U.S. patent application number 09/955175 was filed with the patent office on 2003-01-30 for simple flexible joint for high pressure and high temperature.
Invention is credited to Moog, Olivier.
Application Number | 20030019625 09/955175 |
Document ID | / |
Family ID | 8865865 |
Filed Date | 2003-01-30 |
United States Patent
Application |
20030019625 |
Kind Code |
A1 |
Moog, Olivier |
January 30, 2003 |
Simple flexible joint for high pressure and high temperature
Abstract
A flexible joint for providing a hinged connection with an
underwater transport line or "riser" for transporting an oil or gas
fluid and that is subjected to a traction force. The joint
comprises a substantially cylindrical housing containing: a second
tubular portion fixed to one end of said housing; a first tubular
portion fixed to said underwater transport line and secured to a
laminated hinge abutment fixed to another end of said housing and
against which the traction force of said transport line is exerted;
and tubular isolation means interconnecting said first and second
tubular portions in such a manner as to confine the fluid passing
through the flexible joint.
Inventors: |
Moog, Olivier;
(Aspach-Le-Haut, FR) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Family ID: |
8865865 |
Appl. No.: |
09/955175 |
Filed: |
September 19, 2001 |
Current U.S.
Class: |
166/242.6 ;
166/367 |
Current CPC
Class: |
F16L 27/103 20130101;
E21B 19/004 20130101 |
Class at
Publication: |
166/242.6 ;
166/367 |
International
Class: |
E21B 017/05; E21B
017/01 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2001 |
FR |
01 09905 |
Claims
1/ A flexible joint for providing a hinged connection with an
underwater transport line or "riser" for transporting an oil or gas
fluid and that is subjected to a traction force, the joint
comprising a substantially cylindrical housing containing: a second
tubular portion fixed to one end of said housing; a first tubular
portion fixed to said underwater transport line and secured to a
laminated hinge abutment fixed to another end of said housing and
against which the traction force of said transport line is exerted;
and tubular isolation means interconnecting said first and second
tubular portions in such a manner as to confine the fluid passing
through the flexible joint.
2/ A flexible joint according to claim 1, wherein said tubular
isolation means include a spherical laminated abutment.
3/ A flexible joint according to claim 2, wherein said spherical
laminated abutment is mounted between a first strength member
secured to said first tubular portion and a second strength member
secured to said second tubular portion.
4/ A flexible joint according to claim 3, wherein said first and
second strength members include O-ring type sealing means.
5/ A flexible joint according to claim 1, wherein said second
spherical laminated abutment has a center of rotation O in common
with that of said first laminated hinge abutment.
6/ A flexible joint according to claim 1, wherein said housing
includes a plurality of slots to allow seawater to flow through as
a cooling fluid.
Description
TECHNICAL FIELD
[0001] The present invention relates to the offshore oil industry,
and more particularly it relates to a simple flexible joint for use
with high pressure and high temperature and designed to be fitted
to connection systems for risers (underwater lines carrying
fluid).
PRIOR ART
[0002] FIG. 3 shows an example of a simple flexible joint 10 of the
prior art as used in the offshore oil industry and designed to have
its bottom portion connected (in general via a weld 12) to an
underwater tubular structure 14 or "riser" connected to a well head
(not shown) in a gas or oil field that is to be worked, with its
top portion connected (in general by means of a plurality of bolts
16) to the head 18 of a pipe-line 20 for carrying the extracted gas
or oil fluid.
[0003] That conventional assembly includes a laminated spherical
hinge abutment 30 made up of rigid layers, e.g. of metal,
alternating with elastomer layers, the various layers being bonded
to one another. The abutment is housed between a strength member 32
in the form of a spherical cap and forming an integral portion of a
first tubular portion 34 of said assembly that is designed to be
fixed to the extraction line 14, and a strength member 36
constituted by a ring which is fixedly connected, e.g. by a
plurality of bolts 38, to a second tubular portion 40 of said
assembly and presenting in the example shown the general external
shape of a bell surmounted by a flange 42 for receiving the line
head 18. The faces of the layers of the abutment and the faces of
the cap and of the ring between which the abutments are disposed
are concentric spherical surfaces centered on a common point O
situated on the flexible hinge axis (which coincides with the axis
of the transport line). Internally, this tubular portion has a
spherical emerging end portion 44 which is designed to come into
contact with and cooperate with the spherical cap 32 so as to avoid
putting the laminated abutment 30 under tension while the riser 14
is being installed.
[0004] That conventional structure gives complete satisfaction
under most circumstances of offshore use, in particular when the
pressures involved do not exceed 400 bars and the temperatures do
not exceed 100 degrees Celsius (.degree. C.). Nevertheless, as
liquid or gas hydrocarbon reserves become rarer, more and more
fields are being worked in deep water. Unfortunately, at very great
depths (greater than 1500 meters (m)), the pressure and the
temperature of the extracted fluid are both very high (greater than
or equal to 600 bars and 120.degree. C., respectively) and
conventional assemblies of the kind described above cannot
withstand them, in particular because the laminated hinge is not
protected from the fluid.
OBJECT AND DEFINITION OF THE INVENTION
[0005] An object of the present invention is to mitigate the
above-described drawbacks by proposing a simple flexible joint
which can be guaranteed to operate under extreme conditions of
pressure and temperature. Another object of the invention is to
provide an assembly that is particularly reliable and that also
presents a long lifetime. Yet another object of the invention is to
protect the laminated hinge effectively against chemical attack by
the fluid.
