues, I would have it clearly understood that I do not confine myself to the
exact curvature of the plates, as that would be varied according to the circum-
stances of each case, such as the pressure on the plates, the size of the flue, or the
thickness of the plates, but what I do claim and desire to secure as my
Invention is,
First. The concave plate e, f, g, in combination with the expansion ends c and d,
and as herein set forth and illustrated.
Second. The concave plate in combination with an ordinary flanged joint,
In witness whereof, I, the said William Henry Wood, have hereunto set my
hand and seal, this Twentieth day of October, in the year of our Lord One
thousand eight hundred and eighty one.
WILLIAM HENRY WOOD. (LS.)