WO2008010711A1

WO2008010711A1 - System and method for measuring on a wall of a pipeline with the aid of at least one ultrasonic beam

Info

Publication number: WO2008010711A1
Application number: PCT/NL2007/050353
Authority: WO
Inventors: Reinier Antonius Parie; Thomas Theodorus Arnoldus Van Overbeek; Herman Jozef Moolenaar; Paul André de Jong
Original assignee: Röntgen Technische Dienst B.V.
Priority date: 2006-07-17
Filing date: 2007-07-17
Publication date: 2008-01-24
Also published as: NL1032185C2

Abstract

A system for performing measurements, with the aid of at least one ultrasonic beam, on a wall of a pipeline from a position in the pipeline, wherein the system is provided with a device which is arranged to be positioned in the pipeline, provided with a measuring body, which measuring body comprises a plurality of transducers for transmitting the ultrasonic waves, wherein, in use, the at least one beam has a propagation direction with a component in radial direction of the pipeline, wherein the system is further provided with a control device for controlling the transducers, wherein the transducers are arranged with respect to each other such that in combination they extend distributed over at least one path, which path extends substantially in tangential direction of the pipeline around an axis which, in use, extends in axial direction of the pipeline, wherein the system is arranged such that, in use, in each case per transducer a beam can be formed, wherein the control device is arranged for consecutively selecting in each case at least one transducer for consecutively transmitting in each case at least one beam, wherein for transmitting beams in mutually different directions, mutually different transducers are selected.

Description

Title: System and method for measuring on a wall of a pipeline with the aid of at least one ultrasonic beam

This invention relates to a system for performing measurements, with the aid of at least one ultrasonic beam, on a wall of a pipeline from a position in the pipeline, wherein the system is provided with a device which is arranged to be positioned in the pipeline, provided with a measuring body, which measuring body comprises a plurality of transducers for transmitting the ultrasonic waves, wherein, in use, the at least one beam has a propagation direction with a component in radial direction of the pipeline. The invention further relates to a method for performing measurements, with the aid of at least one ultrasonic beam, on a wall of a pipeline from a position in the pipeline.

Such a system and such a method are known per se and are used for detecting defects in metal parts of the pipe wall of a pipeline, such as cracks and corrosion. Here, the system can utilize techniques to obtain information about the wall on the basis of responses of the ultrasonic beam on the wall, caused by reflections or diffractions of the ultrasonic beam on the wall.

These responses can be measured with the same transducers as those with which the ultrasonic waves are transmitted. Also, the device can utilize time-of-flight diffraction (TOFD) or tandem technique. In TOFD and tandem technique, responses are mostly received with other transducers than the transducers with which the beams were transmitted. Such techniques are described inter alia in the European norm ENV 583-6, January 2000 (TOFD) and "Ultrasonic Testing of Materials", J. & H. Krautkramer, ISBN 3-540-07716-2, New York, 1977 (Tandem). The device is typically designed to be transported through the pipeline for scanning the pipeline. To be able to perform measurements in as many directions as possible, the measuring body is often designed to be rotatable relative to the pipeline, that is, rotatable relative to the remainder of the device. In use, the device is introduced into the pipeline. Then, the measuring body is rotated, so that each of the transducers transmits a beam each time in a modified direction. Thus, a ring-shaped zone is scanned. After scanning of the zone, the device can be transported further in the pipeline for subsequently scanning a next ring-shaped zone. Also, transportation through the pipeline and rotation can be carried out simultaneously, so that the pipe wall is scanned along a helix.

A drawback of the known device is that measuring through rotation of the measuring body in the pipeline takes relatively much time. The necessity of rotating the measuring body can constitute a considerable limitation on the speed of movement of the device in axial direction, since the rotation speed is limited by technical possibilities and/or a measuring speed.

Also, rotation requires much energy, which may present problems especially if the system involves a battery-supplied device.

To reduce the necessity for rotation, according to the invention, the system is characterized in that the system is further provided with a control device for controlling the transducers, wherein the transducers are arranged with respect to each other such that in combination they extend distributed over at least one path, which path extends substantially in tangential direction of the pipeline around an axis which in use extends in axial direction of the pipeline, wherein the system is arranged such that, in use, in each case per transducer a beam can be formed, wherein the control device is arranged for consecutively selecting in each case at least one transducer for consecutively transmitting in each case at least one beam, wherein for transmitting beams in mutually different directions, mutually different transducers are selected.

