Improvements in Boiler Flues.
Year: 1899

page_text: Date of Application, 1st Feb., 1899
Complete Specification Left, 31st Oct., 1899-Accepted, 2nd Dec., 1899
PROVISIONAL SPECIFICATION.
Improvements in Boiler Flues.
We, GEORGE COOPER, and THE LEEDS FORGE COMPANY LIMITED, both of the
Leeds Forge, Leeds, in the County of York, Engineers, do hereby declare the
nature of this invention to be as follows:-
In manufacturing boiler tubes according to this invention, we first form in a
manner well understood a plain tube of a uniform thickness slightly greater than
it is intended the thinnest portion of the finished flue shall be. This tube is
then heated to the required temperature and rolled in a mill having rolls arranged
and corrugated in such a manner as to form the said tube with alternating cylin-
drical portions of greater thickness than the original tube and annular outwardly
projecting corrugations, the thickness of which is sufficient to enable the flue to
withstand the working pressure for which it is designed, but is, nevertheless,
less than that of the cylindrical parts. The tube is thus in the course of manu-
facture thinned where it is formed with outwardly projecting corrugations and
is thickened between the said corrugations.
In some cases, instead of forming the flue with thickened cylindrical portions
alternating with outwardly projecting corrugations, those thickened portions of
the flue between the said corrugations may be suitably curved.
Improvements in Boiler Flues.
We, GEORGE COOPER, and THE LEEDS FORGE COMPANY LIMITED, both of the
Leeds Forge, Leeds, in the County of York, Engineers, 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:-
In manufacturing flues according to this invention, we first form in a
manner well understood a plain tube of a uniform thickness slightly greater than
it is intended the thinnest portion of the finished flue shall be. This tube is
then heated to the required temperature and rolled in a mill having rolls arranged
and corrugated in such a manner as to form the said tube with alternating cylin-
drical portions of greater thickness than the original tube and annular outwardly
projecting corrugations, the thickness of which is sufficient to enable the flue to
withstand the working pressure for which it is designed, but is, nevertheless,

page_text: less than that of the cylindrical parts... The tube is thus in the course of manu-
facture thinned where it is formed with outwardly projecting corrugations and
is thickened between the said corrugations.
Referring to the accompanying drawings, Fig. 1 shows in longitudinal section
a portion of a flue according to this invention, the thickness of the tube before
being corrugated being indicated by the dotted lines. a, a are the cylindrical
portions of the flue and b, b are the outwardly projecting corrugations; the parts a
have been slightly thickened during the corrugating operation owing to the
diameter of the tube at these parts being thereby reduced in diameter whilst the
parts, have been slightly thinned owing to the diameter of the tube at the
said parts having been increased. Fig. 2 is a diagrammatic view of a pair of
corrugating rolls with a finished flue tube between them; the thickness and
diameter of the plain tube before corrugation is indicated in dotted lines.
In some cases, instead of forming the flue with thickened cylindrical portions
alternating with outwardly projecting corrugations, those thickened portions of
the flue between the said corrugations may be suitably curved.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, we declare that what
we claim is :-
The manufacture of a corrugated boiler flue from a plain tube of uniform
thickness slightly greater than is to be the thinnest portion of the finished flue
by operating upon such tube by rollers arranged and corrugated so as to form
the flue with alternately disposed portions of greater thickness than the original
tube and outwardly projecting corrugations of less thickness than the thickened
intermediate portions, substantially as hereinbefore described..
Dated this 31st day of October 1899.
For the Applicants,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.