Coaxial Pipe Assembly Including a Thermalloy Insulating Sleeve

• US 20110186169A1
• Filed: 10/22/2009
• Published: 08/04/2011
• Est. Priority Date: 10/29/2008
• Status: Active Grant

• Current Assignee: Saipem SA (Saipem)
• Original Assignee: Saipem SA (Saipem)
• Inventors: Delebecque, Loïc, Pionetti, François-Régis
• Granted Patent: US 9,267,637 B2
• Time in Patent Office: Days
• US Class Current: 138/114
• CPC Class Codes: F16L 1/18 the pipes being S- or J-shaped and under tension during laying
• CPC Class Codes: F16L 39/005 for concentric pipes
• CPC Class Codes: F16L 59/141 in which the temperature of the medium is below that of the ambient temperature rigid pipes of wood F16L9/006; vacuum insulation F16L59/065
• CPC Class Codes: F16L 59/16 Arrangements specially adapted to local requirements at flanges, junctions, valves or the like

Abstract

An assembly of two coaxial pipes of the PiP type, comprising at least two coaxial pipe unit elements each comprising an inner pipe and an outer pipe, defining an annular space, preferably filled with an insulating material, and assembled end to end by welding, including a sleeve with a hollow tubular wall made of rigid or semirigid material, preferably of plastics material or composite material, surrounding said pipe in register with the welded junction zone between said two coaxial pipe unit elements, said hollow tubular wall of the sleeve comprising an outer casing and an inner casing connected together at their longitudinal ends in leaktight manner, thereby defining an internal volume that is completely filled with a quasi-incompressible thermally insulating material.

Claims

1. An assembly of coaxial pipes of the PiP type, comprising at least two coaxial pipe unit elements each comprising an inner pipe and an outer pipe, with an annular space, preferably filled with an insulating material, and assembled end to end by welding, wherein the assembly includes a sleeve with a hollow tubular wall made of rigid or semirigid material, preferably of plastics material or composite material, surrounding said pipe in register with the welded junction zone between said two coaxial pipe unit elements, said hollow tubular wall of the sleeve comprising an outer casing and an inner casing connected together at their longitudinal ends in leaktight manner, thereby defining an internal volume that is completely filled with a quasi-incompressible thermally insulating material that constitutes an insulating gel.

2. The assembly of coaxial pipes according to claim 1, wherein said quasi-incompressible thermally insulating material is an insulating gel of PCM.

3. The assembly of coaxial pipes according to claim 1, wherein at least said inner casing or preferably at least said outer casing of said sleeve is formed integrally with connection elements at its longitudinal ends, suitable for closing the space between the inner and outer casings of the hollow tubular wall of the sleeve at their ends, said part being made of thermostatic material of small thickness, less than 10 mm, preferably of thickness lying in the range about 4 mm to about 8 mm, being obtained by rotational molding, and said part being fastened to the other casing, respectively the outer or the inner casing, of the hollow tubular wall of the sleeve via said connection elements.

4. The assembly of coaxial pipes according to claim 3, wherein said part obtained by rotational molding comprises a said inner or preferably outer casing of the sleeve together with said end connection elements, and includes corrugations or grooves forming rounded or square projections or recesses in said inner casing or preferably in said outer casing of the sleeve.

5. The assembly of coaxial pipes according to claim 3, wherein one of said inner or outer casings of said sleeve that is made integrally with said end connection elements is obtained by rotational molding, while the other casing of the sleeve, respectively the outer or the inner casing, is obtained by extrusion or by rotational molding, and is fastened to said connection elements by adhesive or by heat-sealing.

6. The assembly of coaxial pipes according to claim 1, wherein said hollow tubular wall comprising said inner and outer casings and said end connection elements is obtained as a single piece in the form of a one-piece rotational molding, the inner casing preferably presenting a shape that is slightly conical, without said corrugations or grooves, so as to enable it to be unmolded.

