WO2009130091A1

WO2009130091A1 - Method of and apparatus for sealing underwater pipes using a plug and a sealer; welding unit for such apparatus

Info

Publication number: WO2009130091A1
Application number: PCT/EP2009/053157
Authority: WO
Inventors: Matti Emil Heikkila
Original assignee: Technip France Sa
Priority date: 2008-04-22
Filing date: 2009-03-17
Publication date: 2009-10-29
Also published as: GB0807269D0; GB2459325A; NO340716B1; GB2459325B; NO20101561A1

Abstract

The present application relates to a method of providing a sealed joint between first and second underwater pipes (10, 12) having first and second pipe-ends (IS, 18), comprising at least the steps of : (a) locating a plug (22) into the first pipe-end (18) to plug the first pipe (10); (b) locating a sealer (26) over the first and second pipe-ends (16, 18); (c) removing water around the first and second pipe-ends (16, 18); (d) providing a welding unit (42) along the second pipe (12) to at least the second pipe-end (18); and (e) creating internally one or more welds around the first and second pipe-ends (16, 18) to provide the sealed joint between the first and second pipes (10, 12). The present application relates also to such an apparatus and a welding unit.

Description

METHOD OF AND APPARATUS FOR SEALING UNDERWATER PIPES USING A PLUG AND A SEALER ; WELDING UNIT FOR SUCH APPARATUS

5 The present invention relates to method and apparatus for sealing underwater, such as subsea, pipes, in particular for repairing a broken subsea pipeline.

For subsea pipelines for fluids such as oil, any damage to the pipeline

10 needing repair, for example caused by the environment or caused by collision with other equipment or corrosion or even buckle of the pipeline, can, where the pipeline is not too deep, be brought to the surface and the repairing operation carried out above surface prior to re-laying of the pipeline underwater, such as on the seabed.

15

Where such pipes or pipelines are in deeper water, there are increasing difficulties. Divers can be used, but the depths to which they are allowed to work has been reduced over the years due to increasing safety consideration, and in some locations is limited to 180 meters.

20

WO2006/004428 A1 describes a remote-controlled joining system for 'diverless welding'. A pipe sleeve is located around the two pipe ends, and then a welding clamp is put around the pipelines to weld the pipe sleeve to the outsides of the pipelines. The welding tool is integrated with

25 the welding clamp to provide a very particular piece of equipment able to integrate the clamp and the welding tool, and to properly locate and operate them. For that reason, WO2006/004428 prefers that a remotely operated vehicle (ROV) is still involved, with attendant cost. US 5,437,517 describes a method for automatically repairing an underwater pipeline involving a "single working module" which is lowered onto the seabed by a crane, and which carries out various operations requiring very specific alignment, heavy equipment, and perfect alignment of the replacement pipe piece for coupling by locking flanges. Connection using locking flanges is known in the art to be less secure than welding.

One object of the present invention is to provide an improved method of joining two pipelines underwater.

According to one aspect of the present invention, there is provided a method of providing a sealed joint between first and second underwater pipes having first and second pipe-ends, comprising at least the steps of:

(a) locating a plug into the first pipe-end to plug the first pipe;

(b) locating a sealer over the first and second pipe-ends;

(c) removing water around the first and second pipe-ends;

(d) providing a welding unit along the second pipe to at least the second pipe-end; and (e) creating internally one or more welds around the first and second pipe-ends to provide the sealed joint between the first and second pipes.

By providing the welding unit along the second pipe to reach at least the second pipe-end, and generally to be in the vicinity of both the first and second pipe-ends, the or each weld created by the welding unit is internal, or is at least internally provided, from within the pipes. This is in contrast to the conventional provision of external welds to underwater pipes. Thus, the present invention is a method able to provide an internally- welded sealed joint based on joining the two underwater pipes from inside the pipes.

The present invention is able to provide a sealed joint between first and second underwater pipes able to convey any type of fluid, being gaseous, liquid or a combination of same, including various hydrocarbons.

The present invention can be used at any underwater such as subsea depth whether this be within safety range of a diver or not.

The plug to be located in the first pipe-end provides a plug of the first pipe during the welding. Plugs such as isolation pigs, units or other devices are well known in the art. Removal of such plugs after the welding is also well known in the art using other known pipeline equipment such as clearance pigs.

