GB2044872A

GB2044872A - A pipe connection assembly

Info

Publication number: GB2044872A
Application number: GB8006970A
Authority: GB
Original assignee: Rheinmetall GmbH
Current assignee: Rheinmetall Industrie AG
Priority date: 1979-03-23
Filing date: 1980-02-29
Publication date: 1980-10-22
Also published as: DE2911448C2; FR2452049A1; IT1130312B; IT8020386A0; DE2911448A1

Abstract

Two pipes (2) have outwardly- flared ends (4) between which an inner ring (16) is located. An outer ring (24) can be tightened by a bolt (34) so that the flared ends (4) of the pipes are clamped between abutment surfaces (28) of the outer ring and abutment surfaces (22) of the inner ring which, as well as the flared ends (4) of the pipes, are preferably part-spherical so that the angular orientation of the axes of the pipes (2) can be varied by slackening and subsequently retightening the bolt (34). <IMAGE>

Description

SPECIFICATION A pipe connection assembly This invention relates to a pipe connection assembly.

In accordance with the present invention there is provided the assembly of two pipes with opposed, outwardly-flared ends (as herein defined) and connection means comprising an inner annular member which is tapered inn radial section so as to have axially opposite abutment surfaces respectively complimentary to the radially inner surfaces of the flared ends of the pipes and an outer annular member having radially inner, axially spaced-apart abutment surfaces respectively to engage the radially outer surfaces of the flared ends of the pipes, means being provided whereby the outer annular member may be restricted so that the flared ends of the pipes will be clamped between the abutment surfaces of the inner and outer annular members.

As used herein and in the appended claims the expression "flared" is intended to distinguish the pipe ends of the assembly of the invention on the one hand from conventional flanged ends, in which a pipe has an end flange lying in a plane perpendicular to the axis of the pipe, which can be bolted or otherwise secured to the similar flange of another pipe, and on the other hand from pipe ends which are not flanged at all, being, for example, screw-threaded. The flared end of a pipe used in the assembly of the invention is enlarged and progressively reduces both in its internal and external cross-sectional areas from its free end edge to its junction with the non-enlarged portion of the pipe.

Preferably the radially inner surface of each flared pipe end and the corresponding abutment surface of the inner annular member are part-spherical upon spheres of similar diameter, the arrangement being such that the angular orientation of the pipes may be altered by slackening and subsequently retightening the outer annular member. The radially outer surface of each flared pipe end and the corresponding abutment surface of the outer annular member are preferably part-spherical upon spheres of similar diameter, and the centres of the spheres upon which the radially outer and inner surfaces of a flared pipe end lie preferably coincide with the axis of said pipe. Said centres may be spaced apart along said axis so that the wall thickness of said flared end varies in the radial direction.In this construction the wall thickness of said flared end may increase in the radially outward direction and it may be provided in a radially outer region of its radially inner surface with a circumferential recess in which resilient sealing means is located to engage the corresponding abutment surface of the inner annular member.

Alternatively, said centres may coincide with one another.

Each said abutment surface of the outer annular member is preferably of lesser axial extent than the associated flared pipe end and terminates at its axially inner end at a step serving to limit movement of said pipe end axially inward of the outer annular member.

The abutment surfaces of the inner annular member may have circumferential grooves in which resilient sealing rings are located for sealing engagement with the respective pipe ends.

The outer and inner annular members may be formed or provided in their median planes with male and female formations which interengage to maintain said members in a predetermined orientation independent of the angular orientation of the pipes. The outer annular member may be formed with a radially inward projection which is engageable in a recess in the circumference of the inner annular member, and the arrangement may be such that when the outer annular member is restricted the inner annular member is locked against angular movement relative to the outer annular member.

The restriction means may comprise at least one bolt which acts between separated surfaces of the outer annular member to tend to reduce the diameter of the latter, or the outer annular member may comprise two parts which are separable axially of the member and the restriction means may comprise bolts circumferentially spaced around the member and operable to draw the parts axially toward one another. In the latter arrangement the inner annular member may comprise two parts respectively formed with said abutment surfaces and having a screw-threaded connection such that the axial dimension of the inner annular member can be varied.

