Improvements in the Manufacture of Corrugated Furnaces and Flues for Steam Boilers.
Year: 1886

page_text: Date of Application, 9th Mar., 1886
Complete Left, 7th Dec., 1886
Complete Accepted, 7th Jan., 1887
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Corrugated Furnaces and Flues
for Steam Boilers.
I, SAMSON Fox, of the Leeds Forge, New Wortley, Leeds, in the County of York,
Engineer and Ironmaster, do hereby declare the nature of this invention to be as
follows:-
Corrugated boiler furnaces and flues have been largely constructed under former
Patents of mine, plates of inetal being first heated and bent to tubular form and
welded, the corrugations being afterwards formed out of the thickness of the metal
by rolling in a suitable mill, and, finally, the wings and end rings or parts for attach-
ment to the body of the boiler being formed in a flanging machine to a thickness
approximately the same as that of the corrugated portions of the furnace or flue.
Owing to the additional strength to resist collapsing strain imparted by the corruga-
tions, it has been practicable to use corrugated furnaces and flues made of much
thinner metal than has been necessary with plain flues intended to withstand the
same pressure; but it has been necessary to employ with such flues not only separate
longitudinal stays, but also lateral stays applied to the wings and end rings; and,
moreover, as the corrugations have been formed entirely around the welded tube, the
process of manufacture has been tedious and costly, owing to the liability of injury to
the welded joint in the process of corrugating.
Now, the object of my present invention is to obviate this difficulty in the manu-
facture and to produce in a simple and economical manner a corrugated furnace or
flue such as will enable me to dispense with the use of both longitudinal and lateral
stays such as herein above referred to.
For this purpose I use for the manufacture of the flue a plate of greater thickness
than heretofore, which is heated, bent to the form of a tube and welded, then is placed in
the corrugating mill and has corrugations formed partly, but not entirely, around it,
leaving a plain uncorrugated portion of plate throughout the length of the furnace or
flue to form a strong longitudinal stay, in which is comprised the longitudinal welded
joint.

page_text: Afterwards, the end ring and wings are formed in the ordinary way but approxi-
mately of the thickness of the original plate, so as to be sufficiently strong for use
without the lateral stays already mentioned. For the purpose of affording additional
resistance to collapsing strain, without increasing the depth of the corrugations, and
without any preliminary rolling process; I form and arrange the corrugating rolls in
such a manner that the metal of the furnace or flue, when finished, shall be of greater
thickness at the inner and outer ridges than at the sides of the inner and outer
channels of the corrugations, being reduced in thickness at the last mentioned parts in
the process of corrugating.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Corrugated Furnaces and Flues
for Steam Boilers.
I, SAMSON Fox, of the Leeds Forge, New Wortley, Leeds, in the County of York,
Engineer and Ironmaster, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
Corrugated boiler furnaces and flues have been largely constructed under former
Patents of mine, plates of metal being first heated and bent to tubular form and
welded, the corrugations being afterwards formed out of the thickness of the metal by
rolling in a suitable mill, and finally the wings and end rings or parts for attachment
to the body of the boiler being formed in a Hanging machine to a thickness approxi-
mately the same as that of the corrugated portions of the furnace or flue. Owing to
the additional strength to resist collapsing strain imparted by the corrugations, it has
been practicable to use corrugated furnaces and flues made of much thinner metal
than has been necessary with plain flues intended to withstand the same pressures, but
it has been necessary to employ with such flues not only separate longitudinal stays,
but also lateral stays applied to the wings and end rings, and moreover as the corruga-
tions have been formed entirely around the welded tube, the process of manufacture
has been tedious and costly as compared with the manufacture hereinafter to be
described, owing to the liability of injury to the welded joint in the process of corru-
gating.
By my present invention I am enabled to obviate the difficulty above indicated and
to produce in a simple and economical manner a corrugated furnace or flue such as
will enable me to dispense with the use both of longitudinal and lateral stays such as
hereinabove referred to.
For this purpose I use for the manufacture of the flue a plate of greater thickness
than heretofore, which is heated, bent to the form of a tube, and welded, then is
placed in the corrugating mill and has corrugations formed partly, but not entirely
around it, leaving a plain uncorrugated portion of plate throughout the length of the
furnace or flue so that the full strength of the longitudinal welded joint is main-
tained.
Afterwards the end rings and wings are formed in the ordinary way but approxi-
mately of the thickness of the original plate so as to be sufficiently strong for use
without lateral stays such as already mentioned. For the purpose of affording addi-
tional resistance to collapsing strain without increasing the depth of the corrugations,
and without any preliminary rolling process, I forin and arrange the corrugating
rolls in such a manner that the metal of the furnace or flue when finished, shall be of
greater thickness at the inner and outer ridges than at the sides of the inner and
outer channels of the corrugations, being reduced in thickness at the last mentioned
parts in the process of corrugating.
The accompanying drawings illustrate the formation of a furnace tube according to
my invention. Fig. 1, being a longitudinal vertical section, and Fig. 2, an end
elevation, a, a' are corrugations in the upper portion only of the tubular structure;

page_text: c, is the lower part, it is plain and of the normal thickness of the plate from which it
is formed, in this part is located the welded joint, thus obviating the risk of injury
thereto during the process of corrugating and forming a rigid longitudinal tensile
stay to the ends of the boiler that admits of dispensing with separate stays such as
usually employed as above referred to. And in order that a tube constructed as
described may be enabled to withstand great collapsing strain the inner and outer
ridges of the corrugations are as shewn at a¹, of greater thickness than the sides of
parts a, that is to say, they are as nearly as possible of the thickness of the plate
from which the tube is made, whereas the sides a, of the channels are drawn thinner
in the process of corrugating so that the evaporative effect obtainable shall remain as
nearly as possible equal to that in a corrugated tube wherein the ridges and channels
are practically of equal thickness throughout. b. b, are the wings and end rings also of
the normal thickness or thereabout, of the plate from which the tube is made, and are
capable of withstanding the strain brought to bear upon those parts without the use
of lateral stays. Fig. 3 is an enlarged section of the corrugations shewing the varia-
tion in thickness as above referred to. In the modification illustrated in Fig. 4 the
parts of greatest thickness are formed by projecting ribs or beads, the other parts of
the corrugations are of an equal thickness as heretofore in order not to impair the
evaporative efficiency. I have stated that according to my present invention I use
for the manufacture of the flue a plate of greater thickness than heretofore.
By way of example, in the case of a firebox or flue to resist a working pressure of
say seventy to ninety pounds per square inch, wherever heretofore it has been usual
to employ a plate having a normal thickness of say :-from three eighths of an inch
to half an inch thick.
Now according to my present invention, a plate having a normal thickness of
three fourths of an inch, can be advantageously employed so as to work up to the
modern pressure of one hundred and fifty to two hundred pounds per square inch.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
1. The hereinabove described improved construction of corrugated welded furnace
or fluc for a steam boiler.
2. The formation of a steam boiler furnace or flue with corrugations thicker at the
inner and outer ridges than at the sides of the corrugations substantially as described
above for the purpose stated.
3. The formation of a steam boiler furnace or flue tube with corrugations at its
upper part, a plain bottom part in which is located a longitudinal welded joint, and
with the parts known as the end rings and wings b, for joining to the body of a
boiler, of a thickness or thereabout corresponding to the normal thickness of the
plate of which such furnace or flue tube is formed, substantially as hereinabove
described with reference to the drawings.
Witness,
THOS. E. CRAVEN, C.E., Fel. Inst. Patent Agents,
24, Victoria Chambers, Leeds.
DAMDUN TUA.