Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGR0~1ND OF THE INVENT ION
The invention relates to a sealedcoupling device
for hollow cylindrical lengths, said device having a female
member and a male member.
The invention relates especially to sealed
coupling device which can be submitted to high pressures
and temperatures, higher than 100 bars and 100C respec-
tively, without significant reduction of mechanical and
tightness properties even during tests submitting said
10 device to thermal shocks,to many pressure setting cycles
and to quickened ageing.
In known couplings having flanges between wich
an O-ring is disposed, a fluid under pressure in a pipe
having such a coupling applies a force tending to thrust
15 aside flanges at a location radially inside relatively
to O-ring, and holdin~ means apply an holding force
having a direction inverse to that of the force applied
by fluid, at a location radially outside relatively to
O-ring, such as said forces form a couple tending to
20 thrust aside the flange surfaces at the O-ring location
and to reduce sealing properties.
PRIOR ART
British patent n 820 113 discloses a coupling
device of such general type, in which a sealing ring is
25 very close to the internal surface of pipe lengths in
order to reduce the thrusting aside forces applied to
pipe lengths, due to fluid under pressure acting on
areas between said internal surface and sealing ring,
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by reduction of the area on whichthe fluid pressure is
applied. However, holding force of the two flanges is
applied radially outside relatively to sealing ring so
that, when the pressure of fluid in the pipeis high, the
5 two lengths tend to be thrusted aside and to reduce the
sealing properties. Moreover, according to said patent,
sealing ring is not all around confined so that the
internal fluid pressure can push said ring in a cavity
disposed radially outside.
French patent n 2 138 250 discloses a coupling
device in which an O-ring is received in a groove which
is formed as inwards as possible,because it is limited
on one face by a spigot of a pipe length which enters
into a bore of a complementary length. Said patent so
15 discloses an arrangement in which the thrusting aside
forces applied radially inside relatively to the O-ring
are reduced to substantially zero. However, holding means
of the two coupling members also applies an holding force
radially outside relatively to O-ring such as sealing
20 properties are also reduced at the O-ring location.
In the application considered in said French patent,
such feature has not a great importance because pipes
havea very small diameter and a very great thickness
comparatively to diameter, so as sealing is not a
25 substantial problem.
However, the disclosed arrangements are com-
pletely useless in the case of very large diameter pipe
lengths. Indeed, for reducing space, weight and espec1ally
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cost, it is not possible to use thicknesses higher than
that which are strictly required for resisting to high
forces applied by fluid under pressure. So, in the case
of pipe lengths having a diameter of 508 mm and containing
5 the fluid at a service pressure of 70 bars, the thrusting
aside force, at a test pressure of 105 bars, is 2,1.106 N.
Using technics such as disclosed in above
mentioned patents would require a considerable over-
dimensioning of members.
OBJECTS OF THE INVENTION
An object of the invention is to provide a
solution to the mentioned problem not by overdimensioning
of the different elements but by removing force couples
just at the location where their effect is the most
15 detrimental.
Another object of the invention is to remove
the force couples tending to thrust aside pipe lengths
at the location of a sealing ring by application of
holding force resultant in such a manner that its compo-
20 nent parallel to the axis of the coupling device inter-
sects said sealing ring.
Another object of the invention is to provide
a coupling device in which, when all forces applied are
considered in space, the geometrical locus of application
25 points of resultant of forces applied by the holding
device is on a circle having a diameter substantially equal
to the mean diameter of a groove receiving sealing ring.
Another object of the invention is to provide
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a coupling device which may be submitted to high pressures
and temperatures.
Another object of the invention is to provide
a coupling device having a good resistance to thermal
5 shocksand to pressure setting cycles.
According to the invention, there is provided
a sealed coupling device for two hollow cylindrical
lengths, including : :
- a femalemember def1nins a cylindrical
10 cavity whose bottom forms a first supporting surface
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substantially perpendicular to the axis of said cavity,
- a male member having a second supporting
surface and for penetrating in female member, :
at least a sealing r1ng received in a cir- -
15 cular groove formed in one of said supporting surfaces
} and for sealingly engaging ~ the:other supporting
surface when male and fèmalemembers are engaged, and
a clamping ring or securing~ma~le member
::~ in female member ¢avity, by application of;forces pushing
20 male member to supporting surface of female member.
According to the invention, when maIe and female members
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are secured one against the other by said clamping ring,
- said two supporting surfaces are mutually
in contact and all around confine said sealing ring in;
25 the groove, and ~ .
- the geometrical locus of application points
~ of resultant of forces applied by said cIamping ring
i to said male member:in each axial half-plane is on a
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circle whose diameter is substantially equal to the mean
diameter of said groove.
Preferably, the mean diameter of said other
supporting surface which has not said groove is also
5 approximatively equal to said mean diameter of said
- groove.
In a first embodiment, said female member
has protrusions directed inwards said cavity and said
clamping ring has protrusions for engaging
10 protusions of said female member, said protrusions
being evenly disposed at the internal perimeter of said
female member and at the external perimeter of said
clamping ring in such a manner to form a bayonet assembly.
