A New Method for Securing the Tubes of the Boilers and Condensers of Marine and other Engines.
Year: 1888

page_text: Date of Application, 31st Oct., 1888
Complete Specification Left, 24th July, 1889-Accepted, 31st Oct., 1889
PROVISIONAL SPECIFICATION.
A New Method for Securing the Tubes of the Boilers and Condensers
of Marine and other Engines.
THOMAS CAMPBELL "Hazelwood" Venner Road Sydenham Admiralty Overseer do
hereby declare the nature of my invention for SECURING THE TUBES OF BOILERS AND
CONDENSERS OF MARINE AND OTHER ENGINES to be as follows:-
The tube holes in tube plates of Boilers and Condensers of Marine and other
Engines to have shallow spiral grooves cut in them, like shallow or not full threads
and the tubes to be expanded into these grooves with a tube expander so as to fill the
grooves in the tube holes-This method will render the use of Boiler stay tubes with
bickened ends and consecutive threads on ends unnecessary and will also render the
use of glands and packings for Condenser tubes unnecessary.
Dated 31st October 1888
THOMAS CAMPBELL.
COMPLETE SPECIFICATION.
A New Method for Securing the Tubes of the Boilers and Condensers
of Marine and other Engines.
I, THOMAS CAMPBELL, of Hazelwood, Venner Road, Sydenham, in the County of
Surrey, Admiralty Overseer, 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 :—
My invention has reference to a simple method of firmly securing the tubes in the
tube plates of the boilers and condensers of marine and other engines in such a
manner that they can be when required withdrawn and readily replaced. Various
modes of securing such tubes have from time to time been proposed. Amongst the
methods proposed, the following may be mentioned viz.,
(a) To first drill or cut out the holes in the tube plate in the ordinary manner so
that the tubes will drive moderately tight into them about the centre of the thickness
of the tube plates, then to cut or form in the tube holes, circular cavities or spaces,
such central cavities being thus of larger diameter than the tube holes as ordinarily
required; then to place the tube in its proper position in the tube plate; then to
drive into the tube an expanding mandril having a circular projection, bend or flange
formed upon it, corresponding in general form with the cavity within the tubo plate
and thereby to cause the tube to expand and fill the cavity, and afterwards to rivet
the ends of the tube against the circumference of the tube hob by any of the ordinary
methods.
(b) To expand the tube into a groove cut into a mid-thickness of the tube plate
as well as, and in addition to, the expanding of the same tube on each side of the tube
plate.
(c) To effect the fitting or jointing of tubes and tube plates by a tapered screwed
tube end and a correspondingly tapered screwed tube plate, bearing or seat, the sizes
of the tube ends and the holes being so arranged that the tubes project beyond the
tube plate and these projecting ends being turned outwards or beaded over against the
tube plate.
(d) To first cut or form an annular recess about midway in the hole in the plate ;
then place the end of the tube therein, then by means of a suitable expanding tube to
bulge out or expand the tube so as to fill the said annular recess and thus fix the tube
in the plate, and then to expand the mouth of the tube in the usual manner, and (if
preferred) drive an ordinary ferrulo into the same.

page_text: (e) To countersink the hole in the tube plate or seating on its outer face, form one
or more circular grooves in its inner surface, and swell the metal of the tube into the
countersink and groove or grooves (which may be a screwed thread cut in the surface
of the hole) by means of one or more rollers.
With each of the foregoing arrangements, in order to remove the tube from the
tube plate, its end has to bo damaged to such an extent as to preclude its being
replaced.
For the purpose of fixing tubes so that they might be taken out and replaced as
required, it has been proposed to interpose rings between the exterior of the tube and
the hole in the tube plate, constructing such rings with one or more grooves at or on
the interior surface of the ring so that a portion of the metal of the tube when
expanded therein by the action of a tube expander, should be forced into the groove
or grooves and thereby the ring and tube become firmly connected together. The
grooves might be either in planes, parallel to the tube plate or helical. But this
arrangement is open to the following objections viz., that two joints require to be made
instead of one at the end of the tube, and when the tube is withdrawn together with
its ring it could not be readily replaced. Further with this construction tubes cannot
be placed so close together as where rings surrounding the tube are not used;
consequently the maximum heating or cooling surface, as the case may be, cannot be
obtained in a boiler, or a condenser fitted with such tubes.
Now according to my invention in order that the tubes of boilers and condensers of
marine and other engines may be readily secured in the tube plates, and withdrawn
and replaced as required without injury to the tubes, the tube holes in the tube plates
have shallow spiral grooves cut in them, like shallow or not full threads and each tube
is simply expanded into these grooves by means of a tube expander in such a manner
as to fill the grooves in the tube holes. But the metal of the tube is not swelled into
any countersink, nor is the end of the tube turned over or rivetted; thus I am
enabled to dispense with the use of boiler stay tubes having thickened ends and
continuous threads on the ends as also with the use of glands and packings for
condenser tubes.
In the accompanying sheet of drawings,
Fig. 1 represents in section part of a tube plate 1 having the hole therein formed
with a shallow spiral groovo 2 into which part of the metal of the end of a tube
plate 3, (shewn in elevation) is expanded by any suitable form of tube expander.
The spiral groove should be very shallow for instance like a female screw thread
partly formed, that is, not cut to the full depth. In some cases the tube plate hole
may be formed with two or more shallow spiral grooves thus forming multiple
threads.
The shallow groove or grooves may be formed by an ordinary screw-tap the size of
which must be such that the depth of the thread formed thereby does not exceed say
about of an inch for a tube of say 24" in diameter and upward. For a tube of "
in diameter and under, with say 20 threads to the inch, satisfactory results have been
obtained with a groove of about 4th of an inch in depth.
Figs. 2 and 3 are views drawn to a smaller scale and being respectively a
longitudinal section and an end elevation of parts of a condenser whereof some of the
tubes (see those marked 3ª) are secured according to this invention at one end only,
their other ends being secured by expanding them in the ordinary manner into plain
holes whilst other tubes (see those marked 3b) are secured by my method at both ends
so that they will serve as stay tubes.
Fig. 4 represents in elevation to a larger scalo one of the tubes 3ª withdrawn ; and
Fig. 5 is a similar view of one of the tubes 3°.
Tubes secured either at one or both ends, in the manner herein before described,
may be readily withdrawn from and replaced in the tube-plates by any suitable form
of apparatus that can be caused to take a firm hold of a tube and then be rotated. A
suitable apparatus for this purpose forms the subject of another application for Letters
Patent filed by me dated 3 June 1889, No. 9156.
Not only will my invention enable the tubes of any boiler or condenser tubed

page_text: according thereto to be withdrawn without injury to the tubes; but farthermore the
thickness of the tube plates can be materially reduced, the holding power of each
tube be considerably increased in the boiler or condenser tube plates, and thus weight
can be saved, and the tube plate can be rendered more efficient and durable.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The hereinabove described method of securing the tubes of boilers and condensers
of marine and other engines one or each tube plate hole intended to receive a tube
having a shallow spiral groove or grooves formed therein and the tube being simply
expanded in such hole so that metal of the tube is forced into and caused to fill the
said shallow groove or grooves thereby securing the tube in the tube plate or plates
but leaving the tube free to be unscrewed or withdrawn, and replaced when required
as set forth.
Dated this 24th day of Tul. 1980.
T. CAMPBELL.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.