GB2169682A - Pipe collars - Google Patents

Abstract

The present invention relates to collars for repairing, and in some cases for joining, pipes. A particular field of use of such collars is for sealing a leak in the wall of an underground gas, water or allied industry's main. In accordance with the present invention there is provided a segment for a pipe collar comprising an arcuate body (1), preferably part-cylindrical, having a curvature corresponding substantially to the curvature of the pipe on which it is to be used, inter-engaging means for slidably engaging the segment circumferentially with at least one other like segment in order to encircle the pipe, the inter-engaging means being disposed on each circumferential margin of the segment body and comprising at least one finger portion (2) and adjacent finger slot (3), each finger portion being dimensioned to fit into a corresponding slot so as to prevent substantial axial movement of the segment relative to the or each other segment when inter-engaged therewith around the pipe, and means e,g. bolts for facilitating the connection of the segment with at least one other like segment. <IMAGE>

Description

SPECIFICATION Improvements in pipe collars The present invention relates to collars for repairing, and in some cases for joining, pipes.

A particular field of use of such collars is for sealing a leak in the wall of an underground gas, water or allied industry's main.

For the main supply pipes used by the gas, water and allied industries, a number of different materials are in practice used, e.g. castiron, steel to BS3601 and ductile iron to BS4772, but although the nominal diameter of such pipes may be the same the actual diameter of the pipes is generally not equal to the nominal diameter, and may be either larger or smaller according to the material used.

Thus when a repair man comes to deal with a leak in such a pipe line, he must first establish the type of pipe used, and then order up a fitting, such as a collar, appropriate to the actual size of that pipe. Also for fixed diameter fittings a large stock of fittings must be maintained to cater for all of the different actual sizes of pipes currently in use.

Although collars of variable size are known, generally such collars are tightened around the leaking pipe by a clamping device positioned at only one or two points on the circumference of the collar. By tightening such a collar at only one point, leakage is often found to occur between the clamp and the pipe at a point approximately diametrically opposite the point of clamping, since although in theory the collar should be drawn in uniformally towards to pipe, in practice the deformable seal generally positioned between the collar and the pipe binds against the pipe in the vicinity of the clamping device thereby hindering the tightening movement of the collar remote from the clamping device. With known two-segment collars, leakage remote from the clamping points has similarly been found.

The present invention lies in a segmented collar of at least two parts clampable together around the pipe, each part being a sliding fit into its neighbouring part or parts.

In accordance with the present invention there is provided a segment for a pipe collar comprising an arcuate body, preferably partcylindrical, having a curvature corresponding substantially to the curvature of the pipe on which it is to be used, inter-engaging means for slidably engaging the segment circumferentially with at least one other like segment in order to encircle the pipe, the inter-engaging means being disposed on each circumferential margin of the segment body and comprising at least one finger portion and adjacent finger slot, each finger portion being dimensioned to fit into a corresponding slot so as to prevent substantial axial movement of the segment relative to the or each other segment when inter-engaged therewith around the pipe, and means for facilitating the connection of the segment with at least one other like segment.

Preferably the connection-facilitating means comprises at least one upstanding lug associated with the interengaging means for carrying at least one clamping means for connecting the segment to an inter-engaging segment.

Preferably the clamping device comprises a conventional nut and bolt suitable for withstanding a tightening torque of approximately 100 Nm.

A suitable position for such a lug is adjacent the root of the or each finger portion, with a reinforcing web being provided therebetween to strengthen both the lug and the or each finger portion. An integral construction of segment body and lugs is preferred for strength.

In its preferred aspect, the segment of the invention is modular in nature so that both or all of the segments for a given collar are essentially identical. Thus the order of assembly of a plurality of such segments is immaterial. To facilitate this, the inter-engaging means are complementary, i.e. where one has a finger portion of a given configuration, the other has a matching finger slot dimensioned to fit that finger portion.

For ease of assembly, it may be desirable when clamping bolts are used to arrange for the lugs not to be symmetrical, by providing one half of the lugs with slots rather than bolt holes. By this means segments can be supplied with bolts already threaded through half the number of the lugs and secured therein by nuts, so that the repair man need only bring adjacent segments together and slide the shank portion of each bolt into the slot of the corresponding lug in order to be able to commence clamping of the segments together.

The need to thread clamping bolts through two sets of holes on site is thereby obviated.

Clearly with such arrangement, it is desirable in accordance with standard practice to provide either the bolt holes or the bolt slots with suitable angular recesses to engage a corresponding angular portion of each bolt head, in order to resist rotation of the clamping bolts during tightening thereof. Alternatively, instead of recessing the lugs, the bolt shanks can be unsymmetrical e.g. D-shaped, to wedge into the bolt slots.

For strength, the finger portions of the segment are preferably integral with the segment body, are of uniform thickness, and have an inner surface which follows the general curvature of the body. To facilitate interdigitation of the finger portions of neighbouring segments, both the finger slots and the finger portions are preferably parallel-sided. A particularly suitable material for the segment body, as well as its finger portions when integral therewith, is malleable iron. Although any conventional sealing gasket can be used with the segment of the present invention, in its preferred aspect, the present segment includes, preferably bonded thereto, a resilient pad covering at least a major part of the inner surface thereof for providing a circumferential seal for the pipe when the segment is positioned around the pipe.Although for a small and discrete leak the pad need only cover a relatively small proportion of the segment's inner surface, it is desirable for essentially the whole of the inner surface of the segment, including much of its finger portions and finger slots, to be covered.

It has been found best in practice for the extreme ends of the finger portions not to be covered by the pad.

Such an extended pad will, of course, have both of its circumferential margins so shaped as to inter-engage with the pad(s) of neighbouring segment(s). In such an arrangement the pad constitutes part of the inter-engaging means. In order to facilitate sliding engagement between the pads of inter-engaging segments, the circumferential margins of each pad are preferably tapered in thickness towards their edges, the rate of tapering being such that for clamping pipes with an actual diameter smaller than their nominal diameter a sufficient thickness of pad is provided by the combination of the two tapered portions of engaging pads to seal the pipes effectively at these points. For such an extended pad the segment is desirably bonded to the pad only in the region of its body portion so as to allow free sliding engagement of the finger portions thereof.

Although for sealing a pipe having a relatively rough external surface a smooth pad can be used, it is generally preferred that the inner surface of the pad be roughened, especially at each lateral edge, so as to facilitate better sealing with the smooth-surfaced pipes generally in use at the present time. A particularly suitable form of surface roughening comprises one or more upstanding ribs or ridges running circumferentially across the surface, whereby when the collar is assembled at least one substantially continuous circumferential rib is formed around the pipe both up-stream and down-stream of the leak or join. A suitable material for the pad is a deformable material, such as a synthetic rubber, which can take up and thereby seal the irregular surface of a cracked or broken pipe when compressed thereonto by the segments.

In order to strengthen the deformable pad at its thin engaging margins, it has been found useful to dispose in this region a bridging plate between the segment and the pad, the plate being conveniently bonded to the latter.

By arranging for the plate to extend over essentially the whole of the inner surface of the finger portions and finger slots of the inter-engaging means of the segment, it has been found that the resilient pad can be essentially prevented from being outwardly distorted by the squeezing action exerted thereon during clamping of the collar, this squeezing tending to force the pad radially outwardly between finger portions of interengaging segments and so interfering with sealing against the pipe. Desirably the plate consists of a sheet of flexible stainless steel, and is moulded into the pad, the latter in that case being thermoplastic. Usually only one plate is needed per pair of inter-engaging means.

When the segment of the invention is used to seal a very large crack or actual break in a pipe, it may be necessary to arrange for some support to be provided for the inner one of the tapered pads to prevent its sagging into the crack or break. Preferably therefore a reinforcing plate is provided on the surface of the pad in the region of that tapered portion which in use will lie adjacent the pipe to be mended. In order to avoid disturbing the seal of the pad against the pipe, the reinforcing plate is desirably positioned on the slope of the tapered portion. As with the bridging plate, the reinforcing plate is desirably of stainless steel and moulded into the pad. (The number of modular segments to be used for any one collar generally depends on the diameter of the pipe to be encircled, the larger the diameter the more segments needed.Accordingly, the present invention further provides a pipe collar comprising at least two substantially identical segments of the invention disposable in mutally-interlocking relationship with means for connecting the segments together in position around the circumference of the pipe. For a nominal six inch (152 mm) diameter pipe, three such segments have been found suitable per collar. For larger diameter pipes, four or more segments can be used.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view taken from above and to one side of a segment according to the invention; Figure 2 is an end view of a pipe encircled by a collar formed of three of the segments of Fig. 1 clamped together, the pipe being of the maximum diameter for these segments; Figure 3 is a fragmentary elevational view of the collar of Figure 2 taken in the direction of arrow Ill showing the inter-engagement of two of the segments; Figure 4 is an enlarged fragmentary view, partly in section, of the collar of Figure 2 in the region IV; Figures 5 and 6 are similar views to those of Figures 2 and 3 except that the collar now encircles a pipe that is of the minimum diameter for the segments, the arrow being labelled VI; and Figure 7 is an under plan view of the sealing pad of the segment of Figure 1.

Referring particularly to Fig. 1, each segment is of identical construction and comprises a segment body 1, eight finger portions 2 with eight adjacent finger slots 3, two bolt lugs 4, and a sealing pad 5 with its moulded bridging plate 6 and reinforcing plate 6a.

The body 1 is of malleable iron and is cast integrally with the finger portions 2, whereby the whole inner surface of the body and finger portions is smoothly and uniformly curved, so as when inter-engaged with two other like segments to encircle a straight pipe. For the illustrated collar, the segments have been designed to fit a pipe of six inch (152 mm) nominal diameter. The body and its finger portions are essentially of the same thickness throughout, except that in the central region of the body 1 the thickness of metal can be reduced, thereby leaving upstanding reinforcing ribs 7 along the lateral edges thereof.

The finger portions 2 are squared off at their ends and have parallel sides, and are arranged in two groups of four so that the finger portions and corresponding slots of the segment can interdigitate the finger portions and corresponding slots of another like segment so as to form a collar of uniform thickness and width as illustrated in Figures 3 and 6. The finger portions and adjacent slots are complementary, essentially of the same width, and symmetrically arranged across each end of the segment, so that like segments can be inter-engaged regardless of their order of assembly. Only four pairs of complete finger portions and finger slots are visible in Fig. 1, the others being concealed behind the background lug 4.Although the finger slots 3 can have their roots tapered so as to force the finger portions 2 of neighbouring segments to "ride up" when clamped about a smaller than nominal pipe, it has been found that sometimes this "riding up" can so disturb the uniform clamping action of the segments that leaks can develop. Thus it is preferred that the finger slot roots are squared off as at 8 in the Figures. When fully clamped about the smallest possible pipe, the tips of the fingers of each segment will just abut the roots 8 of the finger slots of each neighbouring segment.

In order to clamp effectively a pipe of any diameter smaller than this, a collar with smaller segments would have to be used.

For clamping of the segments together, bolt lugs 4 are provided near the roots of the finger portions and finger slots, webs 9 being provided to reinforce both the lugs and the neighbouring finger portions. Again these lugs and webs áre integrally cast with the segment body. In order to resist deformation of the lugs 4, each lug is provided with symmetri cally-disposed reinforcing webs 9 extending from the edges of the lugs down to the left hand edges of the finger portions.By this means the clamping force exerted through each lug is evenly distributed over two pairs of finger portions and corresponding slots, with the line of the force being directed at the centre of each group of two pairs of finger portions and slots, which in the illustrated example having even widths of finger portions and slots is aligned along the right hand edge of the left hand finger portion of each pair. (In the present context, "left" and "right" are taken as looking outwardly from the centre of the segment body 1.) Both lugs 4 are of essentially the same construction, except that the bolt holes 10 at one circumferential end of the segment have been rectangularly slotted at the other end, as at 11, in order to accommodate the shank portion of a clamping bolt.No recesses are provided for a bolt head, since in the illustrated embodiment the segment is intended to be used with bolts having shanks which are squared-off adjacent their heads.

Shoulders 12 are, however, provided at the ends of the slotted holes 11 in order to resist sliding-out of a clamping bolt during tightening thereof. It will also be seen that the bolt holes 10 are not circular but more oval in order to permit some pivoting of the clamping bolts during tightening thereof.

On the inner surface of the segment body 1, and bonded by adhesive thereto, is the sealing pad 5, which pad extends over essentially the whole of the inner surface of the body and much of the associated finger portions 2. The pad is of a synthetic, thermoplastic, nitrile rubber and is bonded to the segment body by "impact" adhesive only in its central third leaving each outer circumferential third unbonded for ease of engagement with the pads of the two neighbouring segments.

At the start of the un-bonded section of the pad, the thickness of the pad is reduced in the form of a gradual taper commencing at 13. The tapering at one circumferential margin is arranged inwardly, whilst at the other it is arranged outwardly, so that when two segments are inter-engaged their respective pads overlap and can slide to some degree over each other as the segments are clamped together. The rate of taper at both ends is such that, when the segment is used on a nominal diameter pipe having an actual diameter within the segment's range (as explained below), the combined thickness of the two overlapping pads precisely fills the space between the pipe and the inner surface of the segment.

Figures 2 and 5 show this uniform filling of the space between the pipe and the collar after clamping up thereof for both large and small diameter pipes, respectively.

Upon being "squeezed" by the segment when clamped, the pad 5 has been found to have a tendency sometimes to "extrude" sideways, i.e. longitudinally of the pipe, out from underneath the segment. In order to resist this movement, the illustrated segment carries inwardly-directed gripping bands 14 on both left and right marginal edges. With the provision of these raised bands, the inner surface of the segment takes the form of a shallow trough into which the sealing pad 5 fits, being free to extend around the pipe but not longitudinally of the pipe. Clearly the bands 14 should not project inwardly from the inner surface of the segment by more than the very minimum thickness to which the pad 5 can be compressed otherwise interference with the sealing action of the clamp may result.In practice it has been found that the height of the bands should be no more than about one third of the thickness of the pad. As can be seen best from Fig. 7, the under surface of the pad carries a series of circumferential parallel sealing ribs ("scratch seals") 15 in order to seal effectively a pipe having a relatively smooth external surface. Three pairs of evenly-spaced ribs are provided towards the lateral edges of the pad, leaving the central third smooth. Ribs 15 extend right from one end of the pad 5 to the other, including its tapered portion, in order to ensure an effectively continuous run of ribs right round the pipe regardless of the extent of overlap of neighbouring pads, i.e. regardless of pipe dimension.

Moulded into the pad 5 is the stainless steel bridging plate 6 which extends approximately from the start of the un-bonded region 13 of the pad to just beyond its extreme circumferential edge. Only one such plate is provided on the segment since it serves as a bridge between interengaging segments, and with three segments only three such bridges are required. As shown in Fig. 1, the plate 6 is bonded to the outer surface of the outwardly tapering portion of the pad 5, so that it always lies in direct contact with one set of the finger portions 2, so as to prevent any of the underlying pad from being deformed between the fingers of inter-engaging segments during clamping together thereof. The plate 6 extends width-wise across the entire segment, but within the gripping bands 14, and is thus of the same width as the pad 5.The plate 6 is of uniform thickness throughout and is sufficiently flexible to conform easily to the contours of the pipe to be encircled whilst at the same time being sufficiently rigid to resist substantial deformation under the pressure of the underlying rubber trying to erupt between interdigitating finger portions during clamping.

Although moulded into pad 5 in its flat state, bridging plate 6 is then passed through a roll in order to precurve the plate for ease of assembly of the clamp.

Like bridging plate 6, the stainless steel reinforcing plate 6a is also bonded to the pad 5, but on the sloping surface of the inwardly tapering portion of the pad, so that it always lies in direct contact with the tapered portion of the neighbouring pad. Again the width of the plate 6a is the same as that of the pad 5.

In addition to the function of plate 6a to support the inner sealing pad, it also assists in the compression to a flattened state of the raised sealing ribs 15 of the neighbouring segment's sealing pad in the region where the two sealing pads overlap, particularly along the line of their meeting adjacent the pipe.

Without this flattening of the ribs 15, it will be appreciated that at least one open channel to atmosphere could be left for leaking fluid from the pipe immediately adjacent, and following the line of, the ribs 15. Clamping up of the segments causes their respective reinforcing plates 6a to bite into the tapered portion of each neighbouring sealing pad 5 thereby sealing off these possible leakage channels.

In Figures 2 to 4, a pipe 16 is shown fitted with a collar formed by the clamping together by bolts 17 and nuts 18 of three identical segments of the type shown in Fig. 1. It will be seen especially from Fig. 3 that the interengagement of the finger portions 2 and finger slots 3 results in a collar of uniform width encircling the pipe 16, wherein the relative longitudinal movement of any individual segment 1 is resisted by the interdigitation thereof with its neighbouring segments By dimensioning the finger portions and finger slots so that a tight sliding fit is achieved therebetween, skewing of any one segment upon clamping up thereof is resisted thereby facilitating uniform compression of the underlying sealing pad 5 against the pipe 16.

