The present invention relates to pipe cleaning apparatus and more particularly to a pipe cleaning apparatus for passage along a pipe so as to clean debris or residue from the inside of the pipe.

Such a pipe cleaning apparatus is often referred to as a pig.

Conventional cleaning apparatus of this kind typically takes the form of a body arranged to fit within the pipe to be cleaned such that bristles or other cleaning formations depending outwardly from the body contact the inner surface of the pipe. The frictional contact between the cleaning formations and the inside surface of the pipe cause cleaning or scouring of the pipe during passage of the body along the pipe in use. However problems arise when a pipe to be cleaned follows a path having one or more curves or bends. The contact between the body of the cleaning apparatus and the pipe can be non-uniform about a bend. This can impact on the cleaning of the pipe and can cause deposits to build up in the vicinity of a bend. Furthermore, the body of the pipe cleaning apparatus cannot pass about bends which exceed a certain curvature and the pipe cleaning apparatus can become stuck part way along a pipe.

The retrieval of a pig which has become lodged part-way along a pipe can be problematic and costly to the pipe operator. In addition, the blockage caused by a lodged pig prevents passage of material along a pipe and can cause costly downtime of a pipeline. For certain applications, such as, for example, oil and gas pipelines, this cost alone is of considerable concern.

It has been proposed in the past to simply provide a cleaning apparatus having a body of reduced diameter but with longer bristles so as to maintain contact with the inner surface of the pipe. A smaller body can follow a more tortuous path than a wider body which offers little clearance with the inner pipe diameter.

However it has been found that such designs often fail to provide the requisite cleaning action since the resistance of the bristles is insufficient to adequately scour the pipe surface. That is to say that relatively short and stiff bristles have been found to provide improved cleaning for a number of industrial applications. It is an aim of the present invention to provide a pipe cleaning apparatus which provides adequate cleaning whilst allowing passage about bends or curves in a pipe. According to the present invention, there is provided a pipe cleaning apparatus arranged for passage along a pipe during use, the apparatus comprising: a first body portion having a retaining formation for holding a cleaning member such that the cleaning member depends radially outwardly from said first body portion for contact with an inner wall of a pipe during use; a second body portion spaced from said first body portion; and a spring member connected between said first and second body portions.

The present invention is advantageous in that the first and/or second body members may be formed such that they have only a small clearance from the inner pipe wall to be cleaned. The spring member may allow for flexing between the first and second body members in order to allow the apparatus to pass about bends or corners in the pipe to be cleaned without jamming and without detriment to the possible cleaning action of the apparatus.

The second body portion may comprise one or more retaining formations for holding a plurality of bristles such that said bristles depend radially outwardly from said second body portion. The first and/or second body portions may comprise a plurality of opposing members, between which the bristles may be trapped. The first and/or second body portions may comprise opposing plate members, which may be bolted together in use so as to trap the bristles therebetween.

The first and/or second body portions may have a circumferential edge arranged to be locatable within the diameter of a pipe to be cleaned such that the bristles extend between said circumferential edge and said inner surface of the pipe during use. The bristles may be provided by way of an annular support member or ring having bristles mounted therein. The bristles may be arranged circumferentially about said annular support member and may extend radially outwardly therefrom. This type of construction may allow bristles to be supplied and easily replaced in a modular fashion. The apparatus may comprise a plurality of spring members disposed and/or connected between said first and second body portions. The or each spring member may be twisted or coiled. A first spring member may be biased in an opposing direction to a second spring member. This may help provide structural rigidity to the apparatus whilst allowing a degree of controlled flex. The first and second spring members may be biased in opposing torsional directions.

The spring member may comprise for example leaf or coil springs. Coil springs have been found to be particularly beneficial in that a first coil spring may be mounted between the first and second body portions such that it is coiled in a first direction, whilst a second coil spring may be mounted between the first and second body portions such that it is coiled in a second or opposing direction.

In one embodiment, a plurality of spring members may be spaced about a central axis of the apparatus. A central spring member may be provided and a plurality of further spring members may be disposed about said central spring member.

The or each spring member may have a connector formation at either or both ends thereof. In one embodiment the connector formation takes the form of a hub member about which the first or second body portion may be located. The first and second body portions may comprise one or more annular members. The connector formation may comprise a flange or plate-like member from which a hub portion depends. The first or second body portions may be connected to the flange or rim by fasteners such as for example bolts or the like.

Modular cleaning members may be provided which are removeable and replaceable within the apparatus. Such cleaning members may be provided in the form of annular supports having bristles mounted therein or else pads or blocks of support material in which a two-dimensional array of bristles may be located.

Working embodiments of the present invention are described below in further detail with reference to the accompanying drawings, of which:

Figure 1 shows a three-dimensional view of an apparatus according to a first embodiment of the present invention from the front; Figure 2 shows a three-dimensional view of the apparatus of figure 1 from the rear; Figure 3 shows a three-dimensional exploded view of the apparatus of figure 1 ;

Figure 4 shows an exploded side view of the apparatus of figure 1 ; Figure 5 shows a cross-sectional view of the apparatus of figure 1 when located in a pipe for use;

Figure 6 shows a three-dimensional view of an apparatus according to a second embodiment of the present invention;

Figure 7 a three-dimensional view of the cleaning members shown in figure 6; and,

Figure 8 shows a three-dimensional view of an apparatus according to a third embodiment of the present invention.

