METHOD FOR INSPECTING PIPELINES AND ASSOCIATED INSPECTION DEVICE

Abstract

A method is provided for inspecting pipelines, in particular pipelines carrying oil, gas or water. A wall of the pipeline is magnetized by a magnetizing apparatus of a first apparatus formed as a pig. A magnetization present in the pipeline wall is used and/or measured as residual magnetization by a second apparatus, which is separate from the first apparatus and formed as an inspection apparatus, in particular at a later time, for inspection purposes. An associated inspection apparatus is also provided.

Claims

1. A method for inspecting pipelines, the method comprising the steps of: magnetizing a wall of the pipeline by a magnetizing apparatus of a first apparatus formed as a pig, using and/or measuring a magnetization present in the pipeline wall for inspection purposes by a second apparatus which is separate from the first apparatus and is formed as an inspection apparatus.

2. The method as claimed in claim 1, wherein the magnetizing apparatus has changed, the polarity of a remanent previous magnetic field already present in the wall of the pipeline in time and/or location before the inspection apparatus is used.

3. The method as claimed in claim 1, wherein after a first inspection operation of the inspection apparatus and before a second inspection operation, a direction of magnetization of the wall of the pipeline is changed again.

4. A method for inspecting pipelines, a wall of the pipeline being magnetized at least in part by the earths magnetic field, the method comprising the steps of: using and/or measuring magnetization in the wall of the pipeline for inspection purposes by an apparatus formed as an inspection apparatus.

5. The method as claimed in claim 1, wherein, before magnetization of the wall of the pipeline, any remanent or natural magnetization present in the wall is measured.

6. The method as claimed in claim 5, wherein the inspection apparatus detects the remanent magnetization to obtain MEL data or EMAT data.

7. The method as claimed in claim 1, wherein the inspection apparatus determines the magnetic field strength by at least one magnetic field sensor.

8. The method as claimed in claim 1, wherein the inspection apparatus located inside the pipeline is moved through the pipeline at a distance from the inside of the wall of the pipeline or as a foam pig and/or as a cup/disc-based pig.

9. The method as claimed in claim 1, wherein the inspection apparatus measures the magnetic field in a circumferential direction.

10. The method as claimed in claim 9, wherein the inspection apparatus measures the magnetic field strength of the wall via two sensor rings, the sensors of which are located at different distances from a longitudinal center axis of the inspection apparatus.

11. The method as claimed in claim 1, wherein the inspection apparatus located outside the pipeline picks up information for determining the position of the pipeline by the magnetization of the wall and/or follows the course of the pipeline by the magnetization.

12. The method as claimed in claim 1, wherein a voltage measurement is carried out to determine a condition of a cathodic protection of a pipeline, with errors caused by the inspection apparatus moved relative to the pipeline due to additionally generated voltages being taken into account by determining the magnetic field present in the wall of the pipeline.

13. An inspection apparatus for carrying out a method as claimed in claim 1, wherein at least a part of the inspection apparatus using or measuring the magnetization is formed without its own magnetizing apparatus.

14. An inspection apparatus for carrying out a method as claimed in claim 11, wherein at least a part of the inspection apparatus using or measuring the magnetization is formed without its own magnetizing apparatus, wherein the inspection apparatus is formed as an ROV, or as an AUV.

15. An arrangement comprising: at least a first apparatus formed as a pig with a magnetizing apparatus, and an inspection apparatus as claimed in claim 13 which is separate from the first apparatus.

16. The method for inspecting pipelines of claim 1, wherein the step of using and/or measuring the magnetization present in the pipeline wall for inspection purposes occurs at a later time by the second apparatus.

17. The method as claimed in claim 2, wherein the magnetizing apparatus has reversed the polarity of the remanent previous magnetic field already present in the wall of the pipeline in time and/or location before the inspection apparatus is used.

18. The method as claimed in claim 8, wherein at least one ultrasonic sensor being present for detecting the position of the inspection apparatus in the pipeline.

19. The method as claimed in claim 9, wherein the inspection apparatus measures the magnetic field in the circumferential direction by at least one sensor ring.

20. The inspection apparatus of claim 9, wherein the entire inspection apparatus is formed without its own magnetizing apparatus.

21. The arrangement of claim 15 wherein at least the first apparatus formed as the pig with the magnetizing apparatus is formed without sensors for recording MEL, EMAT, EC and/or other magnetic field data.

