AU630495B2

AU630495B2 - A seal ring for a sleeve joint

Info

Publication number: AU630495B2
Application number: AU61423/90A
Authority: AU
Inventors: Jyri Jarvenkyla
Original assignee: Uponor NV
Current assignee: Uponor NV
Priority date: 1989-08-30
Filing date: 1990-08-14
Publication date: 1992-10-29
Anticipated expiration: 2010-08-14
Also published as: JPH04501597A; CA2040416A1; FI892915A0; EP0441915A1; AU6142390A; WO1991003674A1; FI892915A

Description

I:.

WO 91/03674 PC/F90/00196 1 A seal ring for a sleeve joint This invention relates to a seal ring for a sleeve joint, which seal ring is intended to be placed in a sealing groove of a sleeve between the sleeve and an insert end and which seal ring is of a flexible material and arranged to be pressed against the sleeve and the insert end to lock these together in the direction of their longitudinal axles.

In water pipes and in some effluent pipes, such as pressure effluent pipes, the medium to be transported is subjected to pressure. The pressurization iF provided for instance by feeding the medium into a pipeline by means of pumps. Typical pressures are 3 to 8 bars. In certain situations, e.g. when the pumps are stopped, a considerable underpressure can also be created in the pipeline.

At points of change of course and discontinuity of pressurized pipelines, such as bends, valves and branch connections, the pipes and interconnectors of the pipeline shall be locked together in order to keep the mutual location of the parts unchanged during a pressure load. Because the pipeline parts must not be displaced with respect to the surrounding earth either, parts shall be locked together along such a distance that the friction between the pipes and the earth is large enough to anchor the bend point in its place. Locking rims are generally used to lock the pipes together and to the interconnectors, which rims surround the joint and grip the insert end by means of teeth thrusting into its surface.

The use of such a locking rim naturally causes costs, and because many plastic pipe materials, such as PVC, are sensitive to notch effect, the notches caused by the teeth weaken the pipe.

It is the object of the present invention to overcome or substantially ameliorate the above disadvantages.

There is disclosed herein a seal ring for a sleeve joint, which seal ring is adapted to be placed in a sealing groove of a sleeve between the sleeve and an insert end, the seal ring being formed of flexible material and adapted to be pressed against the sleeve and the insert end to lock these together in the direction of their longitudinal axes, the seal ring being at least partially of a material which expands when brought into contact with a liquid, wherein the inner surface of the seal ring to be against the insert end comprises a layer of friction increasing material.

The pressing force of the seal ring, directed to the sleeve and the insert end under the influence of the swelling, i.e. expanding, material included in the seal ring, typically increases when the pipeline is filled with water, the pipes being locked together in their longitudinal direction. Accordingly, there is generally no need to use locking rims, due to which the pipeline costs are decreased and the installation time is shortened.

20 According to an advantageous embodiment, a seal ring consists of three concentric layers, the innermost and outermost layer of which are of a conventional material used for seal rings and the middle layer is of said expanding material. In a seal ring constructed in this manner, those surfaces which have a sealing and locking effect are of a conventional sealing material, which is most suitable for these purposes, while the middle part of the ring includes expanding material, the sealing effect of which is not always on the same level as that of a conventional seal ring material, such as rubber.

In order that a material expanding under the influence of humidity would expand as fast and much as possible ,hen the pipeline is supplied with a liquid, it is advisable that the layer of the expanding miaterial comprises recesses, such as holes, which open to the surface of the ring facing the interior 1/01731 WO 91/03674 PCT/FI90/00196 3 of the pipe. Due to the recesses, the surface of the layer of the expanding material toward the interior of the pipe is larger than if the surface were even, thanks to which the advantages mentioned above are reached.

The locking effect of the seal ring can be decisively improved by means of an embodiment of the invention, according to which the inner surface of the seal ring facing the insert end comprises a layer of a material increasing friction. The material increasing friction can be a grinding agent, such as corundum, and due to that the locking force between the seal ring and the insert end becomes greater than if the mere sealing material were pressed against the insert end.

