U.S. patent application number 13/547874 was filed with the patent office on 2012-11-08 for part for connecting pipes including an internal liner, a covering method, and a method of assembly.
This patent application is currently assigned to Saipem S.A.. Invention is credited to Francois-Regis PIONETTI.
Application Number | 20120280488 13/547874 |
Document ID | / |
Family ID | 36084320 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120280488 |
Kind Code |
A1 |
PIONETTI; Francois-Regis |
November 8, 2012 |
Part for connecting pipes including an internal liner, a covering
method, and a method of assembly
Abstract
A method of covering the inside surface of a steel connection
part having an empty inside volume (1-2) defined by said inside
surface, with a liner constituted by a layer of substantially
uniform thickness of a thermoplastic material. The connection part
including at least two open tubular ends suitable for being
connected respectively to at least two steel pipe elements, each
including the same internal liner. A rotary molding method is
implemented in which the connection part acts as a mold. The
present invention also provides a connection part obtained by the
rotary lining method of the invention, and to methods of assembling
a connection part of the invention, as obtained by rotary lining,
with a likewise lined pipe element.
Inventors: |
PIONETTI; Francois-Regis;
(La Baleine, FR) |
Assignee: |
Saipem S.A.
Montigny Le Bretonneux
FR
|
Family ID: |
36084320 |
Appl. No.: |
13/547874 |
Filed: |
July 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11988255 |
Jan 3, 2008 |
8256089 |
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13547874 |
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Current U.S.
Class: |
285/55 ;
137/15.01 |
Current CPC
Class: |
Y10T 137/0402 20150401;
B05D 3/0254 20130101; Y10T 29/49982 20150115; B05D 1/32 20130101;
Y10T 29/49826 20150115; B05D 7/52 20130101; B05D 1/30 20130101;
Y10T 29/49885 20150115; B05D 1/002 20130101; Y10T 403/17 20150115;
F16L 58/1009 20130101; Y10T 29/4998 20150115; B05D 7/222 20130101;
B05D 2202/10 20130101 |
Class at
Publication: |
285/55 ;
137/15.01 |
International
Class: |
F16L 9/147 20060101
F16L009/147; B23P 11/00 20060101 B23P011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2004 |
FR |
PCT/FR2006/001354 |
Jul 5, 2005 |
FR |
05/07153 |
Claims
1. A steel connection part having an empty inside volume defined by
a non cylindrical inside surface, with a liner constituted by a
layer of substantially uniform thickness of a thermoplastic
material, said connection part having at least two open tubular
ends suitable for connecting respectively to at least two steel
pipe elements having the same internal liners.
2. The connection part according to claim 1, further comprising at
at least one of its ends, a first connecting flange which is welded
thereto, said first connecting flange being suitable for
co-operating with a second connecting flange of one of said two
pipe elements for connection to said connection part.
3. The connection part according to claim 1, wherein at at least
one of its said open tubular ends said internal liner of
thermoplastic material includes an end portion of thickness that is
reduced relative to the thickness of the remainder of said liner,
which end portion is obtained by machining and thus defines an
inside surface of revolution of inside diameter greater than the
inside diameter of the remainder of said internal liner and
terminating at a certain distance from the end of said connection
part.
4. The connection part according to claim 1, wherein the
thermoplastic material comprising of polyethylene, polypropylene,
polyamide, and polyvinyl.
5. The connection part according to claim 1, wherein said
connection part is a bent pipe element suitable for enabling two
pipe elements that extend in different directions to be connected
together by being connected to respective ends of said bend element
constituting said connection part.
6. The connection part according to claim 1, wherein said
connection part is a T-shaped element suitable for enabling three
pipe elements to be connected to its respective ends, the elements
extending in two directions making between them an angle lying in
the range 0 to 90.degree., and preferably of 90.degree..
7. The connection part according to claim 1, wherein said
connection part is a tapering tubular sleeve presenting two tubular
ends of circular cross-sections that are of different inside
diameters, suitable for enabling two pipe elements of diameters
corresponding respectively to the inside diameters of the two
tubular ends of said tapering tubular sleeve to be connected
thereto.
8. The connection part according to claim 1, wherein said
connection part comprises walls with zones of smaller thickness,
said zones of smaller thickness being thermally insulated.
9. The connection part according to claim 1, wherein said layer
comprises a first layer of a first thermoplastic material; and a
second layer of a second thermoplastic material different from said
first material, said second thermoplastic material covering said
first material.
10. The connection part according to claim 2, wherein said
connection part comprises, at at least one of its tubular ends,
said first connecting flange, and the said layer is made
continuously over the entire combined inside surface of the
connection part and over said first connecting flange with a layer
of said thermoplastic material, said first flange being fastened by
welding to the end of said connection part.
11. The connection part according to claim 10, wherein said first
flange comprises an external bearing face bearing against said
second flange and whereby said first flange bears against said
second flange, said layer of thermoplastic material being made
continuously over said inside surface of the connection part and
said inside surface of said first connecting flange, and also over
said external bearing face of said first flange bears against said
second flange.
12. An assembly method of assembling a pipe, wherein a connection
part is assembled with a pipe element including an internal liner,
said connections part comprising: an empty inside volume defined by
a non cylindrical inside surface, with a liner constituted by a
layer of substantially uniform thickness of a thermoplastic
material, said connection part having at least two open tubular
ends suitable for connecting respectively to at least two steel
pipe elements having the same internal liners.
13. The assembly method according to claim 12, wherein: said
connection part includes a first connecting flange to which it is
welded, with the entire combined inside surface of the connection
part and of said first connecting flange, and also the external
bearing face of said first flange for bearing against said second
flange are covered in a said continuous layer of thermoplastic
material; and said pipe element includes at its end a second
connecting flange to which it is welded, the entire combined inside
surface of said pipe element and of said second connecting flange,
and also the external bearing face of said second flange for
bearing against said first flange are covered in a said continuous
layer of thermoplastic material; and said first and second
connecting flanges are connected together, preferably against an
interposed gasket.
14. The assembly method according to claim 12, wherein a said
connection part is assembled with a said pipe element with the help
of a tubular junction sleeve, and in that said junction sleeve is
inserted inside the open tubular end of said connection part at one
end of said sleeve, which sleeve presents substantially the same
inside diameter as is presented by said internal liner of said
connection part.
15. The assembly method according to claim 14, wherein said
junction sleeve is inserted: via one end of said sleeve into the
inside of the open tubular end of said connection part, which end
does not have a connecting flange; via the other end of said sleeve
into the inside of the corresponding end of said pipe element,
which end does not have a said connecting flange; and the ends of
said connection part and of said pipe element are moved towards
each other and welded together over said junction sleeve.
16. The assembly method according to claim 15, wherein the
following steps are performed: a) said connection part, said pipe
element, and said tubular junction sleeve are prepared in such a
manner that: each of the internal liners of thermoplastic material
at the open ends of said connection part and of said pipe element
includes an end portion of thickness that is reduced relative to
the thickness of the remainder of said liner; and said sleeve
presents at each of its ends an end portion of thickness that is
reduced relative to the thickness of the central portion of said
sleeve, said end portion of the sleeve defining an outside surface
of revolution of outside diameter less than the inside diameter of
the non-lined ends of said connection part and of said pipe, said
sleeve presenting substantially the same inside diameter as said
internal liner of the main portions of the connection parts and of
said pipe element; and b) said tubular junction sleeve is inserted
into said open tubular ends of reduced thickness of the liner of
said connection part and of said pipe element so as to overlap said
reduced-thickness end portions of liner.
17. The assembly method according to claim 12, wherein a connection
part is assembled and the following steps are performed: a)
initially the following are prepared: said connection part
including a first connecting flange to which it is welded, with the
entire combined inside surface of the connection part and of said
first connecting flange being covered in a said layer of
thermoplastic material; said pipe element having at its end a
second connecting flange to which it is welded, the entire combined
inside surface of said pipe element and of said second connecting
flange being covered in a said layer of thermoplastic material; and
b) machining the internal liners of thermoplastic material at the
ends of said connection part having a said first flange and of said
pipe element having a said second flange in such a manner as to
create in each of said internal liners an end portion of thickness
that is reduced relative to the thickness of the remainder of said
liner, and terminating at a certain distance from said ends of said
connection part and of said pipe element respectively such that the
inside surfaces of said first and second flanges are not lined; and
c) inserting at each of the open ends of said first and second
flanges tubular junction half-sleeves for reinforcing the junctions
between said connection part and said first flange and between said
pipe element and said second flange, each said half-sleeve
presenting: at its front end, a front end portion of tubular wall
of thickness that is reduced relative to the central portion of the
tubular wall of said half-sleeves; at its rear end, a rear end
portion of tubular wall of thickness greater than the thickness of
the central portion of said half-sleeve; each half-sleeve being
inserted in such a manner that said front end portions of reduced
wall thickness of said half-sleeves overlap said end portions of
reduced thickness of said liners of said connection part and of
said pipe elements respectively; d) welding said half-sleeves to
said first and second flanges respectively at said rear ends of
said half-sleeves and external bearing faces of said first and
second flanges, respectively; and e) moving together and fastening
to each other said first and second connection flanges.
18. The assembly method according to claim 17, wherein: said
tubular junction sleeves, and where appropriate said tubular
junction half-sleeves are of material that withstands corrosion;
and the outside diameter of the cylindrical central portion of said
sleeve or of said half-sleeve is less than the inside diameter of
the non-lined ends of the steel walls respectively of said
connection part, of said pipe element, or where appropriate of said
first and second flanges.
