NEWT, ESPECIALLY INSPECTION OR CLEANING NEWT

Description

[0001] The present invention relates to a pig, in particular an inspection or cleaning pig, for passing through a pipeline with a pipeline wall, wherein the pig has a functional unit for cleaning the pipeline and / or recording pipeline information and at least one magnet unit provided for magnetizing the pipeline wall with a plurality of magnets.

[0002] DE 10 2013 011 626 A1 discloses an object according to the preamble of claim 1. Such a pig, which in particular runs through water, gas, or oil pipes or pipelines, has a magnetic unit that exerts a braking effect by generating eddy currents in the pipe wall and their interaction with the magnetic field generating them. This keeps the speed within a reasonable range for inspection, measurement, or even cleaning. A disadvantage is that the braking unit according to the invention becomes large and heavy, particularly in the case of longer pigs, in order to apply the necessary forces. This has the consequence that, due to the length of the magnetic units relative to the longitudinal center axis of the pig, this axis becomes comparatively large, thus impairing the pig's ability to negotiate bends.

[0003] The object of the present invention is to improve the bending ability of a pig.

[0004] The object is achieved by an object according to claim 1, advantageous embodiments of the invention can be found in the subclaims and the description.

[0005] This object is achieved by a pig according to the preamble of claim 1, in which the magnet unit has several segments, each with at least one magnet, and the magnetization direction of adjacent segments is angled or tilted relative to one another by at least approximately 90°, preferably by exactly 90°. By forming such a magnet unit, the magnetic flux densities can be increased, resulting in a range of possible arrangements in which the flux densities in the pipeline wall are increased. The magnetic field acting on the pipeline wall and the magnetic fields generated there are stronger than with conventionally used magnets, so that the entire magnet unit can be shorter.

[0006] Preferably, a segment comprises a single magnet, in particular a permanent magnet, but it can also comprise several magnets, in particular those with the same direction of magnetization.

[0007] Adjacent magnets are magnets that are separated by a magnet holder or are in direct contact with each other. Magnets separated by a magnet holder are located on opposite sides of the magnet holder, with the magnet holder, which is particularly non-metallic, having a significantly smaller dimension than the magnets themselves. Adjacent magnets are, in particular, spaced no further than 3 mm apart and are preferably located directly next to each other. A frame for the segments of the magnet unit, however, can have a similar thickness to the focusing element.

[0008] In particular, the magnets are arranged next to each other when viewed in a direction transverse to the longitudinal direction of the pig, which during operation is parallel to a longitudinal extension of a pipeline, and thus one behind the other when viewed in the longitudinal direction.

[0009] The magnets of the segments or the magnet unit are preferably permanent magnets, in particular neodymium magnets. In particular, the poles of two segments that are directed towards each other and are separated by a further segment have identical polarity, i.e. they both form either north or south poles that are directed towards each other, with a magnet from a further segment being arranged between the magnets or segments. In particular, this segment arranged in between also points in the direction of the pipeline wall with its own north pole or south pole side during operation. This already results in an initial focusing of the magnetic field lines towards the pipeline wall during operation, while on the side of the magnet unit facing away from the pipeline wall, which is then generally directed towards the longitudinal central axis of the pig, the magnetic field lines are weakened.Such magnet units constructed in the manner of Halbach arrays already lead to higher flux densities and higher magnetic field strengths in the pipeline wall, which means that the magnet units and thus the corresponding pig segments can be built shorter.

[0010] In the following, the segments whose magnets are provided with a magnetization direction (north-south direction) essentially perpendicular to the pipeline wall (during operation) are also referred to as vertical segments. The magnetization direction, which is indicated by an imaginary line from the north to the south pole, lies within an angular range of ± 15° around a perpendicular to the surface of the pipeline wall. Accordingly, the magnetization direction is inclined by 75° to 105°, preferably by 90°, to the longitudinal center axis of the pig when the pig runs in a desired normal position centered within the pipeline. The magnetization direction of a segment corresponds to the magnetization direction of the magnet(s) forming the segment. For the purposes of the application, "angled at least approximately 90° to one another" means angled between 85° and 95° to one another.

[0011] The vertical segment leads to the introduction of magnetic field lines that are directed approximately or directly perpendicular to the pipe wall during operation, which is advantageous, for example, for EMAT wall thickness measurements.