In Figures 2 to 4, the pipe 16 around which the collar is clamped is of the maximum diameter possible for the size of segments 1 illustrated, i.e. at each segment junction the finger portions 2 and finger slots 3 only just interdigitate. By contrast the pipe 16a around which the same segments are clamped as shown in Figures 5 and 6 is of the minimum diameter possible for these particular segments, i.e., at each segment junction the finger portions 2 are fully interdigitated with their corresponding finger slots 3 so as just to abut the slot roots 8.Because the same segments, nuts and bolts have been used for this smaller pipe, it will be seen that the lugs 4 of neighbouring segments are further apart in the collar of Figs. 2 to 4 than in the collar of Figures 5 and 6, and that consequently the nuts 18 of that latter collar are further away from the ends of the threaded portions of their respective bolts 17. Uniform tightening of the clamping bolts results in approximately equal interdigitation of the segments and thus approximately uniform compression of the sealing pad 5 against the underlying pipe.

In both large diameter and small diameter collars the circumferential tapers of the pads 5 of neighbouring segments overlap in such a way that the space between the pipe 16 and the collar is fully filled so as to provide a good seal against the pipe at the junctions of the segments. Bridging plates 6 can be seen to extend across the whole of the interdigitated junctions of the segments, whilst reinforcing plates 6a support the junctions from between the overlapping pads.

The depth of interdigitation between neighbouring segments depends, of course, on the diameter of the pipe to be fitted, but then is limited by the length of the finger portions 2 and the depth of the finger roots 8. Although in theory the finger portions of neighbouring segments need only just meet for the largest possible pipe, it is preferred that a small amount of overlap actually occurs, e.g. quarter of an inch (6.4 mm) so that firm sealing of the pipe in the interdigitated regions occurs and that relative axial movement between the segments is firmly resisted. These limits define the maximum diameter of pipe around which segments of a given radius of curvature can be fitted. This is shown in Fig. 3.

At the other extreme, the minimum diameter of pipe about which the segments can be fitted depends upon the extent to which the finger portions 2 can slide into their corresponding slots 3 before abutting the roots 8.

This is shown in Figures 5 and 6. Although the roots 8 can be cut back into the body, clearly, for the illustrated segments, a limit is reached when the roots reach the bases of the lugs 4 where they join on to the body 1.

Although openings could be cut into the lugs to allow the ends of the finger portions to slide therethrough, this clearly will weaken the interconnection between the lugs and the body. Furthermore, there is a limit to which the overlapping tapered portions of the sealing pads 5 can effectively fill, and consequently seal, the space between the pipe and the inter-engaging segments in the region of their interdigitation. Whereas for a pipe whose actual diameter equals its nominal diameter this annular space is uniform throughout the circumference of the pipe, it will be appreciated that as one moves to either larger or smaller pipes the variation in thickness around the circumference of the pipe of this annular space to be filled by the overlapping pads becomes greater and greater.Thus with a relatively thin pad 5 as illustrated, it is not possible to accomodate more than a relatively small variation in thickness of this annular space. For the illustrated collar fitting a six inch (152 mm) nominal diameter pipe, the difference in diameter between the maximum and minimum diameter pipes which can be effectively clamped is about 20 mm. This corresponds to an overall diameter of the collar illustrated in Figs. 2 to 4 of about 300 mm, as compared with an overall diameter of approximately 250 mm for the collar of Figures 5 and 6.

As supplied to a repair man, the segments are supplied with bolts 17 extending -through the bolt holes 10, with nuts 18 already threaded thereon at the furthest end of the threaded portion of the bolt remote from its head. To assemble the illustrated collar, three of such segments are used, being positioned on the pipe sequentially, the order of assembly around the pipe being irrelevant. The first segment can be placed on the pipe in either circumferential orientation, i.e. with the bolts pointing clockwise or anticlockwise around the pipe, but thereafter the remaining two segments must be fitted so that all of the bolts point in the same direction around the pipe.The second segment to be assembled is slidingly engaged with the first segment so that the finger portions 2 and slots 3 interdigitate, and the pads 5 overlap one another with the pre-curved bridging plate 6 being between the overlapping pads and the finger portions.

When the second segment is loosely engaged with the first segment, the shanks of the bolts 17 at the segments' junction can be pushed into the slotted holes 11 with the bolt heads lying below the shoulders 12. This loose connection between the first two segments should generally be sufficiently strong for the third segment to be brought up to engage the two positioned segments around the other side of the pipe without the repair man having to hold the first two segments together. As with the first inter-connection, the third segment is inter-engaged with the remaining free finger portions and finger slots of the first and second segments, with the other bolts being similarly loosely positioned. By using bolts with squared-off shanks adjacent their heads, they can slide into the slotted holes 11 thereby preventing rotation of the bolt during subsequent tightening thereof.