19. The assembly method according to claims 17, wherein the
non-lined rear ends of the inside surfaces of said first and second
flanges respectively in contact with said rear end portions of said
half-sleeves, and said external bearing faces in the zone where
said first and second flanges are welded to said rear end portions
of said half-sleeves, are locally covered in the same
anti-corrosion metal as the metal constituting said
half-sleeves.
20. The assembly method according to claim 16, wherein the outside
surfaces of said end portions of reduced thickness of said sleeves,
or of said half-sleeves, are notched surfaces, having a
substantially tapering chamfered end enabling insertion and
anchoring against the inside surfaces of the end portions of
reduced thickness of the corresponding liners, thus providing a
mechanical connection between said outside surfaces of said sleeves
or half-sleeves and the inside surfaces of said liners of reduced
thickness, merely by forced-engagement of said sleeve, or where
appropriate said half-sleeve, in the axial longitudinal direction
into said open ends respectively of said connection part, of said
pipe element, or of said first and second flanges, respectively.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/988,255 which was filed with the U.S. Patent and
Trademark Office on Jan. 3, 2008. Priority is claimed for this
invention and application, corresponding application(s) having been
filed in France on Jul. 5, 2005, No. 05/07153.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to the field of pipes for
conveying fluids, in particular corrosive fluids, on land or at
sea, and more particularly undersea pipes specifically for
conveying sea water, and it also relates to pipe connection parts
including an internal liner.
[0004] 2. Description of the Related Art
[0005] More particularly, the invention relates to connecting
together two unitary pipe elements having respective internal
linings, and still more particularly to elements having a length of
24 meters (m) to 48 m installed on oil fields in deep water, e.g.
at depths in the range 2000 m to 3000 m, or even more, from a
laying ship fitted with J-lay towers, with the help of a connection
part that is not entirely cylindrical, being an element of the pipe
bend type, of the T-branch connection type, or indeed of the
tapering sleeve type.
[0006] More particularly, the present invention relates to a method
of covering the inside surface of a steel connection part having an
empty inside volume defined by said inside surface, the covering
comprising a liner constituted by a layer of substantially uniform
thickness of a thermoplastic material, said connection part having
at least two open tubular ends suitable for being connected
respectively to at least two steel pipe elements that are
preferably lined in the same internal.
BACKGROUND OF THE INVENTION
[0007] For a long time, rehabilitating water, gas, and drainage
networks has made use of technologies that avoid trenching, i.e.
technologies that consist in inserting a tubular liner inside an
existing pipe, the liner generally being made of a flexible
material such as thermoplastic or thermosetting materials or
composite thermosetting materials, said liners either being
inserted after being folded up along a longitudinal generator line
so as to form a kidney-shaped cross-section and then rounded out
merely by raising internal pressure, or else being inserted after
being stretched by being put under traction so that the diameter of
said sleeve is reduced to a value that is smaller than the inside
diameter of said pipe. Under such circumstances, after being put
into place, the tension on the liner is released and said liner
then returns to its initial diameter and naturally presses against
the inside face of said pipe. That mode of insertion is known under
the term "swagelining" and it is commonly used for rehabilitating
water or gas pipes over unit distances that may be as long as 500
m, or even 1 kilometer (km) in a straight line.
[0008] That technology is also implemented when transporting
corrosive fluids under high pressure, thus making it possible to
use a conventional pressure-withstanding pipe made of carbon steel,
that is therefore inexpensive and easy to connect by welding, with
the ability to withstand corrosion being provided by the internal
liner. This makes it possible to produce unit lengths that may be
several hundreds of meters long that need to be connected together
while ensuring continuity of the protection against corrosion.
Three types of connection are in common use: connection by flanges,
by a screw joint, or by a welded joint. When connection is by
flanges, it suffices to fold out the liner over the face of the
flange, with the flanges, once clamped together, then pinching the
liners face to face, and thus providing continuity in the
anti-corrosion function. With screw joints, continuity may be
provided for example by a ring provided with gaskets that provide
sealing relative to each of the upstream and downstream liners.
With welded joints, it is appropriate to terminate the liner at a
significant distance from the end of the pipe, e.g. lying in the
range 100 millimeters (mm) to 200 mm, so that the heating of the
steel wall during welding does not damage said liner. The problem
that then arises is providing protection against corrosion in the
non-lined zone that extends between the end of the liner in pipe N
and the end of the liner in the following pipe N+1.
[0009] Patent GB-2 218 488 describes the so-called "swagelining"
method that consists in stretching a circular pipe of flexible
material, referred to below as a "liner", so as to reduce its
diameter to enable it to be inserted in a pipe by being pulled
through, with the diameter of said liner at rest being greater than
the inside diameter of said pipe. Another way of inserting such a
liner is to deform it by folding it so as to obtain a kidney-shaped
cross-section that can be inscribed within a circle of diameter
that is much smaller thus making insertion possible merely by
pulling the folded liner through the steel pipe. Once pulled
through, the ends project considerably and naturally return to a
substantially circular shape, and it is simple to fit a plug
thereto. By pressurizing its inside with compressed air, the liner
is caused to return to its circular shape, and it then presses
firmly against the inside wall of the steel pipe.
[0010] The following patents GB-2 391 547, GB-2 298 256,
WO-2004/015321, and WO-2004/011840 describe assembling together two
pipe elements with the help of a tubular junction sleeve inserted
into non-lined ends of the steel walls of two pipe elements that
are to be assembled together, said tubular junction sleeve being
made of a material that withstands corrosion.
[0011] Non-published application FR 04/11055 (2876773) in the name
of the Applicant describes a method of fitting an internal liner to
tubular pipe by threading it through, and a method of welding
together pipe elements lined in that way, which methods are both
mechanically reliable and also simpler and less expensive to
perform, in particular when assembly is performed on site from a
ship at sea, on pipe elements of length that is short and suitable
for being laid from a ship at sea. Such methods and devices for
lining and assembling pipe elements require some minimum number of
parts for connecting the non-lined ends of the pipe elements for
assembly, and they do not require special tools such as crimping
tools to be used while assembling together two lined pipe elements.
Those methods and devices for lining and assembling pipe elements
are designed to make pipes that are suitable for being laid in
great depth, and more particularly pipes that are suitable for
injecting water, and more specifically for injecting sea water.
[0012] The lining methods described in the state of the prior art
are not suitable for internally lining a connection part of inside
volume that is defined by a surface that is not cylindrical, i.e. a
surface that is not constituted by a single cylinder. When it is
desired to continue a pipe with a major change in direction,
whether to go from the sea bed towards the surface via a connection
part constituted by an element in the form of a pipe bend, or to
make a branch connection to another pipe with a connection part
constituted by an element in the form of a T-branch connection, it
is necessary to make use of connection parts that have inside
surfaces that are not constituted by a single cylinder only.
Similarly, when it is desired to assemble pipe elements having
different inside diameters, it is necessary to make use of sleeves
of tapering diameter, presenting an inside diameter at one end that
corresponds to the diameter of one of the pipe elements, and an
inside diameter at the other end that corresponds to the diameter
of the other pipe. For such parts having inside surfaces that are
not formed essentially by a single cylinder, methods of lining by
threading a liner through are unsuitable.
[0013] JP 58 067383 describes a method of lining walls of a
non-cylindrical inside volume in a junction part having open
tubular orifices, in which a hot-melt resin is inserted into said
part before said orifices are closed. Said part is then subjected
to rotation in multiple directions at high speed while being
heated.
[0014] In that method, the hot-melt type resin has strong bonding
properties on the wall and it is the centrifugal force generated by
the rotation that serves to spread the resin over the entire
combined inside surface of the part, with heating encouraging
bonding of the resin on the surface of the wall. However, that
method does not make it possible to obtain a distribution of
genuinely uniform thickness over the entire wall of the inside
volume of the part, since centrifugal force is necessarily of
varying strength, given that it varies with the square of the
distance between the place where it is exerted and the axis of
rotation of the part, and this applies even when multidirectional
rotation is provided.
SUMMARY OF THE INVENTION
[0015] The object of the present invention is to provide an
improved method that is suitable for internally lining such
connection parts having an inside surface that is not
cylindrical.
[0016] Another object of the present invention is to provide
methods of assembling connection parts lined in this way with lined
pipe elements, which methods are suitable for the various
conditions under which said connection parts are implemented,
regardless of whether they are for pipes that are to be used under
low-pressure conditions such as the pipes used in civil engineering
on land, in particular for public works, or at sea in shallow
water; or on the contrary whether they are for pipes that are used
under high-pressure conditions, in particular pressures of more
than 30 bars (3 MPa), and more particularly at sea in waters of
great depth.
[0017] For this purpose, the present invention provides a method of
covering the inside surface of a steel connection part having an
empty inside volume defined by said inside surface, with a liner
constituted by a layer of substantially uniform thickness of a
thermoplastic material, said connection part having at least two
open tubular ends suitable for connecting respectively to at least
two steel pipe elements having the same internal liners, wherein
the following steps are performed:
[0018] a) closing said open ends of said connection part with
covers, at least one of said covers presenting a filler orifice
with an isolation valve suitable for enabling granules of a said
thermoplastic material to be introduced into said inside volume,
and preferably also a ventilation or purge orifice with an
isolation valve, and all other openings, if any, in said part are
plugged; and
[0019] b) introducing said granules of said thermoplastic material
into said inside volume through a said filler orifice, in an amount
that is necessary and sufficient for obtaining a layer of said
thermoplastic material over all of said inside surface with a
substantially uniform desired thickness; and
[0020] c) heating the walls of said connection part defining said
inside volume to a temperature enabling said granules to be melted;
and
[0021] d) causing said connection part to turn simultaneously about
at least two different axes of rotation for a length of time that
is sufficient and at a speed that is sufficiently low to enable
said thermoplastic material to melt on said inside surface and to
be distributed in substantially uniform manner over all of said
inside surface; and
[0022] e) cooling said connection part or allowing it to cool prior
to removing said covers, while maintaining said rotation.
