IE883454L

IE883454L - Sleeve for connecting two pipes in abutment

Info

Publication number: IE883454L
Application number: IE883454A
Authority: IE
Inventors: Marc De Preter
Original assignee: Eternit Nv
Priority date: 1987-11-20
Filing date: 1988-11-18
Publication date: 1989-05-20
Also published as: EP0317546B1; EP0317546A1; ES2024696B3; DE3864985D1; IE61424B1; TNSN88124A1; BE1001227A4

Abstract

This connector system is composed of a connection sleeve (16) designed to fit over two tubular components (17) having at each of their ends a bevel (27) and a circumferential groove (21) cut into their outer surface. Each half of the sleeve (16) carries on its internal surface a rectangular groove (20) in which a split lock ring (28) is inserted, and at least one sealing hoop (18) positioned between the rectangular groove (20) and the free end of the sleeve (16). <IMAGE> [EP0317546A1]

Description

6 1 4 2 4 A tension-resistant, fluid-tight, connecting system for smooth-ended pipes.

The invention relates to a tension-resistant, fluid-tight, connecting system for substantially smooth-ended pipes.

The connecting system according to the invention rnav be used to ensure a tension-resistant joint between tubular members made from different 5 kinds of materials, such as, for examplet fibre cement, asbestos cement, metal, organic plastics materials, or fibre-reinforced plastics (especially fibre-reiiiforced polyester). The connecting system according to the invention may be used not only for pipes for conveying liquid or gaseous fluids, but also for pipes for conveying solids in powder form or in 10 suspension.

In the description which follows, more particular mention is made of fibre cement pipes for the conveyance of water. However, this represents a non-1isniting example only, and the invention clearly applies to any pipework comprising smooth-ended pipes.

During the installation of such pipework, assembly of tubular members using connecting sleeves is widely known. In this, the ends of" two adjacent pipes are introduced into a connecting cylindrical sleeve, whose internal diameter is slightly greater than the external diameter of the ends of the pipes. Fluid-tightness between the connecting sleeve and the ends of the 8 pipes is ensured by means of one or more resilient sealing rings. It is a 5 recognised fact, however, that as a rest?It of the hydraulic pressure within ( the pipe, the axial forces produced tend to separate the adjacent tubular members. Thus, as the hydraulic pressure in water-conveying pipes may reach values of the order of 1,500 KPa, the forces which tend to separate the adjacent tubular members are particularly high (more especially in pipes of 10 large diameter). When the pipes are assembled in a straight line and buried, the surrounding soil helps to prevent axial movements of the pipes. It is however necessary in most cases, and more particularly for curved parts and at the ends of pipes, to provide connections furnished with tension-resistant means.

In the present state of the art, such tension-resistant connections are known.

A well-known tension-resistant connection system comprises a cylindrical sleeve into which the ends of two adjacent tubular members are introduced; the resistance to tension is obtained by inserting, through an 2o opening provided in the sleeve, a steel cable, a flexible plastics strip, or a metal band,, into an annular space formed by two grooves provided opposite one another on the internal surface of the sleeve and on the external surface of the pipe. Fluid-tightness of the connection is obtained by a resilient ring disposed between the sleeve and the end of the pipe, nearer to the middle of 25 the sleeve than the cable or strip which ensures the resistance to tension.

However, this type of pipe connection has an important disadvantage, in that it is necessary to form a groove near the ends of the pipes- The transverse section of the pipe at this groove thus constitutes the critical section for the calculation of the force required to resist internal hydraulic 30 pressure6 for in fact there is no external pressure to compensate for this internal pressure. It follows that a pipe provided with this type of tension-resistant connection must be proportionally thicker along its entire length than a standard pipe resistant to the same pressure. It must also be noted that on a construction site, the insertion of a steel cable (or other 35 flexible member) into the annular space provided for its reception is often a very difficult operation. Also, when such a connection is used, it is difficult, and indeed practically impossible, to replace a defective pipe.