[0012] A functional unit is generally defined as at least one component of a pig, which may also have multiple segments, that performs a function for the pig and, in particular, has the functionality required for the pig's intended use (cleaning and / or recording pipeline information). This can also be a functional unit for speed control. Pigs used for repairing a pipeline can also be a functional unit for recording pipeline information. The magnet unit can therefore also be part of a functional unit.

[0013] A pig according to the invention is further improved if, according to a further embodiment of the invention, the vertical segment, viewed radially outward from a longitudinal center axis, is delimited by a focusing element. Such a focusing element, in particular formed at least substantially from steel, serves to further focus and amplify the magnetic field lines. The focusing element is, in particular, magnetizable.

[0014] Surprisingly, it has been shown that the additional use of the focusing element allows for very high flux densities to be achieved more effectively than with magnet arrangements similar to a Halbach array without focusing element(s), where the maximum application of the magnetic field is limited by the saturation flux density. Efficiency, i.e., the magnetic field strength measurable in a pipeline during operation, increases by up to a factor of 3. Conversely, units used to achieve previous flux densities in the pipeline wall material can be significantly smaller than before, which in turn improves bend clearance in the pipeline.

[0015] Accordingly, a design of a pig according to the invention in which the focusing element is bounded by a magnet on at least three sides, with the poles of the magnets located on these sides having identical polarity, but in particular simultaneously belonging to different segments, results in a drastic increase in the magnetic field strengths and flux densities in the pipeline wall. Such a device according to the invention is significantly shorter than prior art devices generating the same forces.

[0016] The flux densities present in the focusing element, which is in particular constructed at least substantially from steel comprising cobalt and iron, are in particular up to 2.5 T, but at least up to 2.3 T. For example, a magnet unit provided with nine magnets arranged one behind the other, in which successive magnets have magnetization directions tilted to one another and which are arranged in a type of Halbach array, results in an attractive force to the pipeline of up to 45 kN. A magnet unit additionally provided with focusing elements as described above, but otherwise constructed in the same sequence and magnetization direction of the equally strong magnets, results in attractive forces of 180 kN. Typical pipelines in the oil and gas sector with a wall thickness of 3 cm, for example, can thus be completely saturated in the radially outward direction.

[0017] Pigs equipped with corresponding magnet units can thus be significantly shorter while maintaining the same forces and exhibit improved ground penetration. The smaller and therefore lighter design of the pigs according to the invention reduces the load on the pipeline during the pig's passage.

[0018] For the purpose of further focusing the magnetic field lines toward or away from the pipeline wall, according to a further embodiment of the invention, the magnet units can have a longitudinal enclosure made of a magnetizable material, at least partially, which defines the magnets of the magnet unit. In a view transverse to the longitudinal direction of the pig, corresponding enclosures are present in the magnet unit, for example, at the front and rear in the direction of travel.

[0019] Alternatively or additionally, a preferably elongated magnet unit of a pig according to the invention can also be oriented transversely to the longitudinal central axis, in which case its outer side is preferably adapted to the curvature of the pipeline wall. Magnet units designed with their longitudinal extension parallel to the longitudinal central axis of the pig can also be provided with an outer side whose curvature is adapted to the curvature of the pipeline wall.

[0020] The frame as well as the focusing element are made in particular of cobalt-iron steel, but at least and in particular of magnetizable steel.

[0021] According to a further development of the invention, the magnet unit is provided with a sensor for recording pipeline information, i.e. inspection data. This sensor is arranged in particular in the focusing element, in a recess thereof and / or on the focusing element and is thus arranged centrally in the magnet unit. According to the above, the magnetization directions of the segments not designed as vertical segments preferably run parallel or approximately parallel to the longitudinal center axis of the pig. In addition or as an alternative to such a design as an inspection pig, for example with an EMAT and / or wall thickness sensor, the magnet unit can at least co-form an eddy current braking unit, wherein preferably a plurality of magnet units are arranged adjacent to one another in the circumferential direction around the longitudinal center axis of the pig, i.e.are arranged side by side and, if necessary, offset in the direction of the pig's longitudinal center axis. In addition, an eddy current braking unit has design features including connections to a supporting structure, spring elements for damping, and / or connection options for additional pig segments.