[0023] In the present invention, the part is thus rotated at a
speed that is sufficiently slow to ensure that the granules always
remain in the bottom of said inside volume until they have melted
and bonded to the wall. It is by prolonged contact with a certain
zone of said inside surface of the wall over a sufficient period of
time that a certain quantity of said material can, at the beginning
of the process, melt and bond to the wall to form a thin film.
Then, on the next rotation, a certain quantity of said material
bonds to said melted film and melts in turn, thereby building up
the thickness of the layer little by little as rotation of the part
continues, until all of the granules have been used up. The
thickness of the layer can thus be controlled by controlling the
transfer of heat between the heater device and the wall, and also
between the wall and the material inside the part. Heat transfer
can be controlled by the heating temperature, by the cycle of
tumble rotation of the part (speed and path about multiple axes),
and also by the thermal mass of the metal part, which can
advantageously be adjusted, where appropriate, with the help of
localized shields that reduce heat transfer.
[0024] Thus, the method of the invention makes it possible to
obtain a liner of thickness that is genuinely uniform over the
entire combined inside surface of the part.
[0025] While said part is being heated, the pressure of the gas
contained in said inside volume increases, thereby contributing to
keeping said molten material pressed against said inside
surface.
[0026] However in order to avoid or reduce the risk of the internal
liner of said material coming unstuck, in particular when a
thermoplastic material is used that presents a high degree of
shrinkage, such as high density polyethylene (HDPE), it is
preferable to maintain the pressure inside said inside volume, thus
having the effect of pressing the liner strongly against the wall
of the part throughout the cooling stage, thereby avoiding
shrinkage of said sleeve relative to the inside wall of said
part.
[0027] In a preferred implementation, the pressure inside said
volume is increased prior to cooling by pressurizing said inside
volume with the help of a gas, preferably an inert gas such as
nitrogen, or with water under pressure, introduced via said
ventilation or purge orifice, and said greater internal pressure is
maintained during cooling, preferably at a value of not less than
10 bars (10.sup.6 pascals (Pa)).
[0028] This high internal pressure thus also serves, where
appropriate, to eliminate microbubbles of gas trapped in the
thickness of the liner while still in a pasty state.
[0029] When maintaining a high internal pressure, it is preferable
to use said covers that present a dome shape and that are
preferably welded to said ends of said connection part. The curved
shape of the cover wall is better at withstanding high pressures
inside said internal volume, and this avoids any need to use
gaskets, given that gaskets are very difficult and expensive to
implement at the high pressures associated with the high
temperatures that are required by the method.
[0030] If materials are used that present little shrinkage such as
low density polyethylene, it is possible to work at atmospheric
pressure. This type of liner is suitable for pipes that are used
for conveying fluids in conventional networks, in particular urban
water or gas networks. Under such circumstances, the connection
between said connection part and said pipe elements can be provided
with the help of conventional connecting flanges.
[0031] According to more particular characteristics of the covering
method of the invention:
[0032] in step c), said walls are heated by placing said part in a
heater device such as an oven, or a gas burner strip, thus enabling
all of the zones of said part to be heated uniformly; and
[0033] in step d), said connection part is caused to rotate with
the help of a multidirectional rotation device for rotary molding,
with rotation about each of said axes of rotation preferably being
controlled by means of a computer.
[0034] Rotary molding methods and machines are known, in particular
such as those described in patent U.S. Pat. No. 3,600,754, or other
similar systems that are used inside an oven.
[0035] More particularly, the granules of thermoplastic material
are granules of thermoformable polymers selected from polyethylene,
polypropylene, polyamide, polyvinyl, in particular
polyvinylchloride (PVC), polyvinyldienefluoride (PVDF),
polytetrafluoroethylene (PTFE), polyether-etherketone (PEEK), and
all other thermoformable polymers.
[0036] These polymers present melting temperatures in the range
160.degree. C. to 360.degree. C.
[0037] For these polymers, the connection part is heated to a
temperature that is 20.degree. C. to 40.degree. C. higher than the
melting temperature of said polymer, without excessively exceeding
said values in order to avoid damaging the molecules, since that
would have the effect of degrading the mechanical performance of
the resulting liner. Preferably, the inside volume of the part is
maintained under an atmosphere of inert gas, such as nitrogen,
whether it is at ambient pressure or at high pressure.
[0038] In a preferred implementation of a covering method of the
invention:
[0039] a first said covering is made to obtain a said liner
comprising a first layer of a first thermoplastic material; and
[0040] a second covering is made to obtain a second layer of a
second thermoplastic material different from said first material,
said second thermoplastic material being contained in a different
reservoir and being introduced into said connection part via a said
cover once said first material has melted completely and has bonded
to said walls, said second material covering said first material
and being melted to obtain the desired final thickness.
[0041] As mentioned above, said connection part may have a variety
of shapes and functions, and in particular, depending on the
following particular embodiments, in which:
[0042] said connection part is a bend pipe element suitable for
enabling two pipe elements that extend in different directions to
be connected together by being connected to respective ends of said
bend element constituting said connection part; or
[0043] said connection part is a T- or crossed-shaped element
suitable for enabling three or four or even more pipe elements to
be connected to its respective ends, the elements extending in at
least two directions making between them an angle lying in the
range 0 to 90.degree., and preferably of 90.degree.; or
[0044] said connection part is a tapering tubular sleeve presenting
two tubular ends of circular cross-sections that are of different
inside diameters, suitable for enabling two pipe elements of
diameters corresponding respectively to the inside diameters of the
two tubular ends of said tapering tubular sleeve to be connected
thereto.
[0045] The method of the invention is more particularly
advantageous and necessary for lining a connection part of inside
surface that is not cylindrical. Under such circumstances,
traditional methods of lining by threading through cannot be
implemented validly.
[0046] The term "non-cylindrical" is used herein to mean a surface
that is not entirely cylindrical, it nevertheless being possible
for said inside surface to have one or more portions that are
cylindrical, but the surface itself is not formed essentially by a
single cylinder.
[0047] In an advantageous implementation, during the cooling step,
said inside volume is pressurized with water at high temperature
that is cooled by being caused to flow through a heat exchanger,
enabling it to lose heat, while maintaining the desired level of
pressure until all of said connection part and said thermoplastic
material applied as a layer thereon is completely cooled.
[0048] The thickness of the layer of thermoplastic material results
from the transfer of heat between the hot atmosphere of the oven
and the wall of said inside volume of the connection part. If a
large amount of heat is transferred, then said layer of
thermoplastic material will have a large thickness, if only a small
amount of heat is transferred, then said layer of thermoplastic
material will not have sufficient thickness.
[0049] In order to ensure that thickness is uniform over the entire
surface of said connection part, heat transfer between the heater
device and the inside of the part is adjusted, advantageously by
thermally insulating localized zones of the wall of said connection
part that present a greater rate of heat transfer, e.g. the
connection zone between the part and its flange or its end plug.
For this purpose, a thermally insulating material is advantageously
applied locally on the outside surface of said wall to act as a
shield.
[0050] In a particular implementation, said connection part
comprises, at at least one of its tubular ends, a first connecting
flange suitable for co-operating with a second connecting flange of
a said pipe element for connection to said connection part, and the
covering is made continuously over the entire combined inside
surface of the connection part and over said connecting flange with
a layer of said thermoplastic material, after said first flange has
been fastened by welding to the end of said connection part and the
open end of said first flange has been closed with a said
cover.
[0051] Implementing a connecting flange facilitates the final step
of connecting the connection part with a pipe element in situ on
the laying site, in particular on the sea bottom as explained
below.
[0052] Advantageously, a said cover is used presenting a shape and
means for fastening to said flange that enable the covering
comprising a layer of thermoplastic material to be made
continuously over the entire combined inside surface of the
connection part and of said first connecting flange, and also over
the external bearing face whereby said first flange bears against
said second flange.
[0053] The present invention thus also provides a connection part
having an empty inside volume defined by an inside surface coated
with the liner of substantially uniform thickness obtained by a
liner covering method of the invention.
[0054] More particularly, the present invention provides a
connection part having its said inside surface in the form of a
surface that is not cylindrical.
[0055] A connection part of the invention may include at at least
one of its ends a said first connecting flange to which it is
welded.
[0056] In an advantageous embodiment of a connection part of the
invention for assembly to a pipe element or to a connecting flange
via a tubular junction sleeve at at least one of its said open
tubular ends, said liner includes an end portion of thickness that
is reduced relative to the thickness of the remainder of said
liner, which end portion is obtained by machining and thus defines
an inside surface of revolution of inside diameter greater than the
inside diameter of the remainder of said internal liner and
terminating at a certain distance from the end of said connection
part. After being machined, the end of said connection part is thus
no longer lined.
[0057] This makes it possible to insert a tubular sleeve by force
as described below and in accordance with patent application FR
04/11055.
[0058] The present invention also provides a method of assembling a
pipe in which a connection part of the invention is assembled with
a said pipe element.