Because the desired direction of the beam can be chosen through selection of the at least one transducer, in many cases rotation of the measuring body relative to the housing can be at least partly or wholly avoided. In this way, therefore, embodiments of the system are possible whereby the measuring body, in use, does not rotate relative to the pipeline, or relative to the remainder of the system, which can be beneficial to the accuracy of the measurements. Also, the invention affords the possibility of a lower energy consumption, since no energy needs to be spent on the rotary movement of the measuring body.

It is further preferred that the at least one path forms a loop closed upon itself. This is especially advantageous in detecting defects, such as cracks and corrosion, near a weld interconnecting two parts of the pipeline. The device of the system can stand still at a particular position in the pipeline and perform a circumferential scan on and/or near the weld.

Thus, the wall can be scanned with different beams without the measuring body needing to rotate. Preferably, it holds that the control device is arranged, in use, to consecutively control mutually different transducers of the at least one path, for consecutively transmitting mutually different beams for screening the wall.

In particular, it holds that the control device is arranged, in use, in each case to simultaneously control a plurality of different transducers of the at least one path, for simultaneously transmitting different beams in mutually different directions. Thus, different parts of the wall can be examined simultaneously.

According to an advanced embodiment, it holds that the control device is arranged, in use, to consecutively control mutually different pluralities of transducers, for consecutively transmitting mutually different pluralities of beams for scanning the wall. Thus, a pipeline can be scanned whereby different beams are transmitted simultaneously.

An advanced embodiment of the system according to the invention has the feature that the transducers extend over a plurality of such paths. Here, it is possible that the control device is further arranged for transmitting beams as discussed before, per path. This means that the control device may be arranged for, per path, transmitting mutually different beams for scanning the wall; for, per path, simultaneously transmitting different beams in mutually different directions; or for, per path, transmitting mutually different pluralities of beams for scanning the wall. In this way, too, the measuring speed can be raised further.

A preferred embodiment of the system according to the invention is characterized in that the path is formed as a loop at least substantially closed upon itself, especially a circumferential circle at least substantially closed upon itself. Such a simple setup has the advantage that use can be made of the rotation symmetry that is often present in a pipeline. If the path extends over a circle, it is possible that, in use, the transducers of the path have substantially a same distance to the inner and/or outer surface of the pipeline. Further, such an embodiment is particularly suitable for performing a scan performed by consecutive beams transmitted with the aid of the transducers in tangential direction.

Preferably, at least one subset of the number of transducers extends over the at least one path, these transducers being each arranged for forming a beam and for receiving reflections of the at least one beam, wherein the direction of the beam has at least substantially exclusively a radial and axial component. Due to the absence of a tangential component, a measurement requires little space in tangential direction and it is possible to perform many measurements simultaneously. It is possible that a first path is provided with transducers of a first type, for instance transducers utilizing pulse echo, and/or a second path is provided with transducers of a second type, for instance transducers utilizing time-of- flight diffraction (TOFD) and/or tandem technique. An advantage of this is that a better imaging can be created, since strong properties of both types of measurement can be exploited. It is possible that the measuring body is provided with an acoustic lens for converging the at least one beam, which provides the advantage that a better focus on an area on or in the wall can be achieved.

Below, the invention will be further elucidated with reference to the drawing, wherein:

Fig. 1 shows in perspective view a first embodiment of a system according to the invention;

Fig. 2 shows a cross section of the device from Fig. 1 adjacent the transducers; Figs. 3a-c show detailed views of the portion delineated with a broken line in Fig. 2;

Fig. 3d shows a cross section of the device from Fig. 1 adjacent the transducers;

Fig. 4 shows in perspective view a third embodiment of a system according to the invention; and

Fig. 5 shows a detailed view of the longitudinal section of the device adjacent the arrows PP'.

Fig. 1 shows a first embodiment of a system S according to the invention. Fig. 2 shows a cross section of the device from Fig. 1. The device 1 is situated in a pipeline 22 (shown only in Fig. 2) provided with a wall 23 with an inner surface 24 and an outer surface 26. The system S comprises a device 1 which is shown in perspective view in Fig. 1. The device 1 is provided with a housing 2 which, at least in this first embodiment, comprises a cylinder-shaped measuring body 4 and at the two ends 6, 8 thereof a frame, in this example in the form of a suspension 10. In the embodiment shown in Fig. 1, the suspensions 10 are so arranged and mounted on the measuring body 4 that the measuring body 4 can be introduced in a centered manner into a pipeline with an axial axis A. To that end, in this embodiment, each of the suspensions 10 is provided with three arms 11, with each of the arms 11 having at an end remote from an axial axis A' of the cylinder-shaped body 4 a small wheel 12 and a springing element (not shown in the drawing) situated between the axial axis A' and the wheel 12. The axial axis A of the pipeline coincides in use, when the device is in the pipeline 22 to be inspected, with the axial axis A' of the device. Further, a radial direction B' of the device is defined to coincide with a radial direction B of the pipeline when the device is in the pipeline (see Fig. 2). Also, a tangential direction C of the device is defined as coinciding with a tangential direction C of the pipeline when the device is in the pipeline (see Fig. 2). The three arms 11 are separated at an angular distance of approximately 120° with respect to each other through for instance bent bars 14. Further, one suspension 10 at one end 6 is staggered approximately 60° with respect to the other suspension 10 at the other end 8. The suspension being arranged in this way allows the device to be moved in axial direction of a pipeline 22 with a favorable speed of, for instance, 0.5 to 1 m/sec, while the measuring body 4 remains properly centered. The cylinder-shaped measuring body 4 comprises a number of transducers 16i (i=l,2,3,...,n), which transducers 16i extend over a path 18, which path 18 in this embodiment extends as a loop closed upon itself along a circle on and around the cylinder-shaped measuring body 4, as can also be seen in Fig. 1. The path 18 is shaded in Fig. 1. The number of n transducers 16i as shown in the drawing is intended only by way of illustration. The transducers 16i are known per se and are each arranged for transmitting an ultrasonic beam. Further, the transducers 16i in this example are also arranged for receiving ultrasonic waves. To this end, the transducers 16i are mostly provided with a piezo crystal. Further, it holds in this example that each transducer is arranged to generate only one beam in a predetermined fixed direction. Furthermore, it holds that the device is settable, such that the beams adjoin each other or at least partly overlap each other at the wall of the pipeline, so that complete circumferential coverage is obtained. Further, it holds that the beams can be generated by transducers which extend in combination in tangential direction distributed over one path, which path extends in the tangential direction. More generally, it holds that by consecutively selecting different pluralities of transducers, mutually different pluralities of ultrasonic beams are transmitted for scanning the pipeline.

Furthermore, the system S is provided with a control device 20 which is communicatively connected with each of the transducers, so that with the control device 20 transducers 16i can be selected for transmitting ultrasonic beams. Ultrasonic signals that are received with the transducers are supplied via the connection between the transducers and the control device to the control device for further processing. These received ultrasonic signals are transmitted beams which have been reflected on a wall of the pipeline. In this example, the control system is mechanically connected with the device. However, this is not requisite; the control system may also be placed at a distance from the device, for instance outside a pipeline 22 to be inspected. In this embodiment, the control device 20 is provided with electronic components, such as for instance an electronic microprocessor and electronic memory components (not shown in the drawing). It is also possible, however, that optical components (not shown in the drawing either) form part of the control device 20.

Further, the control device in this embodiment is arranged for passing on received ultrasonic signals to signal processing means 21. The communicative connection between the signal processing means 21 and the control device 20 is preferably wireless, but may also be realized with a cable.

In the first embodiment, as mentioned, each transducer 16i is arranged to transmit an ultrasonic beam and to receive ultrasonic waves. In the first embodiment, the device is so designed that the distance between the transducers on the one hand and an axial axis A' of the device on the other hand is the same in each case. In use, the axial axis A' of the device coincides with an axial axis A of the pipeline 22. Here, this means that in use a distance d from one of the transducers 16i to the inner surface 24 of the cylinder-shaped pipeline 22 is at least substantially the same for each transducer 16i (i=l,2,...n). The transducers 16i are positioned with respect to each other such that in combination they extend distributed over the path 18, which path 18 extends at least substantially in tangential direction around the axial axis A' of the device. In this example, the path 18 forms a loop closed upon itself, viz. a circle. The cylinder-shaped measuring body 4 is further provided, at its circumference, with an acoustic lens (not shown in the drawing). In the first embodiment, the lens serves for focusing the waves coming from the transducers 16i to form beams, in such a manner that with the aid of each transducer a beam can be transmitted in a particular direction. The operation of the device is further explained with reference to

Figs. 3a-c. Figs. 3a-c show on an enlarged scale the portion of Fig. 2 framed with the broken line I.

A first step is shown in Fig. 3a. In the first step, the control device 20 causes, with the aid of the transducer 16i, a beam Z.I, diverging in this example, to be transmitted in a direction of a nearby first part 23.1 of the wall 23. Thus, the beam Z.I will have a component in radial direction B'. Reflections of the beam Z.I in this example are received with the aid of the transducer 16i. It is also possible that reflections are received by neighboring transducers such as for instance the transducers 16_n and I62. The thus received ultrasonic signals are supplied to the control unit 20 for further processing. The control unit in this example sends the received ultrasonic signals on to the signal processing unit 21 which processes the signals further for analyzing the wall 23 of the pipeline 22 in a known manner. A second step is shown in Fig. 3b. In Fig. 3b, it can be seen that thereupon, in the same manner, again a beam Z.2 is formed. Now, however, the selected transducer 16i with the aid of which the control device 20 causes a beam Z.2, different from beam Z.I, to be transmitted is the transducer I62. Since now a different transducer has been selected, viz. the transducer I62, a beam Z.2 directed at a different location of the wall 23 is transmitted. The beam Z.2 corresponds to a beam Z.I shifted in tangential direction. In the second step, the control device 20 therefore causes, with the aid of the transducer I62, a beam Z.2 to be transmitted in a direction of a nearby second part 23.2 of the wall 23. Thus, the beam Z.2 will have a component in radial direction B'. Reflections of the beam Z.2 in this example are received with the aid of the transducer I62. It is also possible that further reflections are received by neighboring transducers such as for instance the transducers 26i and 263. The thus received ultrasonic signals are supplied to the control unit 20 for further processing. The control unit 20 in this example sends the received ultrasonic signals on to the signal processing unit 21 which processes the signals further for analyzing the wall 23 of the pipeline 22 in a known manner.

A third step is shown in Fig. 3c. In Fig. 3c, it can be seen that thereupon, in the same manner, again a beam Z.3 is formed. Now, however, the selected transducer 16i with the aid of which the control device 20 causes a beam Z.3, different from beam Z.2, to be transmitted is the transducer I63. Since now a different transducer has been selected, viz. the transducer I63, a beam Z.3 directed at a different location of the wall 23 is transmitted. The beam Z.3 corresponds to a beam Z.2 shifted in tangential direction. In the third step, the control device 20 therefore causes, with the aid of the transducer I63, a beam Z.3 to be transmitted in a direction of a nearby third part 23.3 of the wall 23. Thus, the beam Z.3 will have a component in radial direction B'. Reflections of the beam Z.3 in this example are received with the aid of the transducer I63. It is also possible that further reflections are received by neighboring transducers such as for instance the transducers 262 and 264. The thus received ultrasonic signals are supplied to the control unit 20 for further processing. The control unit 20 in this example sends the received ultrasonic signals on to the signal processing unit 21 which processes the signals further for analyzing the wall 23 of the pipeline in a known manner.

Entirely analogously, likewise, beams can be consecutively transmitted with the aid of the other transducers of the first path 18. Thus, the inner surface adjacent the path 18 can be scanned in the tangential direction C, C without the measuring body 4 needing to be rotated relative to the suspension 10 (that is, relative to the remainder of the device) or relative to the pipeline.

Thus, consecutively, in each case at least one transducer 16i is selected for consecutively transmitting at least one beam for measuring on a particular part of the wall of the pipeline. Here, for transmitting beams in mutually different directions, mutually different transducers are selected.

By carrying out the above-mentioned steps with, for instance, in succession the transducers I61, I62, I63, 164,...16_n, a scan in tangential direction can be performed without the necessity for rotating the measuring body 4. The scan in this example forms a loop closed upon itself. In this example, the control device is therefore arranged, in use, to consecutively control mutually different transducers of the at least one path for consecutively transmitting mutually different beams for scanning the wall.

Here, it preferably holds that neighboring beams Zi and Z.i+1 adjoin or partly overlap in or near the wall of the pipeline, so that the complete wall can be scanned.

Under the control of the control device, the wall of the pipeline can also be scanned in a different manner by selecting the transducers in a different sequential order and/or by selecting a plurality of transducers simultaneously. An example of this will now be discussed with reference to Fig. 3d.

