The present invention relates to improvements in or relating to pipe reinforcement.

Situations exist in which pipes need to be reinforced. For example, large underground pipes, such as utility pipes, may suffer local weakening due to aging or corrosion where local reinforcement becomes necessary as a means of repair. A rather different scenario is observed in explosions of natural gas pipelines where fast propagating cracks run for distances of several kilometers along the pipeline, if not arrested.

Previous proposals have applied reinforcing material around the pipe. This may be at the site of the damage or defect, or periodically along the pipe to arrest cracks which arise between reinforcement locations. In these proposals, the reinforcing material is applied manually. The earth is dug away around the pipe to allow access for workmen on both sides of the pipe, and underneath. In the case of a large underground pipe, the labour and time involved in adequately exposing the pipe can be considerable, creating cost and delay. Large mats of reinforcing material are typically used, to simplify the manual procedures involved.

Examples of the present invention provide apparatus comprising: a stationary structure having a mounting arrangement releasably operable to mount the stationary structure to the outside of a pipe; a moving structure which is movably carried, in use, on the stationary structure to be able to turn around a pipe on which the stationary structure is mounted; the moving structure comprising a reinforcement dispensing arrangement operable to dispense reinforcing material while turning around the pipe, to wrap the reinforcing material around the pipe.

The mounting arrangement may comprise at least one releasable clamp arrangement operable to clamp around the pipe to mount the stationary structure thereon. There may be a plurality of releasable clamp arrangements as aforesaid. There may be a plurality of releasable clamp arrangements axially spaced along the pipe, in use, the dispensing arrangement being located between two axially spaced clamp arrangements. There may be a plurality of releasable clamp arrangements axially spaced along the pipe, in use, and substantially rigidly connected by one or more connecting members. The, or at least one of the clamp arrangements may comprise a flexible member to engage the outer surface of the pipe, in use, and a tightening mechanism operable to tension the flexible member to grip the pipe. Alternatively, the, or at least one of the clamp arrangements may comprise a collar carrying blades of an iris arrangement to close around the pipe.

The dispensing arrangement may comprise a ring extending, in use, around the pipe and operable, in use, to turn around the pipe. There may be a drive arrangement operable to drive the dispensing arrangement around the pipe for dispensing the reinforcing material. There may be a variable slipping clutch arrangement operable to control rotation of the dispensing arrangement relative to the stationary structure to control tension in the dispensed reinforcing material. The slipping clutch arrangement may comprise cooperating friction surfaces and an adjustable clamping mechanism operable to press the friction surfaces together. The clutch arrangement may be lockable to drive the dispensing arrangement without slip, for loading reinforcing material onto the dispensing arrangement.

The apparatus may further comprise an axial drive arrangement operable to drive the dispensing arrangement axially relative to the stationary structure, to move axially, in use, relative to a pipe being wrapped. The axial drive arrangement may be operable to provide a rate of axial movement which is variable relative to the rate of turning around the pipe, to change the winding angle of the reinforcing material around the pipe. The axial drive arrangement may comprise a worm gear providing drive between the dispensing arrangement and the stationary structure.

The dispensing arrangement, in use, may dispense reinforcing material in the form of a filament, fibre, yarn or other elongate element.

(n another aspect, examples of the invention provide a method of wrapping a pipe in reinforcing material, in which: apparatus as defined above is mounted on the pipe; reinforcing material is wound on to the dispensing arrangement from a supply; and the dispensing arrangement is turned around the pipe to dispense the reinforcing material to wrap the pipe.

Examples of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of one example of apparatus according to the invention, with some components removed for clarity; Fig. 2 is a further perspective view of the apparatus of Fig. 1 , from a different angle; Fig. 3 illustrates a clamping arrangement of the apparatus, in isolation;

Fig. 4 is a perspective view of two clamping arrangements and part of the moving structure of the apparatus; Fig. 5 is a section at the line 5-5 in Fig. 1 ;

Fig. 6 illustrates the apparatus in use on a pipe.

Figs. 7 to 1 1 correspond generally with Figs. 1 to 4 and 6, showing a second example apparatus.

Overview

Turning particularly to Fig. 1 and Fig. 2, the accompanying drawings illustrate apparatus 10 comprising a stationary structure 12 and a moving structure 14. The stationary structure 12 has mounting arrangements indicated generally at 16, which are releasably operable to mount the stationary structure 12 to the outside of a pipe 18 (Fig. 6). The moving structure 14 is movably carried, in use, on the stationary structure 12, as will be described. This allows the moving structure 14 to turn around a pipe 18 on which the stationary structure 12 is mounted. The moving structure 14 comprises a reinforcement dispensing arrangement 20 operable to dispense reinforcing material 22 (Figs. 5 and 6) while turning around the pipe 18, to wrap the reinforcing material 22 around the pipe 18.

Stationary structure The stationary structure 12 has two mounting arrangements 16, in this example. In other examples, a single mounting structure 16 or additional mounting structures 16 could be provided. Each mounting structure 16 is in the form of circular collar provided by two collar parts 24 which meet at two fixing locations 26. The fixing locations 26 are approximately diametrically opposite. The fixing locations 26 provide suitable formations to allow the two collar parts 24 to be securely but releasably fixed together, to form the circular collar. This allows the collar parts 24 to be placed around a pipe 18 (Fig. 3) and then secured together at the locations 26, forming a collar around the pipe.

Figure 3 illustrates one of the mounting arrangements 16, in more detail. The two collar parts 24 have been brought together to form a complete circular collar. The fixing locations 26 also provide mounts for flexible straps 28. Each flexible strap 28 is secured at each end to an elongate threaded member 30 which is, in turn, threaded through a smooth bore provided by the fixing locations 26, and secured by a cooperating nut (now shown). The straps 28 are mounted opposite each other in the arrangements 16, so that the pipe 18 is embraced between them. The threaded members 30 allow the straps 28 to be tightened. That is, when the cooperating nuts are turned on the threaded members 30, tension in the straps 28 can be increased, causing the straps 28 to grip the pipe 18 more tightly, thereby securing the mounting arrangements 16 to the pipe 18, primarily by means of friction between the straps 28 and the pipe 18. This mounts the stationary structure 12 to the outside of the pipe 18.

The two mounting arrangements 16 are axially spaced along the pipe 8, as can be seen from Fig. 1 and other drawings. Several connecting members 32 are provided at positions around the circumference of the mounting arrangements 16. The connecting members 32 are in the form of elongate bars extending between mounting arms 34 on the mounting arrangements 16. This provides a substantially rigid connection between the two mounting arrangements 16. Additional cross-links may be provided between the connecting members 32, to further improve the rigidity. Moving structure

The moving structure 14 can now be described. For simplicity and clarity, attention is first drawn to Fig. 4, which shows only part of the moving structure 14 and part of the stationary structure 12.

The moving structure 14 includes two drive rings 36, associated with respective mounting arrangements 16. The drive rings 36 are concentric with the respective mounting arrangements 16 and all of these components will be concentric, in use, with the pipe 8. The drive rings 36 have a toothed inner edge 38 which engages several idler pinions 40. The idler pinions 40 are carried by short shafts 42 supported on the coilar parts 24. Accordingly, the idler pinions 40 maintain the concentric position of the driven rings 36, relative to the mounting arrangements 16. Further connecting members 44 extend between the driven rings 36 and are securely fixed thereto, so that the driven rings 36 will turn together as a cylindrical structure, substantially without twist. Cross-links may be provided between the connecting members 44 to provide increased rigidity. One of the mounting arrangements 16 includes a motor 46 driving a further pinion 48 engaging the toothed inner edge 38. This allows the corresponding driven rings 36 to be driven by the motor 46 to turn around the pipe 1 8 and also to cause the other driven rings 36 to turn in similar manner, by virtue of the connection through the connecting members 44. A gearbox (not shown), which may be fixed or variable, may be provided between the motor 46 and the pinion 48, in order to control the speed of rotation of the driven rings 36. Other arrangements may be provided for driving the driven rings 36. For example, the driving shaft for the pinion 48 can be extended to a bearing support beyond the other driven ring 36, and carry another pinion (not shown) to engage the other driven ring. This results in both driven rings 36 being driven from the same shaft, to avoid undue twist in the moving structure 14.

Returning to Fig. 1 and Fig. 2, additional features of the moving structure 14 can now be described. These additional features relate primarily to the dispensing arrangement 20. The connecting members 44 carry an outer ring 50 which is constrained to rotate with the connecting members 44 and with the driven rings 36. The connecting members 44 are received in unthreaded bores through the outer ring 50. Another connecting member 44a (Fig. 2) is a worm gear received in a cooperating sleeve 44b riding on the edge of the outer ring 50. Accordingly, rotation of the worm gear 44a causes the dispensing arrangement 20 to be driven axially relative to the stationary structure 12, with the unthreaded bores of the ring 50 sliding over the members 44. The worm gear 44a can be driven for rotation by a motor 51 mounted on one of the mounting arrangements 16. The outer ring 50 has a channel 52 around its outer circumference (Fig. 5). An inner ring 54 is housed within the channel 52. The inner ring 54 also has a channel 56 around its outer circumference. The inner ring 54 is free to slip around the channel 52, relative to the outer ring 50, except as follows. Arrangements are provided to create a variable slipping clutch arrangement 58 between the inner ring 54 and the outer ring 50. The clutch arrangement 58 comprises cooperating friction surfaces 60 and an adjustable clamping arrangement 62. The friction surfaces 60 may be formed of hard-wearing, high friction material, such as is typically found in automobile braking systems. Other materials could be used. One of the friction surfaces 60 is fixed to the outer face of the inner ring 54. The other friction surface 60 is mounted on an inner face of the channel 52 by means of a threaded member 64. The threaded member 64 can be tightened to press the corresponding friction surface 60 against the other friction surface 60. Thus, by pressing the friction surfaces 60 together, the degree of friction between the outer ring 50 and the inner ring 54 can be adjusted. The significance of this will be described below.

At another position, a bolt 66 is provided, to act between the outer ring 50 and the inner ring 54. When engaged, the bolt 66 prevents the inner ring 54 slipping relative to the outer ring 50, so that both will turn together when the outer ring 50 is driven as described above.

Various guide rollers 68 are provided to guide the path of reinforcing material, as will be described. The driven rings 36, the outer ring 50 and the inner ring 54 are all formed in multiple parts, such as two semicircular parts each, so that they can be assembled around a pipe 18, and removed after use.

Use of the apparatus

The manner of use of the apparatus 10 described above can now be described in more detail, particularly with reference to Fig. 6. Some components of the mounting arrangements 16 are removed from Fig. 6, in the interests of clarity only. They would be present in use and reference should be made to the other drawings in conjunction with Fig. 6, in order to understand their contribution to the operation of the apparatus 10.

The pipe 18 may be prepared, if required, by a conventional preparation step. The disassembled stationary structure 12, consisting of the mounting arrangements 16 and connecting members 32, is then reassembled around the pipe 18 to mount the stationary structure 12 on the pipe 18. The threaded members 30 and straps 28 (not shown in Fig. 6) are then tightened around the pipe 18, to further secure the stationary structure 12.

The moving structure 1 is then assembled by assembling the driven rings 16, outer ring 50 and inner ring 54 around the pipe 18 and around the stationary structure 12, until the moving structure 14 is fully assembled and carried by the stationary structure to be able to turn around the pipe 18. In particular, the driven rings 36 are engaged with the idler pinions 40 and further pinion 48, as the various components are assembled.

At this stage, the channel 56 in the inner ring 54 is empty. The next stage of the method is to load reinforcing material 22 into the channel 56. The reinforcing material is in the form of a filament, fibre, yarn or other elongate member, which may be pre-impregnated with resin or other setting or adhesive systems. The reinforcing material is loaded into the channel 56 as follows. First, the bolt 66 is engaged. This locks the inner ring 54 to turn with the outer ring 50. The motor 46 is then operated to turn the whole of the moving structure 14, including the outer ring 50 and thereby to turn the inner ring 54, allowing the reinforcing material to be wound on to the channel 56 of the inner ring 54, from a bobbin (not shown) or other supply. When the required length of reinforcing material has been wound on to the inner ring 54, the bolt 66 can be released.

At this stage, the rings 50, 54 should be at one end of the stationary structure 12, adjacent one of the mounting arrangements 16. If they are not, the worm gear 44a is used to move the rings 50, 54 to this position.

The free end of the reinforcing material is then taken from the ring 54 to the outer surface of the pipe 18, by threading it around the guide rollers 68. The free end of the reinforcing material may be secured temporarily to the pipe 18, until winding begins. The slipping clutch 58 is engaged by clamping the friction surfaces 62 to create a required degree of friction. Winding can then begin by operating the motor 46 to turn the outer ring 50. This also causes the inner ring 54 to turn. The inner ring 54 turns relative to the outer ring 50, this relative movement being driven by the tension in the reinforcing material, and resisted by the friction in the slipping clutch 58. Accordingly, appropriate setting of the slipping clutch 58 will cause the inner ring 54 to turn more slowly than the outer ring 50, dispensing reinforcing material as it does so, and applying a pre-tension to the reinforcing material, by virtue of the friction and slippage arising within the clutch 58. The slippage within the clutch 58 also takes into account the difference in the diameters of the pipe 18 and the channel 56.

While the inner ring 54 is turning around the pipe, dispensing the reinforcing material, the worm gear 44a is also used to move the outer ring 50, and hence the inner ring 54, axially along the stationary structure 12. This causes the reinforcing material dispensed by the inner ring 54 to be wrapped around the pipe 18 in a helical wound fashion. The speed with which the motor 51 turns the worm gear 44a determines the rate of axial movement of the inner ring 54, relative to the rate of turning around the pipe 18. Thus, the relative speeds of the motors 46, 51 is used to control the winding angle of the reinforcing material around the pipe 18.

Accordingly, control of the slipping clutch 58 and of the motors 46, 51 allows the reinforcing material to be wound around the pipe 18 with control over the winding tension and the winding angle. Winding tension contributes directly to the degree of hoop reinforcement provided for the pipe 18. The winding angle contributes directly to the degree of axial reinforcement achieved. For these reasons, the performance achieved is expected to be greatly improved over that achieved by manual systems. Furthermore, the results are expected to be more reliable and reproducible, being achieved by the functioning of the apparatus, rather than by manual techniques.

Overview (2 ^nd example) Turning particularly to Fig. 7 and Fig. 8, the remaining drawings illustrate another example apparatus 10a. Many features correspond closely with features of the first example described above, and are therefore given the same reference numerals.

The apparatus 10a comprises a stationary structure 12 and a moving structure 14. The stationary structure 12 has mounting arrangements indicated generally at 16a, which are releasably operable to mount the stationary structure 12 to the outside of a pipe 18 (Fig. 11). The moving structure 14 is movably carried, in use, on the stationary structure 12. This allows the moving structure 14 to turn around a pipe 18 on which the stationary structure 12 is mounted. The moving structure 14 comprises a reinforcement dispensing arrangement 20 operable to dispense reinforcing material 22 (Fig. 1 1 and 6) while turning around the pipe 18, to wrap the reinforcing material 22 around the pipe 18.

Stationary structure (2 ^nd example)

The stationary structure 12 has two mounting arrangements 16a, in this example. In other examples, a single mounting structure 16a or additional mounting structures 16a could be provided. Each mounting structure 16a is in the form of circular collar provided by two collar parts 24 which meet at two fixing locations 26. The fixing locations 26 are approximately diametrically opposite. The fixing locations 26 provide suitable formations to allow the two collar parts 24 to be securely but releasably fixed together, to form the circular collar. In this example, one fixing location 26 serves as a hinge, and the other fixing location 26 serves as a latch, so that the collar parts can be closed or opened in the manner of jaws. This allows the collar parts 24 to be placed around a pipe 18 and then secured together at the locations 26, forming a collar around the pipe. Figs. 9a to 9c illustrate one of the mounting arrangements 16a, in more detail. In Fig. 9a, the two collar parts 24 are open, for fitting around a pipe. In Fig. 9b, the two collar parts 24 have been brought together to form a complete circular collar. The collar parts 24 also provide mounts for pivot mounting of blades 24a forming an iris, Control hoops within the collar can be turned around the collar to swing the iris blades 24a in or out, either opening the collar (Fig. 9b) or closing the collar around the pipe 18 (Fig. 9c). This causes the iris blades 24a to grip the pipe 18, thereby securing the mounting arrangements 16a to the pipe 18, primarily by means of friction between the blades 24a and the pipe 18. This mounts the stationary structure 12 to the outside of the pipe 18.

The two mounting arrangements 16a are axially spaced along the pipe 18, as can be seen from Fig. 7 and other drawings. Several connecting members 32 are provided at positions around the circumference of the mounting arrangements 1 6a. The connecting members 32 are in the form of elongate bars extending between the mounting arrangements 16a. This provides a substantially rigid connection between the two mounting arrangements 16a.

Additional cross-links may be provided between the connecting members 32, to further improve the rigidity.

Moving structure (2 ^nd example)

The moving structure 14 can now be described. For simplicity and clarity, attention is first drawn to Fig. 10, which shows only part of the moving structure 14 and part of the stationary structure 12.

