PIPELINE DEFECT MONITORING

1 . A pipeline apparatus comprising:

a pipe body including:

an annular cavity between annular innermost and outermost fluid impermeable barrier layers; and

a plurality of armour wires extending along at least part of the length of the pipe body in the annular cavity, the plurality of armour wires including a first armour wire electrically isolated from the other armour wires along at least part of the length of the armour wires; and

a measurement device arranged to electrically couple to the first armour wire at a first end of the pipe body, and to measure the electrical impedance of the first armour wire;

wherein variation of the electrical impedance of the first armour wire is indicative of a defect of the first armour wire.

2 . The pipeline apparatus according to claim 1 , further comprising at least one insulation member arranged to insulate the first armour wire from the remainder of the plurality of armour wires along at least part of its length.

3 . The pipeline apparatus according to claim 1 , wherein the measurement device is configured to supply direct current or variable frequency alternating current to the first armour wire.

4 . The pipeline apparatus according to claim 1 , further comprising an end fitting coupled to the first end of the pipe body, wherein the measurement device couples to the first armour wire through the end fitting.

5 . The pipeline apparatus according to claim 1 , wherein the first armour wire is electrically connected to at least one other armour wire at a part of the pipe body distal to the first end of the pipe body;

wherein the measurement device is further arranged to electrically couple to the at least one other armour wire at the first end of the pipe body, such that impedance is measured through a circuit comprising the first armour wire and the at least one other armour wire connected in series.

6 . The pipeline apparatus according to claim 1 , further comprising sensing wires arranged in a four-terminal sensing configuration, wherein the sensing wires are electrically connected to the first armour wire at the first end of the pipe body and a part of the pipe body distal to the first end of the pipe body, for measuring the impedance of the first armour wire.

7 . The pipeline apparatus according to claim 6 , wherein the sensing wires are provided adjacent to and parallel with the first armour wire in the annular cavity.

8 . The pipeline apparatus according to claim 7 , wherein the measurement device comprises a current sensor arranged to measure a current through the first armour wire and a voltage sensor arranged to measure a voltage across the first armour wire.

9 . A method of monitoring a condition of an armour wire provided in a pipeline apparatus, the method comprising:

coupling a measurement device to a first armour wire among a plurality of armour wires extending along at least part of the length of a pipe body in an annular cavity of the pipe body of the pipeline apparatus and electrically isolated from the other armour wires along at least part of the length of the armour wires, the annular cavity being defined between annular innermost and outermost fluid impermeable barrier layers, the measurement device being coupled to the first armour wire at a first end of the pipe body; and

measuring the impedance of the first armour wire;

wherein variation of the electrical impedance of the first armour wire electrically is indicative of a defect of the first armour wire.

10 . The method of claim 9 , wherein the current supplied to the first armour wire is direct current or alternating current.

11 . The method of claim 9 , further comprising:

varying the frequency of the current supplied to the first armour wire;

measuring the impedance of the first armour wire at two or more different frequencies; and

determining an impedance profile across the cross section of the first armour wire.

12 . The method of claim 9 , further comprising:

determining a rate of change of the impedance of the first armour wire.

13 . The method of claim 10 , further comprising:

identifying a type of defect of the first armour wire based on a frequency of alternating current supplied to the first armour wire and the measured impedance of the first armour wire.

14 . A method of forming a pipeline apparatus, the method comprising:

providing a pipe body including:

an annular cavity between annular innermost and outermost fluid impermeable barrier layers; and

a plurality of armour wires extending along at least part of the length of the pipe body in the annular cavity, the plurality of armour wires including a first armour wire electrically isolated from the other armour wires along at least part of the length of the armour wires; and

coupling a measurement device to the first armour wire at a first end of the pipe body, the measurement device being arranged to measure the electrical impedance of the first armour wire;

wherein variation of the electrical impedance of the first armour wire electrically is indicative of a defect of the first armour wire.

15 . The method of claim 14 , further comprising adapting the pipeline apparatus comprising:

a pipe body including:

an annular cavity between annular innermost and outermost fluid impermeable barrier layers; and

a plurality of armour wires extending along at least part of the length of the pipe body in the annular cavity, the plurality of armour wires including a first armour wire electrically isolated from the other armour wires along at least part of the length of the armour wires; and

a measurement device arranged to electrically couple to the first armour wire at a first end of the pipe body, and to measure the electrical impedance of the first armour wire;

at least one insulation member arranged to insulate the first armour wire from the remainder of the plurality of armour wires along at least part of its length,

wherein variation of the electrical impedance of the first armour wire is indicative of a defect of the first armour wire.