[0059] In a first variant of the connection method of the
invention, more suitable in particular for connecting pipes that
are to be used under conditions of pressure inside the pipe that is
less than 30 bars (3 megapascals (MPa)):
[0060] said connection part includes a said first connecting flange
to which it is welded, with the entire combined inside surface of
the connection part and of said first connecting flange, and also
the external bearing face of said first flange for bearing against
said second flange are covered in a said continuous layer of
thermoplastic material; and
[0061] said pipe element includes at its end a said second
connecting flange to which it is welded, the entire combined inside
surface of said pipe element and of said second connecting flange,
and also the external bearing face of said second flange for
bearing against said first flange are covered in a said continuous
layer of thermoplastic material; and
[0062] said first and second connecting flanges are connected
together, preferably against an interposed gasket.
[0063] In this first variant of the assembly method, there is no
need to use a tubular junction sleeve for assembling said junction
part with a said pipe element.
[0064] In a second variant implementation of the assembly method of
the invention, that is more suitable in particular for connecting
pipes that are to be used under conditions of pressure inside the
pipe greater than 30 bars (3 MPa), a tubular junction sleeve is
used and said junction sleeve is inserted into the open tubular end
of said connection part via one end of said sleeve, which sleeve
presents substantially the same inside diameter as said internal
liner of said connection part.
[0065] In a first implementation of this second variant of the
assembly method of the invention, suitable for making the
connection on the surface, in particular on board a laying
ship:
[0066] the junction sleeve is inserted:
[0067] via one end of said sleeve into the inside of the open
tubular end of said connection part, which end does not have a
connecting flange; and
[0068] via the other end of said sleeve into the inside of the
corresponding end of said pipe element, which end does not have a
said connecting flange; and
[0069] the ends of said connection part and of said pipe element
are moved towards each other and welded together over said junction
sleeve.
[0070] More particularly, in this first implementation of the
second variant, the following steps are performed:
[0071] a) said connection part, said pipe element, and said tubular
junction sleeve are prepared in such a manner that:
[0072] each of the internal liners of thermoplastic material at the
open ends of said connection part and of said pipe element includes
an end portion of thickness that is reduced relative to the
thickness of the remainder of said liner; and
[0073] said sleeve presents at each of its ends an end portion of
thickness that is reduced relative to the thickness of the central
portion of said sleeve, said end portion of the sleeve defining an
outside surface of revolution of outside diameter less than the
inside diameter of the non-lined ends of said connection part and
of said pipe, said sleeve presenting substantially the same inside
diameter as said internal liner of the main portions of the
connection parts and of said pipe element; and
[0074] b) said tubular junction sleeve is inserted into said open
tubular ends of reduced thickness of the liner of said connection
part and of said pipe element so as to overlap said
reduced-thickness end portions of liner.
[0075] In a second implementation of this second variant of the
assembly method of the invention, suitable for being implemented at
the bottom of the sea, and in particular at great depth, the
following steps are performed:
[0076] a) initially the following are prepared:
[0077] a said connection part including a said first connecting
flange to which it is welded, with the entire combined inside
surface of the connection part and of said first connecting flange
being covered in a said layer of thermoplastic material; and
[0078] a said pipe element having at its end a said second
connecting flange to which it is welded, the entire combined inside
surface of said pipe element and of said second connecting flange
being covered in a said layer of thermoplastic material; and
[0079] b) machining the internal liners of thermoplastic material
at the ends of said connection part having a said first flange and
of said pipe element having a said second flange in such a manner
as to create in each of said internal liners an end portion of
thickness that is reduced relative to the thickness of the
remainder of said liner, and terminating at a certain distance from
said ends of said connection part and of said pipe element
respectively such that the inside surfaces of said first and second
flanges are not lined; and
[0080] c) inserting at each of the open ends of said first and
second flanges tubular junction half-sleeves for reinforcing the
junctions between said connection part and said first flange and
between said pipe element and said second flange,
[0081] each said half-sleeve presenting:
[0082] at its front end, a front end portion of tubular wall of
thickness that is reduced relative to the central portion of the
tubular wall of said half-sleeves; and
[0083] at its rear end, a rear end portion of tubular wall of
thickness greater than the thickness of the central portion of said
half-sleeve; and
[0084] each half-sleeve being inserted in such a manner that said
front end portions of reduced wall thickness of said half-sleeves
overlap said end portions of reduced thickness of said liners of
said connection part and of said pipe elements respectively;
and
[0085] d) welding said half-sleeves to said first and second
flanges respectively at said rear ends of said half-sleeves and
external bearing faces of said first and second flanges,
respectively; and
[0086] e) moving together and fastening to each other said first
and second connection flanges, preferably with a toroidal gasket
being interposed between them, more preferably a gasket that
provides metal-on-metal sealing.
[0087] In this method, steps a) to d) can be implemented on the
surface in a fabrication site, where appropriate on board a
pipe-laying ship, however step e) should be performed in situ on
the laying site, in particular at great depth.
[0088] Advantageously, said tubular junction sleeves or where
appropriate said tubular junction half-sleeves are made of a
material that withstands corrosion, preferably of the stainless
steel or Inconel alloy type, with the connecting flanges also
having zones of corrosion-withstanding material, preferably of the
stainless steel type or of the Inconel alloy type.
[0089] Preferably, the outside surfaces of said end portions of
reduced thickness of said sleeves, or where appropriate of said
half-sleeves, are notched surfaces, preferably having a
substantially tapering chamfered end enabling insertion and
anchoring against the inside surfaces of the end portions of
reduced thickness of the corresponding liners, thus providing a
mechanical connection between said outside surfaces of said sleeves
or half-sleeves and the inside surfaces of said liners of reduced
thickness, merely by forced-engagement of said sleeve, or where
appropriate said half-sleeve, in the axial longitudinal direction
into said open ends respectively of said connection part, of said
pipe element, or where appropriate of said first and second
flanges, respectively.
[0090] The terms "internal/external", "inside/outside", or
"inner/outer" are used relative to the inside/outside of the
connection part, the pipe, the sleeve, or the half-sleeve, as
appropriate.
[0091] The inside surface of each of the liner end portions is
substantially cylindrical and is subjected to creep on said sleeve
being inserted by force, and also on elastic deformation of its
notched outside surface by pressure from the notched outside
surface of the sleeve against said inside surface of the liner.
[0092] More particularly, the present invention provides a
connection part and a pipe suitable for being laid at great depths
in the sea, preferably depths of as much as 3000 m, and said pipe
elements present a length lying in the range 20 m to 50 m.
[0093] More particularly, the pipe is for injecting water, in
particular sea water, or even non- . . . sea water.
[0094] In an implementation, a said cross-linkable material or a
said gel is injected through a hole previously drilled through the
wall of said sleeve or said steel wall of the pipe or of the
connection part and via a vacuum chamber fitted in register with
said hole, after evacuating said annular chamber, and then said
vacuum chamber is removed and said hole is plugged.
[0095] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0096] Other characteristics and advantages of the present
invention appear in the light of the following detailed description
with reference to the following figures, in which:
[0097] FIG. 1 is a side view in section of a connection part of the
lined bend type fitted at its bottom portion with a first
connection flange facing the end of a pipe element that is fitted
with a second connection flange;
[0098] FIGS. 1A and 1B are sections on planes AA and BB in FIG.
1;
[0099] FIG. 2 is a perspective view showing the principle of rotary
lining;
[0100] FIG. 3 is a side view in section of a bend 1a-1 fitted with
a first flange 6a during the final stage of rotary lining;
[0101] FIG. 4 is a variant of FIG. 3 in which the rotary lining is
performed under high pressure;
[0102] FIG. 5 is a side view in section showing a connection part
1a of the invention assembled to a pipe 1b with the help of a
tubular junction sleeve;
[0103] FIGS. 6A and 6B are side views in section showing the end of
a lined connection part at the end of the rotary lining process,
respectively before (FIG. 6A) and during (FIG. 6b) machining of
said liner;
[0104] FIG. 7 shows the detail of the notched surface 3-2 at the
end of the tubular junction sleeve 3;
[0105] FIG. 8A is a side view in section of a connection part of
the lined bend type 1a-1 fitted with a junction sleeve 3 at its
right-hand end ready for being assembled by insertion with a unit
length of pipe 1b;
[0106] FIGS. 8A to 8C are side views in section of a connection
part of (FIG. 8A), of the T type (FIG. 8B), and of the shrink
sleeve type (FIG. 8C) fitted with a junction sleeve at its end
after being assembled by insertion with a unit length of pipe;
[0107] FIGS. 8D and 8E are side views in section of the tubular end
of a connection part fitted with a first connecting flange before
(FIG. 8D) and after (FIG. 8E) machining the end of its internal
liner;
[0108] FIG. 8F shows the end of a said connection part fitted with
a first connecting flange facing the end of a pipe element fitted
with a second connecting flange and having inserted therein two
tubular junction half-sleeves;
[0109] FIG. 9A is a side view of an installation ship fitted with a
so-called J-lay tower;
[0110] FIGS. 9B and 9C are side views in section showing stages of
assembling tubular ends of a connection part with a lined pipe
element, respectively during an approach stage (FIG. 9B) and a
welding stage (FIG. 9C);
[0111] FIG. 9D is a section relating to FIG. 9B showing in detail
how the centering spacers are positioned close to the welding
zone;
[0112] FIG. 10 is a section showing the connection of the tubular
junction sleeve and the liner, showing in detail how a fluid is
injected into the annular chamber extending between said sleeve,
the ends of the liners, and the wall of the steel pipe, whether
from the outside or from the inside;
[0113] FIGS. 11A to 11F are diagrams resulting from finite-element
calculations showing in detail six stages of inserting a sleeve or
a half-sleeve and showing how their notched surfaces deform and how
the flexible material constituting the liner is subjected to
creep;
[0114] FIG. 12A is a result of finite-element calculation showing
details of how the sleeve and half-sleeve with a notched surface
deform and how the sleeve deforms plastically when the pipe is
subjected to an internal pressure, the chamber extending between
said sleeve, the ends of the liners, and the steel pipe remaining
substantially at atmospheric pressure; and
[0115] FIG. 12B shows a detail of the notched outside surface of
the sleeve corresponding to FIG. 12A.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0116] FIG. 1 shows a connection part 1a-1 of the invention of the
bend type having a liner 2, the part having a top open tubular end
1a' for connection by welding to a lined rectilinear pipe element
1b, and a bottom open tubular end 1a' having a first flange 6a
welded 5-1 thereto, said liner 2 extending continuously over the
outside bearing face 6a' to the periphery of said flange 6a. Said
first flange 6a is for fastening to a second connecting flange 6b
at the end of a pipe element 1b with a gasket 6c therebetween.