The sealer may comprise one or more elements or bodies, provided separately or integrally, able to enclose the first and second pipe-ends such that water around the first and second pipe-ends can then be removed.

In one embodiment of the present invention, the sealer comprises a sleeve, optionally including one or more internal seals, able to be located longitudinally over the first and second pipe-ends. Optionally, the sleeve includes one or more internal circumferential seals, able to create at least a temporary water-proof seal between the sleeve and pipe-ends.

The sealer may include insulation around the sleeve to assist reduction or the escape of heat during the weld creation. In another embodiment to the present invention, the sealer includes one or more dams or clamps, usually provided in two or more parts, and able to envelope the first and second pipe-ends to allow the removal of water around the first and second pipe-ends. Dams such as cofferdams and clamps such as Dearman clamps, are well known in the art.

The sealer may include one or more induction coils able to assist the preparation of the pipes and/or the pipe-ends prior to welding.

Preferably, the second pipe extends to above the surface of the water, for example above sea level. Such extension may be due to the existing alignment or pathway of the second pipe, or as a particular step in advance of the method of the present invention.

In this way, atmospheric pressure and/or the provision of one or more other gases can be provided along the second pipe from where it is above the surface of the water, to the location of the first and second pipe-ends. The welding can thus be provided at or near atmospheric pressure and/or in a desired gaseous atmosphere, allowing the method and operation of the welding to be relatively and technically simply compared with underwater welding at high water pressures.

The welding unit may comprise one or more of the group comprising: pipe cleaners, pipe-end shapers, cameras, lights, and pipe-end aligners. The welding unit may be self-mobile, or one or more pipe-internal apparatus, device or units, such as crawlers, can be used to provide motion to the welding unit. The operation(s) of the welding unit may also be self-powered, or have power provided thereto by the use of one or more umbilical lines known in the art along the second pipe. The removal of water around the first and second pipe-ends is known in the art, and usually involves the provision of one or more hoses, preferably in association with the sealer, to dewater the area or vicinity around the first and second pipe-ends.

The welding unit may provide any type of welds, or combination of same, such as butt welds, fillet welds, etc. so as to provide the sealed joint between the first and second pipe from within the vicinity of the pipe-ends. The provision of welds between pipe-ends and/or one or more sleeves or the like, optionally being part of the sealer, are well known in the art and are not further discussed herein.

According to a second aspect of the present invention, there is provided apparatus for providing a sealed joint between first and second underwater pipes having first and second pipe-ends, comprising at least:

(a) a plug for locating into the first pipe-end to plug the first pipe;

(b) a sealer for sealing over the first and second pipe-ends; (c) one or more hoses to remove water around the first and second pipe-ends;

(d) a welding unit provided along the second pipe to at least the second pipe-end, and able to internally create one or more welds around the first and second pipe-ends to provide the sealed joint between the first and second pipes.

According to a third aspect of the present invention, there is provided a welding unit able to internally create one or more welds around first and second pipe-ends of first and second underwater pipes to provide the sealed joint between the first and second pipes, wherein the welding unit is provideable along the second pipe.

Embodiments of the present invention will now be described by way of example only, and with reference to the accompanying schematic drawings in which:

Figure 1 is a cross-sectional diagrammatic view of a first embodiment of the present invention;

Figure 2 is a cross-sectional diagrammatic view of a second embodiment of the present invention;

Figure 3 is a side view of the welding unit shown in Figure 2; and

Figure 4 is a view along line AA of Figure 3.

Referring to the drawings, Figure 1 shows a method of providing a sealed joint between a first underwater, such as subsea, pipe 10 and a second underwater pipe 12.

Figure 1 shows a sea level or water surface level 14 by way of illustration only, and without limitation as to the depth of the location of the first and second pipes 10, 12 where it is intended to conjoin or rejoin them.

The nature and material of the first and second pipes 10, 12 are well known in the art, and can vary depending upon the type of fluids or fluids being passed therealong, and their properties and parameters. Common fluids are those based on one or more hydrocarbons such as methane, or heavier hydrocarbons such as oil. The first and second pipes 10, 12 may have any size and/or dimensions. Commonly, although the invention is not limited thereto, the inner and outer diameters of the first and second pipes 10, 12 are the same. This is especially where the method of the present invention is being applied to repair of an existing pipeline.