The present invention provides an apparatus suitable for cleaning pipes or any other kind of conduit for which a pig may conventionally be used.

Turning to figures 1 and 2, there is shown a pipe cleaning apparatus 10 having a first end 12 and a second end 14, which may be referred to hereinafter as respective front and rear ends.

The apparatus generally comprises a first body portion 16 located towards the front end 12 of the apparatus and a second body portion 18 located towards the rear end14 of the apparatus. A plurality of coil springs 20 are connected in the force path between the first 16 and second 18 body portions.

The coil springs 20 in this embodiment comprise a central spring 22 oriented about a longitudinal axis of the apparatus such that the central spring 22 is substantially coaxial therewith. In addition, a number of further coil springs 24 are spaced circumferentially about the axis or central spring 22. In an alternative embodiment, either the central spring or else the further springs may be omitted.

A total of four further springs 24 are disposed about the central spring. Each end of the springs 20 and 22 is attached to a respective connection formation 26 or 28 which connects the springs to the first 16 and second 18 body portions. Opposing pairs of springs of the set of springs 24 are wound or coiled in opposing directions. Thus two of the four springs 24 may be coiled or wound in an anticlockwise orientation, whilst the other two springs 24 may be coiled or wound in a clockwise direction. The opposing bias of the springs in this regard has been found to preserve the required alignment of the body portions and to adequately resist deformation of the pig 10 for passage along a pipeline.

Springs biased in opposing directions may be disposed about the axis of the pig in an alternating manner. Alternatively, springs of the same bias may be located in one region, such as on one half, of the pig, whilst springs of the opposing bias may be located in another region, such as on the other half.

Turning now to figures 3 and 4, further details of the body portions and connection formations are shown. In figures 3 and 4 the first body portion 16 has been exploded to show further details thereof as well as the construction of the corresponding connection formation 26. It will be appreciated that the second body portion 18 and corresponding connection formation 28 is of matching construction and will not be additionally described for conciseness. All features described with respect to the first body portion may also be attributed to the second body portion.

The first body portion 16 comprises a first body member 30 and a second body member 32, which opposes the first body member 30 once assembled. The first body member 30 takes the form of an annular plate-like structure such as a disk 34 which has a peripheral rim formation 36. The peripheral rim 36 extends rearwardly of the disk 34 and is outwardly angled so as to form a skirt about the disk.

The second body member 32 also takes the form of an annular plate-like structure such as a disk and is spaced from the first body member once assembled by spacer members 38, 40 and intermediate member 42.

Each of the first and second body members, the spacer members and the intermediate member 42 have a central aperture for location about a hub 46 which protrudes from the connection formation 26 and the springs 20. The hub 46 may comprise a generally cylindrical protrusion for mounting of the first body portion 16 including its individual components on the apparatus. The central aperture of those individual components may be of size and shape to closely surround the hub 46. Retaining means in the form of screws or bolts 44 are provided to hold the components of the first body portion together. Correspondingly shaped apertures may be provided in each of the first and second body members, the connection formation 26, the spacer members and the intermediate member 42 for passage of the retaining members therethrough so as to bolt those components together. A series of nuts 48 may be provided to retain the bolts 44 in a secured condition.

Once assembled as shown in figures 1 and 2, the individual components of the first body portion are held on the hub 46 in a tightly abutting relationship. A locking member 50 is also provided to be located at the front most end of the first body portion to further secure the first and second body members, the spacer members and the intermediate member 42 on the hub 46. The locking member 50 comprises an end plate having an aperture for location about hub 46 and an annular locking formation 52 disposed about the aperture. As can be seen in figure 4, the hub 46 has a corresponding locking formation in the form of a notch or groove 54 in which the locking member 50 can be located. The locking member 50 has pivotable arms 56 to allow selective locking and unlocking of the locking member within the groove 54. The peripheral edge of the skirt 36 is arranged to contact the inner wall 58 of a pipeline 60 to be cleaned as shown in figure 5. It can be seen that the radial dimension of intermediate member 42 is substantially equal to that of the skirt 36 such that their respective peripheral edges are substantially aligned. Thus the intermediate member and the first body member can provide a combined cleaning action as the pipe cleaning apparatus passes along a pipe of suitable internal diameter such that both the intermediate member and skirt maintain contact therewith.

Accordingly the intermediate member may be considered to be a cleaning member. In such an embodiment the intermediate member may be provided in the form of an annular body having bristles or other elongate cleaning formation depending radially outwardly therefrom. Additionally or alternatively, such annular cleaning members may be located about either or both of the spacer plates 38, 40 such that they are trapped and locked between adjacent plate formations during use. In any embodiment, it is preferred that the elongate cleaning formations or bristles are of sufficient length to contact the inner wall of a pipe to be cleaned about substantially the entire inner circumference of the pipe. The provision of an annular cleaning member of this type is beneficial in that it can simply be removed from the apparatus and replaced as necessary without specialist tools. Thus the design of the apparatus can be considered to be modular in that replacement plates or cleaning members can be supplied as required. Similarly plates and/or cleaning members of different diameters can be provided to suit pipe of differing internal diameters without modifying the design of the core or body of the apparatus.