FIGS. 1A and 1B are sections respectively seen from above and from
the side on respective planes AA and BB. The steel bend is
constituted by a curved portion of radius R extended upwards by a
straight portion of length L1 of diameter substantially equal to
that of the curved portion. The liner is of thickness that is
substantially constant over all of the inside surface of the
connection part, including the surface of said flange.
[0117] With steel pipes of large thickness, the curved portion is
generally obtained by localized induction heating up to a
temperature lying in the range 800.degree. C. to 900.degree. C.,
associated with mechanical bending to the desired radius of
curvature. This process generally requires there to be a straight
portion of pipe at each of the ends so that the assembly can be
held in the induction bending machine. Another method that is used
on smaller thicknesses consists in welding a straight portion onto
a bend of given angle that is curved to the desired radius.
[0118] FIG. 2 is a perspective view showing the principle of lining
by rotary molding, known to the person skilled in the art, and
consisting in causing a forming mold to rotate in three dimensions,
generally in pseudo random manner about two axes 8a, 8b that are
generally mutually perpendicular, with granules of a thermoplastic
material such as polyethylene, polypropylene, polyamide, or indeed
PVDF or PEEK, being introduced into the mold and then heated
progressively, preferably in an oven, up to a temperature at which
the granules reach their melting temperature, and preferably a
temperature that is 20.degree. C. to 40.degree. C. above said
melting temperature. The molten granules then stick to the wall of
the mold, and since the mold is set into pseudo random rotation
about two axes, the thickness of the plastic increases in
substantially uniform manner over the entire combined inside
surface of the mold. Once all of the granules have melted, rotation
is continued and then the outside wall of the connection part
acting as a mold is cooled either in the open air or in a flow of
air, or indeed having water splashed thereon. When the mold is
cold, it is opened and the rotary molded part is removed therefrom,
with unmolding generally taking place without difficulty since the
thermoplastic material shrinks by about 1% to 3%, depending on the
material.
[0119] For an internal liner of a connection part of the invention,
such as bend or a T, the connection part acts as a lost mold and
the liner 2 remains therein. Furthermore, it is desired to minimize
or eliminate shrinkage so that the thermoplastic material is in
intimate contact with the inside surface 1-1 of said connection
part, and it is desired to improve the bonding of said liner on
said pipe. Thus, the accessory itself acts as a "lost mold" since
the liner stays in place permanently, whereas in the prior art, the
mold used to be opened and the finished part extracted from said
mold.
[0120] In the preferred version of the invention as shown in FIG.
3, the steel bend 1a-1 that is terminated upwards by a straight
portion and downwards by a first flange, is provided with a cover
1-3 at each of its ends 1a' so as to seal the inside volume 1-2 of
the bend. In the top portion, a filler orifice 1-4 is installed
that includes an isolation valve, and a ventilation orifice 1-5 is
also installed, for a purpose that is explained in greater detail
below. The granules 2-1 are introduced via said filler orifice 1-4,
as shown in the top portion of the figure to the left of section
CC, and then the entire assembly is secured in a rotation machine 8
having two axes 8a, 8b. The assembly is then heated and rotated
slowly until the granules 2-1 that remain in the bottom portion of
the inside volume of said part become fully melted and stuck to the
zone of the wall that is in contact with said granules, as shown in
the bottom left-hand portion of said section CC. When the closure
covers 1-3 are put into place, care is taken to plug temporarily
the bolt holes 6a-3 in the flange 6a. The pseudo random rotation of
the part throughout the duration of the heating and cooling cycle
makes it possible to cover the entire inside surface of said part
both progressively and regularly. After the assembly has cooled,
the covers 1-3 are removed and beside the flange, the thermoplastic
material is cut at 6a-2 flush with the free face of the liner of
said material, and holes corresponding to the holes 6a-1 in the
flange are counterbored after removing the plugs 6a-3 closing said
holes in said flange, as shown in FIG. 1.
[0121] In contrast, in FIG. 1, the top open tubular end 1a' of said
connection part is for being machined, as shown in FIGS. 6A-6B that
are described in greater detail below.
[0122] For clarity of the drawings, the thermoplastic layer is
shown as having uniform thickness with connections at right angles,
however in reality said layer presents thickness that is
substantially constant and is clearly rounded over each corner, in
particular in the vicinity of the face of the flange.
[0123] This method is particularly suitable for application to
thermoplastic materials that shrink little, for example low density
polyethylene (LDPE), thus making it possible to ensure
substantially intimate contact between the thermoplastic liner and
the tubular steel wall.
[0124] In a preferred version shown in FIG. 4 relating to a bend
1a-1 without an end flange, both ends of the pipe are initially
closed with dome-shaped end walls 1-3 that are welded thereto 5-3,
thus enabling the assembly to withstand internal pressure that is
high or even considerable, and then the internal volume 1-2 is
filled with the required quantity of granules 2-1, and finally heat
is applied and the part is set into rotation. During heating, the
pressure of the gas imprisoned therein increases because of the
temperature. And at the end of the cycle, pressure is
advantageously further increased via the purge orifice 1-5 so that
the internal volume 1-2 is raised to a higher pressure, e.g. 15
bars or 20 bars, or even more, so as to keep the liner pressed
firmly against the inside wall of the tubular pipe throughout the
cooling stage and so as to resorb microbubbles of gas trapped in
the thickness of the liner while in the pasty state prior to
cooling. At the end of cooling, the pressure is released and the
connection part is cut perpendicularly to its axis on plane DD at
each of its ends 1a'. The liner 2 then remains intimately bonded
with the steel wall of the inside surface 1-1 of said connection
part, and any shrinkage is thus avoided. To improve bonding between
said liner 2 and said inside surface 1-1, the inside of the pipe is
advantageously sanded beforehand, thereby increasing the roughness
of the surface and increasing the bonding of the thermoplastic
resin.
[0125] This method is particularly applicable for thermoplastic
materials presenting a high degree of shrinkage, such as high
density polyethylene (HDPE), thus making it possible to guarantee
intimate contact between the thermoplastic liner and the steel wall
regardless of the thermoplastic material selected. To avoid using
air or a gas under pressure, it is advantageous to pressurize the
connection part with water at high temperature, which is
advantageously cooled by making it circulate through a heat
exchanger so as to enable it to lose heat while maintaining the
desired level of pressure, until the assembly has cooled down
completely.
[0126] The rotary lining machine has a main axis constituted by a
horizontal shaft driven by a first motor and turning at a speed
that is variable over the range 0 to 10 revolutions per minute
(rpm), with a secondary axis installed at the end thereof and
constituted by a second shaft that is generally perpendicular to
the first and that is driven by a second motor rotating at a speed
that is variable over the range 0 to 10 rpm. A structure secured to
the second shaft supports the connection part. Said connection part
is initially filled with granules of micronized granules of
material, i.e. with particles having grain size that is generally
less than 500 micrometers (.mu.m) to 800 .mu.m. The weight of
powder is calculated very precisely from the inside area that is to
be covered and from the thickness that is desired for the liner.
The assembly is then placed in an oven, preferably a forced-air
oven at a temperature of about 250.degree. C. for polyethylene and
about 300.degree. C. for polypropylene, and rotation about both of
said axes is maintained for a duration of 60 minutes (') to 200' in
order to obtain a lining with a thickness 12 millimeters (mm) to 15
mm. The assembly is then extracted from the oven for the cooling
stage during which rotation is maintained about both axes until the
connection part is at ambient temperature. At the beginning of
cooling, the internal cavity is advantageously raised to a high
pressure, e.g. 15 bars to 30 bars, in order to keep the liner well
pressed against the inside wall of said connection part. Cooling is
advantageously accelerated by setting up a stream of cool air, or
by watering the assembly from the outside, or indeed by combining a
stream of air with watering. Cooling is also advantageously
accelerated by causing cool air to flow inside the cavity of the
liner, e.g. by the orifice 1-5, having taken care to ensure that
there is a similar second orifice that is preferably situated at
the opposite end of the connection part, so that hot air, and thus
heat coming from the internal cavity, can be extracted via said
second orifice.
[0127] On the basis of a few tests, the quantity of powder needed
can be adjusted so as to obtain the desired thickness over the
entire surface, and if there is any local extra thickness,
corresponding locally to excessive transfer of heat, said transfer
of heat is advantageously reduced by placing insulating pads
locally on the outside of said connection part.