In United States Patent Specification No. 2,637,239, a tension-resistant fluid-tight connecting system for smooth-ended pipes is 5 described. Connection of two tubular members is achieved by a substantially cylindrical sleeve, which is symmetrical with respect to a median plane perpendicular to its axis. In each half of the sleeve, a resilient sealing ring is mounted, which is partially engaged in an annular groove provided for the purpose in the internal face of the sleeve. In each half of the sleeve, 10 a second annular groove is also provided, between the sealing ring and the free end of the sleeve; a transversely split securing ring is engaged in this second groove. An annular groove is also provided on the external periphery of each pipe member to be connected. The relative dimensions of the different parts of the assembly are such that on inserting the tubular member 15 into the sleeve, the securing ring is dilated or expanded and engaged in the annular groove of the pipe when this latter arrives opposite the groove of the sleeve which carries this securing ring, so rendering the connection resistant to tension.

With a connecting system such as is described in United States Patent 20 Specification f*!o. 3,537,239, connecting pipes is decidedly easier than with a connecting system in which the resistance to tension is obtained by a cable or other flexible member engaged between the pipe and the sleeve through an opening provided in this latter. However„ in the system described in United States Patent Specification Mo. 3,637,239, nothing is provided to enable 25 disengagement of a pipe member from the sleeve in which it has been encased, and thus replacement of a defective pipe poses a very difficult problem.

German Patent Specification No. 1928050 has for an object, a connecting system which, on the whole, is very similar to that described in United States Patent Specification No. 3,637,293. However, at each end of 30 the connecting sleeve, slots are provided between the end of the sleeve and the groove in which the securing ring is mounted. These slots, which give access to the free ends of the securing ring (split ring) are provided to permit disengagement of a pipe member from the sleeve in case of necessity (for example, to replace a defective pipe). However, when a pipe is buried, 35 the said slots allow penetration of earth between the pipe member* and the . 4 _ sleeve, which can lead to complete obstruction of the annular space in which the securing ring is housed; in such circumstances, disengagement of a pipe member from the sleeve is often difficult.

In any case, for the tension-rfesistant connecting system described in German Patent Specification Mo. 1928060, just as for that which is described in United States Patent Specification No, 3,637,293, the annular groove provided near the end of the pipe member implies that this member must be thicker along its entire length.

Another system of tension-resistant connection is also known, in which a ring of rubber in a V-shape fulfills at the same time, the functions of fluid-tightness and resistance to tension.

Such connections are, however, only suitable for use at relatively low pressures. It must also be noted that it is still necessary to provide a groove near the end of the pipe, which must, in this instance also, be thicker along its entire length.

It is an object of the invention to provide a connecting system in Nhich the groove near the end of the pipe no longer necessitates the use of a pipe of increased thickness along its entire length.

It is also an object of the invention to provide a connecting system which facilitates the connection of pipes, and, in case of necessity, replacement of a defective pipe.

According to the Invention, there is provided a tension-resistant fluid-tight connecting system for smooth-ended pipes, comprising a substantially cylindrical sleeve, in which two tubular members are sleevingly received means for rendering the connection fluid-tight and resistant to tension, and at least one sealing ring disposed between the sleeve and each sleeved tubular member. Each tubular member is provided, at each of its free ends, with a chamfer directed towards the exterior, and is provided, on its external surface, near each of its free ends, with a circumferential groove; this groove has a bottom surface and two lateral or side surfaces, the bottom surface being essentially smooth and parallel to the external surface of the tubular member, the lateral or side surface which is nearest to-the free end of the tubular member being perpendicular to the longitudinal axis of said tubular member, and the other lateral or side surface having a frustoconical configuration, sloping gently from the bottom of the groove to the external surface of the tubular member. Each half of the sleeve, which is symmetrical with respect to a median plane perpendicular to its longitudinal axis, is provided, on its internal surface, with a circumferential rectangular groove, the lateral or side surfaces of which are parallel to said median plane* this rectangular groove contains or accommodates a transversely-split securing ring of rectangular section,: this ring, when not stressed, has an internal diameter which is less than the internal diameter of the sleeve and an external diameter which is greater than the internal diameter of the sleeve but less than the diameter of the bottom of the rectangular groove. Each half of the sleeve is provided with at least one resilient sealing ring between the rectangular groove which contains the securing ring and the end of the sleeve. The relative dimensions of the different parts of the connection are such that during reception or encasing of a tubular member in the sleeve, the securing ring is engaged by the chamfer of the free end of the tubular member, is then dilated or expanded, and is finally engaged by its resilience in the groove of the tubular member, and this when the two grooves of the tubular member are aligned opposite one another, thus rendering the connection resistant to tension.