[0022] An eddy-current braking unit is designed to generate a speed-dependent braking force through the interaction of the magnets with the pipeline wall due to eddy-current-induced magnetic fields. The radial component of the magnetic flux density relevant to the braking force is maximized due to the design according to the invention.

[0023] The magnet unit preferably has at least three magnets arranged one behind the other in its longitudinal direction. According to a further embodiment, in particular, seven magnets are arranged one behind the other, so that there are preferably two focusing elements bounded by the north poles of permanent magnets and one focusing element bounded by the south poles. Furthermore, it is particularly possible to have respective focusing elements laterally bounded not only by three but also, in particular, by five magnets.

[0024] While magnet units for forming eddy current braking units and / or for inspection are typically cuboid, block-shaped and / or elongated, according to a further embodiment of the invention it may be advantageous to form ring-shaped magnet units in order to specifically generate corresponding magnetic fields in the pipeline wall.

[0025] In order to avoid adhesion effects on the pipeline wall, a pig according to the invention according to a further embodiment has at least one spacer, which is preferably adjustable with regard to a distance of the magnets from the wall, and via which the magnet unit can be positioned at a distance from the pipeline wall.

[0026] The length of the magnet unit, including any enclosures, is preferably less than 0.5 times the diameter D Pipe of the pipeline, preferably less than 0.3 times D Pipe , where D Pipe = diameter of the pipeline in meters. The length of the magnet unit is relative to the longitudinal center axis of the pig.

[0027] In an embodiment of the magnet unit according to the invention as an eddy current braking unit, this is designed at a speed of 2 m / s in the pipeline to generate a braking force F depending on the pipeline diameter of at least 7,000 N / m multiplied by D Pipe, where D Pipe = the diameter of the pipeline in meters.

[0028] Further advantages and details of the invention can be found in the following description of the figures. Schematically shown: Fig. 1 a spacer with a magnet unit of a pig according to the invention in a perspective view, Fig. 2 the object according to Fig.1 in a partially cut-away view, Fig. 3 shows part of a pig according to the invention comprising a plurality of magnet units in a side view, Fig. 4 shows a pig according to the invention in a partially cut-away view, Fig. 5 shows a simplified view of a magnet unit in a partially cut-away illustration, Fig. 6 shows a magnet unit of a further article according to the invention, Fig. 7 shows a view of an article according to the invention in an operating position in a sectional illustration, Fig. 8 shows magnetic field lines in a magnet unit of an article according to the invention and an adjacent pipeline wall, Figs. 9-11 show further variants of a magnet unit.

[0029] Individual technical features of the exemplary embodiments described below can also be combined with previously described exemplary embodiments as well as the features of the independent claim and, if applicable, further claims to form subject matter according to the invention. Where appropriate, functionally equivalent elements are provided with identical reference numerals.

[0030] In the future, Fig. 1 a spacer 1 of a pig according to the invention having a magnet unit. The spacer 1 comprises a housing 2 in which a Fig. 3 The housing 2 is mounted with its side facing the pipe wall in the Fig.1 Shown facing upwards. A distance from the pipeline wall is adjusted via a wheel 4, which is rotatably mounted in a fork 6. At the opposite end of the spacer 1, another fork 8 is shown, which can be mounted on a support frame of the pig and / or, if necessary, equipped with another wheel.

[0031] The magnet unit 3 has two magnets 10, whose magnetization directions (north-south direction) run parallel or at least approximately parallel to the longitudinal center axis of the pig and whose north pole sides 12 face each other ( Fig. 2 ). At the same time, both north pole sides 12 rest against a focusing element 14. On its radial side, located towards the longitudinal center axis 24 of the pig, which will be described in more detail later, another magnet rests with its north pole side 16 (cf. Fig. 3 ). This magnet 18 has a magnetization direction that is tilted or angled by 90° to the magnetization direction of the magnets 10.

[0032] In the longitudinal direction of the pig, the magnet unit has enclosures 20 which are constructed from a magnetizable material, preferably a steel comprising cobalt and iron, wherein the enclosures 20 delimit the magnets of the magnet unit in such a way that they adjoin them in the longitudinal direction at the front and rear.