Existing subsea pipelines can be in need of repair due to a number of reasons such as those described above. In such circumstances, the pipeline may require removal of one or more sections, thus creating a first pipe 10 having a first pipe-end 16 and a second pipe 12 having a second pipe-end 18.

It may be desired to provide some preparation of the first and second pipes 10, 12 and in particular the first and second pipe-ends 16, 18 in advance of the present embodiment of the present invention. This could include cleaning the first and second pipe-ends 16, 18, and/or removing any coating (not shown) around the first and second pipes 10, 12, in particular around their first and second pipe-ends, 16, 18, to assist the provision of the joint between them. Some pipes and pipelines have particular coatings which may inhibit the final provision of a sealed joint between the first and second pipes 10, 12.

Figure 1 shows a plug 22 such as an isolation pig, which has been inserted into the first pipe-end 16. The insertion may be carried out by one or more divers, or by a suitable underwater apparatus. The plug 22 may include a circumferential seal 24, adapted to increase the engagement of the surface of the plug 22 with the inner circumference of the first pipe 10, so as to increase the seal therebetween, especially as the pressure differential across the plug 22 increases as discussed hereinafter. Figure 1 shows a first sealer comprising a sleeve 26, optionally a sleeve pipe, having four inner circumferential seals 28. The sleeve 26 may be located around the first and second pipe-end 16, 18 by one or more divers, or by a suitable underwater apparatus.

Preferably, the sealer includes thermal insulation therearound, so as to reduce heat loss away from the subsequent welding operation. Thermal insulation coats or coatings 32 are well known in the art, and are not further discussed herein.

Optionally, additionally, there may be one or more further collars 34 located between the first and second pipes 10, 12 and the sleeve 26, and optionally the thermal insulation 32, so as to increase the interconnection of same during subsequent processing.

Figure 1 shows two hoses 35, 36 on opposite sides of the sleeve 26, having valves and taps 37, 38. The hoses 35, 36 are adapted to remove water around the first and second pipe-ends 16, 18 in a manner known in the art, such as by the use of one or more vacuum pumps.

Figure 1 also shows the second pipe 12 extending above the water or sea level 14, such that atmospheric pressure may extend down the second pipe 12 and be the prevailing pressure within the vicinity or area around the first and second pipe-ends 16, 18. The plug 22 ensures that the higher pressure of any water or other fluid in the first pipe 10 does not affect the pressure around the first and second pipe-ends 16, 18. Similarly, the use of the seals 28 with the sleeve 26, and the additional collars 34, allows the pressure in the area or vicinity between the first and second pipe-ends 16, 18 to be as desired. If desired or necessary, one or more welding gases could be pumped down the second pipe 12 so as to provide the correct or desired welding atmosphere and/or pressure around the first and second pipe-ends 16, 18.

Figure 1 also shows a first welding unit 42 able to be provided along the second pipe 12, such as from an above sea level location. The first welding unit 42 may include one or more circumferential wheels to assist its motion along the second pipe 12. Figure 1 also shows a drive mechanism such as a first crawler 44 known in the art, able to provide the motion to the first welding unit 42. Figure 1 also shows an umbilical 46 in the second pipe 12 able to provide power to the first welding unit 42.

The forward face of the first welding unit 42 may include one or more units, devices, instruments or other equipment adapted to assist the preparation, cleaning, alignment, etc. of the one or more locations or places where it is intended to provide welding. In the embodiment shown in Figure 1 , it is intended to provide fillet welds 60 between the first and second pipe-ends 16, 18 and the inner circumference of the sleeve 26 thereinbetween. In this regard, one or more instruments at the front of the first welding unit 42 may assist final cleaning of such locations.

Thus, the fillet welds 60 are provided internally of or within the first and second pipe-ends 16,18 and the sleeve 26. That is, not externally of the first and second pipes 10, 12 and the sleeve 26.

Preferably, the first and second pipe-ends 16, 18 are aligned, and also preferably provided with a gap thereinbetween. The gap may be a suitable distance, such as in the range 10-30cm. The first welding unit 42 includes an arm 52, preferably including one or more articulations, at the end of which is a welding point 54 able to create the fillet welds 60 mentioned above.

In this way, the embodiment to the present invention shown in Figure 1 is able to provide internal welding between the first and second pipe-ends 16, 18 (and thus inherently between the first and second pipes 10, 12) and the sleeve 26, to create an internally-welded sealed joint between the first and second pipes 10, 12.

