Improvements in and relating to Metallic Tubes for Bollers and the like.
Year: 1892

page_text: Date of Application, 29th Dec., 1892
Complete Specification Left, 29th Sept., 1893-Accepted, 4th Nov., 1893
TRUVIDIONAL DI BUIFICATION.
Improvements in and relating to Metallic Tubes for Bollers and
the like.
I, SAMUEL EARNSHAW HOWELL Sheffield Tube Works, Wincobank, Sheffield
in the County of York, Manufacturer, do hereby declare the nature of my invention
to be as follows:-
This invention has for its object to increase the heat absorbing and transmitting
surface of the interior of metallic tubes, such as are used for marine and locomotive
boilers and the like.
It consists briefly in the introduction within a tube of a metallic coil or spiral,
of the same or of another metal, and of any desired pitch of coil or twist.
I propose therefore to construct a coil, say of iron or of steel by preference and
of an oblong cross section, or of a form approximating thereto, and of a size
suited to dimensions of the tube, thus for example only, for a tube of two and a
half inches in diameter, the coil may be half an inch deep by one eighth of an
inch in thickness or thereabouts. I coil this from the flat rod or bar, edgeways,
into a long spiral the full size of the interior or bore of the tube, having the
desired amount of twist...
I propose to draw the coil so made by any suitable means into the interior of the
tube, the elongation due to its elasticity while being so drawn, causing it to be
slightly reduced in diameter and thus to pass readily to the required position in the
tube, against which it will fit tightly when the pressure is withdrawn.
I propose then to bring the tube and the coil to a welding heat and pass them
through a pair of rolls, or other compressing tools and so cause them to become
welded together.
Although I prefer to weld the parts together, I may braze or hardsolder them,
or in some cases I may make a perfect contact between the two by pressure alone.
The coil may not extend to the full length of the tube, but a few inches may be
left at each end for expanding purposes.
Although I have mentioned one tube only I may use two or more coils, inter-
coiled, so as to obtain a larger transmitting surface with a quick pitch of coil.
Dated the 24th day of December 1892.
ROBT. F. DRURY, C.P.A.,
Bank Buildings, George Street, Sheffield, Agent for Applicant.
COMPLETE SPECIFICATION.
Improvements in and relating to Metallic Tubes for Boilers and
the like.
I, SAMUEL EARNSHAW HOWELL Sheffield Tube Works, Wincobank, Sheffield
in the County of York, Manufacturer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
My invention has for its object to increase the heat absorbing and transmitting
surface of the interior of metallic tubes, such as are used in marine and locomotive
boilers, and for other like purposes.
The invention is illustrated in the annexed sheet of drawings which shows one
method of carrying it into practice.
Fig. 1, is a longitudinal section of a piece of tube, with a single internal coil.
Fig. 2, end view of same.

page_text: J
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The invention consists briefly, in the introduction within a tube, of a metallic
coil or spiral of the same, or of another metal, to which may be given any desired
amount of pitch, coil, or twist, or more than one coil may be used if desired.
In carrying out the invention, in the manner illustrated in the drawings, that is
with one coil only, I construct the coil B, of the desired diameter and pitch of
coil, and of any desired cross section such as that shown at C, which is oblong, but
I do not bind myself to any particular form, but for example, a suitable size for a
tube of two and a half inches in diameter, would be half an inch deep, by one
eighth of an inch thick.
I coil this from the rod or bar, edgeways, into a long spiral, the full size of the
interior or bore of the tube A, having the desired amount of twist, and I then
draw the coil so made, into the interior of the tube, by any effective means,
mechanical, or by hatid.
While the coil is being drawn into position the elongation due to its elasticity
causes it to be slightly reduced in diameter, and allows it to pass readily to the
required position in the tube, against the surface of which it will fit tightly when
the pull of the drawing action ceases.
I then bring the tube with the inserted coil to a welding heat, and pass them
through a pair of rolls, or other compressing tools, by which the coil B, and the
tube A, are welded together at the point of contact, leaving a central longitudinal
path D, throughout the length of the tube.
I
may in some cases braze, or hardsolder, the two parts together, and for some
purposes efficient contact may be made between the two by pressure alone.
Although I have mentioned and shown one coil only, inserted into the tube, I
may use two or even more coils, within the same tube, in which case I prefer that
the pitch of each coil is increased, and the coils are intercoiled one with the other.
I prefer that the coil or coils shall not extend the full length of the tube, but
that a few inches of tube shall be left at each end for the purpose of expansion.
Having now particularly described and ascertained the nature of my said 'inven-
tion, and in what manner the same may be carried into effect I declare that what. I
claim is :-
1. A metallic tube for steam boilers and like purposes, having an inserted coil
or spiral web attached to the tube by welding, substantially in the manner herein-
before described, and illustrated.
2. A metallic tube having an inserted coil or spiral web secured to the tube by
brazing or hard soldering as herein before described for the purpose specified.
3. A metallic tube, having an inserted coil or spiral web with its edge held in
close contact with the internal surface of the tube, for the purpose specified.
Dated the 26th day of September 1893.
ROBT. F. DRURY, C.P.A.,
Bauk Buildings, George Street, Sheffield, Agent for Applicant.