[0128] By way of example, a connection element in the form of a
bend corresponding to FIG. 3 and made out of pipe having an inside
diameter of 30 centimeters (cm) having a straight length of 40 cm
and a 90.degree. bend with an inside radius of curvature of 100 cm,
fitted at its bottom end with a flange having a diameter of 40 cm,
and plugged at both ends needs a volume of 32.6 liters (L) of
compact resin, and thus a weight of 30.6 kilograms (kg) of HDPE
presenting relative density of 0.94, in order to obtain an internal
liner with a thickness of 15 mm. The heating cycle lasts for about
90' with the oven at a temperature of 265.degree. C. Cooling is
performed under a stream of ambient air for a duration of 90' to
120'.
[0129] Similarly, a T-shaped connection element without flanges,
constituted by a main pipe having an inside diameter of 30 cm and a
length of 160 cm and closed at each end by a plug, with a branch
with an inside diameter of 12 cm also closed by a plug, requires a
volume of 25.8 L of compact resin, and thus a weight of 24.2 kg of
HDPE with relative density of 0.94, to obtain an internal liner
with a thickness of 15 mm. The parameters of the heating and
cooling cycles are substantially similar to those of the connection
part in the form of a bend.
[0130] Similarly, a reducing connection element having no flanges,
constituted by a main pipe with an inside diameter of 30 cm and a
length of 30 cm, a pipe of reduced diameter of 20 cm and length of
30 cm, and a transition zone with length of 30 cm, being closed at
each end by a plug, requires a volume of 10.5 L of compact resin,
and thus a weight of 9.8 kg of HPDE with relative density of 0.94,
in order to obtain an internal liner with thickness of 15 mm. The
parameters of the heating and cooling cycles are substantially
similar to those of the connection part in the form of a bend.
[0131] FIGS. 1 and 8A show a connection part 1a that is coated with
an internal liner 2 of the present invention, the part being
constituted by a pipe element 1a-1 suitable for connecting together
two pipe elements extending in two perpendicular directions via
each of its open tubular ends 1a'.
[0132] FIG. 8B shows a lined connection part of the invention in
the form of a T suitable for connecting together three pipe
elements via each of its tubular ends 1a', namely:
[0133] two pipe elements 1b co-operating with the two opposite
tubular ends 1a' disposed at 180.degree. from each other; and
[0134] a third pipe element of smaller diameter, disposed at
90.degree. relative to the other two pipe elements 1b that are in
alignment, said third pipe element 1b co-operating with the open
tubular end 1a' of axis that is disposed at 90.degree. relative to
the other two open tubular ends 1a' of said T element 1a-2.
[0135] FIG. 8C shows a connection part constituted by a tapering
tubular sleeve 1a-3 having two open tubular ends 1a' lying on the
same axis XX', but in which the inside diameter of the circular
cross-section at one of the open tubular ends 1a' is smaller than
the inside diameter at the other open tubular end of said
connection part.
[0136] These three connection parts 1a-1, 1a-2, and 1a-3 have their
inside surfaces covered in liners constituted by a layer of
thermoplastic material 2 that is not entirely cylindrical in shape.
In the T-shaped connection parts 1a-2 and in the connection part in
the form of a tapering tubular sleeve 1a-3, said inside surface
respectively comprises a combination of two cylindrical portions
disposed at 90.degree. (connection part 1a-2) or disposed end to
end (connection part 1a-3).
[0137] In a preferred version of the invention, multilayer lining
is performed so as to obtain a first layer of said covering having
a given thickness in contact with the wall, followed by at least
one second covering layer of a different thermoplastic material,
generally a material presenting improved characteristics compared
with the first. Said second material is generally more "noble" and
thus more expensive than the first, so its thickness is kept down
to the necessary minimum. The rotary lining method is then slightly
different from the method described above, since the second
thermoplastic material in the form of a micronized powder is
contained in a closed reservoir secured to one of the covers and
situated remote from the walls of the connection element. Once the
first material has melted fully and bonded to the walls, after a
known length of time, the reservoir containing the second material
is opened, either automatically by a mechanical timer, or manually
by the operator acting from the outside. The second thermoplastic
material is then released and begins to melt, covering the first
material until all of the micronized powder has melted, thereby
obtaining the desired final thickness for the liner. Such a
multilayer technique makes it possible to obtain a liner that is
proof against gas and/or hydrocarbons migrating, by using a second
material that is proof against gas and/or hydrocarbons, said second
material advantageously being applied as a thin layer with
thickness of only a few millimeters, because of its high cost. It
is possible in the same manner to apply a second material that is
constituted by a mixture of the first material and of an addition
material, for example a material that facilitates sliding such as
Teflon, or that improves resistance to abrasion, said addition
material being dispersed in very small quantities in the base
material. It remains within the spirit of the invention to apply a
third material or even a fourth or more, in order to build up the
total thickness of the liner.
[0138] FIGS. 8A, 8B, and 8C show how to assemble an open tubular
end 1a' of a connection part 1a with an open tubular end 1b' of a
pipe element 1b with the help of a junction sleeve 3.
[0139] In the method of the invention, said junction sleeve 3 is
inserted:
[0140] via one end of said sleeve into the inside of the open
tubular end 1a' of said connection part, said end not having a
connecting flange; and
[0141] via the other end of said sleeve, into the inside of the
corresponding end 1b' of said pipe element, said end not having a
connecting flange; and
[0142] bringing together and welding 5 said ends of said connection
part and of said pipe element over said junction sleeve 3, as shown
in FIG. 5.
[0143] The sleeve 3 presents substantially the same inside diameter
as the internal liner 2-2 of said connection part.
[0144] More particularly, the following steps are performed:
[0145] a) providing a said connection part, a said pipe element,
and a said tubular junction sleeve, such that:
[0146] the internal liners of thermoplastic material at the open
ends 1a', 1b' of said connection part and of said pipe element each
comprise an end portion 2a, 2b of thickness that is reduced
relative to the thickness of the remainder 2c of said liner, said
end portion 2a, 2b thus defining an internal surface of revolution
of inside diameter that is greater than that of the remainder of
said internal liner and terminating at a certain distance d from
the ends of said connection part and of said pipe element,
respectively; and
[0147] said sleeve presents at each of its ends an end portion 3a,
3b of thickness that is reduced relative to the thickness of the
central portion 3c of said sleeve, said end portion 3a, 3b of the
sleeve defining an outside surface of revolution of outside
diameter that is smaller than that of the central portion 3c of the
sleeve and less than the inside diameter of said non-lined end
portions of said connection part and of said pipe element, and a
cylindrical inside surface of inside diameter that is substantially
the same as that of the main portion of the liner of said open
tubular ends and of said central portion of the sleeve, which
sleeve 3 presents substantially the same inside diameter as said
internal liner of the main portions of the connection parts and of
said pipe element; and
[0148] b) inserting said tubular junction sleeve inside said open
tubular ends having liners of reduced thickness in said connection
part and said pipe element, so as to overlap said reduced-thickness
end portions of the liners.
[0149] FIG. 5 shows an assembly of the invention with a tubular
junction sleeve 3 providing the junction between the tubular ends
1a', 1b' of a connection part 1a and of a straight pipe element 1b
having internal liners 2 that are assembled end to end. Said
tubular ends 1a' and 1b' are welded 5 to each other and each said
tubular end 1a', 1b' comprises:
[0150] an internal liner of thermoplastic material 2, preferably
identical on both sides, presenting at each end an end portion 2a,
2b of thickness reduced relative to the thickness of the main
portion 2c of said liner, defining an internal surface of
revolution of inside diameter that is greater than that of the main
portion 2c of said liner and terminating at a certain distance d
from the end of said pipe element, and of axis XX' substantially
coinciding with the axis of said tubular ends 1a', 1b'; and
[0151] a single tubular junction sleeve 3 of material that
withstands corrosion, preferably an Inconel alloy, having
substantially the same inside diameter as said liner, interposed
inside the abutting ends of the two tubular ends 1a', 1b', so as to
overlap said end portions of the two liners 2a, 2b, said sleeve
presenting at each of its ends an end portion 3a, 3b of thickness
that is reduced relative to the thickness of the central portion 2c
of said sleeve, said end portions 3a, 3b of the sleeve defining an
external surface of revolution of outside diameter less than that
of the central portion 3c of the sleeve and an internal cylindrical
surface having the same inside diameter as the main portion of the
liner and of the central portion 3c of the sleeve, its axis XX'
coinciding substantially with the axis of the tubular ends 1a',
1b'.
[0152] In FIG. 7A, said external surface of revolution of each end
portion 3a, 3b of said sleeve constitutes a notched surface
3.sub.2, in particular a surface having three to five notches
3.sub.2 with slopes, in particular as shown in FIG. 7A, at an angle
.quadrature. that is less than 45.degree., preferably about
30.degree., and at an angle .quadrature. that is greater than
45.degree., preferably about 60.degree., enabling insertion and
anchoring against the inside surface of the end portions 2a, 2b of
reduced thickness of the corresponding liner, the end notch giving
the sleeve an end with a substantially tapering chamfer 3-1, as
shown in FIG. 7A. This provides a mechanical connection between
said two surfaces, the outside surface of the sleeve and the inside
surface of the liner, merely by forcing said sleeve into engagement
along the longitudinal axial direction inside a said tubular end
1a', 1b'.
