Apparatus and methods for mounting sensors on a structure

Abstract

A sensor mounting apparatus 10 for mounting acoustic sensors on a curved structure comprises a plurality sensor mounting elements or brackets 12 movably connected to one another by mechanical articulated joint(s) 16. Each element mounts an acoustic sensor on the structure. The sensors may be ultrasonic transducers, preferably with acoustic probes which function through the transmission and detection of Guided Elastic Waves (GEW) or Guided Ultrasonic Waves (GUW). The sensor mounting elements may comprises a sensor receptacle(s) 18. The articulated joints may comprise a pivot joint, a hinge joint, a ball joint and / or a universal joint. Preferably linking members 14, together with the articulated joint(s), connect the sensor mounting elements to one another. Each linking member may be rigid and / or is H-shaped, U-shaped and / or I-shaped or straight or curved in profile. First and second ends of the apparatus connect to one another and may be tensioned around the curved structure such that sensors are pressed against the outer surface(s) of the curved structure, preferably with a tension wire. Expansion element(s) facilitate any change in length of the apparatus. A method and installation of mounting acoustic sensors is also claimed.

Description

The present invention relates to apparatus and methods for mounting sensors on curved structures. The invention has particular application to the mounting of acoustic sensors on large-scale curved structures, primarily vessels, containing fluid. In addition, the invention has particular application to the mounting of sensors on structures used in industrial applications which transport, store or process fluids and mixed phase media, including the hydrocarbon industry, for example in the monitoring of levels of media contained within oil and gas separators. Background to the invention The installation of sensors on structures in industrial settings can be problematic; particularly where the structures themselves are large-scale. Mounting sensors across multiple points on a large-scale structure (such as a vessel) typically necessitates access equipment, such as scaffolding, to enable personnel to reach the required locations. Accessibility for this task can also be an issue where the layout of industrial facilities is crowded or complex. In some circumstances, scaffolding and other access equipment may have to be moved and re-erected several times throughout a sensor mounting operation. These factors, amongst others, can increase the cost and complexity of sensor mounting operations. They can also significantly increase the time taken to undertake sensor mounting operations and the risks involved. As a knock-on effect, specialist personnel may be required. If, for any reason, it is necessary to change locations of the sensors in the future, similarly disruptive operations are likely to be required. If a sensor mounting operation has been particularly complex and time-consuming, there is an increased likelihood that one or more of the sensors will have been installed poorly (for example, in a less than optimum position or orientation), and / or that the suite of sensors will fail to have uniform installation properties. This can impact the accuracy of the readings produced from the suite of sensors. The above factors are particularly relevant to methods of inspection which utilise multiple sensors. For example, certain methods of acoustic-based inspection used for the inspection of media contained within structures - specifically Guided Elastic Waves (GEW) and Guided Ultrasonic Waves (GUW) - rely on the positioning of multiple ultrasonic transducers around a vessel; a task which can be time-consuming and laborious, particularly for large-scale structures where access constraints exist. Various sensor mounting apparatus are known. For example: CN108776178A describes a magnet clamping device for mounting electromagnetic ultrasonic transducers to a pipeline, the device being made up of two symmetrical semicircular pieces connected at their respective ends by a hinge and a buckle; US2021 / 129452 relates to a weld seam testing chain for rotatably mounting an ultrasonic testing device on a welded plastic pipeline for testing weld seams; and WO 2022 / 263173 describes mounting test heads to cylindrical pressure vessels using tension straps. However, none of these sensor mounting approaches address the unique complexities of mounting multiple sensors on large-scale vessels, whilst optimising sensor installation properties to produce uniform and reliable outputs. Summary of the invention There is generally a need for a method and apparatus which addresses one or more of the problems identified above. It is amongst the aims and objects of the invention to provide apparatus and methods for mounting sensors on a large-scale structure. In particular, one aim of an aspect of the invention is to provide apparatus and methods for mounting sensors on a large-scale structure, such as a vessel, in a reliable, timely and safe manner. A particular aim of an aspect of the invention is to provide apparatus and methods for mounting ultrasonic transducers on a large-scale vessel in a reliable, timely and safe manner. According to a first aspect of the invention, there is provided a sensor mounting apparatus for mounting a plurality of acoustic sensors on a curved structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements; wherein each of the plurality of sensor mounting elements are movably connected to one another by one or more mechanical articulated joints; and wherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure. Preferably, the sensor mounting apparatus is for mounting acoustic sensors in the form of ultrasonic transducers on the curved structure. In embodiments of the invention, the ultrasonic transducers comprise acoustic probes which function through the transmission and detection of Guided Elastic Waves (GEW), or Guided Ultrasonic Waves (GUW). The curved structure may be a substantially cylindrical vessel. The curved structure may be a large vessel. In this specification, large may be defined as having an outer diameter of 3 meters or greater. More specifically, the large vessel may have an outer diameter in the range of 4 meters to 12 meters. More specifically yet, the large vessel may have an outer diameter in the range of 5 meters to 9 meters. There is no upper or lower limit to the size of the curved vessel to which the sensor mounting apparatus can be installed, but there are particular benefits when the sensor mounting apparatus is applied to large vessels with an outer diameter of 3 or more meters. Benefits include simplified installation procedures requiring fewer steps than prior art procedures and less specialist equipment, access equipment and personnel. The curved structure may be a vessel arranged with an axis in a horizontal orientation. The axis may be a longitudinal axis. The curved structure may be a large vessel arranged with a longitudinal axis in a horizontal orientation, herein referred to throughout this specification as a “large horizontal vessel”. Preferably, the curved structure is a substantially cylindrical, large horizontal vessel. Alternatively, the curved structure may be a spherical vessel. The plurality of sensor mounting elements may comprise a plurality of sensor brackets. One or more sensor mounting elements of the plurality of sensor mounting elements may comprise at least one sensor receptacle for receiving an acoustic sensor therein. Alternatively, or in addition, one or more of the plurality of sensor mounting elements may comprise an integrated acoustic sensor. The plurality of sensor mounting elements are movably connected to one another. In other words, the plurality of sensor mounting elements are connected to one another in such a way that each of the plurality of sensor mounting elements is movable with respect to adjacent sensor mounting elements. There may be a rotational degree of freedom between at least two adjacent sensor mounting elements of the plurality of sensor mounting elements. Each of the plurality of sensor mounting elements may be directly connected to one another by one or more mechanical articulated joints. Alternatively, each of the plurality of sensor mounting elements may be indirectly connected to one another by one or more mechanical articulated joints and one or more intermediate elements, objects and / or parts. Some of the plurality of sensor mounting elements may be directly connected to one another by one or more mechanical articulated joints, whilst some may be indirectly connected to one another by one or more mechanical articulated joints. The one or more mechanical articulated joints may comprise (not exclusively): a pivot joint, a hinge joint, a ball joint and / or a universal joint. The apparatus may comprise a variety of mechanical articulated joints. The sensor mounting apparatus can generally be described as, an assembly of (not exclusively) sensor mounting elements arranged in series, and / or as a chain of repeated sensor mounting elements. The apparatus may comprise a plurality of linking members. Each of the plurality of linking members, together with the one or more mechanical articulated joints, may connect each, or some, sensor mounting elements of the plurality of sensor mounting elements to one another in such a way that the plurality of sensor mounting elements are movably connected to one another. In other words, the plurality of linking members, together with the one or more mechanical articulated joints, may connect each, or some, of the plurality of sensor mounting elements to one another in such a way that each of the plurality of sensor mounting elements is movable with respect to adjacent sensor mounting elements. One or more linking members of the plurality of linking members may be positioned between adjacent sensor mounting elements. In other words, the plurality of sensor mounting elements may be connected to one another indirectly, via (at least) one or more linking members. In some configurations, two or more senor mounting elements may also be directly connected to one another, without the presence of a linking member inbetween. The sensor mounting apparatus may generally be described as, non-exclusively, an assembly of sensor mounting elements and linking members arranged in series, and / or as a chain of sensor mounting elements and linking members. Each linking member of the plurality of linking members may be rigid. One or more of the plurality of linking members may each be formed as a single piece. Such linking members may take the form of a bar or rod, for example. Alternatively, or in addition, one or more of the plurality of linking members may comprise an assembly of parts. Where one or more of the plurality of linking members comprises an assembly of parts, the parts forming the assembly may be rigidly connected to one another. One or more of the plurality of linking members may be pre-fabricated components. One or more of the plurality of linking members may have a H-shaped, U-shaped and / or l-shaped profile, or a combination of such profiles and / or any other suitable profile. One or more of the plurality of linking members may be a straight linking member, which may have straight longitudinal edges. One or more of the plurality of linking members may be a curved linking member. A curved linking member may have a curved portion configured to substantially correspond to the curvature of an outer surface of the curved structure. In other words, a curved linking member may have a curved portion having a radius of curvature substantially the same as a radius of curvature of the outer surface of the curved structure. The plurality of linking members may be a plurality of curved linking members. The curved portion of a curved linking member may be a curved surface and / or edge. The curved portion of a curved linking member may be configured to face the outer surface of the curved structure, in use. The curved portion of a curved linking member may be configured to contact the outer surface of the curved structure, in use. One or more of the plurality of sensor mounting elements may be a curved sensor mounting element. A curved sensor mounting element may have a curved portion, configured to substantially correspond to the curvature of an outer surface of the curved structure. In other words, a curved sensor mounting element may have a curved portion having a radius of curvature substantially the same as a radius of curvature of the outer surface of the curved structure. The plurality of sensor mounting elements may be a plurality of curved sensor mounting elements. The curved portion of a curved sensor mounting element may be a curved surface and / or edge. The curved portion of a curved sensor mounting element may be configured to face the outer surface of the curved structure, in use. The curved portion of a curved sensor mounting element may be configured to contact the outer surface of the curved structure, in use. The sensor mounting apparatus may have first and second ends. The first and second ends of the sensor mounting apparatus may be configured to be connected to one another. In this case, the sensor mounting apparatus may be described as forming a closed or continuous chain or loop comprising (not exclusively) the plurality of sensor mounting elements. Where first and second ends of the sensor mounting apparatus are connected to one another, the sensor mounting apparatus may be described as forming a closed or continuous chain or loop comprising the plurality of sensor mounting elements and the plurality of linking members. The sensor mounting apparatus may comprise a connector or connecting arrangement for connecting its first and second ends. The sensor mounting apparatus may be tensionable; that is, it may be operable to be tensioned around the curved structure, in use, such that the sensor mounting elements and / or sensors located in the sensor mounting elements are pressed against the outer surface or surfaces of the curved structure. The connector or connecting arrangement for connecting the first and second ends of the sensor mounting apparats may be configured to apply tension to the apparatus, in use. The sensor mounting apparatus may comprise tension wire. The sensor mounting apparatus may comprise tension strap. The sensor mounting apparatus may comprise one or more wire transition elements which facilitate a connection between any component or element of the sensor mounting apparatus and a section of wire. The sensor mounting apparatus may comprise one or more expansion elements. The expansion elements may be configured to facilitate a change in length of the sensor mounting apparatus which may compensate for changes in the dimensions of the structure (for example, due to thermal expansion and contraction). The provision of expansion elements is beneficial because they help to ensure that the sensor mounting elements of the assembly, or sensors, remain pressed into close contact with the outer surface of the structure despite thermal contraction and / or expansion of the structure. The expansion elements may comprise one or more springs. The one or more springs may comprise a tension spring. Alternatively, or in addition, the one or more springs may comprise a compression spring. The expansion elements may comprise one or more flexible tension elements. The expansion elements may comprise one or more elements which are slidable relative to one another. The sensor mounting apparatus may comprise additional functional components. Alternatively, or in addition, the sensor mounting apparatus may be configured to receive, support and / or connect to one or more additional functional components, which may be introduced following its construction and / or after it has been secured to the curved structure. One or more of the plurality of linking members may be configured to receive, support and / or connect to additional functional components. Additional functional components may include one or more protective structures configured to protect the sensors and / or cables, connectors and components associated with the sensors. The one or more protective structures may be cage like structures. The one or more protective structures may be connected to one or more of the plurality of linking members. The one or more protective structures may be connected to one or more of the plurality of linking members by rivets. The one or more protective structures may be connected to one or more of the plurality of linking members by screws. According to a second aspect of the invention, there is provided a method of mounting a plurality of acoustic sensors on a curved structure, the method comprising: (a) providing a sensor mounting apparatus comprising a plurality of sensor mounting elements, wherein each of the plurality of sensor mounting elements are movably connected to one another by one or more mechanical articulated joints; (b) locating the sensor mounting apparatus at a starting position on or beside an outer surface of the curved structure; (c) directing first and second ends of the sensor mounting apparatus in opposite directions around the outer surface or surfaces of the curved structure, starting from the starting position; (d) connecting the first and second ends of the sensor mounting apparatus to one another such that the sensor mounting apparatus forms a closed loop which surrounds the outer surface or surfaces of the curved structure; and (e) applying tension to the sensor mounting apparatus, thereby pressing the sensor mounting elements, and / or sensors therein, into contact with the outer surface or surfaces of the curved structure. The sensor mounting apparatus may be a sensor mounting apparatus according to the first aspect of the invention. The method may comprise a step of installing sensors into each of the plurality of sensor mounting elements. This step may be performed between steps (a) and (b). The step of installing sensors may comprise installing sensors into sensor receptacles provided in each of the plurality of sensor mounting elements. The step of installing sensors may comprise screwing and / or pressing sensors into sensor receptables provided in each of the plurality of sensor mounting elements. The starting position may be a position which is generally above the curved structure. The curved structure may be a substantially cylindrical vessel. The curved structure may be a large vessel. In this specification, large may be defined as having an outer diameter of 3 meters or greater. More specifically, the large vessel may have an outer diameter in the range of 4 meters to 12 meters. More specifically yet, the large vessel may have an outer diameter in the range of 5 meters to 9 meters. There is no upper or lower limit to the size of the curved vessel to which the sensor mounting apparatus can be installed, but there are particular benefits when the sensor mounting apparatus is applied to large vessels with an outer diameter of 3 or more meters. Benefits include simplified installation procedures requiring fewer steps than prior art procedures and less specialist equipment, access equipment and personnel. The curved structure may be a vessel arranged with an axis in a horizontal orientation. This may be a longitudinal axis. The curved structure may be a large vessel arranged with its axis in a horizontal orientation, herein referred to throughout this specification as a “large horizontal vessel”. Preferably, the curved structure is a substantially cylindrical, large horizontal vessel. Alternatively, the curved structure may be a spherical vessel. The method may comprise providing a means for connecting the first and second ends of the apparatus to one another. The sensor mounting apparatus may comprise a means for connecting its first and second ends. Embodiments of the second aspect of the invention may include one or more features of the first aspect of the invention or its embodiments, or vice versa. According to a third aspect of the invention, there is provided a sensor installation comprising: a sensor mounting apparatus comprising: a plurality of sensor mounting elements; wherein each of sensor mounting elements are movably connected to one another by one or more mechanical articulated joints; and wherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure; a curved structure; and a plurality of acoustic sensors located in or on the plurality of sensor mounting elements of the sensor mounting apparatus; wherein the sensor mounting apparatus is installed on the curved structure such that it forms a closed loop which surrounds an outer surface or surfaces of the curved structure. Embodiments of the third aspect of the invention may include one or more features of the first or second aspects of the invention or their embodiments, or vice versa. According to a fourth aspect of the invention, there is provided a method of assembling a sensor mounting apparatus, the method comprising: providing a plurality of sensor mounting elements configured to mount an acoustic sensor on a structure; and movably connecting the plurality of sensor mounting elements to one another, in series, by providing one or more mechanical articulated joints between each of the plurality of sensor mounting elements. The method may comprise installing sensors into each of the plurality of sensor mounting elements. The step of installing sensors may comprise installing sensors into sensor receptacles provided in each of the plurality of sensor mounting elements. The step of installing sensors may comprise screwing and / or pressing sensors into the sensor receptables provided in each of the plurality of sensor mounting elements. The method may comprise comprising providing a plurality of linking members. The method may comprise connecting the plurality of sensor mounting elements to one another using the linking members, in such a way that the plurality of sensor mounting elements. One or more linking members may be positioned between respective sensor mounting elements. In some configurations, senor mounting elements may be directly connected to one another, without the presence of a linking member in-between. The assembled sensor mounting apparatus may comprise a plurality of curved elements, each curved element of the plurality of curved elements having a curved portion. The curved portion may be configured to substantially correspond to the curvature of an outer surface of a curved structure on to which the sensor mounting apparatus is intended to be mounted. The plurality of curved elements may comprise one or more of the sensor mounting elements. Alternatively, or in addition, the plurality of curved elements may comprise one or more of the linking members. Embodiments of the fourth aspect of the invention may include one or more features of the first to third aspects of the invention or their embodiments, or vice versa. According to a fifth aspect of the invention, there is provided a sensor mounting apparatus for mounting a plurality of acoustic sensors on a curved structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements movably connected to one another; wherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure; and wherein the apparatus comprises a plurality of curved elements, each curved element of the plurality of curved elements having a curved portion configured to substantially correspond to the curvature of an outer surface of the curved structure. Embodiments of the fifth aspect of the invention may include one or more features of the first to fourth aspects of the invention or their embodiments, or vice versa. According to a sixth aspect of the invention, there is provided a sensor mounting apparatus for mounting a plurality of acoustic sensors on a curved structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements; and a plurality of linking members connecting the plurality of sensor mounting elements to one another in such a way that each of the plurality of sensor mounting elements is movable with respect to adjacent sensor mounting elements; wherein each of the plurality of linking members has a curved portion configured to substantially correspond to the curvature an outer surface of the curved structure. Preferably, the sensor mounting apparatus is for mounting sensors in the form of ultrasonic transducers on the curved structure. In such an embodiment, the sensor mounting elements are suitable for holding sensors in the form of ultrasonic transducers. Embodiments of the sixth aspect of the invention may include one or more features of the first to fifth aspects of the invention or their embodiments, or vice versa. According to a seventh aspect of the invention, there is provided a sensor mounting apparatus for mounting a plurality of acoustic sensors on a structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements connected to one another in a continuous, substantially linear arrangement; wherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure; and wherein the sensor mounting apparatus is configured to be secured to the structure by one or more securing elements arranged substantially perpendicularly to a longitudinal direction of the sensor mounting apparatus. The sensor mounting apparatus may be suitable for mounting a plurality of acoustic sensors on a surface or an edge of the structure. The structure may be a cylindrical vessel and the sensor mounting apparatus may be configured to mount a plurality of acoustic sensors on an outer surface of the cylindrical vessel, in a longitudinal direction of the cylindrical vessel. The structure may be a square or rectangular vessel and the sensor mounting apparatus may be configured to mount a plurality of acoustic sensors on an outer surface or edge of the square or rectangular vessel. Each of the plurality of sensor mounting elements may be directly connected to one another. Alternatively, or in addition, each, or some, of the plurality of sensor mounting elements may be connected to one another indirectly (for example, via one or more intermediate elements, objects and / or parts). The sensor mounting apparatus may comprise a plurality of linking members. The plurality of linking members may connect each, or some, sensor mounting elements of the plurality of sensor mounting elements to one another. The sensor mounting apparatus may be secured to the structure at one or more points along its length. The sensor mounting apparatus may be secured to the structure using one or more tension straps. In such an embodiment, the one or more tension straps may be arranged substantially perpendicularly to a longitudinal direction of the sensor mounting apparatus. The sensor mounting apparatus may comprise additional functional components. Alternatively, or in addition, the sensor mounting apparatus may be configured to receive, support and / or connect to one or more additional functional components after its construction and / or after it has been secured to the curved structure. One or more of the plurality of linking member may be configured to receive, support and / or connect to additional functional components. Additional functional components may include one or more protective structures configured to protect the sensors and / or cables, connectors and components associated with the sensors. The one or more protective structures may be cage like structures. The one or more protective structures may be connected to one or more of the plurality of linking members. The one or more protective structures may be connected to one or more of the plurality of linking members by rivets. The one or more protective structures may be connected to one or more of the plurality of linking members by screws. Embodiments of the seventh aspect of the invention may include one or more features of the first to sixth aspects of the invention or their embodiments, or vice versa. According to a eighth aspect of the invention, there is provided a sensor mounting apparatus for mounting a plurality of acoustic sensors on a structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements connected to one another in a continuous, substantially linear arrangement; wherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure; and wherein each of the plurality of sensor mounting elements is rigidly connected to one another. Embodiments of the eighth aspect of the invention may include one or more features of the first to seventh aspects of the invention or their embodiments, or vice versa. According to a ninth aspect of the invention, there is provided a method of mounting a plurality of acoustic sensors on a surface or an edge of a structure, the method comprising: (a) providing a sensor mounting apparatus comprising a plurality of sensor mounting elements connected to one another in a continuous, substantially linear arrangement; (b) locating the sensor mounting apparatus on a surface or an edge of the structure; (c) securing the sensor mounting apparatus to the structure at one or more points along the length of the sensor mounting apparatus. The method may comprise a step of installing sensors into each of the plurality of sensor mounting elements. This step may be performed between steps (a) and (b). The sensor mounting apparatus may be secured to the structure using one or more tension straps. In such an embodiment, the one or more tension straps may be arranged substantially perpendicularly to a longitudinal direction of the sensor mounting apparatus. Embodiments of the ninth aspect of the invention may include one or more features of the first to eighth aspects of the invention or their embodiments, or vice versa. Brief description of the drawings There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which: Figure 1A is a simplified, schematic representation of a sensor mounting apparatus according to an embodiment of the invention; Figure 1B is a detailed, perspective view of a section of the sensor mounting apparatus of Figure 1A; Figure 2 is a simplified schematic representation of a sensor mounting apparatus according to an alternative embodiment of the invention; Figures 3A to 3C are simplified schematic representations of a method of installing a sensor mounting apparatus according to an embodiment of the invention; Figure 4 is a detailed, perspective view of a section of a sensor mounting apparatus according to an embodiment of the invention; Figure 5 is a schematic representation of a sensor mounting apparatus according to an alternative embodiment of the invention; and Figure 6 is a schematic representation of a sensor mounting apparatus according to an alternative embodiment of the invention. Detailed description of preferred embodiments Referring firstly to Figure 1A there is shown, generally at 10, a simplified, schematic representation of a sensor mounting apparatus according to an embodiment of the invention. The sensor mounting apparatus 10 is shown as being installed around a horizontally oriented, large, cylindrical vessel 11 indicated by the dotted line. For simplicity, the sensors themselves are not shown in this representation. The sensor mounting apparatus 10 comprises multiple sensor mounting elements (brackets 12) and curved linking members 14. The brackets 12 and linking members 14 are connected to one another by joints 16 and the curved linking members 14 are connected to one another by joints 17 comprising pivot pins. Together, the arrangement of brackets 12 and linking members 14 forms an articulated, chain-like formation in which each of the brackets 12 can rotate relative to neighbouring brackets about the pivot pins of the joints 17. Each sensor mounting bracket 12 has a receptacle 18 into which a sensor can be installed. The sensor receptacle 18 extends through the sensor mounting bracket 12 to facilitate the mounting of a sensor in contact with the vessel. The bracket 12 can be configured to mount sensors in various ways. In one such example, the receptacle may comprise an internal screw thread designed to mate with an external screw thread on the sensor or sensor housing. Other sensor installation methods known in the art may be employed for this purpose. The brackets 12 are arranged to allow the sensors (not shown) to contact the outermost surface of the vessel, in use. However, depending on the exact configuration of the brackets 12, they may or may not be configured to also contact the vessel. In the described embodiment, the linking members 14 are formed from rigid bars which have a rectangular cross-section and curved longitudinal edges. The radius of curvature of the bars is substantially the same as, or close to, the radius of curvature of the outer surface of the vessel. At either end of the chain-like arrangement of sensor mounting brackets 12 and linking members 14 a wire transition member 20 comprising a wire transition piece 21 is provided. Each wire transition member 20 is connected at one end to a curved linking member 14 and, at the other, the wire transition piece 21 is connected to a section of tension wire 22. The sections of tension wire 22 are connected to each other at their free ends by a connector 24 capable of placing and holding the apparatus 10 in tension such that the apparatus 10 forms a closed loop or chain around the vessel 11. A tension lock could be used for this purpose. As mentioned above, in its fully installed state the sensor mounting apparatus 10 is designed to be placed in tension around the surface of the vessel 11. This is advantageous because tensioning the apparatus 10 results in improved contact between the sensors and the outer surface of the vessel 11; the tension provided effectively causes the brackets 12 to press the sensors on to the vessel. This is an important effect which improves the accuracy and reliability of the sensor readings. Another beneficial effect results from the use of the curved linking members 14. When the apparatus is tensioned, the complimentary curved inner and outer surfaces of the linking members 14 and the vessel 11, respectively, allows the apparatus 10 and thus the brackets 12 and sensors (not shown) to get as close to the vessel as possible. The rigidity of the curved linking members 14, interspersed between the brackets 12, helps to impart a rigidity to the entire apparatus 10 when it is locked or fastened into its closed state which produces, or reinforces, the force pressing the sensors into close contact with the surface of the vessel 11. The features of the curved linking members 14 and the tensioning of the apparatus 10 around the vessel 14 therefore produce synergistic advantageous results. The invention is has particular application in the use of acoustic sensors - specifically, those used to determine properties of the media contained with a structure - as these sensors benefit from being pressed into close, uniform contact with the wall of a structure and provide clearer and more reliable readings as a result. Figure 1B is a perspective view of the apparatus 10 showing the section circled in Figure 1A in more detail. With reference to Figure 1B, it can be seen that the sensor bracket 12 comprises a sensor receptacle 18 with an internal screw thread. The sensor (not shown) to be mounted on the vessel 11 will comprise a mating external thread, allowing it to be securely fitted in the mounting apparatus. In this particular embodiment of the invention, the curved linking members, (shown generally at 14) are prefabricated components made up of several parts 14a, 14b and 114c. Each curved linking member 14 is pre-assembled with the sensor brackets prior to the assembly of the sensor mounting apparatus. The curved linking members 14 are rigidly connected to the bracket 12 by fixed joints 16. In the embodiment shown, one part 14c of the curved linking member 14 is connected to the others 14a and 14b by a pivot pin 17, to provide for articulation between the linking member 14 and the wire transition member 20. In alternative embodiments, this connection may not be articulated. In the embodiment shown, a flexible expansion element 24 is provided between the linking member 14 and the wire member 20. The expansion element can take any form, but in the embodiment shown the flexible expansion element 24 is incorporated into the linking member 14 and transition member 20 and comprises a bolt 24a, a compressible spring 24b and a shoulder 24c created, in this case, by the head of the bolt 24. The compressible spring 24b is located around the shaft of the bolt 24a, between the shoulder 24c of the expansion element and part of the wire transition member 20. The bolt, which at one end is screwed into a threaded bore (not shown) of part 14c of the linking member 14, is slidable with respect to the wire transition member such that the flexible expansion element 24 is able to compensate for thermal expansion and contraction of the vessel 11, whilst maintaining a close contact fit between the mounting apparatus and the vessel 11. The spring 24b is compressed upon thermal expansion of the vessel 11 and, when the vessel 11 contracts, returns the apparatus 10 back to its starting state. It will be appreciated that, whilst the embodiment of the invention shown and described with reference to Figures 1A and 1B comprises mechanical articulated joints between adjacent, interconnected linking members 14 (pivot pins 17), in alternative embodiments of the invention the mechanical articulated joints may be located elsewhere in some, or all, cases. For example, some or all of the joints 16 which connect the linking members 14 to the sensor brackets 12 may be mechanical articulated joints, such as pivot pins, and some or all of the joints between linking members 14 (if interconnected linking members are present) could be rigid joints facilitated by a screw, for example. It will also be appreciated that, although the embodiment of the invention shown and described with reference to Figures 1A and 1B comprises separate sensor mounting elements 12 and curved linking members 14, this may not always be the case. For example, in alternative embodiments of the invention the sensor mounting elements may themselves be curved and linking members may be omitted. An example of such an arrangement is shown in Figure 2, where it can be seen that the sensor mounting apparatus, shown generally at 110, comprises multiple, curved sensor mounting elements 112 connected by pivoting joints 117. Referring now to Figures 3A to 3C, there is shown, schematically, a method of installing a sensor mounting apparatus according to an embodiment of the invention. Before installing the apparatus on a vessel, the apparatus is pre-assembled off-site to increase the speed and efficiency of the on-site installation process. This process includes installing sensors into the sensor brackets. The installation process begins by positioning the sensor mounting apparatus 210 on top of a horizontally oriented, cylindrical vessel, as can be seen in Figure 3A. At this stage, the apparatus 210 is folded, by virtue of its articulation, about its connection points. This reduces the overall size of the apparatus and to make it easier to handle. The next step - shown in Figure 3B - is to direct each end of the apparatus 210 down, around opposite sides of the vessel 211. This can be done from the top access point and does not require any additional side access. Finally, with access from beneath, the free ends of the sensor mounting apparatus 210 are connected to one another and the apparatus 210 is tensioned around the vessel 211. The installation process requires access to the top and the bottom of the vessel only. Side access is, on the whole, not required which is particularly advantageous in space constrained locations. The mounting apparatus allows for several sensors to be reliably mounted on a vessel in a single operation. This reduces the time taken to carry out sensor mounting, and also reduces the equipment and personnel required. The features and configuration of the apparatus, discussed in more detail with reference to Figure 1A, ensure uniform installation properties across the sensors using the installation technique described. The mounting apparatus and installation method has particular application to large-scale vessels where, ordinarily, mounting sensors around the circumference of a vessel is an arduous, time-consuming process which requires individual access at each sensor mounting location. This likely requires a large amount of scaffolding, or other access equipment, which may have to be reconfigured several times throughout the mounting process. Not only is the installation process streamlined by the provision of the sensor mounting apparatus, but also the results which the sensor mounting apparatus yields in terms of sensor mounting quality are improved. The sensor mounting apparatus 210 is able to uniformly bring each of the sensors which it holds into close and reliable contact with the vessel in a few simple steps, meaning that the sensor readings are of consistent quality across the suite of sensors. Figure 4 is a perspective view of a sensor mounting apparatus according to an alternative embodiment of the invention. The apparatus, generally shown at 310, is similar to the apparatus 10 and will generally be understood from Figures 1A,1B and their accompanying description. Like features are given like reference numerals incremented by 300. The linking members 314 of the sensor mounting apparatus 310 differ from those 14 of the apparatus 10 in that they have a H-shaped profile provided with threaded apertures 328. The linking members 314 are designed to support additional components, such as a protective structure 326. In the embodiment shown, the protective structure 326 is a U-shaped channel formed from perforated metal sheets with a detachable lid (not shown), although it will be appreciated a protective structure may take any other appropriate form. The protective structure is configured to enclose cables (not shown) and / or connectors between sensors installed in the sensor mounting brackets 312. The structures 326 also help to ensure that the sensors and their associated components cannot be disconnected or removed during operation, accidentally or otherwise. The protective structures 326 are connected to the linking members 314 by screws (not shown), which are screwed into apertures 328. The linking members, (or protective structures) could alternatively be provided with rivets or any other convenient fastening means for securing additional components. Referring now to Figure 5 there is shown a sensor mounting apparatus 410 according to an alternative embodiment of the invention. The apparatus 410 is similar to the apparatus 10 and will generally be understood from Figures 1A,1B and their accompanying description, with like features are given like reference numerals incremented by 400. In this embodiment of the invention, the linking members 414 of the sensor mounting apparatus 410 differ from those 14 of the apparatus 10 in that they are not curved. Instead, the linking members 414 have straight longitudinal edges. An alternative sensor mounting apparatus is shown, generally at 510, in Figure 6. Like the sensor mounting apparatuses described in the foregoing description, the sensor mounting apparatus 510 comprises sensor mounting brackets 512 and linking members 514. However, in this embodiment, the brackets 512 and linking members 514 are rigidly connected to one another in a straight line. The mounting apparatus 510 is installed upon a vertically oriented cylindrical vessel 511 for mounting a plurality of acoustic sensors on an outer surface of the vessel in a longitudinal direction of the vessel. Tension straps 530 are strapped around the circumference of the vessel 511, over the mounting apparatus 510, to hold the apparatus 510 in place and to ensure that the sensors are in good contact with an outer surface of the vessel. The apparatus 510 may conceivably be secured to the vessel in alternative ways. In an aspect of the invention, the invention provides a sensor mounting apparatus for mounting a plurality of acoustic sensors on a curved structure. The apparatus comprises a plurality of sensor mounting elements movably connected to one another by one or more mechanical articulated joints. Each sensor mounting element of the plurality of sensor mounting elements are configured to mount an acoustic sensor on the structure. Various modifications to the above-described embodiments may be made within the scope of the invention, and the invention extends to combinations of features other than those expressly claimed herein. For example, the embodiments described above have been described as having rigid connections between the sensor brackets and the curved linking members and connections providing articulation between adjacent linking members; however, it will be appreciated that this may not always be the case. The connections between these components may not allow for articulation, in some cases, only some of the connections may provide articulation. In an alternative embodiment, a number of sensor mounting elements may be rigidly connected to one another in addition to a number of sensor mounting elements being movably connected to one another by one or more mechanical articulate joints. It will also be appreciated that any number of sensor brackets and linking members may be provided in a sensor mounting apparatus. For example, where the foregoing description describes the provision of two linking members between each sensor mounting bracket, it will appreciated that only one linking member may be provided and that the articulation may be provided elsewhere, between different components (such as between the brackets and the linking members). The brackets and linking member components could be configured to extend around the entire vessel, or over only some of it, in use. Multiple chain-like arrangements of brackets and curved linking members can be provided in a single apparatus, connected by wire sections (or similar). Various configurations of the sensor mounting apparatus can be envisioned within the scope of the invention and the apparatus may be provided with more, or less, features and components to best suit its application and desired results. For example, the configuration may be designed to locate sensors at optimum positions around the circumference of a vessel. Although not illustrated, in embodiments of the invention, it is possible to alter the position of the sensor brackets and curved linking members within the apparatus. For example, this can be achieved in one embodiment by providing one or more adjustable length components within the apparatus. The adjustable component(s) could be the curved linking members themselves, or could take the form of adjustable length wire sections provided between some or all of the brackets and the linking members.

Claims

1. A sensor mounting apparatus for mounting a plurality of acoustic sensors on a curved structure, the sensor mounting apparatus comprising: a plurality of sensor mounting elements;wherein each of the plurality of sensor mounting elements are movably connected to one another by one or more mechanical articulated joints; andwherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure.

2. The sensor mounting apparatus according to claim 1, wherein the sensor mounting apparatus is for mounting acoustic sensors in the form of ultrasonic transducers on the curved structure.

3. The sensor mounting apparatus according to claim 2, wherein the ultrasonic transducers comprise acoustic probes which function through the transmission and detection of Guided Elastic Waves (GEW) or Guided Ultrasonic Waves (GUW).

4. The sensor mounting apparatus according to any preceding claim, wherein the curved structure has an outer diameter of 3 meters or greater.

5. The sensor mounting apparatus according to any preceding claim, wherein one or more sensor mounting elements of the plurality of sensor mounting elements comprises at least one sensor receptacle for receiving an acoustic sensor therein.

6. The sensor mounting apparatus according to any preceding claim, wherein there is a rotational degree of freedom between at least two adjacent sensor mounting elements of the plurality of sensor mounting elements.

7. The sensor mounting apparatus according to any preceding claim, wherein the one or more mechanical articulated joints comprise (not exclusively): a pivot joint, a hinge joint, a ball joint and / or a universal joint.

8. The sensor mounting apparatus according to any preceding claim, further comprising a plurality of linking members, wherein one or more of the plurality of linkingmembers, together with the one or more mechanical articulated joints, connect each, or some, sensor mounting elements of the plurality of sensor mounting elements to one another.

9. The sensor mounting apparatus according to claim 8, wherein each linking member of the plurality of linking members is rigid.

10. The sensor mounting apparatus according to any of claims 8 to 10, wherein one or more of the plurality of linking members is a pre-fabricated component.

11. The sensor mounting apparatus according to any of claims 8 to 10, wherein one or more of the plurality of linking members has a H-shaped, U-shaped and / or l-shaped profile.

12. The sensor mounting apparatus according to any of claims 8 to 11, wherein one or more of the plurality of linking members is a curved linking member.

13. The sensor mounting apparatus according to claim 12, wherein the curved linking member has a curved surface and / or edge configured to substantially correspond to the curvature of an outer surface of the curved structure.

14. The sensor mounting apparatus according to any of claims 8 to 11, wherein one or more of the plurality of linking members is a straight linking member having straight longitudinal edges.

15. The sensor mounting apparatus according to any preceding claim, wherein one or more of the plurality of sensor mounting elements is a curved sensor mounting element having a curved surface and / or edge configured to substantially correspond to the curvature of an outer surface of the curved structure.

16. The sensor mounting apparatus according to any preceding claim, wherein the apparatus comprises first and second ends configured to be connected to one another.

17. The sensor mounting apparatus according to claim 16, further comprising a connector or connecting arrangement for connecting its first and second ends.

18. The sensor mounting apparatus according to any preceding claim, wherein the sensor mounting apparatus is operable to be tensioned around the curved structure such that sensors located in the plurality of sensor mounting elements are pressed against the outer surface or surfaces of the curved structure.

19. The sensor mounting apparatus according to any preceding claim, further comprising tension wire.

20. The sensor mounting apparatus according to any preceding claim, further comprising one or more expansion elements configured to facilitate a change in length of the sensor mounting apparatus.

21. A method of mounting a plurality of acoustic sensors on a curved structure, the method comprising:providing a sensor mounting apparatus comprising a plurality of sensor mounting elements, wherein each of the plurality of sensor mounting elements is movably connected to one another by one or more mechanical articulated joints;locating the sensor mounting apparatus at a starting position on or beside an outer surface or surfaces of the curved structure;directing first and second ends of the sensor mounting apparatus in opposite directions around the outer surface or surfaces of the curved structure, starting from the starting position;connecting the first and second ends of the sensor mounting apparatus to one another such that the sensor mounting apparatus forms a closed loop which surrounds the outer surface or surfaces of the curved structure; andapplying tension to the sensor mounting apparatus, thereby pressing the sensor mounting elements, and / or sensors therein, into contact with the outer surface or surfaces of the curved structure.

22. The method according to claim 21, further comprising a step of installing sensors into each of the plurality of sensor mounting elements.

23. The method according to claim 21 or claim 22, wherein the starting position is a position which is generally above the curved structure.

24. The method according to any of claims 21 to 23, wherein the curved structure has an outer diameter of 3 meters or greater.

25. A sensor installation comprising:- a sensor mounting apparatus comprising:a plurality of sensor mounting elements;wherein of the plurality of sensor mounting elements are movably connected to one another by one or more mechanical articulated joints; andwherein each sensor mounting element of the plurality of sensor mounting elements is configured to mount an acoustic sensor on the structure;- a curved structure; and- a plurality of acoustic sensors located in or on the plurality of sensor mounting elements of the sensor mounting apparatus;wherein the sensor mounting apparatus is installed on the curved structure such that it forms a closed loop which surrounds an outer surface or surfaces of the curved structure.27

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