Improvements in Flexible Metallic Tubing.
Year: 1899

page_text: Date of Application, 5th Oct., 1899
Completo Snanifination Loft 25th Move 4000
1
CIL
JABA
Improvements in Flexible Metallic Tubing.
A communication by CHARLES RUDOLPH, of 66, Rue du Théatre, Paris, in the
Republic of France, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., Agent for Foreign Patent
Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to that kind of flexible tubing which is formed by
giving a suitable cross section to metal strips and winding them helically in
such a way that the coils of the successive turns engage one with the other.
This invention has for its object to provide improvements in the cross sec-
tions actually employed so as to give more strength, durability and tightness
to this kind of tubing, whilst preserving to them a great flexibility or elasticity.
In English Patent No. 9478 of the 8th August 1885, tubing of this kind is
described as being made (as may be seen in the drawings thereof) by means
of a metallic strip of double channelled or S section, that is to say having
corrugations forming two juxtaposed channels (m n) having one side (a) in
common, the cavities of these channels being turned in reverse directions. In
winding this shaped strip spirally, the extreme edges (6 c) interlock reciprocally
in the adjacent channels of the strip of one coil or turn and of the following,
and as there is play in this system of interlocking, the pipe may elongate or
contract or be bent in all directions. In order to ensure the tightness of the
joints of this tubing, a thread or strip of indiarubber (h) or other suitable
material adapted to ensure the tightness of the joint, is inserted between the
edges of the strips which interlock one with another. This tubing is intended
for containing fluids and liquids of all kinds, but it has been found that gases
or fluids and even air or water somewhat rapidly oxidises the extreme edges (b_c)
of the shaped metallic strips and that these edges being partly worn away by
this oxidisation, the tubing soon becomes useless. It has also been found that
the elastic packing was not always sufficiently held in its place, especially
when the tubing contains steam or other fluid under pressure.
In the improvements which form the object of this invention, these draw-
backs are remedied in the following manner:-The extreme edges (b c) are
strengthened by means of a prolongation given to the strip which forms the
suitably shaped or profiled band for forming the tubing, said prolongation being
bent down against the external edge of each channel to form a kind of hook.
In this way fluids or liquids commence first by attacking this overlapping

page_text: part or hook-shaped cover of the external edges, and during this time the
external edges of each channel are protected, which imparts a much greater
durability to the tubing. At the same time the external edge of each channel
having thus a double thickness of metal, it is easily understood that the tubing
is rendered much more solid. It is of course evident that according to the
particular circumstances the prolonged edges may be bent back either on the
inner or the outer side of each channel and this will depend on the special
form adopted for each shape of strip.
In case it is necessary to maintain the elastic washer or packing more firmly
in its seating, for instance when the tubing is intended to contain steam,
gutters or grooves are formed in the walls of the cross section parallel to the
axis of the tubing, in which grooves the major part of the elastic washer is
lodged. This may be most conveniently attained by forming the protective
piece in such a way that it is turned or bent on the inner side of the channel
but preferably horizontally or not far enough to lie flat against the other part
and then forming the grooves in this part.
It will be readily understood that the form given to the protecting or
strengthening piece of the this invention may be varied without departing from
the spirit of the invention.
1
1000
A communication by CHARLES RUDOLPH, of 66, Rue du Théatre, Paris, in the
Republic of France, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., Agent for Foreign Patent
Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil 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 relates to that kind of flexible tubing which is formed by
giving a suitable cross section to metal strips and winding them helically in
such a way that the coils of the successive turns engage one with the other.
This invention has for its object to provide improvements in the cross sec-
tions actually employed by thickening their ends so as to give more strength,
durability and tightness to this kind of tubing, whilst preserving to them a
great flexibility or elasticity.
The object of the invention is shown clearly in the accompanying drawings,
in which,
Figure 1 is a view in perspective partly in section of a tube formed by wind-
ing helically a shaped band;
Figure 2 is a section on an enlarged scale of a shaped metallic band provided
with the improved arrangements;
Figures 3 and 4 are sections of modifications in the shape shown in Figure 2;
Figure 5 is a section of the form at present used not provided with the
improvements;