The inner annular member may be of multipart construction and may comprise a cylindrical sleeve of outer diameter similar to the inner diameters of the pipes adjacent the flared ends thereof, the sleeve having a central, radially outward circumferential projection, and a pair of annuli disposed on opposite sides of said circumferential projection and each of generally triangular radial section to provide the abutment surfaces of the inner annular member. The sleeve may comprise two parts which are separable in the median plane of the circumferential projection and the two parts of the sleeve may be non-coaxial, the axes of the two parts forming an angle determined by the non-perpendicular orientation of at least one of the two projection parts with the associated sleeve part.One part of the circumferential projection may have an annular rib which engages in a corresponding groove in the other part of the circumferential projection.

Each pipe may be of enlarged diameter adjacent its flared end to provide an annular rebate to accommodate one end of the sleeve.

At least one of the pipes may be apertured in the region of the axially inner extremity of its flared end to permit the injection of a filler material into the space between the sleeve and the inner circumference of the associated annulus providing an abutment surface.

The outer annular member may have axial, tubular projections which extend over the flared ends of the pipes and means may be provided for engaging the free ends of said tubular projections to the pipes behind the flared ends thereof.

Preferred embodiments of the invention will now be described with reference to the accompanying diagrammatic drawings, in which: Figures 1-4 are similar sectional elevational views of four different pipe connection assemblies in accordance with the invention, each taken in a plane radial to the axes of the two pipes being joined, Figures 5 and 6 are, respectively, a plan view and a side view of one component of the outer annular member of the embodiment of Fig. 4, Figure 7 is a perspective view of a modified assembly in accordance with Fig. 2 and with the outer clamping ring omitted, and Figures 8-15 are views similar to those of Figs. 1-4 of further embodiments of the invention.

As shown in Fig. 1, two straight pieces of piping 2 are provided with opposed, flared ends 4. Each flared pipe end 4 has a partspherical outer surface 6 and a part-spherical inner surface 8. Each flared pipe end 4 terminates in a free end edge 10. In the example shown in Fig. 1 the centre 12 of the partspherical outer surface 6 and the centre 14 of the part-spherical inner surface 8 coincide with the axis of the pipe but are space apart.

The connection between the opposed flared pipe ends 4 consists of an inner ring 16 and an outer ring 24. The inner ring has an internal diameter equal to that of the straight piece of each pipe 2. It is delimited by partspherical abutment surfaces 22 which contact the inner surfaces 8 of the flared pipe ends 4 and in each of which is formed a circumferential groove 18 in which is located a resilient sealing ring 20. An outer ring 24 has parts 26 which extend behind the flared pipe ends 4 and which have inner part-spherical surfaces 28 to abut the outer surfaces 6 of the flared pipe ends 4. The part-spherical abutment surfaces 28 each terminate at a first boundary 29 of greater diameter than the outer diameter of the straight pieces of piping 2 but of smaller diameter than the free end edges 10 of the flared pipe ends 4.A second boundary is provided by steps 30 which form in the outer ring 24 a circumferential projection 32 which extends radially inwards. The outer ring is divided in a diametral plane into two arcuate parts which can be drawn together by bolts 34. In the assembly operation the inner ring 16 is first of all placed between the flared pipe ends 4. The halves of the outer ring are then placed over the flared pipe ends 4 and drawn together by the bolts 34. The outer ring 24 is dimensioned to ensure that the enlarged pipe ends 4 are clamped between the abutment surfaces of the inner ring 16 and those of the outer ring 24, so that in the finally assembled state there is no angular mobility between the connected pipes 2.

However, the outer ring 24 may be slackened by slackening the bolts 34 so that the pipes 2 may be moved angularly out of coaxial alignment until the free end edges 10 of the flared pipe ends encounter the steps 30 at the axially inner ends of the abutment surfaces 28 of the outer ring.