In Fig. 3d it is shown that the control device 20 is furthermore arranged for controlling the transducers 16i as desired, such that simultaneously by a plurality of transducers, respectively, a plurality of different beams Zi are transmitted. In this example, the starting point is two hundred transducers 16i (n=200) which extend over the path 18. In this example, in a first step, transducers 16i,16δi, Ie₁Oi and I6151 are simultaneously selected for transmitting a beam with each of these transducers. Thus, simultaneously, the beams Z.I, Z.51, Z.101 and Z.151 are transmitted as shown in Fig. 3d. Reflections of the beams are measured with the aid of the transducers 16i,165i, Ie₁Oi and lβiβi as discussed above. Also, it is possible that with the aid of the neighboring transducers I6200 and I62 reflections of the beam Z.I are measured; with the neighboring transducers I650 and I652 reflections of the beam Z.51, etc. The thus received ultrasonic signals are supplied via the control unit 20 to the signal processing unit 21 as discussed above for further processing. In the same manner as described above, thereupon, in a second step the transducers 162,1652, 16iO2 and 16^2 are selected for simultaneously transmitting the beams Z.2, Z.52, Z.102 and Z.152. Of these beams, also, reflections are measured with the aid of for instance the transducers 162,1652, 16iO2 and 16].52 and possibly also with the aid of neighboring transducers thereof as discussed above. In subsequent steps, corresponding modifications are carried out, so that in each case, simultaneously, with the aid of a plurality of transducers 16i, 16i+so, 16i+ioo and lβi+iso, in each case, simultaneously, a plurality of ultrasonic beams Z.i, Z.i+50, Z.i+100 and Z.i+150 are transmitted and this consecutively for i=l,2,...,50. By thus consecutively selecting different pluralities of transducers, consecutively, different pluralities of ultrasonic beams are transmitted, with the aid of which plurality of beams a portion of the wall of the pipeline is scanned. In this embodiment, these scans together form a loop closed upon itself. Accordingly, for the purpose of performing the scan according to Fig. 3d, the control device is arranged, in use, in each case to control simultaneously a plurality of different transducers of the at least one path for simultaneously transmitting different beams in mutually different directions. In this example, it then holds furthermore that the control device is arranged, in use, to consecutively control mutually different pluralities of transducers for consecutively transmitting mutually different pluralities of beams for scanning the wall. Further, in each of the above-outlined exemplary embodiments, the device 1, for instance between two circumferential scans along the loop, can be transported through the pipeline for thus scanning successive ring- shaped areas which preferably adjoin or of which neighboring ring-shaped areas partially overlap. In Figs. 4 and 5, a second embodiment of the device is shown. The second embodiment substantially corresponds to the first embodiment. In this embodiment, the cylinder-shaped measuring body 4 is provided with five paths 18j (j=l,2,3,4,5) which are positioned spaced-apart in axial direction. The transducers are here indicated with 16y, where j indicates the path 18i to which the transducer belongs, and i is the indication of the transducer within the path 18j. One first subset of the number of transducers 16ij (i=l,2,3,...,n; j=l) extends over the first path 18i. The transducers lβu of this first subset are each arranged for forming a beam Z.i,l (i=l,2,...,n), diverging in this example, and for receiving reflections of the respective beam Z.i,l (i=l,2,...,n) as discussed with reference to Figs. 3a-3d for the beams Zi (i=l,2,...,n).

A second subset of the number of transducers 16y (i=l,2,3,...,n; j=2) extends over a second path I82. A third subset of the number of transducers 16ij (i=l,2,3,...,n; j=3) extends over a third path I83. Here, the first path 18i and the third path I83 are separated from each other in axial direction A, A'. The transducers 16i2 of the second subset are respectively arranged for forming a beam Z.i,2 (i=l,2,...,n), diverging in this example. Here, the direction of the beam Z.i,2 has at least substantially exclusively a radial and axial component. This is due to the chosen direction of the transducers. The axial component is in the direction of the third path. The direction of the beam Z.i,2 in this embodiment is such that the beam after refraction on the inner surface 24 of the pipeline includes for instance an angle between 20° and 70°, preferably an angle between 30° and 60° and more preferably between 40° and 50° with a radial direction of the device. In this example, the angle after refraction is approximately 45°. In this example, a normal N to a surface of the transducers 16i,2 and 16i,3 includes an angle of (90 - 16.9) degrees with the axial direction A, A'.

The transducers 16i,2 are arranged for receiving reflections in the wall of beams Z.i,2 transmitted by the transducers. Also, the transducers 16i,3 of the third subset may be arranged for receiving reflections of the beams Z.i,2. In general, a reflection on a fault in the wall 23 of the beam Z.i,2 will be received by the transducer 16i,2 and possibly by the neighboring transducers 16i-].,2 and 16i+i,2. Also, reflections of the beams Z.i,2 (i=l,2,...,n) on the wall can be received in this example by the transducers of the third subset of the transducers 16jj (i=l,2,...,3; j=3). Upon reception of such a reflection on the outer wall, this is an indication there is actually no fault present in the material of the wall there. In general, a reflection on the wall 23 of the beam Z.i,2 will be received by the transducer 16i,3 and possibly by the neighboring transducers lβi-i.s and 16i+₁,3. Entirely analogously to what has been discussed with reference to Figs. 3a-3c, consecutively n beams Z.i,2 (i=l,2,...,n) can be transmitted and the reflections thereof be received for scanning the wall 23. Also, as discussed with reference to Fig. 3d, a plurality of beams Z.i,2, Z.i+50,2, Z.i+100,2 and Z.i+150,2 can be transmitted simultaneously, the reflections of which are received with the transducers of the third subset as discussed above per beam. This can then be repeated for in succession i=l,2,3,—, 50 for scanning the wall along a closed loop.

