Detection apparatus and method

Patent metadata

Field	Value
Publication number	US-2016273994-A1
Application number	US-201415029593-A
Country	US
Kind code	A1
Filing date	Oct 23, 2014
Priority date	Oct 29, 2013
Publication date	Sep 22, 2016
Grant date	—

Abstract

A detection apparatus arranged to detect defects within a flexible pipe body. The detection apparatus comprises an electrical power supply and a first meter. The electrical power supply is arranged to couple between, and to supply current to, first and second electrically conductive members extending at least partially along the length of a flexible pipe body and electrically isolated from one another except for being electrically connected at a point remote from the power supply. The first meter is arranged to detect variation between the current flowing in each electrically conductive member. Detected variation is indicative of a pipe body defect causing an Earth fault along one of the electrically conductive members. A corresponding method, a pipeline apparatus including the detection apparatus and a method of forming the pipeline apparatus are also disclosed.

First claim

1 . A detection apparatus arranged to detect defects within a flexible pipe body, the detection apparatus comprising:
an electrical power supply arranged to couple between, and to supply current to, first and second electrically conductive members extending at least partially along the length of a flexible pipe body and electrically isolated from one another except for being electrically connected at a point remote from the power supply; and a first meter arranged to detect variation between the current flowing in each electrically conductive member; wherein detected variation is indicative of a pipe body defect causing an Earth fault along one of the electrically conductive members.

2 . A detection apparatus according to claim 1 , wherein the variation between the current flowing in each electrically conductive member is indicative of the position of the Earth fault along one of the electrically conductive members.

3 . A detection apparatus according to claim 2 , wherein one of the electrically conductive members comprises a sensor member exposed along at least part of the length of the flexible pipe body and having a predetermined resistance per unit length and the other electrically conductive member comprises a return member which is electrically insulated.

4 . A detection apparatus according to claim 3 , wherein the electrical power supply is arranged to supply a constant current to either the sensor member or the return member;
wherein if a constant current is supplied to the sensor member, variation between the current flowing in each electrically conductive member is indicative of the distance along the sensor member from the electrical power supply to the Earth fault; and wherein if a constant current is supplied to the return member, variation between the current flowing in each electrically conductive member is indicative of the distance along the sensor member from the connection to the return member to the Earth fault.

5 . A detection apparatus according to claim 1 , wherein the electrical power supply comprises a first DC constant current source having a first terminal arranged to supply a constant current to a first electrically conductive member and a second terminal coupled to a second electrically conductive member.

6 . A detection apparatus according to claim 5 , further comprising a first resistor coupled between the second terminal of the first current source and the second electrically conductive member;
wherein the first meter comprises a first voltmeter arranged to measure the voltage across the first resistor and to detect a drop in voltage indicative of an Earth fault.

7 . A detection apparatus according to claim 5 , further comprising a second voltmeter arranged to measure the voltage across the first current source;
wherein one of the electrically conductive members comprises a sensor member exposed along at least part of the length of the flexible pipe body and has a predetermined resistance per unit length and the other electrically conductive member comprises a return member which is electrically insulated; and wherein a change in the voltage across the first current source is indicative of the distance along the sensor member from the end coupled to the first terminal of the first current source to the Earth fault.

8 . A detection apparatus according to claim 7 , wherein the electrical power supply further comprises:
a second DC constant current source having a first terminal arranged to supply a constant current to the second electrically conductive member and a second terminal coupled to the first electrically conductive member; a second resistor coupled between the second terminal of the second current source and the first electrically conductive member; and a third voltmeter arranged to measure the voltage across the second resistor and to detect a drop in voltage indicative of an Earth fault.

9 . A detection apparatus according to claim 8 , wherein the first and second current sources are arranged such that only one supplies current to the electrically conductive members at a time; and
wherein each current source is electrically isolated from the other.

10 . A detection apparatus according to claim 8 , further comprising a fourth voltmeter arranged to measure the voltage across the second current source;
wherein a change in the voltage across the second current source is indicative of the distance along the sensor member from the end coupled to the first terminal of the second current source and the Earth fault.

11 . A method of detecting defects within a flexible pipe body, the method comprising:
coupling an electrical power supply between first and second electrically conductive members extending at least partially along the length of a flexible pipe body and electrically isolated from one another except for being electrically connected at a point remote from the power supply; supplying current form the power supply to the first and second electrically conductive members; and detecting variation between the current flowing in each electrically conductive member; wherein detected variation is indicative of a pipe body defect causing an Earth fault along one of the electrically conductive members.

12 . A pipeline apparatus comprising:
a flexible pipe body including first and second electrically conductive members extending at least partially along the length of a flexible pipe body and electrically isolated from one another except for being electrically connected at a point remote from a first end of the flexible pipe body; an end fitting coupled to at least said first end of the flexible pipe body; and a detection apparatus according to claim 1 coupled to the end fitting; wherein the electrical power supply is coupled between, and arranged to supply current to, the first and second electrically conductive members.

13 . A pipeline apparatus according to claim 12 , wherein the first and second electrically conductive members are positioned within a pipe body annulus between an innermost barrier layer and an outermost barrier layer.

14 . A pipeline apparatus according to claim 13 , wherein one of the electrically conductive members comprises a sensor member exposed along at least part of the length of the flexible pipe body and has a predetermined resistance per unit length and the other electrically conductive member comprises a return member which is electrically insulated.

15 . A pipeline apparatus according to claim 14 , wherein the sensor member and the other electrical member comprise wires;
wherein the pipe body further comprises at least one metallic structural element connected to an Earth; and wherein the sensor member is arranged such that if a pipe body defect admits fluid into the pipe body annulus, fluid between the sensor member and a metallic structural element causes an Earth fault.

16 . A method of forming a pipeline apparatus, the method comprising:
providing a flexible pipe body including first and second electrically conductive members extending at least partially along the length of a flexible pipe body and electrically isolated from one another except for being electrically connected at a point remote from a first end of the flexible pipe body; coupling an end fitting to at least one end of the pipe body; coupling a detection apparatus according to claim 1 to the end fitting; and coupling the electrical power supply between the first and second electrically conductive members.

Assignees

• Ge Oil & Gas Uk Ltd

Inventors

• Mcnab John Cross
• Graham Geoffrey Stephen
• Nott Philip Michael Hunter

Classifications

• G01M3/18 Primary

  for pipes, cables or tubes; for pipe joints or seals; for valves; {for welds; for containers, e.g. radiators} · CPC title

• G01R31/025

  Physics · mapped topic

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title