Improvements in Boiler Tubes and in the Mode of Securing them in Boilers, and in Tools for Fixing the same.
Year: 1889

page_text: Date of Application, 23rd Aug., 1889
Complete Specification Left, 22nd May, 1890-Accepted, 26th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Boiler Tubes and in the Mode of Securing them
in Boilers, and in Tools for Fixing the same.
I, ALFRED WITCOMB of Dolcoath Road Camborne, Cornwall, Boiler Smith, do
hereby declare the nature of this invention to be as follows:-
The object of this invention is the prevention of leakage in tubular boilers,
which arises in many cases from unequal expansion or contraction in the tubes, or
in the metal plate to which they are fitted.
The present method of fitting tubes in the fire-box of a locomotive consists in
enlarging or distending the end of the tube by means of a tube-expander so that it
tapers slightly inwards and thus a shoulder is formed. The end of the tube is
allowed to project beyond the metal plate, and this projecting part is hammered
down to form an annular rivet so that it is impossible for the tube to slip inside the
metal plate. The usual ferrule is inserted in the end of the tube but that I do not
interfere with. In the above arrangement it will be seen that there is no provision
for preventing the plate from being drawn back from the end of the tube, or the tube
from being thrust outwards by expansion beyond the plate as sometimes happens
when some of the tubes are unequally heated, as in that case the less heated tubes
hold back the metal plate from those tubes which are more exposed to heat, or
conversely the more expanded tubes having no power to carry the boiler-plate with
then, project further through it and thus cause leakage.
My improvements which are applicable to tubes generally consists in forming on
the tube just inside the boiler-plate a conical or convex swell, tapering outwards, so
that there shall be a shoulder on each side of the joint with the metal plate, and not
on one side only as at present.
I prefer to have the ends of the tubes specially prepared with a slight conical or
convex swell formed on them, but when this is not done I form the inner swell on the
tube, by means of a tube expander having special rollers hollow in the centre, and not
parallel as now employed. The ends of these rollers being conical or convex, a
corresponding double expansion is formed in the tube, and a double shoulder created,
part of which is inside and part outside the plate.
In this way the tube becomes so firmly fixed to the boiler plate that leakage is
prevented when expansion or contraction takes place.
Dated this 23rd day of August 1880
S. S. BROMHEAD,
97, Newgate Street, E.C., Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Boiler Tubes and in the Mode of Securing them
in Boilers, and in Tools for Fixing the same.
1, ALFRED WITCOMB of Dolwath Road, Camborne, Cornwall, Boiler Smith,
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 the prevention of leakage in tubular boilers, which
arises in many cases from unequal expansion or contraction in the tubes, or in the
metal plates to which they are fitted.
The present method of fitting tubes in the fire box of a locomotive consists in
enlarging or distending the end of the tube by means of a tube expander, so that it
tapers slightly inwards and thus a conical shoulder is formed. The end of the tube is

page_text: allowed to project beyond the metal plate, and this projecting part is hammered down
to form an annular rivet so that it is impossible for the tube to slip inside the metal
plate. The usual ferrule is inserted in the end of the tube but that I do not interfere
with. In the above arrangement it will be seen that there is no provision for
preventing the plate from being drawn back from the end of the tube, or the tube
from being thrust outwards by expansion beyond the plate as sometimes happens when
some of the tubes are heated more than others, as in that case the less heated tubes
hold back the metal plate from those tubes which are more exposed to heat, or
conversely the more expanded tubes having no power to carry the boiler plate with
them, project further through it and thus cause leakage.
My improvements which are applicable to tubes generally, consist in forming on
the tube, just inside the boiler plate a convex swell or boss tapering outwards, so that
there shall be a shoulder on each side of the joint with the metal plate, and not on one
side only as at present.
I prefer to have the ends of the tubes specially prepared or compressed so as to
have a slight conical or convex swell as shewn in the accompanying drawings
(Fig. 1).
I will now proceed to describe my invention with reference to the accompanying
drawings in which
Fig. 1 shews the longitudinal section of my improved form of tube end previous to
expansion.
Fig. 2 shews a longitudinal section of a tube in place, after being expanded by my
improved form of roller.
Fig. 3 shews the plan and end elevation of the expander with rollers in position.
Fig. 4 shews my improved form of roller in detail and full size.
a, is the tube; b, the boiler plate, c is the usual ferule, d, is the expander, an Ie, is
my improved form of roller.
I prefer to have the ends of the tubes compressed before use as before stated, as
they will then require but a slight additional expansion, but when this is not done,
I form the inner swell on the tube, by means of a tube-expander having special rollers,
hollowed in the centre, and not parallel or tapered merely, as now employed. The
end of these rollers being conical or convex, a corresponding double expansion is
formed in the tube and a double shoulder created, part of which is inside, and part
outside the plate.
In this way the tube becomes so firmly fixed to the boiler-plate that leakage is
prevented when expansion or contraction takes place..
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to he performed, I declare that what I
claim is :-
1. In a boiler tube the formation of an internal shoulder or swell inside the boiler
plate, so as to prevent the projection of the end of the tube when expanded by heat
as herein explained and set forth.
2. In a tube expander the use of a special form of roller depressed near the centre
of its length, and having a projection or swell near one end, as shewn in fig. 4, as
herein explained and set forth.
Deted this aa
M1000
HV
S. S. BROMHEAD,
97, Newgate Street, E.C., Patent Agent.