The loosely assembled collar should now be self-supporting around the pipe and leave the repair man free to tighten each nut 18 in sequence around the pipe without the need to grasp any portion of the collar. The nuts are tightened up to the requisite torque, e.g. 100 Nm, and it has been found that the collar of the invention is capable of sealing a leaking gas main up to a pressure of 7 bar at a leakage rate of 10 m3 (st)/h.

For most pipes three-segment collars of appropriate diameters are generally used. For relatively large diameter pipes, or those where a large "maximum-to -minimum" diameter range is needed, four or more segments per collar are desirable, whereas with smaller diameter pipes two-segment collars can be used.

Claims (19)

1. A segment for a pipe collar comprising an arcuate body having a curvature corresponding substantially to the curvature of the pipe on which it is to be used, interengaging means for slidably engaging the segment circumferentially with at least one other like segment in order to encircle the pipe, the interengaging means being disposed on each circumferential margin of the segment body and comprising at least one finger portion and adjacent finger slot, each finger portion being dimensioned to fit into a corresponding slot so as to prevent substantial axial movement of the segment relative to the or each other segment when inter-engaged therewith around the pipe, and means for facilitating the connection of the segment with at least one other like segment.

2. A segment as claimed in claim 1 wherein the connection-facilitating means comprises at least one upstanding lug associated with the inter-engaging means for carrying at least one clamping means for connecting the segment to an inter-engaging segment.

3. A segment as claimed in claim 2 wherein the clamping device comprises a conventional nut and bolt suitable for withstanding a tightening torque of approximately 100 Nm.

4. A segment as claimed in claim 2 or claim 3 wherein the or each lug is disposed adjacent the root of the or each finger portion, with a reinforcing web being provided therebetween to strengthen both the or each lug and the or each finger portion.

5. A segment as claimed in any one of claims 2 to 4 wherein the segment body and the or each lug are of integral construction.

6. A segment as claimed in any one of the preceding claims of malleable iron.

7. A segment as claimed in any one of the preceding claims when of modular construction whereby both or all of the segments for a given collar are freely interengageable.

8. A segment as claimed in any one of the preceding claims including a resilient pad covering at least a major part of the inner surface thereof for providing a circumferential seal for the pipe when the segment is positioned around the pipe.

9. A segment as claimed in claim 8 wherein the pad is adapted to cover essentially the whole of the inner surface of the segment, including at least a part of its finger portions and finger slots, to be covered.

10. A segment as claimed in claim 8 or claim 9 wherein the circumferential margins of the pad are tapered in thickness towards its edges, the rate of tapering being such that for clamping pipes with an actual diameter smaller than their nominal diameter a sufficient thickness of pad is provided by the combination of the two tapered portions of engaging pads to seal the pipes effectively at these points.

11. A segment as claimed in any one of claims 8 to 10 wherein the segment is bonded to the pad only in the region of its body portion so as to allow free sliding engagement of the finger portions thereof.

12. A segment as claimed in any one of claims 8 to 11 wherein the inner surface of the pad is roughened so as to facilitate sealing with smooth-surfaced pipes.

13. A segment as claimed in claim 12 wherein the surface roughening comprises one or more upstanding ribs or ridges running circumferentially across the surface, whereby when the collar is assembled at least one substantially continuous circumferential rib is formed around the pipe.

14. A segment as claimed in any one of claims 8 to 13 including a bridging plate disposed between the segment and the pad, bonded to the pad, and extending over essentially the whole of the inner surface of the finger portions and finger slots of the interengaging means of the segment.

15. A segment as claimed in claim 14 wherein the plate consists of a sheet of flexible stainless steel, and is moulded into the pad.

16. A segment as claimed in any one of claims 8 to 15 including a reinforcing plate bonded to the pad on its inner surface in the region of its marginal edge.

17. A segment as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

18. A pipe collar comprising at least two substantially identical segments as claimed in any one of the preceding claims disposable in mutually-interlocking relationship with the connection facilitating means around the circumference of the pipe.

19. A pipe collar as claimed in claim 18 substantially as hereinbefore described with reference to and as illustrated in Figures 2 to 6 of the accompanying drawings.