An Improved Boiler Flue.
Year: 1889

page_text: Date of Application, 23rd May, 1889.
Complete Specification Left, 29th Jan., 1890-Accepted, 1st Mar., 1890
An Improved Boiler Flue.
I, EDWIN. CHAMBERS JOHN DEVIS, of Laurel Cottage, School Road, Moseley,
Birmingham, in the County of Warwick, Engineer, do hereby declare the nature of
this invention to be as follows:
This invention has for its object to provide a form of internal boiler flue at the
same time capable of withstanding high working pressures and of more efficiently
transmitting heat than the flues generally used.
Flues formed of plain cylindrical portions alternating with stiffening rings, and
those of barrel section are necessarily of comparatively thick metal and inefficient in
proportion, while those formed of close pitched corrugations are of thinner metal but,
on account of the closeness and depth of the corrugations, a large part of the
surface is comparatively sheltered from the heat, both of radiation and of conduction,
and inefficient in proportion.
By my invention both these objections are, to a large extent, eliminated by forming
along the flue a series of ridges of sharp section and at a wider pitch than that of
the corrugations of an ordinary corrugated flue and strengthening the metal between
such ridges by what may be called suspension from them.-That is to say, the flue is
constricted in diameter between ridge and ridge, forming a series of annular or
circumferential flutings whose depth is small compared with their width, thus
allowing of direct exposure of all parts to the radiant heat and to contact of the
hot gases.
The metal at the ridges may, if desired, be made thicker than elsewhere.
An Improved Boiler Flue.
I, EDWIN CHAMBERS JOHN DEVIS, of Laurel Cottage, School Road, Moseley,
Birmingham, in the County of Warwick, Engineer 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 :-
The object of this invention is to provide a form of internal boiler flue at the same
time capable of withstanding high working pressures and of more efficiently trans-
mitting heat than the dues generally used for high pressures.
Flues formed of plain cylindrical portions alternating with stiffening rings, and
those of barrel section are necessarily of comparatively thick metal and inefficient in
proportion, while those formed of close pitched corrugations are of thinner metal but,
on account of the closeness and depth of the corrugations, a large part of the surface
is comparatively sheltered from the heat, both of radiation and conduction, and
inefficient in proportion.
By my invention both these objections are, to a large extent, eliminated by forming
along the flue a series of ridges of sharp section and at a wider pitch than that of the
corrugations of an ordinary corrugated flue and strengthening the metal between such
ridges by what may be called suspension from them.-That is to say, the flue is
constricted in diameter between ridge and ridge, forming a series of annular or
circumferential flutings whose depth is small compared with their width, thus
allowing of direct exposure of all parts to the radiant heat and to contact of the
hot gases.

page_text: The metal at the ridges may, if desired, be made thicker than elsewhere, and besides
the advantages already mentioned. I claim that these tubes will be stiffer longitudinally
than corrugated tubes.
Fig. 1 of the accompanying drawings shows my invention as applied to the flue
tube of an ordinary land boiler. In this case I do not consider it necessary to incur
the expense of thickening the metal at the ridges and the section is as shown in the
enlarged view, fig. 2, the pitch or width of the flutings being from six to nine inches
and the depth about an inch and a half..
Fig. 3 shows my invention as applied to the furnace tube of a marine boiler where
the ridges may be advantageously thickened as shown in fig. 4, which is an enlarged
view of part of the same. In this case the pitch or width of the flutings inay be made
greater, say eight to twelve inches, and the depth about two inches.
I do not, however, limit myself to the dimensions stated, as the best proportions
can only be determined by experience and careful trials.
The flutings may be formed by rolling, by suaging by means of a hydraulic press
or steam hammer, by fluid-pressure direct on to the plate pressing it on to a single
die, or by the indirect fluid-pressure process to which my Letters Patent No. 5122 of
1888 relate. They may all pass entirely round the tube or some 'may be intersected
by plain parts for the attachment of cross tubes, furnace bearers &c.; and in some cases
there may be partial flutings where the tube is incomplete, for instance under the
combustion chamber of a marine boiler, as shown by fig. 3. In other cases the flutings
may be carried round the upper part of the tube only, the lower part being formed of
a plain plate if a complete tube is required.
:
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed; I declare that what I
claim is :-
7
A boiler flue or furnace consisting, as to its general form, of a series of annular
or partially annular flutings connecting a corresponding series of sharp ridges: