Unbonded flexible pipe and an end-fitting

Abstract

An assembly comprising an end-fitting and an unbonded flexible pipe comprising several layers. The unbonded flexible pipe has an end-part entering the end-fitting at the front end and the layers of the unbonded flexible pipe being terminated in the end-fitting. The unbonded flexible pipe further comprises a first electrically conductive layer and a second electrically conductive layer, where the first electrically conductive layer is electrically insulated from the second electrically conductive layer. The end-fitting comprises a first electric zone electrically connected with the first electrically conductive layer, and a second electric zone electrically connected with the second electrically conductive layer, the first electric zone is electrically separated from the second electric zone, and the end-fitting comprises a third electric zone, the third electric zone being electrically separated from first electric zone and the second electric zone.

Claims

1. An assembly comprising an end-fitting with a first-end and a second-end and a through-going opening having a center axis between the first-end and the second-end, and an unbonded flexible pipe comprising several layers and having a center axis along its length, said center axis of the unbonded flexible pipe being substantially coinciding with the center axis of the end-fitting for the part of the unbonded flexible pipe arranged in the end-fitting, said unbonded flexible pipe, having an end-part entering the end-fitting at the first-end and the layers of the unbonded flexible pipe being terminated in the end-fitting between the first-end and the second-end, said unbonded flexible pipe further comprises a first electrically conductive layer and a second electrically conductive layer, said first electrically conductive layer being electrically insulated from the second electrically conductive layer, and the end-fitting comprises a first electric zone electrically connected with the first electrically conductive layer, and a second electric zone electrically connected with the second electrically conductive layer, said first electric zone being electrically separated from the second electric zone, wherein the end-fitting comprises a third electric zone, said third electric zone being electrically separated from first electric zone and the second electric zone, wherein said first electric zone and said second electric zone are arranged along the length of and concentrically in respect of the center axis and at least a part of said third electric zone is located closer to the second end of the end-fitting than the first electric zone and the second electric zone, and the first electrically conductive layer and the second electrically conductive layer are connected with a source for electric power via the first electric zone and the second electric zone of the end-fitting, the applied electric power source is configured for being floating.

2. An assembly according to claim 1, wherein the first electrically conductive layer and the second electrically conductive layer of the unbonded flexible pipe are arranged substantially concentrically in respect of the center axis.

3. An assembly according to claim 1, wherein the end-fitting comprises an outer cover surrounding and being substantially co-axially with at least a part of the first electric zone and/or the second electric zone, said outer cover being of non-conductive material.

4. An assembly according to claim 1, wherein the end-fitting comprises an outer cover surrounding and being substantially co-axially with at least a part of the first electric zone and/or the second electric zone, said outer cover being of electrically conductive material and connected with ground.

5. An assembly according to claim 1, wherein the end-fitting comprises an outer cover surrounding and being substantially co-axially with at least a part of the first electric zone and/or the second electric zone, said outer cover being of electrically conductive material and connected to the third electric zone.

6. An assembly according to claim 5, wherein a void is formed between the outer cover and at least a part of the first electric zone and/or the second electric zone, said void being filled with an electrically insulating material.

7. An assembly according to claim 1, wherein the unbonded flexible pipe from the inside and outwards comprises a carcass, an internal pressure sheath, at least one pressure armor, at least one tensile armor and optionally an outer sheath.

8. An assembly according to claim 1, wherein the unbonded flexible pipe further comprises one or more intermediate layers.

9. An assembly according to claim 1, wherein the unbonded flexible pipe comprises at least one thermal insulating layer.

10. An assembly according to claim 1, wherein the first electrically conductive layer is a carcass.

11. An assembly according to claim 1, wherein the first electrically conductive layer is a pressure armor.

12. An assembly according to claim 1, wherein the second electrically conductive layer is a pressure armor.

13. An assembly according to claim 1, wherein the second electrically conductive layer is a tensile armor.

14. An assembly according to claim 1, wherein the insulation between the first electrically conductive layer and the second electrically conductive layer is constituted at least partly by the internal pressure sheath.

15. An assembly according to claim 1, wherein the applied voltage is in the range 100 V to 10 kV.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The invention will be explained more fully below with reference to the drawings in which:

(2) FIG. 1 shows an end-fitting and an unbonded flexible pipe;

(3) FIG. 2 shows a cross section of an embodiment of the end-fitting and an unbonded flexible according to the invention;

(4) FIG. 3 shows a cross section of another embodiment of the flexible pipe 2 and the end-fitting 3 according to the invention.

(5) The figures are schematic and simplified for clarity, and they show only details which are essential to the understanding of the invention, while other details are left out. The same reference numerals may be used for identical or corresponding parts.

(6) FIG. 1 illustrates an unbonded flexible pipe 2 and an end-fitting 3.

(7) The unbonded flexible pipe 2 comprises, from the inside an out, a carcass 10, an internal pressure sheath 11, a pressure armor 12, an intermediate electric insulating layer 13, a tensile armor 14 and an outer sheath 15.

(8) The carcass 10 is made from elongate members of stainless steel wound with a winding angle of approximately 85 degrees in respect of the axis, indicated by line 16. The pressure armor 12 is made from an elongate member of carbon steel and wound around the internal pressure sheath 11 with a winding angle of approximately 80 degrees in respect of the axis 16.

(9) The intermediate electric insulating layer 13 is an extruded polyethylene layer. The tensile armor 14 is also made from an elongate member of carbon steel and wound around the pressure armor with a winding angle of approximately 45 degrees in respect of the axis 16.