In this example, it moreover holds that the transducers 16i,3 of the third subset are respectively arranged for forming a beam Z.i,3 (i=l,2,...,n), diverging in this example. Here, the direction of the beam Z.i,3 has at least substantially exclusively a radial and axial component. This is due to the chosen direction of the transducers. The direction of the beam Z.i,3 in this embodiment is such that the beam after refraction on the inner surface 24 of the pipeline includes for instance an angle between 20° and 70°, preferably an angle between 30° and 60° and more preferably between 40° and 50° with a radial direction of the device. In this example, the angle after refraction is approximately 45°. In this example, a normal N' to a surface of the transducers 16i,4 and 16i,5 includes an angle of (90 — 11.2) degrees with the axial direction A, A'. The transducers 16i,3 are arranged for receiving reflections in the wall of beams Z.i,3 transmitted by the transducers. Also, the transducers 16i,2 of the third subset may be arranged for receiving reflections of the beams Z..i,3. In general, a reflection on a fault in the wall 23 of the beam Z.1,3 will be received by the transducer 16i,3 and possibly by the neighboring transducers 16i-i,3 and 16i+i,3. Also, reflections of the beams Z.i,3 (i=l,2,...,n) on the wall can be received in this example by the transducers of the second subset of the transducers lβy (i=l,2,...,3; j=2). Upon reception of such a reflection on the outer wall, this is an indication there is actually no fault present in the material of the wall there. In general, a reflection on the wall 23 of the beam Z.i,3 will be received by the transducer 16i,2 and possibly by the neighboring transducers 16i-i,2 and lβi+i^. Also, for instance a beam Zi, 2 transmitted with the second subset of transducers can, upon reflection on the outer wall and a fault in the wall, be received by a transducer 16i,3 for performing a roundtrip tandem measurement, known per se. Entirely analogously to what has been discussed with reference to Figs. 3a-3c, consecutively n beams Z.i,3 (i=l,2,...,n) can be transmitted and the reflections thereof be received for scanning the wall 23. Also, as discussed with reference to Fig. 3d, a plurality of beams Z.i,3, Z.i+50,3, Z.i+100,3 and Z.i+150,3 can be transmitted simultaneously, the reflections of which are received with the transducers of the third subset as discussed above per beam. This can then be repeated for in succession i=l,2,3,— , 50 for scanning the wall along a closed loop. Accordingly, the parts of the transducers that extend over the central and the two outermost paths 18i, 182, and I83 are provided with transducers for both transmitting the ultrasonic waves and receiving ultrasonic waves.

Furthermore, the system is provided with a fourth subset of the transducers 16i,4 which extend over a fourth path I84 and with a fifth subset of transducers 16i,5 which extend over a fifth path I85. The fourth and fifth paths in this example are separated from each other in axial direction A,A and are situated on either side of the first path. The first, fourth and fifth paths are then situated between the second and third paths. The transducers of the fourth and fifth subsets in this example are used for performing so-called time-of-flight diffraction (TOFD), which is described in more detail inter alia in International patent application WO 2006/004402. In this embodiment, with a transducer 16i,4 of the fourth path I84, a beam Z.i,4, diverging in this example, is transmitted, of which a diffraction on the wall of the pipeline is received with an associated transducer 16i,5 of the fifth path I85. Here, also, it holds that a diffraction on the wall may possibly be received also by neighboring transducers such as the transducers 16i+i,5 and lβi-i.δ. Entirely analogously to what has been discussed with reference to Figs. 3a-3c, consecutively n beams Z.i,4 (i=l,2,...,n) can be transmitted and the refractions thereof on the wall are received for scanning the wall 23. Also, as discussed with reference to Fig. 3d, a plurality of beams Z.i,4, Z.i+50,4, Z.i+100,4 and Z.i+150,4 can be transmitted simultaneously, the refractions of which are received with the transducers of the fifth subset as discussed above per beam. This can then be repeated for i=l,2,3,--,50 in succession for scanning the wall along a closed loop.