This arrangement is of advantage if the production of the flared pipe ends 4 is not preceded by an upsetting operation, since in this case the wall thickness of the flared pipe ends 4 decreases as the diameter increases.

In the embodiment shown in Fig 2, each straight piece of piping 2 has a flared end 36 with a part-spherical outer surface 38 and a part-spherical inner surface 40 on spheres having centres 44 which coincide both with the axis of the pipe and one another. An inner ring 40 is provided with part-spherical abutment surfaces 52 which co-operate with the radially inner surfaces 40 of the flared pipe ends 36 and in which circumferential grooves 48 are provided for resilient sealing rings 50.

A recess 54 passes circumferentially around the inner ring in its median plane between the opposite part-spherical abutment surfaces 52.

An outer ring 56, divided in a diametral plane, is placed around the flared pipe ends 36. The parts 58 of the said ring, which extend behind the flared pipe ends 36, terminate in axially outer boundaries 62 and in axially inner boundaries 64 which take the form of steps and which continue in the form of a circumferential, radially inward projection 66. The said projection 66 engages in the circumferential recess 54 in the inner ring 46.

This provides a radial clamping of the inner ring 46 by the outer ring 56 through tightening of the bolts 34, so that a slight clearance 68 remains between the inner ring 46, the outer ring 56 and the flared pipe ends 36.

This ensures that even after a pipeline has been laid the pipe connections according to the invention allow a certain angular mobility between the individual straight pieces of piping 2.

Fig. 3 shows a further embodiment of the pipe connection according to the invention. In this embodiment the straight pieces of piping 2 terminate in flared pipe ends 70, with partspherical outer surfaces 72 and part-spherical inner surfaces 74 lying on spheres of which the centres 78 and 80 do not coincide with one another and which are so arranged that the free end edge 76 of each flared pipe end 70 has a greater wall thickness than in the region of the straight piece of piping 2. This makes it possible, in each flared pipe end 70 to provide a circumferential groove 82 for a sealing ring 84. An inner ring 86 placed between the flared pipe ends 70 and having part-spherical surfaces go is provided with a circumferential groove 88 which has parallel side walls 89.An outer ring 92 which is divided in a diametral plane and which is held together by bolts 34 has axially outer parts 94 which pass behind the flared pipe ends 70 and which have part-spherical abutment surfaces 96 which rest on the part-spherical outer surfaces 72 of the flared pipe ends 70.

The part-spherical surfaces 96 have axially outer boundaries 98 and axially inner boundaries in the form of steps 100 which are continuous with a circumferential projection 102 extending radially inwardly of the outer ring. The said projection 102 engages the circumferential recess 88 in the inner ring 86, providing a mutual centering for the inner ring 86 and the outer ring 92. In this embodiment likewise it is possible by selecting the appropriate dimensions for the outer ring 92 to clamp the flared pipe ends 70 between the inner ring 86 and the outer ring 92, so that after the bolts 34 have been fully tightened up there is no angular mobility between the flared pipe ends 70 or else to provide a certain clearance between the inner ring 86, the flared pipe ends 70 and the outer ring 92, so that even after a pipeline has been laid angular mobility between adjacent pipes is preserved.

The pipe connection shown in Fig. 4 enables greater distances between individual straight pieces of piping 2 to be bridged, which may be of advantage, for instance, when sections of pipeline laid by different gangs come together. In the example illustrated the straight pieces of piping 2 are provided with flared ends 36 in accordance with Fig. 2. Between the flared pipe ends 36 is an inner ring consisting of two parts 104 and 106 which are in screw-threaded engagement. For this purpose one inner ring part 104 is provided with an outer screw thread 110 while the inner ring part 106 is provided with a sleeve having an inner screw thread 108. A cylindrical extension 112 interacts with the inner ring part 106 to provide a seal, the inner ring part 106 being provided for this purpose with an annular groove 114 and with a sealing 116 inserted therein.A cover in the form of a sheet metal tube 118 protects the exposed parts of the outer thread 11 0. Blind bores 120 are provided in the inner ring parts 106 and 104 and can be engaged by hook wrenches in order to rotate the two inner ring parts 106 and 104 in relation to each other.