[0033] The focusing element 14 is also made of a steel comprising cobalt and iron. Due to its arrangement radially outward from a longitudinal central axis 24, the focusing element achieves flux densities of preferably 2 to 3 Tesla. The magnetic flux is pressed by the magnet 18 through the focusing element 14, which is designed as a steel element, in such a way that the magnetic field lines are focused towards the pipeline. While standard Halbach arrays are limited in their maximum application of the magnetic field by the saturation flux density, the inventive design of the pig increases the attractive force by a factor of at least 3, as described above. Weight and costs can therefore be kept correspondingly low. In the exemplary embodiments shown in the figures, the segments of the magnet units are each formed by a single magnet, which then also determines the magnetization direction of the respective segment.

[0034] On the inside of the magnet unit 3 directed towards the longitudinal center axis 24 of the pig, there is an inner enclosure 22 which additionally shields the already almost negligible magnetic field of the magnet unit towards the inside.

[0035] A pig segment of a pig according to the invention is shown in Fig. 3 , wherein a plurality of magnet units 3 are arranged side by side in the circumferential direction around a longitudinal axis 24. In addition, two rings of magnet units 3 are arranged one behind the other with respect to the longitudinal center axis 24 of the pig. Magnet units 3 arranged one behind the other in the longitudinal direction parallel to the longitudinal center axis 24 are connected to each other in an articulated manner, so that a very good arc continuity of the Fig. 3 The spacers 1 themselves are in turn movably mounted on a support frame 26.

[0036] A pig according to the invention has Fig. 4 one in the Fig. 4 The pig segment 28 shown on the left provides propulsion in the direction F. Additionally, sensors 30, shown only partially and schematically, are incorporated into the focusing elements 14. The sensors 30 are, in particular, EMAT-WT sensors, i.e., sensors for electromagnetic-acoustic measurement of the wall thickness of the pipeline wall 32. The pig segment on the right in the figure is thus designed, on the one hand, as an eddy current braking unit and, on the other hand, as a functional unit for recording inspection data or pipeline information. The magnet unit can also be part of the functional unit.

[0037] A magnet unit of a further pig according to the invention with a larger number than three magnets is shown in the Fig. 5 Focusing elements 14 are arranged here on the north pole sides of the adjacent magnets 10 and 18, respectively. A further focusing element 14' is correspondingly limited by the south pole sides of the adjacent magnets. In addition, a magnet unit as already described can Fig. 6 shown frame 20.

[0038] Fig. 7 discloses in the two figures there an alternative design of a magnet unit 3. The Fig. 7 The top right figure shows a perspective view, while in Fig. 7 A corresponding cross-section is shown at the bottom left. A hemispherical focusing element 14 is defined by a single- or multi-part magnet 10 with a circular cross-section, which in turn is arranged within a frame 20.

[0039] The magnetic field lines arising in a magnet unit 3 and a pipe wall 32 arranged close to it during operation are shown in the Fig. 8 symbolized by black, acute-angled triangles. These are located in the Fig. 8 in the cells of a triangular grid created by the simulation, both in the magnet unit 3 and in the pipeline wall 32. The stronger the gradients of the magnetic field lines in terms of direction and / or amplitude, the finer the resolution and the smaller the cells of the grid. The magnetic flux densities present in the focusing elements 14, 14' are particularly large, symbolized by correspondingly large triangles.

[0040] According to a further embodiment of the invention, the magnet unit is designed as part of a functional unit for recording inspection data or pipeline information ( Fig. 9 ). Here, the magnet unit is housed in a similar way to Fig. 2 arranged, with two sensors 30 additionally mounted on the side of the focusing element 14, which is only shown in dashed lines due to the housing, facing the pipeline wall or the metal surface to be inspected. These sensors can be, in particular, EMAT-WT sensors. Further parts of the magnet unit are magnets 10 and 18, also only shown in dashed lines due to the housing. This functional unit uses the magnetic field generated and thereby amplified by the focusing of the Halbach array, for example, to excite acoustic waves with the aid of electromagnetic force transmission, which enables the non-destructive testing of any type of sheet metal with respect to the remaining wall thickness.