In general, relatively soft rubber qualities, to 60 °IRH, are used as sealings. In these cases the sealings are dimensioned for great compressions (of ab. 30 This is usable at joints with small tolerances of sleeve and insert end, i.e. when the clearance is small, so that the pressure does not press the sealing out of the sleeve. Now it has been observed unexpectedly that by using relatively hard rubber qualities together with an expanding material at a seal ring the advantage is reached that the ring endures, except strain by compression, also tension strain without being pushed out of the sleeve. This need appears with emphasis when a joint allowing angular variations is constructed, which makes large joint clearances necessary. When a hard sealing is used, there is a risk that the joint leaks on the groove side. Such leakages can be prevented in such a manner that the rubber ring has a zone of a softer rubber quality on the back side of the ring as well as on the insert end side of the ring.

.0, a ii i i i: i s r WO 91/03674 PCT/F190/00196, C~reSe,,, Cor~ oC re The S l k rir =uuu d n the invention 1 described in the following in greater detail with reference to the enclosed drawing, in which Figure 1 shows a sleeve joint using a seal ring according to the invention, in partial longitudinal section, Figure 2 shows a detail of the joint on a larger scale, the seal ring differing to some extent from the one shown in Figure i, and Figure 3 shows a third embodiment of the seal ring.

Figure 1 shows a sleeve joint between two pipes 1 and 2. At the end of the pipe 1 there is a sleeve 3 surrounding an insert end 4 of the pipe 2. The sleeve 3 is provided with a sealing groove 5 opening inwards and having a seal ring 6.

The seal ring is made of a flexible material and it is dimensioned in a usual manner with a crosssection so great that it is pressed against the sleeve 3 and the insert end 4, to seal the slot between these parts and to lock them together in the longitudinal direction of the pipeline.

According to the invention, the seal ring 6 consists partly of a conventional seal ring material 7 and partly of a material 8 expanding when coming into contact with a liquid.

In the embodiment of Figure i, the seal ring surfaces positioned against the sleeve 3 and the insert end 4 consist of the seal ring material 7 and between them, in the middle part of the ring crosssection, there is a layer of the expanding material 8. This layer extends up to the ring surface on that side of the ring which faces the interior of the pipeline, due to which the liquid in the pipeline comes into contact with the material 8.

WO 91/03674 PCT/FI90/00196 The material 7 preferably consists of a hard rubber, the °IRH of which is at least 70. It can, if necessary, be coated with a layer of a softer rubber, which layer faces the sealing groove 5 of the sleeve and the insert end 2. Figure 1 shows also a mounting socket 9 surrounding the insert end, which socket can be used to facilitate the positioning of the seal ring.

The seal ring according to the invention functions in the following manner. The seal ring 6 is brought to the mounting place in an airtight packing in order that the humidity of air would not cause an expansion of the material 8, which can be for instance hydrophile rubber. The seal ring is taken out of the packing and arranged in the sealing groove of the sleeve, after which the mounting socket 9 is pushed so far into the sleeve that it covers the inner surface of the seal ring. After this the insert end 4 is pushed into the mounting socket and the socket is drawn out of the slot between the sleeve and the insert end.

The invention is intended to be used primarily in connection with pressure pipes, which are disinfected before use and tested as to pressure-tightness. In connection with these measures, the pipe is filled with a liquid seeking its way from the interior of the pipe through the slot between the insert end and the sleeve to the seal ring. The hydrophile material 8 begins to swell when being contacted by the liquid, due to which the outer and inner surfaces of the seal ring are pressed with great force against the sleeve and the insert end locking them in place in the longitudinal direction of the pipe.

Figure 2 shows a seal ring, the structure of which somewhat differs from the ring shown in Figure WO 91/03674 PCT/FI90/00196, 6 1. In this case, the layer 8 of the expanding material extends across the seal ring from edge to edge and said layer has recesses 10 adjacent to each other, one of which is shown in broken lines in Figure 2.