[0153] The outside diameter of said cylindrical central portion 3c
of the sleeve is smaller than the inside diameter of the non-lined
ends 1-1a and 1-1b of the steel walls of said tubular ends 1a',
1b', such that said sleeve is not in direct contact with said steel
walls and co-operates therewith and between the ends 2-1 of the
liners on either side of said sleeve, to define an annular chamber
17.
[0154] Said sleeve is inserted against the end portions 2a, 2b of
reduced thickness of the liner until the end 2-1 of the liner comes
into abutment against a shoulder 3-3 defining the boundary between
said central portion 3c of the sleeve and said smaller-diameter end
portion 3a, 3b of the sleeve.
[0155] In a variant embodiment (not shown), said sleeve is inserted
against the end portion of the liner until the end 3-1 of the
sleeve comes into abutment against the shoulder 2-2 defining the
boundary between the main portion and said reduced-thickness end
portions 2a, 2b of the liner, thereby advantageously reducing
turbulence in the transition zone between the main portion of the
liner 2 and the tubular junction sleeve.
[0156] In FIGS. 8D to 8F, there can be seen another way of
performing assembly when there is a first connecting flange 6a for
assembly with a second connecting flange 6b of a rectilinear pipe
element 1b, with this method of assembly being more particularly
suitable for performing at the bottom of the sleeve under high
pressure conditions, in particular at great depth.
[0157] In this method, the following steps are performed:
[0158] a) initially the following are used:
[0159] a said connection part 1a including a said first connecting
flange 6a to which it is welded 5-1, with the entire combined
inside surface of the connection part and of said first connecting
flange being covered in a said layer of thermoplastic material, the
external bearing face 6a' of said first flange for bearing against
said second flange not being covered in a said layer; and
[0160] a said pipe element 1b having at its end a said second
connecting flange 6b to which it is welded 5-1, the entire combined
inside surface of said pipe element and of said second connecting
flange being covered in a said layer of thermoplastic material, the
external bearing face 6b' of said second flange for bearing against
said first flange not being covered in a said layer; and
[0161] b) machining the internal liners 2 of thermoplastic material
at the end of said connection part having a said first flange and
at the end of said pipe element having a said second flange so as
to create in each of said internal liners an end portion 2a, 2b of
thickness that is reduced relative to the thickness of the
remainder 2c of said liner, said end portion thus defining an
internal surface of revolution of inside diameter greater than that
of the remainder of said liner, and terminating at a certain
distance d from the end of said connection part and of said pipe
element respectively, such that the inside surfaces 1-1a, 1-1b of
said first and second flanges are not lined; and
[0162] c) inserting into each of said open ends of said first and
second flanges, tubular junction half-sleeves 4 for making the
junctions between said connection part and said first flange and
also between said pipe element and said second flange:
[0163] each said half-sleeve 4 presenting:
[0164] at its front end, a front end portion of tubular wall 4a of
thickness reduced relative to the central portion 4c of the tubular
wall of said half-sleeves; and
[0165] at its rear end, a rear end portion of tubular wall 4b of
thickness greater than that of the central portion 4c of said
half-sleeve, the rear end portion 4b having an outside diameter
that corresponds substantially to the diameter of the inside
surface 1-1a, 1-1b of said first or second non-lined flanges as the
case may be, each said rear end portion forming a shoulder, said
front end portions 4a of the half-sleeves defining an outside
surface of outside diameter smaller than that of the remainder 4c
of the wall of said half-sleeves and a cylindrical inside surface
of substantially the same diameter as the cylindrical inside
surfaces of the main portions of said liners of said connection
part and of said pipe element and of the remainder of the tubular
walls of said half-sleeves; and
[0166] each half-sleeve being inserted in such a manner that said
front end portions 4a with reduced wall thickness of said
half-sleeves 4 overlap with said end portions 2a, 2b of reduced
thickness of said liners in said connection part and said pipe
element respectively; and
[0167] said shoulder-forming rear end portions 4b of said
half-sleeves coming into contact with said first and second flanges
respectively beside their open ends; and
[0168] . . . ;
[0169] the rear ends of said half-sleeves 4 reaching the external
bearing faces 6a', 6b' of said first and second flanges,
respectively; and
[0170] d) welding 5-2 said half-sleeves to said first and second
flanges respectively at said rear ends of said half-sleeves and
external bearing faces 6a', 6b' of said first and second flanges
respectively; and
[0171] e) moving together and fastening said first and second
flanges, with a toroidal gasket being interposed between them,
preferably providing metal-on-metal sealing.
[0172] In this method, the steps a) to d) can be performed at the
surface in a manufacturing site, or where appropriate on board a
pipe-laying ship, as explained below. However step e) can thus be
performed in situ where laying is taking place, and in particular
at great depths.
[0173] Said tubular junction sleeves 3, and where appropriate said
tubular junction half-sleeves 4 are made of material that
withstands corrosion, preferably of the stainless steel or Inconel
alloy type; and
[0174] the outside diameter of the cylindrical central portion 3c,
4c of said sleeve or of said half-sleeves, as appropriate, is less
than the inside diameter of said non-lined ends 1-1a, 1-1b of the
steel walls of said connection part 1a, of said pipe element 1b, or
where appropriate of said first and second flanges 6a and 6b,
respectively.
[0175] The non-lined rear ends 1-1a, 1-1b of the inside surfaces of
said first and second flanges respectively in contact with said
rear end portions 4b of said half-sleeve, and said external bearing
faces 6a', 6b' in the welding zone 6d between said first and second
flanges and the rear end portions 4b of said half-sleeve are
locally covered in the same anti-corrosion metal 6d as that
constituting said half-sleeve.
[0176] The corrosion-resistant metal is preferably Inconel alloy.
This can be placed in the contact and welding zone 6d between said
flanges and said half-sleeves 4 being deposited by an electric arc
in a previously-machined zone. Thereafter it is possible to make a
groove 6e in said zone 6d that is to receive an intermediate
toroidal gasket 6c. During rotary molding, said flange 6a is merely
closed by a solid flange backing member having a sealing gasket,
e.g. providing metal-on-metal sealing and co-operating with said
groove 6e. By proceeding as mentioned above, continuity of the
anti-corrosion metal is provided, e.g. continuity of Inconel,
between said half-sleeve, said connecting flanges 6a and the
gasket, likewise made of anti-corrosion metal 6c.
[0177] As shown in FIGS. 6A, 6B, at the end of the lining process,
the liner is cut flush 6a-2 with said steel connection part, and
then a machining machine 12 is installed on the face of the first
end of the pipe element. It is constituted in known manner by a
structure 12a carrying a motor (not shown) that sets the
tool-carrier shaft 12c into rotation, a device 12e that moves the
tool-carrier in the direction XX', and a device 12f that moves the
machining tool 12d radially. The machine is fitted with centering
means 12b that serve to adjust the position of the axis XX' of said
machine so as to make it coincide with the axis of the pipe
element, and so as to be able to machine the inside of the liner at
its ends, in a manner that is entirely concentric with said steel
pipe.
[0178] After the liner has been machined to have the required
profile at each of its ends, the tubular junction sleeve 3 of FIG.
7 is forced into the end 1a' of the connection part 1a which is
then terminated and ready to be shipped to the assembly site.
[0179] A tubular end 1a' of said connection part in which a said
tubular junction sleeve 3 has been inserted presents a liner 2 with
an end portion 2a of reduced thickness. The projecting portion of
said sleeve defines a male end 3-4 suitable for being assembled
with an end that does not have such a sleeve and that defines a
female end 2-3 of a said pipe element 1b.
[0180] The opposite configuration is also possible, with said
sleeve constituting a male end of a said pipe element 1b for
insertion into a female end of a said connection part.
[0181] In FIGS. 9B and 9C, there can be seen how assembly is
performed between a unit length of pipe 1b and a said connection
part 1a, both of which are lined, with assembly taking place during
on-site installation and being performed on board a laying ship 13a
fitted with a J-lay tower 13b, as shown in FIG. 9A. For this
purpose, the end pipe element 1b of an already-laid lined pipe is
held securely in suspension from the bottom of the tower, and a
lined connection part 1a is transferred in known manner from the
horizontal position to an oblique position corresponding to the
angle of inclination of the tower so as subsequently to be placed
on the axis of the lined end pipe element 1b. A said connection
part 1a for assembly is then moved axially towards the suspended
end pipe element 1b. The female end 2-3 having no tubular junction
sleeve of a pipe element for assembly 1b is then introduced over
and inserted by force around the male end 3-4 of the stationary
tubular junction sleeve that projects from the connection part 1a
in the longitudinal direction XX' axially inside said female end
2-3, and then the non-lined ends of the steel walls of the
connection part 1a and of the pipe element 1b are butt-welded
together at 5. The top portion of the sleeve 3 penetrates into the
end of the pipe element 1.sub.2b for assembly until it comes into
contact with the end 2-1 of the liner that has previously been
machined with great precision. Said sleeve is inserted against the
reduced-thickness end portion 2b of the liner until the end 2-1 of
the sleeve comes into abutment against a shoulder 3-3 marking the
boundary between said central portion 3c of the sleeve and said
smaller thickness end portion 3a, 3b of the sleeve. Since said
connection part 1a is nearly vertical, its own weight then suffices
to enable the sleeve to penetrate fully into the liner so as to
reach the configuration shown in FIG. 9C, where said connection
part and said pipe element are held apart at a distance of a few
millimeters, e.g. merely by using spacers (not shown) so as to make
it possible in known manner to perform the welding 5. In FIG. 9C,
towards the top and the left, there can be seen the chamfered walls
5' of the steel pipe spaced apart by a few millimeters, and towards
the bottom and the right a completed weld 5.