7. The assembly of coaxial pipes according to claim 1, wherein said inner casing of said hollow tubular wall of the sleeve includes a middle zone of diameter greater than the end zones adjacent thereto on either side thereof, thus forming a setback in which at least one first leaktight pouch is received surrounding the entire periphery of said coaxial pipe assembly, the pouch being filled with a non-insulating phase-change material, preferably a molten salt, the thickness of said filled pouch preferably being less than the thickness of said setback, more preferably lying in the range 1 cm to 10 cm.

8. The assembly of coaxial pipes according to claim 7, wherein said outer casing of the tubular wall of the sleeve includes a middle portion of diameter greater than the end zones adjacent thereto, in register with said greater diameter middle zone of said inner casing, so as to maintain a substantially constant thickness of quasi-incompressible insulating material within the casing in said middle zone over the entire length of said sleeve.

9. The assembly of coaxial pipes according to claim 1, wherein said sleeve further includes a filler material filling the space or clearance between said inner casing of the tubular wall of the sleeve and said outer pipe or where appropriate inner pipe of the coaxial pipe assembly, said filler material connecting said sleeve to said coaxial pipe assembly, and preferably being a hardenable filler material of the resin or cement type, more preferably being a thermally insulating material.

10. The assembly of coaxial pipes according to claim 1, wherein each of said unit elements of the assembled coaxial pipe assembly includes at its ends a junction piece forming a body of revolution connected to said inner and outer pipes at one end of the junction piece, with the two junction pieces being assembled to each other by welding at their opposite ends, said sleeve being centered over the weld joining the two junction pieces together and extending beyond the connection welds between said junction pieces and each of said coaxial pipe assembly unit elements.

11. The assembly of coaxial pipes according to claim 1, wherein each said coaxial pipe unit element includes an outer pipe end that is set back from the end of the inner pipe, the annular space between said outer and inner pipes being closed by crimping, which consists in deforming the terminal portion of the outer pipe so that its end is directly connected to the surface of the inner pipe, preferably by welding, and the two coaxial pipe unit elements are assembled together by welding to each other via the ends of their inner pipes, said sleeve extending over a distance of at least 50 cm and preferably at least 1 m over said outer pipe beyond the crimp welds, and the space between the inner casing of said sleeve and the inner pipe of the coaxial pipe assembly between the two crimp welds is filled with an insulating material, preferably a phase-change compound, more preferably a molten salt contained in at least one second leaktight pouch completely surrounding said inner pipe, the longitudinal end(s) of said pouch(es) preferably presenting in axial longitudinal section a profile that is chamfered in such a manner as to fit as closely as possible to said outer pipe after the crimp zone between said outer pipe and said inner casing of said sleeve.

12. The assembly of coaxial pipes according to claim 1, wherein each said coaxial pipe unit element includes at its end a said junction piece, said two junction pieces being connected together by welding, and one of said junction pieces including in its outside surface a projection in the form of an abutment or a collar suitable for enabling the coaxial pipe unit element that is connected thereto to be held in suspension in a vertical or an inclined position from a laying ship at sea, and said tubular sleeve includes an end zone with an inner casing of diameter greater than the diameter of the longitudinally opposite end, said greater-diameter end zone of the inner casing covering the coaxial pipe assembly inside said sleeve, at least starting from said projection or collar.

13. The assembly of coaxial pipes according to claim 7, wherein said sleeve contains said first and/or second pouches forming pairs of diametrically opposite semicylindrical pouches on either side of said coaxial pipe assembly.

14. The assembly of coaxial pipes according to claim 1, wherein the length of said sleeve lies in the range 1 m to 10 m, preferably in the range 2 m to 6 m, and is of thickness preferably lying in the range 5 cm to 25 cm, and more preferably said inner and outer casings of the tubular wall of the sleeve present thickness lying in the range 2 mm to 10 mm.

15. The assembly of coaxial pipes according to claim 1, wherein the sleeve comprises a thermally insulating sleeve having a hollow tubular wall filled with a quasi-incompressible thermally insulating material.