According to a preferred embodiment, each sealing ring is partially inserted in a groove of appropriate shape provided for this purpose in the internal face of the sleeve. The sealing rings are normally made from a synthetic or natural elastomer.

According to a particular embodiment;, the sealing rings are joints of the well-known "COMETE" (Trade Hark) type.

Both the sleeve and the tubular members may be made from various materials; fibre cement (among others, asbestos cement), metal, plastics materials, or fibre-reinforced plastics (for example polyester reinforced with fibreglass).

The securing ring can also be made of different materials, such as stainless steel, plastics, or reinforced plastics. It is advantageous for the securing ring to have a shear resistance at least equal to tftat of the sleeve and the tubular members.

The term "smooth-ended pipes" is used here to make the distinction between pipes of this type and pipes having threaded ends or flanged pipes, for which the connecting systems are ve'rv different. Even if, in the 5 connecting system according to the invention, the pipes to be connected are provided, near their ends, with a circumferential groove formed on their external periphery, these pipes are nevertheless of the "smooth-ended" type.

The invention will be better understood from the following description of a non-limiting example and by comparison with the state of the 10 art as well as from the accompanying drawings, in which Figure 1 is a partial longitudinal section of a known connection resistant to tension, Figure 2 is a view similar to Figure 1 of another tension-resistant joint, Figure 3 is a partial longitudinal section of a connecting system according to the invention, and Figure 4 is an enlarged view of a partial longitudinal section of a connecting system according to the invention.

Figure i shows a known connection resistant to tension consisting of 20 a sleeve 1 into the two ends of which tubular members 2 of fibre cement are engaged. Between the sleeved or encased tubular member 2 and the sleeve 1, sealing rings 3 of rubber have been provided which are partially inserted into grooves 4 of the sleeve 1. The sealing rings 3 used in this example are of the "COMETE" (Trade Hark) type. The sleeve 1 is also provided with two 25 grooves 5 situated between its free ends and the grooves 4.

On each tubular member 2, a groove 5 is also provided. When : mounting a tubular member 2 (with a chamfered end 7) in the sleeve 1, an assembly mark 8 allows the relative positions of these two components to be adjusted in such a way that the groove 5 of sleeve 1 and the groove 6 of the 30 tubular member 2 may be disposed opposite one another, thus forming an annular space into which a steel cable 9 may be inserted through a hole 10 bored tangentially in the sleeve 1. The cable 9 ensures that the connection is resistant to tension and that the tube or pipe 2 is locked into the sleeve 1.

It may be noted that the thickhess of the pipe 2 under the groove 6 5 determines the critical section of the pipe 2 for resisting internal pressure, because at this precise point, there is only internal pressure and no external pressure.

As previously explained, one of the consequences of using this type of tension-resistant connection is that the pipe 2 must be thicker throughout 10 its length than a standard pipe resistant to the same pressure. This disadvantage is particularly bothersome, because even with standard pressure-resistant fibre cement pipes, the ends must be thinned down so that the section to be sleeved may be smooth and of exact diameter.