The moving structure 14 includes two drive rings 36, associated with respective mounting arrangements 16a. The drive rings 36 are concentric with the respective mounting arrangements 16a and all of these components will be concentric, in use, with the pipe 18. The drive rings 36 have a toothed outer edge 38 which engages several idler pinions 40. The idler pinions 40 are carried by short shafts 42 supported on the collar parts 24. Accordingly, the idler pinions 40 maintain the concentric position of the driven rings 36, relative to the mounting arrangements 16a.

Further connecting members 44 extend between the driven rings 36 and are securely fixed thereto, so that the driven rings 36 will turn together as a cylindrical structure, substantially without twist. Cross-links may be provided between the connecting members 44 to provide increased rigidity. One of the mounting arrangements 16a includes a motor 46 driving a further pinion 48 engaging the toothed outer edge 38. This allows the corresponding driven rings 36 to be driven by the motor 46 to turn around the pipe 18 and also to cause the other driven rings 36 to turn in similar manner, by virtue of the connection through the connecting members 44. A gearbox 47, which may be fixed or variable, may be provided between the motor 46 and the pinion 48, in order to control the speed of rotation of the driven rings 36. Other arrangements may be provided for driving the driven rings 36. For example, the driving shaft for the pinion 48 can be extended to a bearing support beyond the other driven ring 36, and carry another pinion (not shown) to engage the other driven ring. This results in both driven rings 36 being driven from the same shaft, to avoid undue twist in the moving structure 14.

Returning to Fig. 7 and Fig. 8, additional features of the moving structure 14 can now be described. These additional features relate primarily to the dispensing arrangement 20.

The connecting members 44 carry an outer ring 50 which is constrained to rotate with the connecting members 44 and with the driven rings 36. The connecting members 44 are received in unthreaded bores through the outer ring 50. Another connecting member 44a (Fig. 7) is a worm gear received in a cooperating member 44b riding on the edge of the outer ring 50. Accordingly, rotation of the worm gear 44a causes the dispensing arrangement 20 to be driven axially relative to the stationary structure 12, with the unthreaded bores of the ring 50 sliding over the members 44. The worm gear 44a can be driven for rotation by a motor 51 mounted on one of the mounting arrangements 16a, and further guided by guides 44c.

The outer ring 50 has a channel 52 around its outer circumference in the manner of Fig. 5. An inner ring 54 is housed within the channel 52. The inner ring 54 also has a channel 56 around its outer circumference. The inner ring 54 is free to slip around the channel 52, relative to the outer ring 50, except as follows.

Arrangements are provided to create a variable slipping clutch arrangement to control the inner ring 54. In this example, the clutch arrangement is incorporated as a clamp within the cooperating member 44b and able to grip more or less tightly on a flange 70 to hold back the rotation of the inner ring 54, relative to the stationary structure 12.

At another position, a bolt 66 is provided, to act between the outer ring 50 and the inner ring 54. When engaged, the bolt 66 prevents the inner ring 54 slipping relative to the outer ring 50, so that both will turn together when the outer ring 50 is driven as described above.

Various guide rollers 68 are provided to guide the path of reinforcing material, as will be described. The dispensing arrangement 20 can therefore function as described above.

The driven rings 36, the outer ring 50 and the inner ring 54 are all formed in multiple parts, such as two semicircular parts each, so that they can be assembled around a pipe 18, and removed after use.

Use of the apparatus (2 ^nd example) The manner of use of the apparatus 10a follows the manner of use of the first example, as described above, particularly with reference to Fig. 6. Concluding comments

It is further expected that the process described above may be achieved more quickly than conventional techniques, particularly because the apparatus described can be used in an automated manner. In addition, its compact form reduces the amount of earth removal required to expose the pipe adequately for repair in the manner described.

It is envisaged that the techniques can be used to provide reinforcement around undamaged pipes, to reduce the risk associated with subsequent damage. In particular, the pipe can be reinforced at intervals to provide crack arrestors to limit propagation of cracks in the event of subsequent damage, such as by explosion.

Many alternative arrangements could be devised for the various components described above. Additional components and systems could be incorporated, such as power supplies, control and centre technology, data-logging etc for controlling and monitoring the correct operation of the apparatus.

It is envisaged that the apparatus described above could be used over a range of different pipe sizes, but different machine sizes could be constructed in order to extend the range of pipe sizes which can be addressed by the methods described.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.