page_text: Figure 6 shows the application of the improvement to an already existing
form, which latter is shown in Figure 7;
Figure 8 is a modification of the way of carrying out the improvements;
Figure 9 is a view in perspective partly in section of a band serving for pre-
paring the shaped band shown in Figure 8;
Figure 10 shows the band of Figure 9 rolled out and having its extreme
edges strengthened in the rolling ;
Figure 11 is a similar view to Figure 10 showing a modification in the con-
struction of the outer strengthened ends.
In English Patent No. 9478 of the 8th August 1885, tubing of this kind is
described as being made by means of a helically wound.metallic strip of double
channelled section, Figures 1 and 5, that is to say having corrugations forming
two juxtaposed channels having one side (a) in common, the cavities
of these channels being turned in reverse directions. In winding this
shaped strip spirally, the extreme edges (b c) interlock reciprocally in the adjacent
channels of the strip of one coil or turn and of the following, and as there is
play in this system of interlocking, the pipe may elongate or contract or be
bent in all directions. In order to ensure the tightness of the joints of this
tubing, a thread or strip of indiarubber (f) (Figure 2) or other suitable material
adapted to ensure the tightness of the joint, is inserted between the edges of the
strips which interlock one with another. This tubing is intended for containing
liquids and fluids of all kinds and especially compressed air, but it has been
found that most of these gases or fluids and even water somewhat rapidly oxidises
the extreme edges (c) of the shaped metallic strips which when the band is wound
are inside the tube and that these edges being partly worn away by this oxidi-
sation, the tubing soon becomes useless. Practical experiments have demonstrated
that when the tubing is subjected to the pressure of fluids contained therein,
the edge b on the external face becomes stretched and allows the elastic packing f
to be ejected outwardly. In the Specifications of subsequent British Patents,
various forms of the strips have been described.
In the improvements which form the object of this invention, these draw-
backs are remedied in the following manner, as shown in Figure 2. It will be
seen in this figure that the interior of the tube being on the side indicated by
the arrow, the edge c is protected by a band c¹ bent back on itself and bent
down against the external edge of each channel to form a kind of hook.
In this way fluids or liquids which attack metal and are contained in the
tubing commence first by attacking this bent back part c¹ which at the same
time will rub on the central part a and the part c¹ will be the part which first
wears away.
It is therefore important that this bending down shall be made towards the
outside, because if it were made towards the interior, the side c would wear away
in the first place and this worn side detached from the rest of the band the bent
back part c would no longer be of any use. Further the lowest part of the bent
back edge is slightly turned over against the edge c in order to prevent water
passing between the edges c and c¹ and oxidizing the edge c.
With the object of increasing the strength of the tubing the external edge b
is also doubled, on this side where the attack of rust on the extreme edge bis
not to be feared the bent back part 61 is made against the internal face of the
edge b, as is shown in Figure 2.
In Figure 3 a section is indicated in which the parts 6' and care both bent
back on the external sides of the edges b and c.
In the form shown in section in Figure 4 on the contrary it will be seen
that the parts and c¹ are both bent back on the internal faces of the edges b
and c and according to the particular circumstances for which this kind of
tubing is employed one or other of the arrangements described may be preferable
either for the protection of the tubing from oxidation, or to strengthen it.
It must be understood that my correspondent does not limit his invention of