Furthermore, the assembly of such connections proves difficult, 15 because the steel cable 9 can only be introduced into the annular space 5-5 when the two grooves 5 and 5 are exactly opposite one another. It is also clear that when a connection of this type is used, dust, water and soil may penetrate between the tubular member 2 and the sleeve 1 as far as the sealing ring 3, completely filling the grooves 5 and 6, When a pipe has been 20 underground for some time, it becomes practially impossible to undo a connection, because the cable 9 cannot be extracted from its annular space. For this reason, amongst others, it is, with this type of connection, extremely difficult to replace a defective tubular member 2.

Figure 2 shows the "TOSCHI" joint for pipes, which comprises a 25 double connecting sleeve 11 made from a section of fibre cement for sleeving reception of two tubular members 12. On the internal face of the sleeve 11, at equal distances from its two ends, two grooves 13 are formed. In the same manner, a groove 14 is provided on the external face of each tubular member 12.

After assembly of the parts, a V-shaped sealing ring 15 is inserted 30 into each of the annular spaces formed or defined by the grooves 13 and 14, which face each other.

The sealing ring 15 is required to fulfill simultaneously the functions of sealing and resisting tension, this type of connection being only appropriate for pipes operating at a relatively low hydraulic pressure.

Figures 3 and 4 illustrate a connection system formed according to the present invention for smooth-ended ^ipes.

This connecting system consists of a double connecting sleeve 16 in which two tubular members 17 are sleevinglv received. Between the sleeved tubular members 17 and the sleeve 15, sealing rings 18 of rubber have also been provided, which are partially inserted into the grooves 19 of the sleeve 15. In the present example, the sealing rings are of the "COMETE" (Trade Mark) type.

In the sleeve 16, a pair of rectangular grooves 20 have also been provided, situated between the grooves 1Q and the middle of the sleeve 16-The sleeve 16 is symmetrical with respect to its longitudinal axis and with respect to a median plane M-M perpendicular to this longitudinal axis.

Each tubular member 17 is provided with a groove 21 on its external face, extending around its periphery, the said groove 21 having a bottom surface 22 and two lateral or side surfaces 23 and 24. The bottom surface is smooth and parallel to the external surface 25 of the tubular member 17. The side surface 23 which is nearest to the free end 26 of the tubular member 17 is perpendicular to the longitudinal axis of the tubular member 17. The other lateral or side surface 24 is of a frustoconical configuration and has a gentle slope extending from the bottom of the groove 21 in the direction of the external surface 25 of the tubular member 17.

The free ends 26 of each tubular member 17 are provided with a chamfer 21 on their external portion.

In the groove 20, a securing ring 20 is accommodated, which is split transversely and is of rectangular cross-section.

When it is not stressed (i.e. before the introduction of the tubular member 17 into the sleeve 15), the securing ring 28 has an internal diameter which is less than the internal diameter of the sleeve 16 and an external diameter which is greater than the internal diameter of the sleeVe 16, but less than the diameter of the bottom of the groove 20.

Accordingly, the securing ring 28 is unable to leave the groove 20, but may be outwardly expanded.

When the tubular member 17 is inserted into the sleeve 16, the 5 securing ring 28 is engaged by the chamfer 27 of the tubular member 17. When the tubular member 17 is more deeply inserted into the sleeve 16, the securing ring 28 is dilated or expanded, and then becomes engaged in the groove 21 of the tubular member 17 when the groove 21 becomes aligned with the corresponding groove 20 of the sleeve 16. The tubular member 17 and the 10 sleeve 16 are thus joined in a manner resistant to tension.

The connecting system according to the present invention proves particularly advantageous for use with pipes under pressure, for example, for water supply.

In contrast to the cable 9 used for the connection shown in Figure 1, 15 the securing ring 28 of the connecting system according to the invention is disposed in the wet region of the connection, i.e., it is in direct contact with the water conveyed by the pipe.

The groove 21 which contains the securing ring 28 no longer has a negative effect on the resistance to pressure of the wall of the tubular 20 member 17, because the ring 28 is situated in the wet region and, at this precise point, the internal and external surfaces of the wall of the tubular member 17 are subjected to the same pressure.