[0182] As shown in FIGS. 9B and 9D, spacers 16 are advantageously
installed, e.g. three spacers that are uniformly spaced apart
around the periphery of the tubular junction sleeve and that are
situated close to the welding zone 5, so as to improve the
engagement of said sleeve 3 in said steel pipe 1.sub.1. These
spacers are advantageously machined to precise dimensions and are
inserted by force from the outside into the gap between the outside
surface of the central portion 3c of said sleeve and the inside
surface of the steel wall at the non-lined end 1-1a, 1-1b of said
connection part or of said pipe element for which said sleeve
constitutes a male end.
[0183] The spacers 16 are advantageously made of a material that
does not conduct, and that is therefore not metal, and that
withstands the temperature generated at the location in question by
the process of assembly by welding on board the installation ship
13a. Thus, they are made either of composite materials or else of
ceramic, or even more simply out of a sand-and-cement mortar. In a
preferred version, the spacers are fabricated merely by injecting a
limited volume of mortar by means of a syringe so that on spreading
out, e.g. over a spot having a diameter of 4 cm, serves to create
said spacer in situ, without any need for prior adjustment of
thickness, thereby securely holding said sleeve relative to said
pipe. FIG. 9D is a detail view of such spacing.
[0184] When the weight of said connection part or of said pipe
element is not sufficient to ensure that the tubular junction
sleeve is inserted naturally, then the carriage handling said
string within the J-lay tower is advantageously weighted so as to
provide sufficient extra force capacity. In a preferred version, an
actuator device is used that is secured to the outside of said part
1a or string 1b and that then drives insertion of the tubular
junction sleeve 3.
[0185] In a preferred version shown in FIGS. 1 and 9B, a
passivation agent is advantageously placed around the tubular
junction sleeve before its insertion during construction of the
string, or while it is being installed within the J-lay tower;
under such circumstances, said passivation agent is positioned in
the male end zone 3-4.
[0186] After the connection part and the pipe element have been
joined together, the outside surface of the central portions of the
sleeves or half-sleeves and the corresponding inside surface of the
steel wall of the non-lined end portion of said connection part, of
said pipe element, or where appropriate of said first and second
flanges, together define an annular chamber, because of the
difference between their respective outside and inside diameters.
This makes it possible to avoid any direct contact between the
stainless steel alloy or Inconel of the sleeve and the steel of the
pipe element. Any such direct contact could lead, in the event of
water penetrating into said chamber when the pipe is a water
injection pipe, to electrochemical phenomena whereby the steel pipe
is corroded insofar as said mechanical connection between the
sleeve and the liner is not necessarily leaktight. The absence of
contact between the sleeve and the steel wall of the pipe makes it
possible to perform conventional welding of the type commonly used
for welding pipe lines and makes it possible to avoid expensive
welding using a noble alloy identical to the alloy that is used to
make said sleeve, and in particular Inconel alloy.
[0187] Nevertheless, in one implementation, said tubular junction
sleeve may be made of a composite material of the carbon epoxy
type, said sleeve being made for example by winding filaments on a
blank and then machining in its end zones in order to obtain the
required notches.
[0188] In a preferred version shown in FIG. 10, the annular chamber
17 that exists between the sleeve, the liner ends 2-1, and the
steel outside wall, has a quasi-impressible cross-linkable material
injected therein such as a polyurethane, an epoxy, an acrylic, or
indeed a gel of thick consistency that is not soluble in water, so
as eliminate all bubbles of air present in said chamber. For this
purpose, said material is injected either from outside the pipe, as
shown in the bottom of FIG. 10, or from inside through the tubular
junction sleeve 3, as shown further up in the same FIG. 10. On
proceeding from the outside, a tapped hole 14a is initially made
through the wall and said chamber is put into communication with
the outside. A vacuum chamber 15 is then pressed against the
outside of the pipe in leaktight manner, the vacuum chamber having
a duct 15a for delivering the cross-linkable material and also
having an isolation valve 15b, together with a pipe 15c for
drawing-down the vacuum and an isolation valve 15d.
[0189] The filling sequence is then as follows:
[0190] closing the valve 15b and opening the valve 15d; and
[0191] drawing-down a vacuum in the chamber 17; and
[0192] closing the valve 15d and opening the valve 15b; and
[0193] filling the chamber 7 completely with cross-linkable
material; and
[0194] removing the vacuum chamber 15; and
[0195] closing the orifice with the threaded plug 14b.
[0196] When proceeding from the inside, a small hole 14, e.g.
having a diameter of 3 mm, is previously formed through the tubular
junction sleeve 3, and in similar a vacuum chamber 15 provided with
orifices and isolation valves is put into place and the same
sequence of operations as described in detail above is performed,
except that for the last step, the filler hole is left open and it
suffices to remove any traces of material from the inside face of
the tubular junction sleeve. Once the material has cross-linked, it
acts as a plug.
[0197] FIGS. 11A to 11F are diagrams showing the results of
finite-element calculations concerning the successive stages of
engaging the tubular junction sleeve, and they show how the
thermoplastic material of the liner is deformed plastically, and
also how the tubular junction sleeve deforms elastically. Said
deformation of the sleeve is at its maximum at the top 3-5 of the
chamfered end 3-1 of FIG. 11F, which zone also corresponds to the
maximum plastic deformation of the thermoplastic material of the
liner, thereby creating a sealing ring. The multiple notches 3-2 in
the outside surface of the tubular junction sleeve plastically
deform, to a lesser extent, said sleeve at the tops of the notches
3-2, thereby creating additional sealing rings. Said tubular
junction sleeve then comes into abutment against the liner. Said
sleeve is inserted against the reduced thickness end portions 2a,
2b of the liner until the end 2-1 of the liner comes into abutment
against a shoulder 3-3 marking the boundary of said central portion
3c of the sleeve and said smaller thickness end portion 3a, 3b of
the sleeve. The prestress thus obtained in the tubular junction
sleeve, in association with the plastic deformation of the
thermoplastic material, then clampingly engages said tubular
junction sleeve in the liner and thus in the steel pipe. The axis
XX of the tubular junction sleeve then coincides with the axis of
the steel pipe, thus providing guidance and making it much easier
to insert the female portion 2-3 of the pipe element or of the
connection part for assembly in the male portion 3-4 at the end of
the connection part or respectively the end pipe element of a pipe
that has already been assembled, during installation in the J-lay
tower, as explained above with reference to FIGS. 9A to 9C.
[0198] Over time, the thermoplastic material will be subjected to
creep and the cavities 3-6 between the notches 3-2 become
progressively filled in with said thermoplastic material over a
period of several years or tens of years. In the same manner, the
tubular junction sleeve presenting maximum initial deformation at
3-5 will, merely by its elasticity, return to its natural
cylindrical shape, thereby acting as a spring and compensating for
said creep of the thermoplastic material, thus continuing to ensure
that the annular chamber 17 is leaktight.
[0199] In FIG. 12A, there can be seen the lined pipe subjected to a
service pressure P=50 megapascals (MPa), while the chamber 17
remains substantially at atmospheric pressure. This leads to radial
expansion of the tubular junction sleeve which then alone takes up
the bursting force throughout the zone of the chamber 17, since the
steel pipe is substantially unstressed in said zone by said
bursting effect. Compared with FIG. 12A, FIG. 12B is an enlargement
of the notched zone of the tubular junction sleeve and it shows the
tops of said notches penetrating into the thermoplastic material of
the liner, and also the creep of said thermoplastic material
towards the chamber 17 created by the pressure P acting on the
inside of the lined pipe, in service.
[0200] The sleeves 3 and half-sleeves 4 are described as being made
of a material that withstands corrosion, and more particularly as
being made of a metal, even more particularly of an Inconel alloy,
however it remains within the spirit of the invention to consider
using a composite material, e.g. a carbon or glass fiber composite
within a bonding matrix, e.g. of the epoxy or polyurethane type.
Various methods can be envisaged for fabrication, for example
winding a filament on a mandrel, overmolding organized fibers with
a fluid resin, or any other method suitable for making bodies of
revolution that present great mechanical strength. The resins
should be selected so that they can withstand the heat that is
generated by welding the pipes together, during string assembly on
site, within the J-lay tower, and a heat shield, e.g. of ceramic
fibers, can advantageously be interposed between said tubular
sleeve and said steel pipe, in register with the junction.
[0201] The ends of the tubular junction sleeve 3 and of the
half-sleeve 4 are described as presenting notches in the form of
surfaces of revolution, however it would remain within the spirit
of the invention if the notching were to be constituted by a
helical thread, thus being constituted by a single projection
taking a plurality of turns around the periphery of said tubular
junction sleeve. Thus, putting the tubular junction sleeve into
place on the prefabrication site could be done either by pushing it
in using a press, as explained above, or else by screw-fastening
until said tubular junction sleeve comes into abutment against the
end face of the liner. In the same manner, on-site installation
within a J-lay tower can be performed either by being pushed in
directly, or by screw-fastening, with the notched surface of the
second end of the tubular junction sleeve either constituting a
surface of revolution or being helical in shape.
[0202] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements and/or method steps which perform
substantially the same function in substantially the same way to
achieve the same results are within the scope of the invention.
Moreover, it should be recognized that structures and/or elements
and/or method steps shown and/or described in connection with any
disclosed form or embodiment of the invention may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *