Field of the Invention

[001 ] This invention relates to a clamp device.

[002] The clamp device of the invention can be used in various applications in which it is required to secure elongate members, including rigid and flexible members such as power and other electrical cables or tie-lines, along the outer surface of a conduit or pipe. In such use, a respective one of a plurality of the clamp devices is provided at each of a number of locations spaced along the conduit or pipe. The device of the invention has particular application in securing power and other cables, lines and conduits down along the outer surface of a riser pipe of a borehole, such as within a borehole casing. In large part the invention will be described herein with reference to that application, although it is to be noted that this can have broader application.

Background to the Invention

[003] Within the worldwide subterranean borehole drilling industry, operators bore into the earth to required depths to form boreholes of required diameters, to enable retrieval of suitable water supplies. The boreholes may be vertical, or inclined from vertical by a small angle, usually of not more than about 3 degrees. A casing pipe is driven into the resultant drilled borehole and serves to retain the integrity of earth formations or strata surrounding the borehole. The casing pipe houses a riser pipe comprising a string of end-to-end connected riser pipe sections that have an external diameter less than the internal diameter of the casing pipe. The casing pipe also provides a stable conduit for a number of components to be installed in the borehole in order to pump and control the flow of water from a below ground reserve. The components include items such as an integrated electric lift pump coupled to the lower end of an appropriate length of the riser pipe that has been fed down the borehole to a level selected as suitable for pumping water to the surface.

[004] When the pump has been installed and is operational, it sucks water in through a filtered port and pushes the water upwards through the riser pipe towards the ground surface. In order to power the pump, electrical service cable of appropriate size and capacity extends down the borehole, within an annular, or a part- or semi-annular, space defined between the casing pipe and the riser pipe. In addition, there commonly are other service cables and/or conduits running down through that annular space for various monitoring and information services.

[005] Operators secure the service cables and conduits to the outer surface of the riser pipe at regular intervals, such as at intervals of 1 .5 to 3 metres, along the length of the riser pipe from the surface to the pump. The securement is provided by application of tape or strapping wrap, such a Nitto or other electrical or insulating tape. The securement is achieved manually, by laboriously applying the wrap one roll at a time, as riser pipe sections are connected and lowered into the casing pipe during a programmed installation.

[006] In addition to the cost of the wrap material and the usual need to replace it when the riser pipe needs to be drawn up for servicing the pump or other device, application of the wrap material is very slow and labour intensive. Also, there is propensity for the wrap to wear, tear and degrade, with the risk of fragments of the wrap material entering the water system and causing a pump blockage or water contamination. Additionally, the wrap material does little to ameliorate, and can exacerbate, the effect of both operational bore pump motor torque and water-flow induced vibration and deflection of the riser pipe. As the wrap material binds service cables and conduits as firmly as possible to the riser pipe, the deflection and vibration of the riser pipe can cause abrasion of the cables and conduits and, in the case of damage to the electrical cable, this can lead to failure of the pump motor. In any event, the abrasion can result in an early requirement for the bore string and pump to be drawn up for servicing of the motor of the pump, adding considerably to maintenance costs, particularly as the wrapping material requires replacement each time the borehole is serviced with withdrawal of the riser pipe.

[007] The present invention seeks to overcome at least some of the problems of these arrangements. Summary of the Invention

[008] The present invention provides a clamp device for use in securing at least one elongate member, such as elongate flexible or rigid member, along the outer surface of a conduit or pipe, such as for example a borehole riser pipe. A respective such device can be provided at each of a number of locations spaced along the conduit or pipe at which securement is required. The clamp device has a body that has a split-ring or penannular form. The body defines a hollow core in the form of a through passage into which the conduit or pipe is receivable to enable the body to substantially encircle and firmly engage the conduit or pipe. The body has inner and outer peripheral surfaces with the inner peripheral surface defining the through passage. The body also has oppositely facing side surfaces each extending transversely with respect to the through passage, between the inner and outer peripheral surfaces. Adjacent to and opening to one of the inner peripheral surface and the outer peripheral surface, the body defines at least one pocket extending between and opening at each side surface, with the at least one pocket able to accommodate a rigid or flexible elongate member so that, with the body fitted so as to substantially encircle the conduit or pipe, the elongate member can be secured in relation to the conduit or pipe.

[009] The inner periphery of the core or through passage of the clamp device may be of essentially the same, typically circular, cross-section as the exterior of the conduit or pipe, and of substantially the same diameter. In the case of a body with a penannular form, a gap is defined between adjacent terminals or ends of the body as-formed and opens at each of the inner and outer peripheral surfaces and each of the oppositely facing side surfaces. Alternatively, for a body with a split-ring form, the split enables such a gap to be opened by the body being resiliently deformed to separate terminals or ends of the body at the split. Depending on the width of the gap, if any, in the clamp device as-formed, the diameter of the through passage may be substantially the same as, or up to about 5% greater or less than, the diameter of the conduit or pipe. Most conveniently, the gap of the penannular form of the body can be present in the body as-formed, rather than created later, although the split-ring body ring form more readily is produced by cutting a body that, as produced, is circumferentially continuous.

[0010] The body of the device may be and preferably is of unitary or integral form. In such case, the body may be of a plastics material, such as an engineering plastics material, or of a natural or synthetic rubber. While the body may be, and preferably is, relatively hard, such as substantially to resist compression, it may have sufficient resilience to enable it to be opened by relative movement between the terminals or ends of the body. To achieve such opening, the body may be elastically deformable, such as manually, from an as-formed shape such as by twisting or bending, with or without a degree of stretching, so that the body can be forced onto the conduit or pipe and enable the conduit or pipe to be received into the through passage of the body. Thus, the arrangement may be such that the body is elastically deformable such that the terminals or ends of the body are separated to an extent enabling the conduit or pipe to pass between the terminals or ends to receive or mount the clamp device onto the conduit or pipe with the conduit or pipe received into the passage. After the clamp device is so mounted, the body is allowed to resiliently recover and at least substantially fully resume its as-formed shape, with the body then able substantially to completely encircle the conduit or pipe for firmly holding the conduit or pipe within the passage.

[001 1 ] Most preferably, the clamp device is such that, after the body resiliently recovers to at least substantially encircle the conduit or pipe, the body firmly grips the conduit or pipe with a force sufficient to resist movement of the clamp device along the conduit or pipe under intended in use conditions. Thus, in the case of a clamp device provided on a riser pipe section of a riser pipe string within a borehole, the clamp device is able to retain its position on the vertically disposed riser pipe section during operation with the borehole, such as during start-up of a pump at the lower end of the string and during the pumping of water from the borehole. However, the clamp device may include a holding device or mechanism, such as detailed later herein, that enhances or increases the force with the body is able to grip the conduit or pipe and thereby resist movement along the conduit or pipe. [0012] The terminals or ends of the body of the clamp device may be relatively movable by the body being resiliently bent to separate the terminals or ends along an arcuate path extending substantially parallel to the oppositely facing side surfaces of the body. Alternatively the terminals or ends of the body may be relatively movable by the body being twisted to move the terminals in opposite directions substantially parallel to planes in which the terminals or ends are disposed. In a further alternative, a combination of such bending and twisting can be used to achieve relative movement between the terminals or ends of the body.

[0013] The or each pocket for receiving an elongate member, or each such pocket, may be accessible through a slot extending between the side surfaces and opening through the adjacent peripheral surface of the body. The arrangement may be such that the elongate member can be moved or forced laterally towards the peripheral surface, through the slot and into the pocket in which the elongate member is to be held so as to extend at about 90 degrees to the side surfaces of the body. The pocket or each pocket may have a shape similar to the cross-section of the elongate member it is to accommodate. Thus, the pocket may be substantially circular in form when viewed from either side surface in the case of a pocket to accommodate an elongate member of circular cross-section. The pocket preferably has a diameter such that it is able to neatly receive the intended elongate member and, for this purpose, the pocket may have a diameter that is the same as the diameter of the elongate member or up to about 5%, preferably up to about 3%, greater or less than the diameter of the elongate member.

[0014] The body may be sufficiently stiff that, after elastically recovering to its as- formed shape, it is able to grip a conduit or pipe sufficiently strongly that the body is retainable at a required position on the conduit or pipe. Alternatively, the body preferably is retainable at that position by the clamp device including a holding mechanism or device that, while able to be of a variety of forms, is able to increase the pressure with which the body of the clamp device is able to grip a conduit or pipe so as to be retainable at the required position. In one suitable arrangement, the holding mechanism or device comprises an elongate member, of a suitable metal or plastics material, able to extend or to be positioned to extend around the body and adjusted for applying a compressive force to the body. As such, the elongate member may be separable from, secured to, or incorporated in the body. In one form, the holding mechanism or device may be in the form of a hose clamp, preferably of a form having ends that are co-operable and adjustable, after the body and the elongate member have been applied around the conduit or pipe, for applying a compressive force to the body. Alternatively, the holding mechanism or device may be in the nature of a cable tie. In a further alternative, the holding mechanism or device comprises a woven webbing strap, such as used for motor vehicle seat belts and load restraints, that incorporates sufficient longitudinally extending strands of high tensile strength material as to be substantially inextensible, with the strap having ends able to be joined by a buckle that is adjustable for to cause the strap to apply a compressive force to the body. The strands may comprise an organic fibre, for example an aromatic polyamide such as Kevlar™. In each case, the holding mechanism or device may be incorporated in the body, adjacent to the outer peripheral surface or provided around that outer peripheral surface, such as in a continuous or discontinuous peripheral groove formed in that outer surface. Where the at least one pocket able to accommodate an elongate member is adjacent to the inner peripheral surface, the elongate member will be restrained from moving out of the pocket by the conduit or pipe on which the clamp device is installed. Where the at least one pocket is adjacent to the outer peripheral surface, the physical characteristics of the material of which the body is made may be such as to restrain or tend to restrain the elongate member from moving out of the pocket, although it is preferred that retention of the elongate member in the pocket is enhanced by a holding mechanism or device such as described above. Such holding mechanism or device also can be desirable where the at least one pocket is adjacent to the inner peripheral surface. [0016] The slot providing an opening of the at least one pocket to the inner or outer peripheral surface may be sufficiently wide as to allow the free passage of the elongate member. Where this is the case and the slot opens to the outer peripheral side, a holding mechanism such a described above is required to retain the elongate member in the pocket. However, whether the slot for the at least one pocket opens to the inner or outer peripheral surface, the slot preferably has a width enabling the elongate member to be received into the pocket as a force or snap fit through the slot. The width of the slot may be such that the elongate member is able to be retained in the pocket even though the elongate member has cross-sectional dimensions that are less than corresponding dimensions of the pocket. To enable a force or snap fit of the elongate member through the slot of the at least one pocket, the body along at least one side of the slot may define a lip that is sufficiently resiliently deformable to enable passage of the elongate member into the pocket.

[0017] The body when viewed towards either of the opposed side surfaces, may have a shape around the outer peripheral surface that serves to position the conduit or pipe in relation to surrounding structure. Thus, in the case of a clamp device for use in securing elongate members in relation to a conduit or pipe comprising a riser pipe of a borehole, the body may be such as to hold the riser pipe along a required line within a casing pipe. The arrangement may be such that the through passage of the body and the riser pipe are held so that both the through passage and the riser pipe is substantially co-axial with the casing pipe. For that purpose, the body may have a somewhat elliptical form as viewed towards either surfaces so as the have diametrically opposed lobes each locatable adjacent to a respective side of the inner surface of the casing pipe. Preferably the body has three or four substantially uniformly spaced lobes each locatable adjacent to the inner surface of the casing pipe. There may be even more lobes, although with increasing number they cease to be separate such that the body has a substantially circular form that is of a diameter that enables it to be positioned within the casing pipe.

[0018] The invention also provides a method for securing at least one elongate service line in relation to successive riser pipe sections in the course of forming and installing a riser pipe string in a borehole, wherein the method includes the steps of presenting in turn a first and then each of successive riser pipe sections, in an upright orientation, at an upper end of the borehole; and coupling the second, and each subsequent riser pipe section, end to end to the preceding riser pipe section to build up a length of riser pipe string and progressively lowering the riser pipe string down into the borehole with a corresponding length of the at least one elongate service line until the riser pipe of a required length of riser pipe string is formed and installed. The method further includes the step of securing the at least one service line to each riser pipe section, at one location or at each of at least two locations, along the length of each riser pipe section and prior to the riser pipe section entering the borehole, whereby the at least one service line is drawn into and down the borehole with the length of riser pipe string being built up; the at least one service line being so secured to each successive riser pipe section at the or each location by application of a respective clamp device that has:

(i) a split ring or penannular form of body portion of a material that is resilient to enable elastic deformation, but sufficiently hard as to substantially resist compression, and that defines a hollow core in the form of a through passage and has terminals or ends that are adjacent or define a gap,

(ii) inner and outer peripheral surfaces, with the inner peripheral surface defining the through bore,

(iii) oppositely facing side surfaces extending between the inner and outer peripheral surfaces; and

(iv) at least one pocket adjacent and opening to the inner or outer peripheral surface of the body and extending between and opening at each side surface.

The step of securing comprises elastically deforming each clamp in turn from an initial closed condition, by resilient bending or twisting the body to separate the terminals or ends to an open condition for the body enabling each terminal or end to pass to a respective side of the riser pipe section as the clamp device is presented to the riser pipe section, and then allowing to recover substantially to its original closed condition to capture and grip the riser pipe section in the through passage, with the at least one elongate member held in relation to the riser pipe section by being retained in the pocket.

[0019] In a first form of the method of the invention, the at least one pocket opens to the inner peripheral surface of the body, and the method further includes positioning the at least one elongate member in the at least one pocket before the body is allowed to recover to its original closed position. In a second form of the method, the at least one pocket opens to the outer peripheral surface of the body, and the method further includes positioning the at least one elongate member in the at least one pocket before the body is allowed to recover to its original position. In the second form of method, the at least one pocket opens to the outer peripheral surface of the body, and the method further includes positioning the at least one elongate member in the at least one pocket after the body is allowed to recover to its original position.

[0020] In the method, the body of the clamp device may be able to grip the riser pipe section at the location at which the clamp device is applied with a force sufficient to resist displacement of the clamp device along the riser pipe section under the normal conditions encountered in operation of the borehole. Alternatively, the method further includes tensioning an elongate holding device extending around the body of the clamp device thereby to increase the force by which the body grips the riser pipe section.

Brief Description of the Drawings

[0021 ] In order that the invention may be understood more readily, reference is made to the accompanying drawings, in which:

[0022] Figure 1 is an isometric view of a clamp device according to a first embodiment of the present invention;

[0023] Figure 2 is a plan view from one side of the device of Figure 1 , with the opposite side being substantially a mirror image of that shown in Figure 2; [0024] Figure 3 is an isometric view of a clamp device according to a second embodiment of the present invention;

[0025] Figure 4 is a plan view from one side of the device of Figure 3, with the other side being substantially a mirror image of that shown in Figure 3;

[0026] Figures 5 and 6 correspond to Figures 1 and 3, but show a respective modified form of the device of the first and second embodiment;

[0027] Figure 7 is an isometric view of a clamp device according to a third embodiment of the present invention;

[0028] Figure 8 is a plan view from one side of the device of Figure 7, with the other side being substantially a mirror image of that shown in Figure 7; and

[0029] Figure 9 is a perspective view of the device shown in Figures 7 and 8, but with the device shown in a condition enabling its installation in relation to a riser pipe section and elongate members associated with a riser pipe of which the riser pipe section is to form a part.

Detailed Description of the Drawings

[0030] Figures 1 and 2 show a first form of clamp device 10 according to the invention, intended for securing at least one elongate member in relation to a riser pipe of a borehole, or to another form of elongate conduit or pipe. The specific form adopted for device 10 enables up to four elongate members able to be so secured. A respective device 10 is provided at each of a number of locations along the length of the riser pipe, such as at intervals of 1 .5 to 8 metres, depending on the length of the riser pipe sections, or along such other form of conduit or pipe. One standard length for riser pipe sections is approximately 5 metres and, for sections of that length, a respective device 10 may for example be secured 1 .25 metres from each end of the riser pipe section such that, along a riser pipe being installed, successive clamps are spaced at about 2.5 metre intervals. However, this spacing does not allow for the slight overlap by which successive riser pipe sections are joined; the sections typically being of a quick-fit form, such as of a polycarbonate material. [0031 ] The device 10 is intended for a larger borehole, such as a borehole about 170 to 230 mm in diameter. The device 10 has a penannular body 12 that defines a hollow core or through passage 14. The body 12 has a discontinuous but substantially circular inner peripheral surface 16, an outer peripheral surface 18 and, extending between inner and outer surfaces 16 and 18, oppositely facing side surfaces 20 and 22. A narrow gap 24 is defined between adjacent terminals or ends of body 12 that result from the penannular form, with the gap 24 extending between the inner and outer surfaces 16 and 18 and opening to passage 14, or the gap 24 may be formed by slight separation of the terminals or ends.

[0032] In an in-use orientation for device 10 for securing at least a power cable (not shown) to a riser pipe (also not shown), the surfaces 20 and 22 are disposed substantially horizontally and so comprise a top surface 20 and a bottom surface 22. In that orientation, at least parts of outer peripheral surface 18 are adjacent to the inner surface of a casing pipe for a borehole. In Figure 2, the inner surface of the casing pipe is depicted in broken outline at 26. However, while the inner peripheral surface 16 is substantially circular, the outer peripheral surface 18 departs from a circular form at each of four substantially uniformly spaced locations, to define outwardly projecting lobes 28. The dimensions of body 12 across the outer extremities of the lobes 28 of each of two opposed pairs is slightly less than the inner diameter of casing pipe inner surface 26. As a consequence, device 10 is able to be received readily into and to move along the surface 26 of the casing pipe, but is able to substantially centralise the riser pipe within the casing pipe surface 26. By way of example, the device 10 may have a dimension of about 150 mm across the outer extremities of opposed lobes 28, making it suitable for use within a borehole casing pipe 26 having an internal diameter of about 170 to 200 mm.

[0033] Intermediate of successive lobes, parts of the outer peripheral surface 18 of body 12 are of arcuate form, with the arcuate parts having a common centre of curvature that is substantially co-incident with the centre of curvature of inner peripheral surface 20 and the centre or axis of passage 14. The arcuate parts of surface 18 may have a radius of about 60 to 85 mm, while the body 12 may have a dimension or thickness from top surface 20 to bottom surface 22 of from about 40 to 55 mm, such as about 45 mm. Around the respective junction between each of top and bottom surfaces 20 and 22 and outer peripheral surface 18, body 12 is chamfered to resist catching or binding of body 12 with the inner surface of the borehole casing pipe 26 during installation or removal of a riser pipe.

[0034] The body 12 defines a respective pocket 30 adjacent to the inner peripheral surface 16, in line with each lobe. Each of the pockets 30 extends between the top and bottom surfaces 20 and 22, and opens to passage 14 along a narrow slot 32 that extends between surfaces 20 and 22. The pockets 30 are of different sizes and distinguished as pockets 30a, 30b, 30c and 30d, so each is able to receive and accommodate an elongate member of a similarly sized, corresponding respective cross-section.

[0035] The device 10 is installed on a riser pipe (not shown) having a cross-section able to be accommodated, and neatly secured, in passage 14. Installation necessitates elastically deforming the shape of body 12 so as to open gap 24 sufficiently to enable the clamp device 10 to be presented towards the riser pipe so the riser pipe is received into passage 14. While body 12 is deformed but before it is installed onto the riser pipe, at least one elongate member (also not shown) to be accommodated in one of pockets 30 is able to pass through the respective slot 32 due to the slot 32 being able to open sufficiently by the body 12 resiliently deforming along the opposed edges of the slot 32. While still deformed but after the at least one elongate member has been accommodated in a pocket 30, the body 1 2 is moved so that the open gap 24 then is presented towards a riser pipe, and the body 12 then is moved, if necessary forced, towards the riser pipe until the latter is received into the passage 14 of body 12. When this has been achieved, the body is allowed to recover resiliently to its as-formed shape in which it firmly grips the riser pipe and securely locates the at least one elongate member, so that the elongate member is secured in relation to the riser pipe. [0036] The stiffness of the material of which body 12 is made, and the diameter of passage 14 relative to the diameter of the riser pipe, may be such that clamp device 10 is prevented from moving, under normal in-use conditions, from the position at which it is installed and the elongate member is secured as required. However it may be desirable to enhance the grip on the riser pipe and elongate member by provision of a holding mechanism or device, such as detailed earlier herein, or such as detailed below in relation to Figures 7 to 9. To facilitate this, body 12 is provided with a groove 34 that extends inwardly from the outer peripheral surface 18. A suitable form of holding mechanism or device, such as a strap mechanism or device, can be positioned in and around groove 34 and tightened to provide sufficient securement of body at a required location on the riser pipe.

[0037] If there is water in the casing pipe 26, the lowering and raising of a riser pipe string along which clamp devices 10 are mounted will be resisted by the need for water to be displaced readily around the body 12 of successive devices 10. However, despite a narrow spacing between lobes 28 and pipe 26, the resistance will be minimised due to the greater spacing between the pipe 26 and the arcuate part of the outer peripheral surface 18 of body 12, between successive lobes 28. This enables the lobes 28 to sufficiently close to the casing pipe 26 as to serve to retain each device 10 and, hence the riser pipe centrally within the casing pipe 26.

[0038] Figures 3 and 4 show a second form of clamp device 1 10 according to the present invention that also is suitable for securing at least one elongate member in relation to a riser pipe or to another form of elongate conduit or pipe. The detail of the device 1 10 will be understood from the description of the device 10 of Figures 1 and 2, and parts of device 1 10 corresponding to those of device 10 have the same reference numeral plus 100. Description of device 1 10 therefore is limited to features by which it differs from device 10.

[0039] The device 1 10 has a circular outer peripheral surface 1 18. Thus surface 1 18 and the groove 134 provided round surface 1 18 are substantially concentric with the discontinuous inner peripheral surface 1 16. As a consequence, device 1 10 does not exhibit outwardly projecting lobes corresponding to lobes 28 of device 10 and, apart from gap 124, the top and bottom surfaces are of circular, annular form.

[0040] The clamp device 1 10 is of a form suited for securing elongate service lines in a riser pipe within a relatively small diameter bore-hole casing pipe. Device 1 10 may, for example, have a diameter of about 100 mm, making it suitable for use within a casing pipe having an internal diameter of from about 120 to 140 mm. However, the spacing between devices 1 10 and a casing pipe needs to be sufficient to ensure a sufficiently low level of resistance to raising and lowering a riser pipe having elongate service lines secured by clamps 1 10 in a borehole containing water.

[0041 ] Each of the devices 10 and 1 10 has a relatively smooth inner peri pheral surface 16 and 1 16, respectively. This is well suited for use of the devices 10, 1 10 of preferred materials for the body 12, 1 12, 1 10 with riser pipe sections of some suitable materials. This is the case where the coefficient of friction between the respective materials for the riser pipe and the body 12, 122 is sufficient to prevent the devices 10,1 10, at least when held by a suitable holding device, from moving along the riser pipe section. However, for some combinations of materials for the bodies 12, 1 12 and the riser pie sections, it can be beneficial to use a modified form of the clamp devices 10, 1 10 as shown respectively by devices 210 and 310, shown respectively in Figures 5 and 6. For brevity, it is to be noted that each of devices 210 and 310 differs from the respective devices 10 and 1 10 only is that its inner surface 216 and 316 defines circumferential grooves 40 and ribs 42 that may result in a more favourable coefficient of friction between some combinations of materials for bodies 216 or 316 and for some riser pipe sections. Parts of device 210 of Figure 5 corresponding to parts of device 10 of Figures 1 and 2 have the same reference numeral, plus 200. Similarly, parts of device 310 of Figure 6 that correspond to parts of device 1 1 0 of Figures 3 and 4 have the same reference numerals, plus 200. [0042] Figures 7 to 9 show a third form of a clamp device 410 according to the invention that again is intended for securing at least one elongate member in relation to a riser pipe, or to another form of elongate conduit or pipe. Figures 7 and 8 show the device 410 in its as-formed penannular shape with a gap 424, or as slightly moved to give rise to the gap 424 after being formed with a split-ring shape. However, Figure 9 shows the device 410 after being resiliently bent, substantially parallel to the plane of Figure 8, in readiness for the device 410 to be presented to and mounted on a riser pipe section, by being allowed to resiliently recover to the as-formed shape, and to secure at least one elongate member in relation to the riser pipe section. In Figure 9 the outer periphery of a riser pipe section is shown at 44, while four elongate members 46 are shown in broken outline as laterally spaced disposed around, and as extending along, the pipe section 44. The elongate members 46 differ in diameter and are distinguished as members 46a, 46b, 46c and 46c.

[0043] In line with each of devices 10 and 1 10, clamp device 410 has a penannular body 412 of which terminals or ends define the gap 424, or the ends are able to be separated to provide such gap 424. The device 410 is intended for a larger borehole, such as a borehole about 170 to 230 mm in diameter, and the penannular body 412 defines a hollow core or through passage 414. The body 412 has an inner peripheral surface 416, an outer peripheral surface 418 and, extending between inner and outer surfaces 416 and 418, oppositely facing side surfaces 420 and 422. The narrow gap 424, whether defined between adjacent terminals or ends of body 412 that result from the penannular form or from opening the split-ring form, extends between the inner and outer surfaces 416 and 418 and opens to passage 414.

[0044] While discontinuous, the inner surface 416 of body 412 is substantially circular to enable the body 412 to conform to circumferentially spaced regions of the outer surface of the cylindrical riser pipe section depicted at 44. The discontinuous form of inner surface 416 results from the provision of four pockets 430 formed in body 412 and distinguished as pockets 430a, 430b, 430c and 430d. Each pocket 430 extends inwardly from the inner surface 416 and opening at each side faces 420 and 422. As with the pockets 30 and 130 of previously described clamp devices 10 and 1 10, the pockets 430 are of different sizes and substantially uniformly spaced around the axis of passage 414. However, these parameters can vary as permitted in corresponding variations in the diameters of elongate members and their relative angular spacing around the circumference of riser pipe section 44.

[0045] In contrast to the arrangements for devices 10 and 1 10, the outer peripheral surface 418 of device 410 is somewhat asymmetric as viewed in Figures 8 and 9. This is due to pockets 430a, 430b and 430d being of comparable sizes but each larger than pocket 430c, and to the body 412 having a similar thickness between each of the pockets 430 and the outer surface 418. Thus, each of pockets 430a, 430b and 430d has a centreline that is at substantially the same spacing from the centreline of passage 414 whereas pocket 430c has a centreline that is at a lesser spacing from the centreline of passage 414, and the major width of body 412 is across pockets 430b and 430d. The arrangement is such that, while body 412 has four lobes 428 distinguished as three larger lobes 428a, 428b and 428d and a smaller lobe 428c, the body 412 has a transverse dimension across the larger lobes 428b and 428d that is greater than the corresponding dimension across the larger lobe 428a and the smaller lobe 428c. As can be appreciated by the broken line depiction in Figure 8 of the inner surface of a casing pipe 426, the dimension of body 412 across larger lobes 428b and 428d substantially serve to centre device 410 within a borehole, as that dimension is corresponds to a substantial part of the diameter of the inner surface of casing pipe 426 and so limits the extent to which the body 412 can move in the casing pipe 426 laterally of a line between the pockets 430b and 430d.

[0046] Figure 9 shows the clamp device 410 as resiliently stretched to an open condition, from the closed, or substantially closed, position shown in Figures 7 and 8. In Figure 9, the device 410 is stretched in readiness for clamping engagement with the riser pipe section 44 and securement of elongate members 46 against the riser pipe section. In installing a riser pipe string within the casing pipe 426, a first riser pipe section 44, having a pump (not shown) installed at its lower end, is inserted down into the casing pipe, with a second and subsequent riser pipe sections lowered in an upright orientation and coupled at its lower end to the upper end of the preceding riser pipe section. As the riser pipe string is formed, it is lowered down the borehole so each newly added riser pipe section 44 enters in turn into the casing pipe. However, prior to each riser pipe section entering the borehole, at least one clamp device 410, but preferably each in turn of two longitudinally spaced devices 410, is presented in its open condition to the newly added riser pipe section and to the elongate members 46. The, or each, clamp device 410 then is allowed to recover resiliently substantially to its as-formed shape, so as substantially to encircle elongate members 46 and riser pipe 44. As the recovery occurs, each of elongate members 46a, 46b, 46c and 46d is received into the respective one of pockets 430a, 430b, 430c and 430d and the elongate members 430 are thereby secure adjacent or against the pipe section 44. An elongate holding device mechanism or device, depicted at 450 in Figure 8, then is applied around body 412, such as by being located in groove sections 434 in the outer peripheral surface 418 of body 412, and the ends of mechanism or device 450 are then engaged and adjusted to apply a compressive force retaining device 450 securely on the riser pipe section 44. To enable this mode of operation, the elongate members 430 pass downwardly from above the upper end of the casing pipe 426, such as from respective coils in the case of flexible members 430 from which they are drawn down as required as the riser pipe string lengthens. The body of each of devices 10, 1 10, 210, 310 and 410 may, for example, be produced by machining, from a suitable plastics or rubber material, or by casting or injection moulding of a suitable plastics or rubber material, such as by a process involving curing or vulcanisation. The material may be an engineering plastics material. The material preferably is such that each body is relatively stiff, so as to retain substantially its form once installed on a riser pipe, although each body needs to be sufficiently flexible in order to be elastically deformable to enable installation. The material preferably also has good abrasion resistance in order that the body is able to withstand possible wear due to movement along the casing pipe in repeated insertion in and removal from the casing pipe. The material may be a relatively hard rubber, such as of neoprene or styrene butadiene rubber, although the material may be a plastics material based, for example, on a polyolefin, polyurethane elastomer, PTFE or PPE. Most preferably, the material is a nitrile (butadiene acrylonitrile) rubber, such as a carboxylated nitrile rubber.