This allows a significant reduction in the thickness of material required for manufacture over the entire length of pipe 17.

The connecting system according to the invention also permits displacement of the sleeve 16 beyond its normal position with respect to the tubular member 17. This displacement is made possible by the frustoconical form of the lateral or side surface 24 of the groove 21. The sleeve 16 may thus be completely engaged about a tubular member 17, which enables possible 30 replacement of a pipe 17.

This represents an important advantage not provided by previously known connecting systems.

Claims

CLAIMS 1.
A tension-resistant fluid-tight connecting system for smooth-ended pipes, comprising a substantially cylindrical sleeve in which two tubular members are sleevinglv received, means for rendering the connection 5 fluid-tight and resistant to tension, and at least one sealing ring disposed between the sleeve and each sleeved tubular member, wherein each tubular member is provided, at each of its free ends, with a chamfer directed towards the exterior, and is provided with a circumferential groove on its external surface at each of its free ends, said groove having a bottom surface and two 10 lateral or side surfaces, the bottom surface being substantially smooth and parallel to the external surface of the tubular member, the lateral surface which is nearest to the free end of the tubular member being perpendicular to the longitudinal axis of said tubular member, the other lateral surface being of frustoconical configuration, with a gentle slope from the bottom of the 15 groove to the external surface of the tubular member, while each half of the sleeve, which is symmetrical with respect to a median plane perpendicular to its axis, is provided on its internal surface with a circumferential rectangular groove whose lateral or side surfaces are parallel to said median plane, this rectangular groove containing a transversely-split securing ring 20 of rectangular cross-section, which ring, when not stressed, has an internal diameter which is less than the internal diameter of the sleeve and an external diameter which is greater than the internal diameter of the sleeve but less than the diameter of the bottom of the rectangular groove, each half of the sleeve being provided with at least one elastic sealing ring between 25 the rectangular groove which contains the securing ring and the end of the sleeve, the relative dimensions of the different parts of the connection being such that when the tubular member is encased or received in the sleeve, the securing ring is engaged by the chamfer of the free end of the tubular member, is then dilated or expanded, and is finally engaged, by its resilience, in the 30 groove of the tubular member, when the two grooves of the sleeve and the tubular member are opposite one another, so rendering the connection resistant to tension. 2o A connecting system according to Claim 1, wherein each sealing ring is partially inserted into a groove of appropriate shape provided for this 35 purpose on the internal face of the sleeve. - 12 -
3. A connecting system according to Claim 1 or Claim 2, wherein the sleeve and the tubular members are of fibre cement.
4. A connecting system according to Claim 3, wherein the sleeve and the 1 tubular members are of asbestos cement. V
5. A connecting system according to Claim 1 or Claim 2, wherein the sleeve and the tubular members are of an organic plastics material.
6. A connecting system according to Claim 1 or Claim 2, wherein the sleeve and the tubular members are of fibre-reinforced plastics.
7. A connecting system according to Claim 6, wherein the sleeve and the tubular members are of glass-fibre-reinforced polyester.
8. A connecting system according to any preceding claim, wherein the securing ring has a shear resistance at least equal to that of the sleeve and the tubular members.
9. A connecting system according to any of Claims 1 to 7, wherein the securing ring is of stainless steel.
10. A connecting system according to any of Claims 1 to 7, wherein the securing ring is of an organic plastics material.
11. A connecting system according to any of Claims 1 to 7, wherein the securing ring is of reinforced plastics.
12. A connecting system according to any preceding claim, wherein the resilient sealing rings are of an elastomer.
13. A connecting system according to Claim 12, wherein the resilient sealing rings are of rubber.
14. A connection system according to Claim 1 and substantially as described herein with reference to and as shown in Figures 3 and 4 of the accompanying drawings.
15. A pipe joint made in accordance with the connection system of Claim 1 and substantially as described herein with reference to and - 13 - shown in Figures 3 and 4 of the accompanying drawings. TOMKIMS & CO. - 14 -