[0006] These objects are achieved by a flexible joint for providing
a hinged connection with an underwater transport line or "riser"
for transporting an oil or gas fluid and that is subjected to a
traction force, the joint comprising a substantially cylindrical
housing containing: a second tubular portion fixed to one end of
said housing; a first tubular portion fixed to said underwater
transport line and secured to a laminated hinge abutment fixed to
another end of said housing and against which the traction force of
said transport line is exerted; and tubular isolation means
interconnecting said first and second tubular portions in such a
manner as to confine the fluid passing through the flexible
joint.
[0007] With this particular structure for a flexible joint, the
fluid remains confined within the housing in a central channel that
is defined in succession by the first tubular portion, the tubular
isolation means, and the second tubular portion, thereby isolating
the laminated hinge abutment from attack by the fluid.
[0008] The tubular isolation means comprise a spherical laminated
abutment which is preferably mounted between a first strength
member secured to said first tubular portion and a second strength
member secured to said second tubular portion, the strength members
advantageously including sealing means of the O-ring type.
[0009] In an embodiment, the second spherical laminated abutment
has a center of rotation O in common with the center of rotation of
said first laminated hinge abutment.
[0010] Advantageously, the housing has a plurality of slots for
allowing seawater to flow through as a cooling fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Other characteristics and advantages of the present
invention will appear more clearly from the following description
given by way of non-limiting indication and made with reference to
the accompanying drawings, in which:
[0012] FIG. 1 is a longitudinal section view through a simple
flexible joint of the invention for use with high pressure and high
temperature;
[0013] FIG. 2 is an external perspective view of the simple
flexible joint of FIG. 1; and
[0014] FIG. 3 is a longitudinal section view through a simple
flexible joint of the prior art.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0015] FIGS. 1 and 2 are respectively a longitudinal section and an
outer perspective view of a simple flexible joint of the invention
for use in extracting hydrocarbons from very deep waters (depths in
excess of 1500 m) where pressure and temperature conditions are
extreme, i.e. greater than or equal to 600 bars and 120.degree. C.
The joint itself is commonly located a little below the
surface.
[0016] Like a conventional assembly, this assembly comprises a
single laminated spherical hinge abutment 50 comprising rigid
layers, e.g. of metal, alternating with layers of elastomer, the
various layers being bonded to one another. This abutment is also
received between a first strength member 52 in the form of a
spherical cap on which there comes to rest a first tubular portion
54 of said assembly, which portion is shaped like a golf tee and is
for welding (via a weld 56) to a fluid extraction line 14, and a
second strength member 58 constituted by a ring forming the bottom
of this assembly and securely connected, e.g. by means of a first
set of stud bolts 60 disposed circumferentially to a second annular
portion of the assembly. The connection between the cap and the tee
is advantageously a pressed connection (the abutment 50 being
precompressed during assembly) with mechanical cone-on-cone
contact.
[0017] To make the assembly easier to assemble, the second tubular
portion is advantageously made up of two parts (but it would
naturally be possible for it to comprise a one-part structure as in
the prior art) comprising a cylindrical housing body 62 and a cover
plate 64 covering its top portion and surmounted by a flange 66 for
receiving the line head (not shown). The plate 64 is fixed to the
cylindrical housing in the same manner as the bottom 58 is fixed to
the bottom portion of the housing, by means of a second set of stud
bolts 68 that are likewise disposed circumferentially. The faces of
the abutment layers and the faces of the cap and of the ring
between which the abutment is disposed are concentric spherical
surfaces centered on a common point O situated on the flexible
hinge axis (which coincides with the axis of the extraction
line).
[0018] As in a conventional assembly, the traction force exerted by
the riser 14 is transmitted to the first tubular portion 54 of the
cylindrical housing 62 by the laminated abutment 50 which also
accommodates angular variations of the riser 14 in all
directions.
[0019] According to the invention, the laminated hinge abutment 50
is isolated from attack from the transported fluid by tubular
isolation means 70 disposed between and in line with the first and
second tubular portions to which they are connected to form a
confinement channel 72 for the fluid under pressure and at high
temperature. For this purpose, the first tubular portion 54 is
secured rigidly by first connection means 74 (although a simple
force-fit would also be possible) to a hemispherically-shaped first
strength member 76 of a second laminated abutment 78 whose
ring-shaped second strength member 80 is securely fixed by second
connection means 82 to the plate 64 of the second tubular portion.
This second laminated abutment is likewise of a structure that is
concentric about a center of rotation O in common with that of the
hinge abutment 50.
[0020] The confinement channel is frustoconical in shape, being of
smaller section level with the first tubular portion and isolation
of the fluid is reinforced by sealing means of the O-ring type 84,
86 mounted firstly between the first strength member and the first
tubular portion, and secondly between the second strength member
and the cover plate, and preventing fluid from flowing towards the
laminated hinge abutment 50. In addition, in order to ensure that
heat is removed effectively, the cylindrical housing includes a
plurality of slots 88 that are regularly distributed around its
periphery and that allow seawater to flow inside the housing,
thereby ensuring that it is at the same pressure as the surrounding
ocean. The particularly high internal pressure flowing in the
transport line and passing through the joint therefore does not act
on this housing and thus does not act either on the laminated hinge
abutment 50.
[0021] With this particular structure, the laminated hinge abutment
50 which takes up both tension from the line and angle variations
due to the riser 14 (i.e. which takes up mechanical forces), is
completely protected from chemical attack, and also from the
pressure and the temperature of the fluid, by the second laminated
abutment 78 which performs this separation function (confinement
barrier) between the fluid and the hinge abutment 50. This second
abutment which takes up the pressure of the fluid and which
accompanies the variations of angle (because of its secure
connection to the tee 54 fixed to the riser) can, in contrast,
accommodate a certain amount of damage due to the fluid since it
has little influence on the overall mechanical strength of the
assembly.
* * * * *