Entirely analogously to what has been discussed above for transmitting beams with transducers of the fourth path and receiving diffractions with transducers of the fifth path, the transducers of the fifth path may also be arranged for transmitting divergent beams, while the transducers of the fourth path are arranged for receiving diffractions, so that in this way too a TOFD scan can be performed. Also, the system may be arranged for performing roundtrip tandem measurements with the transducers of the fourth path and fifth path, as discussed above for the second and third paths.

By performing measurements at different angles, as illustrated with reference to Figs. 4 and 5, a better picture of any cracks or defects present in the pipeline can be obtained. It is observed that by the word 'axis' in this description primarily an imaginary line is meant, which does not necessarily need to be embodied by a tangible body.

It will be clear to those skilled in the art that many variants on the embodiments of the invention shown here are possible. However, the invention is not limited thereto. Thus, use can also be made of tandem technique, whereby both transducers for generating a beam and transducers for receiving a response are used. Also, in general, per transducer, more than one beam may be transmitted. Also, converging instead of diverging beams may be generated. In the above examples, the control device is mechanically connected with the device. However, the control device can also be arranged outside the pipeline and for instance be wired to the transducers. Also, the connection between the signal processing means 21 and the control device 20 may be wired or wireless. Also, the transducers may extend along a segment of a circle instead of a complete circle. Also, different numbers of beams than discussed above may be transmitted simultaneously. Also, the loop closed upon itself, instead of being a circle, may also be an oval, square, hexagon, etc.

Claims

1. A system for performing measurements, with the aid of at least one ultrasonic beam, on a wall of a pipeline from a position in the pipeline, wherein the system is provided with a device which is arranged to be positioned in the pipeline, provided with a measuring body, which measuring body comprises a plurality of transducers for transmitting the ultrasonic waves, wherein, in use, the at least one beam has a propagation direction with a component in radial direction of the pipeline, characterized in that the system is further provided with a control device for controlling the transducers, wherein the transducers are arranged with respect to each other such that in combination they extend distributed over at least one path, which path extends substantially in tangential direction of the pipeline extends around an axis which in use extends in axial direction of the pipeline, wherein the system is arranged such that, in use, in each case per transducer a beam can be formed, wherein the control device is arranged for consecutively selecting in each case at least one transducer for consecutively transmitting in each case at least one beam, wherein for transmitting beams in mutually different directions, mutually different transducers are selected.

2. A system according to claim 1, characterized in that the at least one path extends along a segment of a circle in tangential direction.

3. A system according to claim 1 or 2, characterized in that the at least one path is formed as a loop closed upon itself.

4. A system according to claim 3, characterized in that the at least one path extends over a circle in tangential direction.

5. A system according to any one of the preceding claims, characterized in that the measuring body comprises a cylinder-shaped body, with the transducers being arranged spread over the cylinder-shaped body.

6. A system according to any one of the preceding claims, characterized in that the transducers of the at least one path have at least substantially a same distance to the axial axis of the device, which axial axis in use preferably coincides with the axial axis of the pipeline.

7. A system according to any one of the preceding claims, characterized in that the device is arranged such that the beams at the wall of the pipeline adjoin each other or at least partly overlap.

8. A system according to any one of the preceding claims, characterized in that the control device is further arranged for controlling the transducers such that simultaneously a plurality of different beams are generated, with each of the beams being formed with the aid of one transducer.

9. A system according to any one of the preceding claims, characterized in that the control device is arranged, in use, to consecutively control mutually different transducers of the at least one path for consecutively transmitting mutually different beams for scanning the wall.

10. A system according to claim 9, characterized in that the control device is arranged, in use, in each case to simultaneously control a plurality of different transducers of the at least one path for simultaneously transmitting different beams in mutually different directions.

11. A system according to claim 10, characterized in that the control device is arranged, in use, to consecutively control mutually different pluralities of transducers for consecutively transmitting mutually different pluralities of beams for scanning the wall.

12. A system according to any one of the preceding claims, characterized in that the transducers extend over a plurality of such paths.

13. A system according to any one of the preceding claims, characterized in that a first subset of the transducers is arranged for receiving reflections of the beams.

14. A system according to claim 13, characterized in that the first subset of the number of transducers extends over a first path of the at least one path.

15. A system according to claim 14, characterized in that the transducers of the first subset are arranged such that the reflections are received of beams which were transmitted by transducers of the first subset, while in particular the direction of the beams is directed at least substantially in radial direction.

16. A system according to any one of the preceding claims, characterized in that a second subset of the transducers extends over a second path of the at least one path, while the second subset, in use, is controlled for transmitting at least one second beam and for receiving reflections of the at least one second beam on the wall, while preferably the direction of the at least one second beam has at least substantially exclusively a radial and axial component.

