Improvements in the Construction of Metallic Tubes suitable for the Internal Fireboxes and Flues of Steam Boilers and in the Formation of Plates therefor.
Year: 1888

page_text: Date of Application, 19th June, 1888
Complete Specification Left, 19th Feb., 1889
Complete Specification Accepted, 30th Mar., 1889
Improvements in the Construction of Metallic Tubes suitable for the
Internal Fireboxes and Flues of Steam Boilers and in the
Formation of Plates therefor.
I, ROBERT EDWIN PEACOCK CRAVEN of 8 Seamer Street, Armley Leeds, in the
County of York Engineer do hereby declare the nature of this invention to be as
follows:-
This invention has reference to an improved construction of metallic tubes suitable
for the internal fireboxes and flues of steam boilers, and in the formation of plates
therefor and has for its object the production of such tubes that shall be capable of
resisting a greater collapsing strain than fireboxes and flue tubes heretofore
constructed.
For this purpose according to my invention I form such tubes with circumferential
ridges and grooves either at right angles to their axes or helically thereto, but I prefer
them at right angles as being the strongest form.
The said ridges and grooves instead of having the usual serpentine form of corruga-
tion as would be seen in a longitudinal section of such a corrugated tube, I cause the
ridges to be made with flat tops and the grooves with semi-elliptically shaped bottoms,
or with semi-elliptically shaped ridges and flat bottomed grooves. The sides or
parts connecting the said flat ridges with the semi-elliptically shaped grooves or
the semi-elliptically shaped ridges with the flat bottomed grooves, may be straight
and at an obtuse angle therewith, or with the axis of such tube, the corners formed
by the obtuse angular sides or parts adjoining the flat ridges or grooves being
rounded for the more easily drawing of the metal by the action of the rolls during
the formation of a tube or plate.
In place of the beforementioned obtuse angular parts for connecting the flat
ridges and the semi-elliptical bottomed grooves, or the semi-elliptically formed
ridges and flat bottomed grooves, as the case may be, the corners may have a
greater radius for that purpose thus dispensing with the flat portion of such con-
necting parts previously referred to.

page_text: In the manufacture of the above described tubes the formation of the ridges and
grooves and the bending to the circular or tubular form take place at the same
time in a suitably and specially constructed rolling machine for which I make
application for Letters Patent, bearing even date herewith.
By means of the rolling machine above referred to I am enabled to form plates for
use in the construction of tubes for fireboxes and flues of steam boilers, with
corrugations or ridges and grooves of various cross sectional configuration and with
the ends of the plates left plain for a suitable distance.
These plates are afterwards bent to the tubular form until the said plain ends meet
in a butt or lap joint to be afterwards welded in the usual manner, after which
the said plain part may be corrugated by being replaced in the said rolling machine
or if desired may be left plain. Or the lap joint may be rivetted and left in the
plain state.
Dated this Dishtoonth day of Juno 1888

page_text: COMPLETE SPECIFICATION.
Improvements in the Construction of Metallic Tubes suitable for the
Internal Fireboxes and Flues of Steam Boilers and in the
Formation of Plates therefor.
I, ROBERT EDWIN PEACOCK CRAVEN, of 8 Seamer Street, Armley Leeds, in the
County of York 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:-
This invention has reference to an improved construction of metallic tubes, suitable
for the internal fireboxes and flues of steam boilers and in the formation of plates
therefor and has for its object the production of such tubes that shall be capable of
resisting a greater collapsing strain than fireboxes and flue tubes heretofore
constructed.
For this purpose according to my invention I form such tubes with circumferential
ridges and grooves either at right angles to their axes or helically thereto, but I prefer
them at right angles, as being the strongest form.
The said ridges and grooves instead of having the usual serpentine form of corruga-
tion as would be seen in a longitudinal section of such a corrugated tube I cause
the ridges to be made with flat tops, and the grooves with semi-elliptically shaped
bottoms, or with semi-elliptically shaped ridges and flat bottomed grooves. The
sides or parts connecting the said flat ridges with the semi-elliptically shaped
grooves or the semi-elliptically shaped ridges with the flat bottomed grooves, may
be straight and at an obtuse angle therewith, or with the axis of such tube, the
corners formed by the obtuse angular sides or parts adjoining the flat ridges or
grooves being rounded for the more easily drawing of the metal by the action of the
rolls during the formation of a tube or plate.
In place of the beforementioned obtuse angular parts for connecting the flat ridges
and the semi-elliptical bottomed grooves, or the semi-elliptically formed ridges and
flat bottomed grooves, as the case may be, the corners may have a greater radius for
that purpose thus dispensing with the flat portion of such connecting parts previously
referred to.
In the manufacture of the above described tubes, I take a plain plate, heat it to a
suitable degree, and cause the formation of the ridges and grooves and the bending of
it to the circular or tubular form to take place at the same time in a suitably and
specially constructed rolling mill for which I have made application for Letters
Patent bearing even date herewith, and numbered 8927.
By means of the rolling mill above referred to I am enabled to form plates for use
in the construction of tubes for fireboxes and flues of steam boilers, with corrugations
or ridges and grooves of various cross sectional configuration and with the ends of
the plates left plain for a suitable distance.
These plates are afterwards bent to the tubular form until the said plain ends meet
in a butt or lap joint, to be afterwards welded in the usual manner, after which the

page_text: said plain part may be corrugated by being replaced in the said rolling Mill, or if
desired may be left plain, Or the lap joint may be rivetted and left in the
plain state.
In the accompanying drawings
Fig. 1, is an external view of a tube having flat topped ridges and semi-elliptically
bottomed grooves, and Fig. 2, is an external view of a tube having semi-elliptically
shaped ridges and flat bottomed grooves according to my invention.
Fig. 3. is an end view of both Figures 1, and 2.
Figures 4, 5, and 6 show to an enlarged scale, sections of the improved tube. a. are the
flat topped ridges, b the semi-elliptically bottomed grooves, or a¹ the semi-elliptically
shaped ridges and, b', the flat bottomed grooves, the angular parts represented by the
dotted lines c. c. connect the said ridges and grooves, and the parts d, d, the rounded
corners between the said parts a and b. The ridges and grooves in Fig. 6, are
connected by curved parts e. e. only.
These tubes, especially those with flat topped ridges are much stronger than tubes
having a serpentine section of corrugation and are consequently capable of with-
standing a greater collapsing strain.
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
The improved metallic tube suitable for the internal fireboxes and flues of steam
boilers, with flat topped ridges, a, and semi-ellipticalled bottom grooves, b, or with
semi-elliptically shaped ridges a¹, and flat bottomed grooves 6₁ and with parts
connecting the said ridges and grooves of an angular form c. c. or with curved
parts d. d, substantially as hereinabove described and shewn in the drawings.
Dated this Nineteenth day of February 1889.