The recesses in the embodiment of Figure 2 are holes having a bottom and opening to that surface of the ring facing the interior of the pipe, so that liquid can come into the holes when the pipe is filled with water. The object of the holes is to extend the surface of the layer 8 to improve the expanding effect i of the material.

The embodiment of Figure 2 differs from the emi bodiment described earlier also in the respect that the inner surface of the seal ring 6 facing the insert end is provided with a layer of a material increasing friction, for instance a grinding agent, such as corundum. This layer is indicated by the reference numeral 11. In addition to the grinding agent, the layer includes a binding agent binding the grinding agent to the surface of the seal ring. Especially in this embodiment, it is recommendable to use a mounting socket 9, because the grinding agent makes it heavy to push the irsert end into the sleeve otherwise.

The seal ring has a lip 12 arranged to be pushed into a non-shown groove parallel to the periphery and located in the outer surface of the insert In the embodiment of Figure 3, the seal ring 6 has two layers, the outer layer 7 of which consists of a conventional seal ring material and the inner layer 8 of a hydrophile rubber or the like. The inner surface of the ring comprises a layer 11 of a material increasing friction. The inner and outer surface of the sealing additionally have zones 13 consisting i r i i WO 91/03674 PCT/FI90/00196 7 of a seal ring material being softer than the material of the layer 7. The zones prevent leakages when the layer 7 consists of a hard material.

According to Figure 3, the inner surface of the groove 5 and the outer surface of the seal ring facing the sleeve are formed to a circular segment.

This is to an advantage when the pipes are placed in an angle with each other, and additionally, it helps to provide a locking of the insert end, because the sealing can turn in the groove when swelling and can thus be adjusted to a possible angular variation of the joint. Further, in a ready-mounted pipeline the sealing can freely follow possible angular variations.

Differing from the above, the inner surface of the seal ring according to Figure 1 can also be provided with a layer increasing friction or the surface can be handled in some other way so that it engages well in the insert end. So, a split ring made of metal and having teeth on its inner surface can be placed on the inner surface of the seal ring.

The expanding layer 8 extends most preferably along the whole length of the seal ring as a continuous layer. Alternatively, the expanding layer can be a ring, which is loose with respect to a ring of a conventional seal ring material and can be located outside or inside the lastmentioned ring or within it. The expanding material can also form the whole seal ring.

Claims

2. A seal ring according to claim 1, wherein the seal ring comprises three concentric layers, the innermost and outermost layer being of a conventional material used for seal rings and the middle ring being of said expanding material.
3. A seal ring according to claim 1, wherein the expanding material forms a layer on the inner surface of the ring.
4. A seal ring according to claims 2 or 3, wherein the layer of the expanding material has recesses, such as holes, opening to the side of the ring facing the interior of the joint. A seal ring according to any one of the preceding claims, S 20 wherein said expanding material is hydrophile rubber.
6. A seal ring according to any one of the preceding claims wherein the friction increasing material is a grinding agent, such as corundum.
7. A seal ring according to claim 1, wherein the seal ring has a lip arranged to be pushed into a groove on the outer surface of the insert end. o 0
8. A sleeve joint according to claim 1, wherein the material surrounding the expanding material is hard rubber, the °IRH of which is at least
9. A sleeve joint according to claim 8, wherein the hard rubber is on the outer and inner surface of the seal ring and is coated with a layer of a softer rubber. A sleeve joint according to any one of the preceding claims, wherein the surface of the seal ring facing the sleeve has a curved cross-section profile.
11. A seal ring substantially as hereinbefore described with reference to the accompanying drawings. L 1731 9 DATED this TWENTY-SIXTH day of AUGUST 1992 Uponor N.V. Patent Attorneys for the Applicant SPRUSON FERGUSON S S *S S S S *S S S t S S SS I