SENSING PRESSURE VARIATIONS IN PIPELINES

Abstract

A pressure sensing device is operable to monitor pressure variations within a fluid pipeline. The pressure sensing device comprises a pair of complementary sensor elements. At least one of the sensor elements is mounted to a supporting bracket that is mounted to a point on the external surface of the pipeline. At least one sensor element is mounted such that the pair of complementary sensor elements experience relative displacement as the external surface of the pipeline undergoes changes in size or shape. The pair of complementary sensor elements are operable to detect said relative displacement and thereby provide an indication of pressure variation within the pipeline.

Claims

1. A pressure sensing device operable to monitor pressure variations within a fluid pipeline, the pressure sensing device comprising: a pair of complementary sensor elements, at least one of the sensor elements mounted to a supporting bracket that is mounted to a point on the external surface of the pipeline, wherein the at least one sensor element is mounted such that the pair of complementary sensor elements experience relative displacement as the external surface of the pipeline undergoes changes in size or shape; and wherein the pair of complementary sensor elements are operable to detect said relative displacement and thereby provide an indication of pressure variation within the pipeline.

2. A pressure sensing device as claimed in claim 1 wherein each sensor element is mounted to a supporting bracket.

3. A pressure sensing device as claimed in claim 2 wherein at least one of the sensor elements is provided on a reference platform mounted to a supporting bracket.

4. (canceled)

5. A pressure sensing device as claimed in claim 3 wherein each supporting bracket is mounted to a separate point on the external surface of the pipeline.

6. (canceled)

7. (canceled)

8. A pressure sensing device as claimed in claim 1 wherein each supporting bracket is mounted to a point around the surface of the pipeline by means of a brace, said brace provided around the circumference of the pipeline.

9-13. (canceled)

14. A pressure sensing device as claimed in claim 1 wherein each supporting bracket comprises one or more arms.

15. (canceled)

16. (canceled)

17. A pressure sensing device as claimed in claim 1 wherein each supporting bracket comprises one or more feet.

18. (canceled)

19. A pressure sensing device as claimed in claim 3 wherein the supporting brackets support the respective platforms at substantially adjacent positions within the sensing range of the sensor elements.

20. A pressure sensing device as claimed in claim 3 wherein the supporting brackets are adapted to support the respective platforms at a position radially displaced from the exterior surface of the pipeline.

21. (canceled)

22. (canceled)

23. A pressure sensing device as claimed in claim 3 wherein the reference platform additionally comprises a protective housing for the sensor elements.

24-27. (canceled)

28. A pressure sensing device as claimed in claim 1 further comprising a cover for housing the pressure sensing device.

29. (canceled)

30. A pressure sensing device as claimed in claim 1 wherein the pair of complementary sensors elements comprise a proximity sensor.

31. A pressure sensing device as claimed in claim 1 wherein one sensor element comprises one or more light emitting means and the other sensor element comprises one or more light receiving means.

32. (canceled)

33. (canceled)

34. A pressure sensing device as claimed in claim 1 wherein one sensor element comprises a magnet and the other sensor element comprises a magnetic field sensor.

35. (canceled)

36. A pressure sensing device as claimed in claim 1 wherein one sensor element comprises a capacitive proximity sensor and the second sensor element comprises a probe detectable by the capacitive proximity sensor.

37. A pressure sensing device as claimed in claim 1 wherein one sensor element comprises an eddy current proximity sensor and the second sensor element comprises a probe or target detectable by the eddy current proximity sensor.

38. A pressure sensing device as claimed in claim 1 wherein the device comprises a processing unit operable to process signals output by at least one of the sensor elements so as to determine the relative displacement of said sensor elements, pressure variation within the pipeline or an absolute pressure within the pipeline to one or more external devices.

39. (canceled)

40. A pressure sensing device as claimed in claim 1 wherein the device is provided with a communication unit operable to communicate indications of the relative displacement of the sensor elements, the reference platforms, pressure variation within the pipeline or an absolute pressure within the pipeline to one or more external devices.

41. (canceled)

42. (canceled)

43. A method of monitoring a pipeline comprising the steps of: fitting one or more pressure sensing devices to a pipeline, said pressure sensing device operable to monitor pressure variations within a fluid pipeline, the pressure sensing device comprising: a pair of complementary sensor elements, at least one of the sensor elements mounted to a supporting bracket that is mounted to a point on the external surface of the pipeline, wherein the at least one sensor element is mounted such that the pair of complementary sensor elements experience relative displacement as the external surface of the pipeline undergoes changes in size or shape; and wherein the pair of complementary sensor elements are operable to detect said relative displacement and thereby provide an indication of pressure variation within the pipeline; and monitoring the output of each said pressure sensing device.

44. A pipeline for transporting fluid, the pipeline fitted with one or more pressure sensing devices operable to monitor pressure variations within a fluid pipeline, the pressure sensing device comprising: a pair of complementary sensor elements, at least one of the sensor elements mounted to a supporting bracket that is mounted to a point on the external surface of the pipeline, wherein the at least one sensor element is mounted such that the pair of complementary sensor elements experience relative displacement as the external surface of the pipeline undergoes changes in size or shape; and wherein the pair of complementary sensor elements are operable to detect said relative displacement and thereby provide an indication of pressure variation within the pipeline.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0038] In order that the invention may be more clearly understood embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0039] FIG. 1 illustrates a first embodiment of an external pressure sensing device for a fluid pipeline according to the present invention;

[0040] FIG. 2 is a side view of the device of FIG. 1;

[0041] FIG. 3 illustrates a second embodiment of an external pressure sensing device for a fluid pipeline according to the present invention;

[0042] FIG. 4 is a cross-sectional view of the pipeline and device of FIG. 3;

[0043] FIG. 5 is a schematic block diagram of the sensor elements and associated components provided for a pressure sensor according to the present invention;

[0044] FIG. 6 is a schematic horizontal cross-sectional illustration of an optical sensor element arrangement for a pressure sensor according to the present invention;

[0045] FIG. 7 is a schematic vertical cross-sectional illustration of an optical sensor element arrangement for a pressure sensor according to the present invention;

[0046] FIG. 8 is a schematic illustration of an magnetic sensor element arrangement for a pressure sensor according to the present invention;

[0047] FIG. 9 is a schematic illustration of a capacitive sensor element arrangement for a pressure sensor according to the present invention.

[0048] FIG. 10 illustrates a perspective view of a third embodiment of an external pressure sensing device for a fluid pipeline according to the present invention, with the sensor element removed and the device separated from the pipeline;

[0049] FIG. 11 illustrates a perspective view of the device of FIG. 10, with the device mounted to the pipeline and a cover partially fitted to the device; and

[0050] FIG. 11 is a side view of the device of FIGS. 10 and 11, with the device mounted to the pipeline and the cover removed from the device.

[0051] Turning now to FIGS. 1 & 2, an externally mounted pressure sensing device 10 for a pipeline 1 comprises a first support bracket 20, and a second support bracket 30, mounted to different points around the exterior of the pipeline 1. At the distal end of each supporting bracket 20, 30 is provided a protective housing 21, 31 within each housing 21, 31 is a reference platform 25, 35. Upon the respective reference platforms 25, 35 are mounted complementary sensor elements 50, 60.

[0052] As each supporting bracket 20, 30 is mounted to a separate point on the external surface of the pipeline 1, the pair of reference platforms 25, 35 experience relative displacement as the exterior of the pipeline 1 undergoes changes in size or shape due to pressure variation within the pipeline 1. The complementary sensor elements 50, 60 together comprise a proximity sensor and are operable to measure the relative displacement of the platforms 25, 35 and thereby provide an indication of pressure variation within the pipeline 1. The sensor elements 50, 60 may comprise any suitable form of proximity sensor including but not limited to: optical, capacitive, eddy current, magnetic, ultrasonic or the like. Particular examples of suitable proximity sensor arrangements will be discussed in more detail below, by way of example only.

[0053] The supporting brackets 20, 30 are held in position by means of a common brace 40 comprising a pair of circumferential ribs 41. The ribs 41 act to clamp the supporting brackets 20, 30 to the pipeline 1 at the desired mounting points. Accordingly, each supporting bracket 20, 30 moves with changes in size or shape of the pipeline 1 at the respective mounting points. In order to minimise the influence of temperature variation on pressure measurements, the supporting brackets 20, 30 may be formed from a material with a low coefficient of thermal expansion, such as the alloy invar or the like, and they may be formed from the same or a similar material as the pipe wall to ensure they are thermally matched.

[0054] The first support bracket 20 comprises a short arm 23 extending radially from the said mounting point on the pipeline 1 and a base 22 adapted to be clamped by the brace 40. The second supporting bracket 30 comprises a base 32 adapted to be clamped by the brace 40 and a curved arm 33 extending away from the said mounting point and around the exterior of the pipeline 1. For greater stability, as is shown most clearly in FIG. 2, the second supporting bracket 30 comprises a pair of bases 32 adapted to be clamped by the brace 40 at opposing sides of the pipeline 1 and a pair of curved arms 33 extending away from the said mounting point and around the exterior of the pipeline 1. Whilst the base 32 is shown to be of trapezoidal form in FIGS. 1-3, alternative forms may be used if desired or appropriate.

[0055] Turning now to FIGS. 3 & 4, these depict a device 10 utilising an alternative arrangement of the second supporting bracket 30. In FIGS. 4 and 5, the second supporting bracket 30 comprises a single curved arm 33 mounted directly to the pipeline 1 at a point substantially opposite the first supporting bracket. The curved arm 33 extends away from the said mounting point in both directions and around the exterior of the pipeline 1 so as to position the housing 31 and associated reference platform 35 adjacent to the housing 21 and platform 25.

[0056] The embodiment of FIGS. 4 & 5 has the benefit of maximising the separation between the mounting points of the first and second supporting brackets 20, 30. This increases the range of relative displacement between the reference platforms in response to changes in shape or size of the pipeline 1. Nevertheless, the increase in rage comes at a cost of lesser security in attachment and greater susceptibility to vibration induced errors.

[0057] Turning now to the housings 21, 31, in FIGS. 1-5, the housing 21 is shown to slightly overlap the housing 31. This can provide some protection from the local environment for the sensor elements. Typically, the housings 21, 31 may be adapted to house additional components of the device 10 such as a power source 51, 61, processing unit 52 or communication unit 53 as is illustrated schematically in FIG. 5. The skilled man will of course appreciate that in embodiments wherein only one of the sensor elements 50, 60 needs to be powered, the second power source 61 can be omitted.

[0058] In normal operation, the processing unit 52 is operable to receive signals output by at least sensor element 50, to determine the relative displacement of said sensor elements 50, 60 and hence the relative displacement of said reference platforms 21, 31. The processing unit 52 may additionally be operable to process said signals to provide an indication of a pressure variation within the pipeline 1 or an absolute pressure within the pipeline 1.

[0059] The device 10 may also be provided with communication unit 53 operable to communicate with one or more external devices (not shown). Typically, this communication might take place via a suitable wireless datalink, but in appropriate circumstances a hard wired link may be used in addition or as an alternative. Typically, the communication unit 53 will communicate indications of the relative displacement of said reference platforms, pressure variation within the pipeline or absolute pressure within the pipeline to one or more external devices. The communication unit 53 may additionally be operable to receive information and/or instructions from external devices. In some embodiments, the device 10 may additionally be provided with a data storage means. This can allow output data from the sensing elements 50, 60 to be stored within the device 10 and communicated to external devices in batches at prearranged intervals or in response to specific requests. In some such embodiments, the processing unit may be operable to initiate communication of sensor data in response to absolute pressure or pressure variation within the pipeline falling outside threshold limits.

[0060] Turning now to the specific example of FIGS. 6 & 7, these illustrate an embodiment of the device utilising optical sensor elements 50, 60. A light emitting element 60 (for instance an LED) is provided upon platform 35 within housing 30. Light from the light emitting element 60 is collimated by passing through aperture 39. The collimated light is then incident upon light sensing array 50 mounted on platform 25, as the relative displacement of the light emitting element 60 varies with respect to the light sensing array, the position within the array upon which the collimated light is incident varies. By monitoring this point of incidence, the relative displacement of the sensor elements 50, 60 can be determined and hence variations in pipeline 1 pressure can be determined.

[0061] As is shown in FIGS. 6 & 7, such an embodiment may optionally also include a rim 28 on the first housing which at least partially overlaps the end of the second housing 30. This can restrict ambient light from falling on the sensing array 50. It is of course possible in alternative embodiments that the rim may be provided on the second housing. It is still further possible to supplement rim 28 with a further enclosure 29. Such a further enclosure 29 may comprise a ring or flexible sheet.

[0062] In order to help confirm calibration of the device 10 or that the sensors 50, 60 remain within range, it is possible to provide additional light emitting elements 60a, 60b positioned within apertures 39a and 39b and corresponding light sensors 50a, 50 b. in the event that light sensors 50a, 50b fail to detect the light emitted by light emitting elements 60a, 60b, or the light level detected drops below a pre-set threshold, it may be determined that the relative displacement between sensor elements 50, 60 has exceeded a normal range. This may indicate that the device 10 requires recalibration or may be indicative of a significant danger of a leak or other pipeline emergency.

[0063] Turning now to FIG. 8, there is shown schematically an alternative to the optical sensor embodiment discussed above. In this embodiment, the first supporting bracket may carry a capacitive proximity sensor 50 on the reference platform 25 and the second supporting bracket may carry a conductive probe 60 on the platform 35. Once again, as the relative displacement between the capacitive sensor 50 and probe 60 varies, so does the output of the capacitive sensor 50. This allows the relative displacement to be determined and hence variations in pipeline 1 pressure can be determined.

[0064] Turning now to FIG. 9, there is shown schematically another alternative to the optical sensor embodiment discussed above. In this embodiment, the first supporting bracket may carry a Hall effect probe 50 on the reference platform 25 and the second supporting bracket may carry a magnet 60 on the platform 35. Once again, as the relative displacement between the Hall effect probe 50 and magnet 60 varies, so does the output of the Hall effect probe 50. This allows the relative displacement to be determined and hence variations in pipeline 1 pressure can be determined.

[0065] Turning now to FIGS. 10, 11 and 12, an externally mounted pressure sensing device 110 for a pipeline 1 comprises a supporting bracket 120 mounted around the exterior of the pipeline 1. The supporting bracket 120 comprises a pair of curved arms 133 that are attached at a proximal end to a sensor assembly 121. Each supporting bracket 210 is also attached at a distal end to a foot 167. The device 110 is secured to the pipeline 1 by engaging the feet 167 with a pair of circumferential steel bands 168 that are fixed around the exterior of the pipeline 1. The feet 167 fit under the steel bands 168, which are tightened circumferentially to fix the feet 167 and thus the device 110 in its position relative to the pipeline 1.

[0066] The sensor assembly 121 comprises a bracket 162 that has a vertically oriented mounting hole 166 through which a sensor element 150 can be inserted. A ferrous target element 160 is bonded to a top part of the pipe 1 using an adhesive, adjacent and in line with the sensor element 150. Thus, in this embodiment the pair of complementary sensor elements comprises a sensor element 150 and a target element 160. When the device 110 is mounted to the pipeline 1, the bracket 162 is fixed relative to the target element 160. The position of the sensor element 150 is moveable relative to the bracket 162 by loosening and tightening a grub screw 165 that is engageable with a part of the sensor element 150. In this embodiment, the sensor element 150 comprises an eddy current sensor.

[0067] The sensor assembly 121 further comprises a housing 163 and a cable gland 164 of sufficient ingress protection.

[0068] The height of the sensor element 150 relative to the target element 160 can be adjusted by use of the grub screw 165 so that the sensor element 150 can positioned in an optimal sensing position relative to the target element 160, which is around 0.5 mm above the surface of the target element 160.

[0069] As is shown in FIG. 11, the supporting bracket 120, the sensor assembly 121 and the steel bands 168 may be encased in a cover 169 to improve their ingress protection against liquids and solid particles. Indeed, by using the cover 169, some embodiments of the invention are able to obtain a high level of ingress protection, such as an IP68 rating. The cover 169 is particularly important when the device 110 is mounted to an underground pipeline 1.

[0070] In use, a plurality of devices 110 is installed at separate, known positions along the pipeline 1. Thus, each sensor element 150 experiences a different displacement relative to its target element 160 as the exterior of the pipeline 1 undergoes changes in size or shape due to pressure variation within the pipeline 1. The complementary sensor element 150 and target element 160 are together operable to measure this displacement and thereby provide an indication of pressure variation within the pipeline 1, along pipeline 1.

[0071] The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.