The sealing of the inner ring parts 104 and 106 against the flared pipe ends 36 is effected, as in Fig. 2, by means of sealing rings 50 inserted in grooves 48.

There is an outer ring 122 having parts 124 behind the flared ends 36, the axially spaced apart components 124 of the ring 122 being axially displaceable toward one another by bolts 128 and nuts 130.

Each outer ring component 122 is divided diametrally and has parts 132 which overlap in its median plane and are interconnected by bolts 134.

According to the distance between mutually opposed flared pipe ends 36 to be connected the inner ring parts 106 and 104 are screwed together and clamped by the outer ring parts 122 acting on the flared pipe ends 36. This enables considerable differences in distance between mutually opposed flared pipe ends 36 to be accommodated without causing difficulties in the assembly operation.

Fig. 7 shows straight pieces of piping 2 with flared ends 36 formed on bent end portions 136. This arrangement ensures that each flared pipe end 36 has an angle of less than 90 in relation to the axis of its pipe.

This makes it possible to lay a section of piping in a zigzag configuration or around a curve. Taking into account the aforementioned possibility of angular mobility within each pipe connection it is found, as shown in Fig.

7, that when the straight pieces of pipe 2 are pivoted the flared pipe ends 36 will move apart in such a way as to render it possible, without any difficulty, to insert an inner ring 46 between the flared pipe ends 36 and then to produce the pipe connection by means of an outer ring (not shown in Fig. 7).

In the embodiments hitherto described the possible angular mobility of the pipe connection has been eliminated solely by clamping the inner ring, the flared pipe ends and the outer ring radially in relation to one another.

Figs. 8 to 11 show further possible ways of obtaining a connection in which angular mobility between the connected pipes is eliminated. Fig. 8 shows an embodiment similar to that of Fig. 2, but in the embodiment of Fig.

8 the space between the free end edge 42 of each flared pipe end 36 and the associated step 64 on the outer ring 56 is filled by a respective ring 138.

In the embodiment of Fig. 9 the same object is achieved by a special construction of the inner ring 140, which has circumferential projections 42 which fill the spaces between the free end edges 42 and the steps 64 of the outer ring 56.

In the embodiment shown in Fig. 10 the inner ring 46 is exactly the same as that of the embodiment of Fig. 2, but the outer ring 144 is provided with shoulders 146 projecting axially outward beyond the circumferential projection 148 which engages the recess in the inner ring, the shoulders 146 abutting the free end edges 42 of the flare pipe ends 36 without any intervening free space.

In the embodiment shown in Fig. 11 the inner ring 46 likewise resembles that of Fig. 2 but the outer ring 150 is provided on both sides with axial, tubular prolongations 152 which extend over the straight portions of the pipes 2 behind their flared ends. The outer ring 150 with the prolongations 152 is divided in a diametral plane into half shells which are clamped together by bolts 34. This arrangement relieves stress on the flared pipe ends 36, so that with a pipe connection of this kind it is possible for greater distances between adjacent pipes 2 to be bridged without any intermediate support.

The embodiment shown in Fig. 12 enables flow resistance in the region of the pipe connection to be reduced and at the same time places the necessary seals in protected positions. For this purpose the straight piece of piping 2 is provided with a cylindrical enlargement 154 having the flared pipe end 36 at its axially outer end. The inner ring consists of two similar, annular parts 1 56 with part-spherical surfaces 160 to abut the corresponding internal surfaces of the flared pipe ends 36. A sleeve 162 is inserted in the opposed cylindrical enlargements 154 and sealed by means of the seals 168 inserted in grooves 1 66 provided at opposite ends of the sleeve 162.In the centre of the sleeve 1 62 is a circumferential, radially outward projection 164 against opposite sides of which vertical surfaces 158 of the inner ring parts 156 rest.

This centres the sleeve 162 in relation to the flared pipe ends 36. The outer ring 24, corresponding to that of the embodiment of Fig. 1, surrounds the flared pipe ends 36 and in view of its boundaries 29 and 30 permits the pipes a certain angular mobility. In order to ensure that the sleeve 162 does not jam or undergo deformation in this process, which might result in leaks, the end regions of the sleeve 162 have part-spherical radially outer surface portions 170.

As described in connection with Fig. 7, the flared pipe ends may have a certain angle in relation to the straight pieces of piping 2, this being achieved, in the example illustrated in Fig. 7, by an interposed pipe bend 136. In the embodiments shown in Figs. 13 and 14, on the other hand, flared pipe ends 174 are provided, the free end edges 176 of which form an angle of less than 90 with the axis of the straight piece of piping 2 on which each is formed.

As the flared pipe ends 174, as in the other examples, particularly that shown in Fig. 12, are part-spherical in shape, a circular shape for the free end edges 176 is ensured.

A cylindrical enlargement 172 is provided between each straight piece of piping 2 and its flared pipe end 174 and accommodates a sleeve consisting of two parts 188. The plane of separation 204 between the two halves of the sleeve 1 88 is inclined in relation to the axis of each straight piece of piping 2 by the same angle as the plane of the free end front edge 176 of each flared pipe end 174. The plane 204 is the median plane of a two-part circumferential projection comprising parts 1 90 and 192 respectively integral with the parts 188 of the sleeve. One part 190 is provided with an annular rib 194 while the other part 192 has an annular rebate 196.

The rib 194 engages the rebate 196 to centre the parts 188 with respect to each other.

Sealing in the plane of separation 204 is effected by a sealing ring 208 in an annular groove 200. Each part 188 is secured against rotation with respect to the corresponding cylindrical enlargement 172 by means of a radial projection 206 which engages a corresponding recess 208 in the cylindrical enlargement 172. The projection portions 190 and 192 have on opposite sides thereof parts 178 and 180 of the inner ring abutting against the portions 190 and 192 by side surfaces 186. The inner ring part 178 is provided with a sleeve-like shoulder 182 with an internal thread while the inner ring part 180 has an external thread 184 which is screwed into the sleeve-like shoulder 182.

The outer ring 24 is the same as in the embodiments of Figs. 1 and 12. The embodiment of Fig. 14 provides dual angular mobility between the mutually opposed pipe ends.

As a result of the intermediate spaces between the free end edges of the flared pipe ends 174 and the projection 32 of the outer ring 24 the flared pipe ends 1 74 can be pivoted by a small angle between the inner ring parts 178 and 180 and the outer ring 24. In addition, however, the opposed flared pipe ends 174 can be rotated with respect to one another and can assume any angular position in relation to each other up to the maximum angle shown in Fig. 14. This provides a simple means, with the inclusion of a sleeve which reduces flow resistance, of laying a pipeline in such a way that individual pieces of pipe can be adjusted to any desired angle with respect to one another within certain predetermined limits.

In the embodiments of Figs. 12 and 13 the sealing of the pipe connection is effected excusively by the seals provided in the sleeves 162 and 188. In the embodiment of Fig. 15 additional seals 50 are provided in annular grooves 48 in the abutment surfaces of annular inner ring parts 210 and 212 of triangular radial section. Furthermore, a seal 198 is provided in the screw-threaded connection between the inner ring parts 210 and 212. This provides, between the inner ring parts 210 and 212 and the sleeve parts 188, a sealedoff space which is accessible from outside the pipeline through a screw-threaded nipple 214.

This screw-threaded nipple 124 enables the connection to be checked for leakage or permits injection of a sealing medium into the space.

The present invention thus provides a pipe connection which is of simple construction, consists of strong individual parts, of which there are only a moderate number, enables piping systems to be assembled on open ground or on the beds of waterways and which can be rapidly laid and dismantled without grading and aligning operations. If this object is to be achieve it must be possible for a pipe connection to be produced and detached between adjacent pieces of piping without any axial displacement of the pipes.

The present invention provides pipe connections enabling this to be achieved.

Pipe connections in accordance with the invention can be made which will provide a satisfactory seal both at sub-atmospheric and at super-atmospheric pressures and in a wide variety of media. It is desirable that the pieces of piping, including the pipe connections, should be capable of being stored and transported in a space-saving and inexpensive manner, as pipes may only have to be in use for a short time but nevertheless have to be made and stored in advance.

The pipe connection provided by the invention ensures that with comparatively small flanging of the pipe ends, enabling the pipes to be stacked comparatively close together, an adequate pivoting angle will be available within the pipeline. The angular adjustability of adjacent pipes is "stepless", so that the pipes can follow minor displacements without difficulty, or else a selected angle can be made permanent. The pipe ends are of the same shape, so that in storage and transport protection can be provided with one single shape of cover. Other parts of the pipe connection, when screwed together, need no protection in transport, as all functional surfaces occupy a protected interior position.

The pipe connection to which the invention relates also makes it possible to lay comparatively long pipelines in the ground and thus to take thermal expansion into account, replace damaged pipes and insert branch pipes and valves in an existing pipeline.

Without requiring angular mobility within the pipe connection itself the pipe ends can be joined together and installed by turning bent end portions of the pipes through any angle between 0 and twice the angle at which the pipe ends are bent. This also enables pipes to be laid in bends having almost any desired radius of curvature, e.g. along a road, dam or railway, and provided the radius of curvature is not too small this can be done without any additional components.

It is of particular advantage to lay a pipeline in a moderate zigzag configuration. In this case length differences and vibrations can be compensated by a mere adjustment of the position of the connections on the ground, without any appreciable increase in the stresses suffered by the material. This requires no addition parts, and the increase in the length of the pipeline remains very limited.

Flow restrictions in the pipeline will likewise only be slight, thanks to the fact that the full cross-sectional area of the pipeline is available throughout one connection. The adoption of a slight zigzag configuration in the laying of the pipes also makes it possible to remove and replace any desired individual pipe in a laid system without having to detach anything other than the two adjacent pipe connections.

By utilising in a different degree the angle of mobility available in each pipe connection it is possible, after detaching a pipe connection, to pivot the pipe ends far enough to render possible the extraction of a single-piece inner ring of non-variable axial length. Other sections of pipe can also be inserted at these points in such a way as to facilitate the insertion of branch pipes or valves.

Owing to the mobility of the pipe ends in the pipe connections together with ample adjustability of the angular relationship of individual pieces of pipe, the laying of a pipeline can be started in different positions simultaneously, by different groups of operators, and any gaps occurring between two such groups can be closed without difficulty.

Claims

1. The assembly of two pipes with opposed, outwardly-flared ends (as herein defined) and connection means comprising an inner annular member which is tapered in radial section so as to have axially opposite abutment surfaces respectively complimentary to the radially inner surfaces of the flared ends of the pipes and an outer annular member having radially inner, axially spaced-apart abutment surfaces respectively to engage the radially outer surfaces of the flared ends of the pipes, means being provided whereby the outer annular member may be restricted so that the flared ends of the pipes will be clamped between the abutment surfaces of the inner and outer annular members.

2. The assembly claimed in claim 1, wherein the radially inner surface of each flared pipe end and the corresponding abutment surface of the inner annular member are part-spherical upon spheres of similar diameter, the arrangement being such that the angular orientation of the pipes may be altered by slackening and subsequently retightening the outer annular member.

3. The assembly claimed in claim 2, wherein the radially outer surface of each flared pipe end and the corresponding abutment surface of the outer annular member are part-spherical upon spheres of similar diameter.

4. The assembly claimed in claim 3, wherein the centres of the spheres upon which the radially outer and inner surfaces of a flared pipe end lie coincide with the axis of said pipe.