page_text: the addition of the bent back edges on the extreme ends to the peculiar shape
that he has shown in the drawings, but he may employ it with any shape to which
he finds it can be advantageously adapted. For instance he may employ the
shape shown in Figure 7 which forms the object of a patent in the United
States of America No. 605587 obtained by him under date of June 14th 1898.
This shape is characterised by the arrangement in which the packing f is not
placed in channels which engage one in the other but is located in a large special
channel formed in the winding towards the interior of the tubing and the bottom
of which is at the same level as that of the adjacent channels. The characteristic
point of this arrangement is to enable shaped strips to be wound on a mandrel,
which can only be accomplished with the shape indicated, as long as the
bottom of the channel which serves for holding the packing is at the same
level as that of the adjacent channel in such a way that both are supported by
the mandrel on which the winding takes place.
Figure 6 shows how the improvement is applied to a band of the shape indi-
cated in Figure 7.
On the inner side of the tubing, the edge e is protected aganist oxidation by
the bending down of the part e¹ against the external face of the edge e and
the edge b is strengthened in order to offer more resistance to pressure from
the interior of the tubing by means of a part 61 bent back on the internal face
of the edge b.
Figures 8, 9, 10 and 11 illustrate modifications in the means of obtaining the
extreme strengthened edges.
In Figure 8 it will be seen that the strengthened edges are no longer formed
by bands bent back on the extreme edges as in Figures 2, 3 and 4, but that these
strengthened edges are formed in one piece. As may be seen in Figure 8 the
extreme edges m and n have a greater thickness than the rest of the shaped band
forming the tubing. In consequence of this arrangement the edge n thus
strengthened is better adapted to resist the attacks of rust, and the edge m gives
more strength to the tubing for resisting internal pressures. The advantage
of this arrangement over that shown in Figure 2 is that the edges thus strengthened
form a single piece and there need be no fear of gas or liquids being introduced
between the parts c and c¹ shown in Figure 2 bent back one upon the other.
It is also an advantage to form the extreme edge m, Figure 8 of a single piece
instead of being in two parts as shown in Figure 2, because there is no longer
any cause for fear the packing f of india-rubber or other suitable substance will
be pinched and torn between the corner of the part 6 and the adjacent metal.
The shaped band with strengthened edges shown in Figure 8 is then wound
helically as shown in Figure 1 to form the tubing.
In order to provide the shaped bands with strengthened edges in a single piece,
my correspondent proceeds in the following manner. By one method in order
to obtain the band which must be shaped to form the tubing, he selects a flat
metallic band having a greater thickness than that of the finished band. This
thicker flat band is shown in Figure 9. This band is then passed into a rolling
mill in order to give it the form shown in Figure 10. In this figure it will be
seen that the central part of the band is thinner than the edges m and n.
instead of the shoulders of the parts m and n being at right angles with the
remainder of the band as shown in the figure these edges may be rounded. The
band shown in Figure 10 is then bent so as to give it the shape shown in
Figure 8.
Further
My correspondent may also make the extreme strengthened edges in a single
piece in the following manner which will now be described with reference
to Figure 11. For this object he selects a band of metal having a thickness
equal to the final thickness of the band which is to be shaped to form the tubing.
He then bends over the ends at o and p to a thickness corresponding to the
height of the extreme edges, and he connects by fusing, soldering or welding
the bent over ends o and p with the adjacent parts o¹ p¹. Preferably he performs

page_text: this fusing, soldering, or welding by means of electricity, but it is evident that he
may employ any other suitable means. The band thus prepared is then bent
to assume the form shown in Figure 8.
Finally he does not limit himself to the shapes or forms hereinbefore indicated,
but he may apply the strengthening of the extreme edges to any other shape
which he may find it advantageous to employ.
It must also be understood that he may apply the strengthening to only
one of the extreme edges of the tubing if such be considered more desirable.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is:-
1. The improvement in flexible metallic tubing formed of helically wound
shaped metallic strips which consists in strengthening the extreme edges by
bending back parts (6¹ and c¹) of said edges upon themselves towards the exterior
or the interior, substantially as described with reference to Figures 2, 3, 4 and 6
of the accompanying drawings.
2. In flexible tubing formed of helically wound shaped metallic strips the
strengthening of the extreme edges of the shaped strips, by thickened parts form-
ing one piece therewith substantially as described with reference to Figure 8
of the accompanying drawings.
3. The method of obtaining bands or strips with strengthened edges intended
to be shaped and helically wound to form flexible tubing which consists in rolling
metallic strips so as to give them substantially the shape indicated in Fig. 10
in which the extreme edges (m and n) are thicker than the body of the strip,
and in then bending or shaping them to the form substantially as indicated in
Figure 8 of the drawings.
4. The method of obtaining bands or strips with strengthened edges intended
to be shaped and helically wound to form flexible tubing, which consists in bend-
ing over the extreme edges of a flat band or strip as indicated in Figure 11, and
in attaching these bent over edges solidly to the part with which they are in
contact by fusing, soldering, brazing or welding which may be effected by the
usual means but preferably by electricity, the said band or strip being then
shaped substantially as indicated in Figure 8 of the drawings.
Dated this 24th day of May 1900.