Figure 1 shows one embodiment of providing welds around the first and second pipe-ends 16, 18. The present invention is not limited by the number or type or arrangement of welds around the first and second pipe- ends 16, 18, whether they be directly welded together (as shown in Figure 2 below), or indirectly welded via one or more other pieces such as the sleeve 26.

Upon completion of the welding, the first crawler 44 can withdraw the first welding unit 42 by reversal of the operation of its installation, and the plug 22 can be removed by the provision of a cleaning pig or the like known in the art, along the first pipe 10. The pipeline created by the conjoined first and second pipes 10,12 is then ready for use or reuse.

Thus, the present invention provides a method of providing a sealed joint between the first and second pipes 10, 12 using internal dry welding, whose strength and reliability is known better than wet welding externally around underwater pipes.

Figure 2 shows a second embodiment to the present invention involving first and second pipes 10, 12. Similar to the embodiment shown in Figure 1 , the first pipe 10 has had located therein a plug 22 to provide a barrier to the ingress of fluid in the first pipe 10 towards the first pipe-end 16 during the embodiment of the present invention.

Figure 2 shows the location of two sets of clamps around the first and second pipe-ends 16, 18, alternatively or additionally around the first and second pipes 10, 12, to form a second sealer.

The first set of clamps comprises one or more Dearman clamps 62 known in the art. Dearman clamps 62 could be provided in two halves with a hinge, so as to fit around the first and second pipe-end 16, 18. The Dearman clamps 62 could be formed as a composite with a foam core for buoyancy. The Dearman clamps 62 could be installed by divers and/or suitable underwater apparatus. Figure 2 shows ceramic-coated hydraulic powered shoes 64 for the Dearman clamps 62 in a manner known in the art. There also may be installed ceramic-backing strips between the Dearman clamp legs and the pipe-ends.

The Dearman clamps 62 may also include one or more induction coils 66 intended to provide any pre-heating and/or drying desired to the first and second pipe-ends 16, 18.

Around the Dearman clamps 62, can be located one or more dams. Figure 2 shows two half-shell cofferdams 68 to isolate the working area around the Dearman clamps 62 from the surrounding water 70.

Figure 2 shows two hoses 71 , 72 on opposite sides of the cofferdams 68, having valves and taps 73, 74. The hoses 71 , 72 are adapted to remove water around the first and second pipe-ends 16, 18 in a manner known in the art. Optionally, the hoses 71 , 72 can also be used to provide one or more suitable fluids, such as welding gases or backing gases, preferably heated backing gas, into the cofferdams 68 to assist the subsequent welding.

Figure 2 also shows an umbilical power cord 76 to provide power to one or more of the Dearman clamps 62, induction coils 66, etc.

Figure 2 shows the second pipe 12 extending above the water or sea level 78, such that atmospheric pressure may extend down the second pipe 12 and be the prevailing pressure within the vicinity or area around the first and second pipe-ends 16, 18. If desired or necessary, one or more welding gases or other gases could be pumped down the second pipe 12 so as to provide the correct or desired welding atmosphere and/or pressure around the first and second pipe-ends 16, 18.

Figure 2 shows a second welding unit 82 able to be provided along the second pipe 12, such as from an above sea level location. The second welding unit 42 may include one or more circumferential wheels to assist its motion along the second pipe 12. The second welding unit 82 comprises two end-units 84a, 84b with a joining tool section 86.

As shown in more detail in Figures 3 and 4, the joining tool section 86, which may be circular or have any other cross-section, includes one or more tools 88 extending outwardly therefrom, such as orthogonally, which tools 88 can provide different operations and processes. One tool can be an internal pipe cleaner, adapted to assist physical cleaning of the first and/or second pipe-ends 16, 18 or another part of the first and second pipes 10, 12. Another tool may be a high pressure air provider for similar functions. Another tool may be a vacuum port able to extract material around the first and second pipe-ends 16, 18 to prevent any hindrance to the subsequent welding operation.

The present invention is not limited by the nature, number or action or the tools 88. Other tools include grinders, sanding disks, equipment for preheating, wire cutters, nozzle cleaners, lights and a tool changer. Optionally, the connecting section 86 is movable, such as rotatable, so as to allow each tool 88 to be accessible around the internal circumference of the first and second pipe-ends 16, 18.