By example, engaging protxusions - of female member and
lS of clamping ring define helical ramps. Further,
said protrusions of female member and of clamping ring
have preferably different lengths in order that one of
said protrusions extends beyond another protrusion
when the coupling device is in an engaging position.
Moreover, helical surfaces of ramps, in an
axial section, are preferably tilted to a
plane transverse to the female member axis in such a
manner that, when said female member and said clamping
ring are engaged, said protrusions of female member
25 are pushed to the cavity axis.
In a other embodiment, said clamping ring is
screwed in the female member.
Preferably, the clamping ring surface engaging
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said male member and the male member surface engaging
said clamping ring are both truncated cones, having the
same conical angle, in order that the coupling device
clamping provides for mutual centering of male and female
5 members.
In another embodiment, said supporting surfa-
ces of male and female members are truncated cones having
the same conical angle, so that said two members are automa-
tically and mutually aligned when said coupling
10 device is clamped.
Preferably, suitable means prevent clamping
ring rotation relatively to female part when clamping
ring has been clamped.
According to a variant, said clamping ring
15 includes several parts so that it may be positioned
on a pipe after welding of coupling device members
to the two pipe ends.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention
20 can be more fully understood from the following detailed
description with reference to the accompanying drawings
in which :
- fig. 1 is a schematic section of a known
coupling device ;
- fig. 2 is a perspective, with parts removed,
of a first embodiment of coupling device according to the
invention, in engaged position ;
- fig. 3 is a longitudinally sectional viewof
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the clamping ring of the coupling device illustrated in
fi~. 2 ; and
- fig. 4 is an axial section of another embodi-
ment of a coupling device according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
-
Fig. 1 is a schematic section of a coupling de-
vice of the general type to which the invention is related.
In fig. 1, each of two pipe lengths 10, 12 includes a
flange 14, 16 and tightness between the two flanges is
10 provided by an O-ring 18 received in a suitable groove
of one of said flanges 14, 16. As tightness is provided
only by O-ring 18, fluid carried in pipe including lengths
10 and 12 can migrate up to O-ring 18 as indicated by 20.
The fluid under pressure, acting on surfaces of the two
15 flanges 14 and 16, applies thrusting aside forces illus-
trated as their resultant 22. Thrusti~g aside forces
are usually opposed by ~pplication of holding forces
illustrated as their resultant 24. As forces 22 and 24
haveopposed directionson each flange, in each sec-
20 tional plane, as illustrated in fig. 1 by example, eachflange is acted by a force couple tending to thrust
O-ring 18 aside from the opposing surface.
According to the invention, said couple of
forces 22, 24, tending to thrust aside flanges 14, 16
25 at the O-ring 18 location, is removed just at the loca-
tion of said O-ring by application of resultant 24 in
such a manner as its component parallel to coupling de-
vice axis or said resultant 24 itself when it is parallel
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to said axis, intersects O-ring 18.
The coupling device illustrated in fig. 2 and 3,
generally indicated by 28, is for coupling two pipe lengths
30, 32. It includes a female member 34, a male member 36
5 and a clamping ring 38. Female member 34 which has been
welded in a workshop to pipe length 30 as indicated by
39, previously to coupling, includes a cylindrical portion
40 extending from pipe length 30, a flange-like portion
42 forming an internal supporting surface 44 in which
10 a circular groove 46 is machined, and an external cylin-
drical portion 48. Said external portion or sleeve 48 has
protrusions 50 forming bearing surfaces and extending
inwards. Bearing surfaces of protrusions 50 facing suppor-
ting surface 44 constitute helical ramps.
Male member 36 includes a cylindrical portion 52
extending from pipe length 32 to which it is welded as
indicated by 53. Male m~mber further includes a flange
54 extending outwards and forming a supporting surface
56 for engaging said supporting surface 44 of said female
20 member.
Clamping ring 38 includes a cylindrical body 58
having protrusions 60 extending radially outwards and
notches 62 in the radially external surface.
The coupling device further includes an O-ring
25 64 received in groove 46 of female member 34.
According to the invention, the two supporting
surfaces 44 and 56 of female and male members 34 and 36
are in mutual contact and all around confine 0-ring 64.
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Further, forces applied by clamping ring 38 to male mem-
ber flange 54 are such that, in each axial section plane,
the application point 66 of resultant 68 of forces applied
by ring 38 to flange 54 is at the same distance from lon-
5 gitudinal axis 70 of coupling device as the groovecenter. So, application axis 72 of resultant com-
ponent parallelto axis 70 intersects the center of groove
46 approximatively.
Fig. 2 is not drawn to scale. Indeed, female
10 member sleeve 48 is illustrated as being very far from
the external portion of flange 54 to clearly illustrate
engagement of bearing surfaces of protrusions 50 and 60
of female member and of clamping ring respectively. In
fact, proportions are as illustrated in fig. 3 which shows
15 only clamping ring with protrusions 60 forming helical
ramps 74 for engaging with helical ramps of protrusions 50.