The locking members 50 located at either end of the apparatus can be considered to represent front and rear cap formations.

In figure 5 it is also visible that the connection formations 26 and 28 comprise generally disk shaped flange formations, to which the hub 46 and springs 22, 24 are attached on opposing sides thereof. The springs are connected to the connection formations at either end thereof by lug formations 62 which depend from the connection formation and pass a short distance inside the coiled springs. The lug formations 62 are fixed to the connection formations by bolts 64 which pass through radially aligned apertures in the connection formations. The first body members 30 are located rearwardly of the cleaning members during use such that the skirt 38 provides a secondary cleaning action to help remove debris from the inside of the pipe 60. A further set of apertures 66 are provided in each of the first and intermediate body members to allow attachment of annular cleaning members (not shown) as described above.

The direction of travel of the pig 10 during use is shown by arrow A.

Turning now to figure 6, a further embodiment of the present invention is shown in the form of cleaning apparatus 100, comprising first 102 and second 104 body portions separated by spring 106, which is connected therebetween.

The spring 106 is connected to body portions 102 and 104 by respective connecting members 108. A hub section 110 depends from each connecting member 108 away from the spring 106. In this embodiment, the hub and connection member may be hollow so as to define a central passage such that air can flow along the centre of the apparatus through the spring 106. This central passageway can be of use in controlling the pressure difference between the front and rear of the pig as it passes along a pipeline.

One each hub 110 is mounted annular plate members 112 and 114, between which is trapped a series of annular cleaning members 116, which are shown n further detail in figure 7. The annular plate members 112 and 114 each have castellations 115 formed in the peripheral edge thereof. The castellations form a series of peaks and troughs and the bristles of the 118 cleaning members 1 16 are arranged in spaced groups such that each group is aligned substantially with the troughs of the annular plate members 112 and 114.

Each annular cleaning member comprises an annular support member 120 having bristles 118 inserted into bores therein such that the bristles depend radially outwardly from the support member 120. the bores and corresponding bristles are arranged in regularly spaced groups about the periphery of the support ring. The spacing of the groups matches the spacing of the castellations in plate members 112 and 114. In this embodiment, a total of 4 cleaning members are mounted on each hub 110 between plates 112 and 114. Similar annular plate members and cleaning members are mounted at the opposing end of the apparatus. However the castellations 117 at the opposing end of the apparatus are offset or out of phase with the castellations 1 15 such that the peaks of castellations 115 are aligned with the troughs of the castellations 117. Accordingly the groups of bristles 119 in the cleaning members at the opposing end of the device are offset or out of phase with the groups of bristles 118 in cleaning members 116. Such an arrangement has been found to provide an improved cleaning action.

The plates 112 and 114 and cleaning members 1 6 are held on hub 110 by bolts 122 which pass through apertures 124 in the plates 112, 114 and support rings 120. In addition, end cap formations 126 are bolted on each end of the apparatus. The end cap formations are annular in plan and curved in section and are seated on the free end of hub 110.

It will be appreciated that the spring 106 is of greater resilience and/or strength than the individual springs 22 and 24 of the embodiment of figures 1 to 5. The length and/or diameter of the apparatus of figure 6 may also differ from the corresponding dimensions of figures 1 to 5 but the devices are otherwise similar in function.

In figure 8, there is shown a further embodiment which is the same as that shown in figure 6, save that the annular cleaning formations have been replaced with a series of circumferentially arranged cleaning blocks or pads 130. The blocks 130 have a length and width dimension sufficient to allow a two-dimensional array of bristle groups to be held therein. Each block has a corresponding array of bores therein to allow insertion of the bristles 128.

Each block has a transverse bore 132 therethrough which is substantially parallel with the axis of the apparatus to allow insertion of a bolt 122 therein for fixing the blocks 130 to the connection formation 108. The series of blocks are positioned about the circumference of the apparatus in alignment with the troughs of the castellations 1 15 in plates 112 and 1 14. The alignment of the blocks produces groupings of bristles similar to that described in relation to figures 6 and 7 above.

The cleaning members described in relation to figures 6 to 8 may be used in conjunction with the embodiment of figures 1 to 5. Furthermore, it is intended that any features described in relation to any one of the embodiments above are to be considered to be interchangeable as far as practicably possible with corresponding features of any of the alternative embodiments.

It will be appreciated that any reference to "cleaning" of pipes referred to within the present application is intended to refer to the process of passing an apparatus along the pipe to remove or dislodge material deposited on the inner wall of the pipe and/or debris within the pipe. It is not intended that the interpretation of the word "cleaning" be limited by any other chemical or mechanical actions which may be associated with other cleaning processes unless otherwise stated in this application.