The second welding unit 82 may also include one or more cameras 90 and lights 91 to provide visual inspection of the first and second pipe-ends 16, 18, and/or the subsequent welding.

The second welding unit 82 may be self-powered, or may involve a drive mechanism such as a second crawler 92 known in the art, and able to provide motion to the second welding unit 82. Figure 2 also shows an umbilical 94 in the second pipe 12 to provide power to the second welding unit 82.

In use, and after location and connection of the Dearman clamps 62 and the cofferdams 68, water around the first and second pipe-ends 16, 18 can be removed via the hoses 71 , 72, followed by insertion and motion of the second welding unit 82 and the second crawler 92 along the second pipe 12 until located at the work location in the vicinity of the first and second pipe-ends 16, 18. Tools 88 of the joining tool section 86 can then be used to prepare the areas to be welded, optionally followed by any pre-heating and/or drying by use of the induction coils 66. Dried air and/or welding gas could then be pumped along the second pipe 12 to provide the correct atmosphere and/or pressure around the first and second pipe-ends 16, 18, following which the second welding unit 82 provides butt-welds (the first parts 96 of which are shown in Figure 2) to conjoin the first and second pipe-ends 16, 18, and thus provide a sealed joint between the first and second underwater pipes 10, 12.

In this way, the embodiment of the present invention shown in Figure 2 is able to provide internal welding or one or more internal welds between the first and second pipe-ends 16, 18 at a desired atmosphere and pressure. As the welding is taking place against powered shoes 64 and any backing material between the shoes, the root cap for the weld preparation can typically be closed or up to 5mm. Testing of the welding could also be carried out by one or more tools 88 on the second welding unit 82 (and/or by one or more non-destructive testing methods from outside of the first and second pipes 10, 12 after completion of the welding and de-rigging of the equipment).

Various modification and variations to the described embodiments of the present invention would be apparent to those skilled in the art without departing from the scope of the invention as defined herein. Although the invention has been described in connection with the specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.

Claims

1 . A method of providing a sealed joint between first and second underwater pipes having first and second pipe-ends, comprising at least the steps of:

(a) locating a plug into the first pipe-end to plug the first pipe;

(b) locating a sealer over the first and second pipe-ends;

(c) removing water around the first and second pipe-ends;

(d) providing a welding unit along the second pipe to at least the second pipe-end; and

(e) creating internally one or more welds around the first and second pipe-ends to provide the sealed joint between the first and second pipes.

2. A method as claimed in claim 1 wherein the one or more welds are created at or near atmospheric pressure.

3. A method as claimed in claim 1 or claim 2 wherein the sealer comprises one or more sleeves or clamps or a combination thereof.

4. A method as claimed in any one of the preceding claims wherein the second pipe extends above the water level.

5. A method as claimed in claim 4 wherein the welding unit is provided along the second pipe from an above water level.

6. A method as claimed in one or more of the preceding claims wherein the welding unit includes one or more of the group comprising: pipe cleaners, pipe-end shapers, cameras, lights, and pipe-end aligners.

7. A method as claimed in one or more of the preceding claims wherein the sealer includes a sleeve able to extend around the first and second pipe-ends, and the welding unit creates one or more fillet welds between the first and second pipe-ends and the sealer.

8. A method as claimed in one or more of claims 1 to 6, wherein the sealer comprises two or more shell-clamps, and the welding unit creates one or more butt welds between the first and second pipe-ends.

9. A method as claimed in any one of the preceding claims wherein the welding unit is provided along the second pipe by a crawler.

10. Apparatus for providing a sealed joint between first and second underwater pipes having first and second pipe-ends, comprising at least:

(a) a plug for locating into the first pipe-end to plug the first pipe;

(b) a sealer for sealing over the first and second pipe-ends;

(c) one or more hoses to remove water around the first and second pipe-ends; (d) a welding unit provided along the second pipe to at least the second pipe-end, and able to internally create one or more welds around the first and second pipe-ends to provide the sealed joint between the first and second pipes.

1 1 . A welding unit able to internally create one or more welds around first and second pipe-ends of first and second underwater pipes to provide the sealed joint between the first and second pipes, wherein the welding unit is provideable along the second pipe.