[0041] In a further variant of a pig according to the invention with a similarly constructed magnet unit, additional magnets are attached to the sides of the magnet unit, which in an identical manner continue to focus the magnetic field onto the focusing element 14 and thus further amplify it ( Fig. 10 ). Here, too, a sensor 30 is arranged, which enables the recording of inspection data. The variant of the focusing element, which is particularly rectangular in a plan view and is now enclosed on four sides, generates a magnetic field directed almost maximally in the direction of the surface to be inspected and thus an optimal magnetic prestress. The viewing direction B is indicated by an arrow B. The direction B is also the direction of the magnetic field in the direction of the surface. For example, two, three or four of the magnet units can be arranged according to Fig. 10 evenly distributed in the circumferential direction around a pig's longitudinal axis for wall thickness measurement using the associated functional unit.

[0042] A maximally optimized variant is still available in Fig. 11 in which the magnet 10 is arranged in a spherical shell around the central focusing element. A bottom view is shown in the lower left part of the Fig. 11 shown, while a perspective view in Fig. 11 shown in the upper right section. Surrounding the spherical half-shell of magnet 10 is another spherical half-shell made of steel, which serves as a magnetic return path for the focused magnetic field. Sensors 30 are also arranged here to obtain information about the inspected surface.

[0043] In general, the magnet units of a pig according to the invention can be used for the formation of eddy current braking units in which a circulating ring current can be formed in the pipe wall in the circumferential direction due to a plurality of magnet units arranged in the circumferential direction around a longitudinal axis of the pig.

Claims

1. Pig, in particular inspection or cleaning pig, for passing through a pipeline having a pipeline wall (32), comprising at least one functional unit for cleaning the pipeline and / or recording pipeline information and comprising at least one magnet unit (3), which is provided for magnetizing the pipeline wall and has a plurality of magnets (10, 18), wherein the magnet unit (3) has a plurality of segments each with at least one magnet (10, 18), characterized in that the magnetization directions of mutually adjacent segments are angled at least by approximately 90°, preferably by exactly 90°, to one another, in that the magnet unit (3) has magnets (10, 18) formed as permanent magnets, in that the poles (N, S) of two segments which are directed toward each other and which are separated by a further segment have an identical polarity, in that the segment arranged between the two segments as a vertical segment has a magnetization direction directed in the direction of the pipeline wall (32) in operation and preferably formed at least approximately perpendicular to the pipeline wall (32), and in that the vertical segment, viewed from a longitudinal central axis (24), is bounded radially on the outside by a focusing element (14).

2. Pig according to Claim 1, characterized in that the focusing element (14) is bounded by a magnet (10, 18) on at least three sides, wherein the poles of the magnets (10, 18) located on these sides have an identical polarity.

3. Pig according to one of the preceding claims, characterized in that the magnet unit (3) has in the longitudinal direction at least one enclosure (20) at least also formed of a magnetizable material, which bounds the magnets (10, 18) of the magnet unit.

4. Pig according to one of the preceding claims, characterized in that the magnet unit (3) has a sensor (30) for recording inspection data.

5. Pig according to one of the preceding claims, characterized in that the sensor (30) is arranged in the focusing element (14), in a recess in the same and / or on the focusing element (14).

6. Pig according to one of the preceding claims, characterized in that the magnet unit (3) also forms an eddy current braking unit.

7. Pig according to one of the preceding claims, characterized in that the magnet unit (3) has at least three magnets (10, 18) arranged one after another in its longitudinal direction.

8. Pig according to one of the preceding claims, characterized in that a plurality of magnet units (3) are arranged beside one another in the circumferential direction of the pig.

9. Pig according to one of the preceding claims, characterized by at least one in particular adjustable spacer (1), via which the magnet unit (3) can be positioned at a distance from the pipeline wall (32).

10. Pig according to one of the preceding claims, characterized in that the length of the magnet unit (3), including any enclosures, is less than 0.5*DPipe, preferably less than 0.3*DPipe, where DPipe = diameter of the pipeline [m].

11. Pig according to one of the preceding claims, characterized in that at a speed of 2 m / s in the pipeline, the magnet unit is designed to generate a braking force F depending on the pipeline diameter of at least F = m*D Pipe , where DPipe = the diameter of the pipeline [m] and m = 7000 N / m.