5. The assembly claimed in claim 4, wherein said centres are spaced apart along said axis so that the wall thickness of said flared end varies in the radial direction.

6. The assembly claimed in claim 5, wherein the wall thickness of said flared end increases in the radially outward direction and it is provided in a radially outer region of its radially inner surface with a circumferential recess in which resilient sealing means is located to engage the corresponding abutment surface of the inner annular member.

7. The assembly claimed in claim 4, wherein said centres coincide with one another.

8. The assembly claimed in any one of the preceding claims, wherein each said abutment surface of the outer annular member is of lesser axial extent than the associated flared pipe end and terminates at its axially inner end at a step serving to limit movement of said pipe end axially inward of the outer annular member.

9. The assembly claimed in any one of the preceding claims, wherein the abutment surfaces of the inner annular member have circumferential grooves in which resilient sealing rings are located for sealing engagement with the respective pipe ends.

10. The assembly claimed in any one of the preceding claims, wherein the outer and inner annular members are formed or provided in their median planes with male and female formations which interengage to maintain said members in a predetermined orientation independent of the angular orientation of the pipes.

11. The assembly claimed in claim 10, wherein the outer annular member is formed with a radially inward projection which is engageable in a recess in the circumference of the inner annular member.

12. The assembly claimed in claim 11, wherein the arrangement is such that when the outer annular member is restricted the inner annular member is locked against angular movement relative to the outer annular member.

13. The assembly claimed in any one of the preceding claims, wherein the restriction means comprises at least one bolt which acts between separated surfaces of the outer annular member to tend to reduce the diameter of the latter.

14. The assembly claimed in any one of claims 1-1 2, wherein the outer annular member comprises two parts which are separable axially of the member and wherein the restriction means comprises bolts circumferentially spaced around the member and operable to draw the parts axially toward one another.

15. The assembly claimed in claim 14, wherein the inner annular member comprises two parts respectively formed with said abutment surfaces and having a screw-threaded connection such that the axial dimension of the inner annular member can be varied.

16. The assembly claimed in any one of claims 1 to 14, wherein the inner annular member is of multipart construction and comprises a cylindrical sleeve of outer diameter similar to the inner diameters of the pipes adjacent the flared ends thereof, the sleeve having a central, radially outward circumferential projection, and a pair of annuli disposed on opposite sides of said circumferential projection and each of generally triangular radial section to provide the abutment surfaces of the inner annular member.

17. The assembly claimed in claim 16, wherein the sleeve comprises two parts which are separable in the median plane of the circumferential projection.

18. The assembly claimed in claim 17, wherein the two parts of the sleeve are noncoaxial, the axes of the two parts forming an angle determined by the non-perpendicular orientation of at least one of the two projection parts with the associated sleeve part.

19. The assembly claimed in claim 17 or claim 18, wherein one part of the circumferential projection has an annular rib which engages in a corresponding groove in the other part of the circumferential projection.

20. The assembly claimed in any one of claims 16-19, wherein each pipe is of enlarged diameter adjacent its flared end to provide an annular rebate to accommodate one end of the sleeve.

21. The assembly claimed in any one of claims 16-20, wherein at least one of the pipes is apertured in the region of the axially inner extremity of its flared end to permit the injection of a filler material into the space between the sleeve and the inner circumference of the associated annulus providing an abutment surface.

22. The assembly claimed in any one of the preceding claims, wherein the outer annular member has axial, tubular projections which extend over the flared ends of the pipes and wherein means is provided for engaging the free ends of said tubular projections to the pipes behind the flared ends thereof.

23. The assembly of two pipes with opposed, outwardly-flared ends (as herein defined) and connection means therefor substantially as herein described with reference to and as shown in Figs. 1 and 7, Fig. 2, Fig. 3, Figs. 4, 5 and 6, Fig. 8, Fig. 9, Fig. 10, Fig.

11, Fig. 12, Fig. 13, Fig. 140fig. 15 of the accompanying diagrammatic drawings.