22. The method as claimed in claim 4, wherein, before magnetization of the wall of the pipeline, any remanent or natural magnetization present in the wall is measured.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the views.

[0031] FIG. 1 shows a magnetizing apparatus.

[0032] FIG. 2 shows another magnetizing apparatus and an inspection apparatus in a pipeline.

[0033] FIG. 3 shows a magnetizing apparatus according to FIG. 1 and another inspection apparatus in a pipeline.

[0034] FIG. 4 shows a further embodiment of an article according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0035] Individual technical features of the exemplary embodiments described below can also be combined with exemplary embodiments described above and with the features of the independent claims and, where appropriate, further claims to form articles according to the invention. Where expedient, functionally equivalent elements are provided with identical reference signs.

[0036] After a first measurement, not shown, of the magnetization of a wall 2 of a pipeline, a pig 4 with a magnetizing apparatus for magnetizing the pipeline wall is guided through the pipeline in the direction of travel F. Such a pig 4 comprises, in accordance with the embodiment shown in FIG. 1, a permanent magnet 6 as magnetizing apparatus, which furthermore has ring brushes 8 for producing a magnetic circuit with the pipeline and thereby effecting magnetization of the pipeline wall.

[0037] To improve the remanent magnetic field for a subsequent measurement with an inspection apparatus 10 (FIG. 2), which is moved through the pipeline at a distance, indicated by a double arrow 12, of at least 100 meters behind a pig 14 with a further magnetizing apparatus, the magnetic field already introduced into the pipeline by the pig 4 according to FIG. 1 is now rotated with respect to its polarity by the orientation of a permanent magnet 16 rotated with respect to the direction of travel F, indicated by poles S and N now arranged differently from one another. In addition to the two ring brushes 8 of the pigs 4 and 14 in each case, these can have means serving for propulsion in the form of conventional cups, for example.

[0038] The inspection apparatus 10 is formed as an inspection pig and has front and rear pig plates 18 in the form of cups or discs, with magnetic field sensors 20 being arranged on the pig discs at the rear in the direction of travel, which sensors are highly sensitive and are equipped either as a sensor ring with a large number of sensors, for example at least 6 sensors, or for screening of the pipeline with only a few sensors (at least one sensor) in the circumferential direction.

[0039] According to an alternative embodiment of the method according to the invention and with alternatively formed apparatuses, a second premagnetization of the pipeline with sensors in the reversed direction by the magnetizing apparatus 14 according to FIG. 2 is spared and only a pig 4 is moved through the pipeline in the direction of movement F of the medium therein (FIG. 3). This magnetizing apparatus is followed at a suitable distance 12 by an inspection apparatus 22, which does not touch the pipeline wall 2, in the form of a pig which floats freely in the pipeline and has an ultrasonic sensor ring 24 at the front and rear in the direction of movement F, via which the position of the pig in the pipeline can be determined. The pig with magnetizing apparatus 14 and the apparatus 22 formed as an inspection pig represent an arrangement according to the invention.

[0040] A sensor apparatus 26 is arranged in the center of the inspection apparatus 22 and has two sensor rings 28 arranged one inside the other with MFL sensors or magnetometers and is shown additionally above the pipeline for illustration purposes. This sensor arrangement is used to capture MFL data both in the circumferential direction and in the radial direction with respect to a longitudinal axis of the inspection apparatus running in the longitudinal direction of the pipeline.

[0041] In addition, an inspection apparatus moving in the pipeline 2 according to FIG. 2 can be equipped with an odometer and/or can have an MES gyrometer on board. This serves to determine the position of the inspection apparatus in the pipeline later.

[0042] Overall, the inspection apparatuses according to the invention allow significantly better passage characteristics through the pipelines, so that even so-called challenging pipelines, which are characterized by geometric complexity such as diameter changes, bends and installations, can be inspected more effectively.

[0043] According to another embodiment of the invention, an inspection apparatus 30, in the form of an ROV, which has a highly sensitive magnetic field sensor 20 streamlined on its underside, follows the course of a pipeline 32 laid underwater, which partially rests on a sediment 34, but is covered by the sediment 34 in a region B (FIG. 4). Alternatively, the magnetic field sensor might not be installed under an ROV but carried, for example, over any handles that may be present, in order to examine individual areas in greater detail. This measurement method also makes it possible to find buried pipelines, and to follow their course, with the help of the magnetic field in their walls.