(10) In this embodiment, the internal pressure sheath 11 and the outer sheath 15 are both substantially fluid tight. The internal pressure sheath 11 is made from extruded polyethylene and the outer sheath 15 is made from extruded polyamide.

(11) The end-fitting 3 comprises a body part 4, a channel 5 and a flange 6 for connection to either a connector or another end-fitting. The flange 6 comprises holes 7 for bolts which may be used for the connection. The material of the end-fitting is carbon steel.

(12) In FIG. 2, a cross section of an end-fitting with three electric zones and an unbonded flexible is shown.

(13) The flexible pipe 2 enters the end-fitting 3 at the first-end 34 and is terminated in the end-fitting in a known manner. The carcass 10 is terminated with a carcass ring 20. The internal pressure sheath 11 is mechanically locked by clamps 21. The pressure armor 12 is terminated by fixation 22 and the intermediate electric insulating layer 13 is anchored in the end-fitting at 23 by mechanical interlock. The tensile armor 14 is terminated in traditional manner in a resin filled cavity 24. The outer sheath 15 is terminated at 25 and anchored by pressure means.

(14) The internal pressure sheath 11 and the intermediate electric insulating layer 13 are made from polymer material such as polyethylene which is electrical insulating. Thus, the internal pressure sheath 11 and the intermediate electric insulating layer 13 form electrical insulating layers between the carcass 10, the pressure armor 12 and the tensile armor 14, which armor layers are all manufactured from electric conductive metallic material.

(15) The end-fitting comprises three electric zones 31, 32 and 33. The first electric zone 31 is in this embodiment in the mid-part of the end-fitting 3 and has electric connection with the carcass 10. In this embodiment, the second electric zone 32 extends from the first electric zone 31 to the first end 34 of the end-fitting 3. The second electric zone 32 is electrical connected with the pressure armor 12 and the tensile armor 14.

(16) The third electric zone 33 is located between the first electric zone 31 and the second end 35 of the end-fitting 3.

(17) The first electric zone 31 is electrical separated from the second electric zone 32 by means of electrical insulating material 36 and the first electric zone 31 is electrical separated from the third electric zone 33 by means of electrical insulating material 37.

(18) The outer surface part of the end-fitting 3 is coated with an electrical insulating coating 38 of polymer material. As indicated by lines 40 and 41, a voltage is applied to the first electric zone 31 and the second electric zone 32.

(19) In this particular embodiment, a current may be sent from a power source through the carcass 10 and returned by the pressure armor 12 and the tensile armor 14. The three mentioned armor layers may be electrically connected in another end-fitting at a distal end of the flexible pipe 2.

(20) To increase safety the third electric zone 33 is connected with ground via line 42.

(21) FIG. 3 shows a cross section of an alternative embodiment of the flexible pipe 2 and the end-fitting 3.

(22) The pipe 2 shown in FIG. 3 comprises a carcass 10, an internal pressure sheath 11, a tensile armor 14 and an outer sheath 15. The carcass 10 is terminated with a carcass ring 20 in a conventional manner. The internal pressure sheath 11 is terminated by clamping means 21. The tensile armor 14 is terminated in traditional manner in a resin filled cavity 24. The outer sheath 15 is terminated at 25 and anchored by pressure means.

(23) Then an internal pressure sheath 11 forms an insulating layer between the carcass 10 and the tensile armor 14. In this embodiment, the internal pressure sheath 11 is made from an extruded layer of polyethylene which is electrical insulating. The carcass 10 and the tensile armor 14 are made from carbon steel which is electrically conductive.

(24) The end-fitting 3 includes three different electric zones 31, 32 and 33. The first electric zone 31 is located in the mid-part of the end-fitting 3 and electrically connected with the carcass 10. The second electric zone 32 extends from the first electric zone 31 to the first end 34 of the end-fitting 3 and is electrically connected with tensile armor 14.

(25) The third electric zone 33 is mounted at the second end 35 of the end-fitting 3. The first electric zone 31, the second electric zone 32 and the third electric zone 33 are arranged substantially concentrically in respect of the center axis indicated by dotted line 44.

(26) The three electric zones 31, 32 and 33 are electrically separated from each other by means of electrically insulating material 36 and 37.

(27) The end-fitting shown in FIG. 3 also comprises a cover 44 of conductive material encapsulating the first electric zone 31 and the second electric zone 32. Between the cover 44 and first electric zone 31 and the second electric zone 32 a void 45 is formed which is filled with an electrically insulating fluid.

(28) A power supply may be connected to the first electric zone 31 and the second electric zone 32 via lines 40 and 41.

(29) Thus, it is possible to send a current to the power source through the carcass 10 and return the current to the power source via the tensile armor 14. As the case in respect of FIG. 2, the electrically conductive armor layers may be electrically connected in another end-fitting at a distal end of the flexible pipe 2.

(30) To reduce the hazard related to use of high voltage and current the third electric zone 33 is connected with ground via line 42.

(31) As previously mentioned, the figures are schematic and simplified for clarity, and they show only details which are relevant in respect of the present invention. For example the end-fittings may comprise several other parts than shown in the figures, such as bolts and other connection means. Also the indicated three electric zones may each be assembled from several different parts but each still pose a single electric zone in the end-fitting.

(32) The unbonded flexible pipe may also comprise more layers than the layers indicated in the figures. The pipe may e.g. comprise two pressure armor layers and two tensile armor layers and optionally one or more intermediate layers such as anti-wear layers and insulating layers.