17. A system according to claim 16, characterized in that the direction of the at least one second beam includes an angle between 5° and 40°, preferably an angle between 10° and 30° and more preferably between 14° and 20° with a radial direction of the device.

18. A system according to any one of the preceding claims, characterized in that a third subset of the transducers extends over a third path of the at least one path, while the third subset, in use, is controlled for transmitting at least one third beam and for receiving reflections of the at least one third beam on the wall, while preferably the direction of the at least one third beam has at least substantially exclusively a radial and axial component.

19. A system according to claim 18, characterized in that the direction of the at least one third beam includes an angle between 5° and 40°, preferably an angle between 10° and 30° and more preferably between 14° and 20° with a radial direction of the device.

20. A system according to claims 16 and 18, characterized in that the system is further arranged to receive a reflection of the at least one second beam on the pipeline with the third subset of transducers, more particularly to measure a reflection on the outer wall to establish that there is no fault or to measure a reflection on the outer wall and any fault in the wall through a roundtrip tandem measurement.

21. A system according to claims 16 and 18 or according to claim 20, characterized in that the second and third paths are spaced apart in axial direction and the system is further arranged to receive a reflection of the at least one third beam on the pipeline with the second subset of transducers, more particularly to measure a reflection on the outer wall to establish that there is no fault or to measure a reflection on the outer wall and any fault in the wall through a roundtrip tandem measurement.

22. A system according to claim 13 and claim 20 and/or 21, characterized in that the first path, viewed in axial direction, is situated between the second and third paths.

23. A system according to any one of the preceding claims, characterized in that a fourth subset of the transducers extends over a fourth path of the at least one path and a fifth subset of the transducers extends over a fifth path of the at least one path, while the fourth and fifth paths are spaced apart in axial direction and the transducers of the fifth path are arranged for receiving diffractions of the beams transmitted by transducers of the fourth path.

24. A system according to claims 13 and 23, characterized in that the first path, viewed in axial direction, is situated between the fourth and the fifth paths.

25. A system according to any one of the preceding claims, characterized in that the measuring body is furthermore provided with at least one acoustic lens for converging the at least one beam.

26. A system according to any one of the preceding claims, characterized in that the device is arranged for moving through the pipeline in axial direction of the pipeline.

27. A system according to any one of the preceding claims, characterized in that the control device is provided with electronic components for controlling the transducers.

28. A system according to any one of the preceding claims, characterized in that the control device is provided with optical components for controlling the transducers.

29. A system according to any one of the preceding claims, characterized in that the control device is of reprogrammable design.

30. A system according to any one of the preceding claims, characterized in that at least one of the transducers is provided with piezo crystals for generating the ultrasonic waves.

31. A system according to any one of the preceding claims, characterized in that the measuring body in use does not rotate relative to the rest of the device.

32. A system according to any one of the preceding claims, characterized in that at least a part of the control device is mechanically connected with the device.

33. A system according to any one of the preceding claims, characterized in that each transducer is arranged to generate only one beam in a predetermined fixed direction.

34. A system according to any one of the preceding claims, characterized in that the system is provided with at least one path which extends in the tangential direction, along which a plurality of the transducers are arranged spread in tangential direction, while the beams which are generated by these transducers adjoin each other or overlap each other at the wall of the pipeline so that complete circumferential coverage is obtained.

35. A method for performing measurements, with the aid of at least one ultrasonic beam, on a wall of a pipeline from a position in the pipeline, utilizing a system according to any one of the preceding claims, wherein in each case with the aid of one of the transducers a beam is generated, wherein different transducers are selected for transmitting different beams and wherein with the aid of the beams measurements on the wall of the pipeline are performed.

36. A method according to claim 35, characterized in that by consecutively selecting different transducers, mutually different ultrasonic beams are transmitted, with the aid of which beams the wall of the pipeline is scanned.

37. A method according to claim 36, characterized in that scanning is performed such that a scanned portion of the wall forms a loop closed upon itself.

38. A method according to claim 35, 36 or 37, characterized in that in each case simultaneously with the aid of a plurality of transducers, in each case simultaneously a plurality of mutually different ultrasonic beams are transmitted, so that measurements are performed simultaneously on different parts of the wall of the pipeline.

39. A method according to claim 35, characterized in that by consecutively selecting different pluralities of transducers, mutually different pluralities of ultrasonic beams are transmitted for scanning the pipeline.

40. A method according to claim 39, wherein the scan is performed along a loop closed upon itself.