It is to be u~derstood from fig. 2 that bearing
surfaces 76 of female member protrusions 50 and of clamping
ring protrusions 60 are tilted to a plane trans-
20 verse to axis 70 and descend when approaching said axis,in fig. 2, and so, when clamping ring is clamped, applied
forces have a component parallel to axis 70 of coupling
device but also a radial component. Said radial component
is directed inwards on protrusions 50 and outwards on
25 protrusions 60. So, when ring is clamped, protrusions 50
tend to be drawn nearerto axis 70 and prevent spreading
out of female member sleeve 48 which has a higher strength
because applied forces are compression forces. Further,
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clamping ring self-centers relatively to female member
protrusions.
It is further to be understood that, in the
embodiment of fig. 2, engaging surfaces of male member
5 flange 54 and of clamping ring 38 form truncated cones
and, when ring 38 is clamped on female member 34, male
member 36 tends to self-align on female member.
When coupling device is to be used, female mem-
ber 34 is welded to length 30 and male member 36 is welded
10 to length 32, in a workshop, after threading clamping
ring 38 on length 32. When lengths are coupled on the
field, male member is introduced in female member and
clamping ring slides in order that its protrusions 60
are indexed on spacesbetween female member protrusions S0.
15 Then, turning of ring 38 in a suitable direction provides for
engagement of protrusions 50 and 60 and application of
: male member against fema~le member, the O-ring being clamped.
The device may be locked by drilling a hole 77 in sleeve
48 and one of protrusions 60 and by introducing a pin,
20 or by hammering a protruding end of one of protru-
sions.
Fig. 4 shows another embodiment of the invention
in which the clamping ring is threadingly engaged with
the female member. So, coupling device 78 according to
25 the invention is for coupling two pipe lengths 80, 82.
A female member 84 welded to length 80 has a supporting
surface 90 normal to longitudinal axis of device 78 and
in which a groove 92 is formed for receiving an O-ring 94.
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An external portion or sleeve 96 of female member 84 is
provided with female screw 98.
An male member 86 has a supporting surface 100
for engaging said female member surface 90.
A clamping ring 88 has a male screw 102 comple-
mentary to female screw 98. Preferably, the thread is of
the type used in pieces of artillery and apt to support very
heavy loads parallel to the coupling device axis. Said
ring has protrusions 104 extending from its external ra-
10 dial surface and for allowing clamping of ring 88.
When said coupling device according to the in-
vention is to be used, female member 84 is welded to
length 80, in a workshop, and male member 86 is welded
to length 82, after threading ring 88 on said length.
15 When lengths 80 and 82 have been put at the required lo-
cation, male member is introduced in female member and
ring 88 is screwed in fe~ale member so that it pushes
male member against female member. After full screwinq,
ring 88 is preferably locked to sleeve 96 by local dis-
20 torsion of thread with a tool introduced in a hole 103drilled transversallyin sleeve 96.
Obviously, many variants of the coupling device
according to the invention are possible. So, in the embo-
diment of fig.2 and 3, the number of protrusions of
25 fe~ale m~er and of clamping ring may be changed. In the
embodiment of fig. 4, male screw 102 or female screw 98
may be conti~ous or discontinous.
In the embodiment of fig.2 and 3, it is stated
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that engaging surfaces of clamping ring and of male member
are truncated cones and that engaging surfaces of
clamping ring and of female member have tilted helical
ramps in order to provide mutual centering of male member
5 and female member. In the embodiment of fig. 4, no
self-centering means is described. However, the different
embodimentscan include such centering mean~, -
either as described referring to fig.2, or of another
type. By example, supporting surfaces of male and female
10 members may be themselves slightly conical and comple-
mentary so as they themselves provide centering.
The sealing ring is described as received in
female member, but obviously, the groove may also be
formed in male member.
Clamping ring 38 or 88 is described as unitary.
Such feature is not mandatory. Using clamping ring having
at least two parts is especially convenient in order to
allow mounting of said ring on a pipe length having a
coupling device member, after weldingof male or female
20 member on said length. The clamping ring needs only to pro-
vide suitable application of required forces against the
male member flange, after mounting of the different parts
of said clamping ring. By example, in the èmbodiment of
fig. 2, clamping ring may be simply cut diametrally into
25 two parts, with possibly centering or hinge means provi-
ding a suitable positioning of the two parts of said ring.
In the embodiment of fig. 4, said ring can also be diame-
trally slit and centering means, by example having a
13
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V shape, provide suitable positioning of the two half-
rings. In this latter embodiment, interruption of ring
screw near engaging surfaces of ring parts is preferable.
Male and/or female members can obviously be
5 coated by a dielectric layer, the coupling device then
forming an insulating coupler.
The coupling device according to the invention
may be disassembLed without perturbations other than minor ones
which do not preclude its reuse.
The device according to the invention is espe-
cially suitable for carrying under pressure, in pipes
having a great diameter, fluids as hydrocarbons and
natural gas, and solids as minerals and coal, the
internal surface of pipes being then possibly provided
15 with a coating resistant to abrasion by solids.
14
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