AU625643B2

AU625643B2 - A pipe coupling

Info

Publication number: AU625643B2
Application number: AU44765/89A
Authority: AU
Inventors: Stephen Lane
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-05-16
Filing date: 1989-11-17
Publication date: 1992-07-16
Anticipated expiration: 2009-11-17
Also published as: GB2218768B; GB2218768A; GB8910580D0; AU4476589A

Description

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625643 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: 44 C PI 4

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a 4I 4 4 Stephen Lane 7B 11th Avenue Rivonia Sandton Transvaal Republic of South Africa NAME(S) OF INVENTOR(S): Stephen LANE ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: A pipe coupling The following statement is a fuli description of this invention, including the best method of performing it known to me/us:p iir i la BACKGROUND OF THE INVENTION This invention relates to a coupling or joint for connecting co-axial lengths of piping.

It is often difficult to provide a coupling which embodies all of the following features, particularly on large diameter pipes: (a) (b) S• (c) (d) I I 44 15 (e) (f) (g) 20 S(h) (h) l Is easy to fit.

Has good sealing characteristics, especially at high pressures.

Can be easily removed.

Does not require special preparation of the pipe ends.

Will resist angular deflection of the pipe ends.

Will accommodate rotational misalignment.

Will accommodate a variable gap between the pipe ends or allow the pipe ends to butt closely together.

Will withstand both radial and axial pressure components, thus preventing axial separation of the pipes at the coupling at all operational pressures whilst maintaining a leak tight seal.

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141C KAewn-pi4pe-couplings which have been used for this purpose include pipe couplings of the kind to which this invention relates, namely pipe couplings consisting essentially of three main components, i.e. a tubular housing having an externally threaded portion and adapted to receive the pipe ends, two axially split gripping sleeves with an outer tapered surface and designed to surround the pipe ends and two tubular compression sleeves each having an internally threaded axial portion adapted to be screwed onto the externally threaded portion of the housing and having an internal tapering surface adapted to engage the

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-2tapering portion of the gripping sleeve in such a manner that, when the sleeves are screwed onto the housing, the relative displacement of the sleeves with respect to the housing causes the gripping sleeves to contract and thereby grip the pipe ends.

It has been found in practice that difficulties arise as fo 11ows i-cc i

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1) Difficulties in attaching or removing the coupling to or from the pipe, since such couplings use sealing rings which may impose a great resistance, particularly in large diameter pipes, to the insertion of the pipe into the housing bore, 2) Difficulties in ensuring both the effective gripping and sealing of the coupling at high pressures especially on large diameter pipes.

3) Difficulties in the economical production of such couplings again especially on larger sizes where quatities may not warrant expensive tooling and moulds.

SUMMARY OF THE INVENTION The invention provides a coupling for a pipe which includes a tubular body which is formed with an annular groove on an inner surface, a sealing ring which is located in the annular groove, an end of the pipe being 30 located within the tubular body with the sealing ring surrounding the pipe, at least a first pair of opposed shells which are located on an external surface of the 6-nc 4NwN ouerkie t lecsrr -kr-u-e- roove' tubular body/, means for drawing the shells towards one another so tat a compressive force is applied to the tubular body thereby to deform the tubular body so that its inner surface bears against an outer surface of the -3pipe, and so that a fluid tight seal is formed by the sealing ring within the confines of the annular groove and an outer surface of the pipe, the shells extending beyond a first end of the tubular body in the axial direction and including gripping formations at ends of the shells which are adapted to engage with an outer surface of the pipe when compressive force is applied to the tubular body.

The coupling may be adapted for use with two pipes wherein the tubular body is formed with two of the annular grooves 4 which are spaced from each other, two sealing rings are located respectively in the two annular grooves, abutting ends of the two pipes are located within the tubular body with each sealing ring surrounding a respective pipe, a fluid tight seal being formed by each sealing ring within the confines of the respective annular groove and an outer surface of the respective pip,, and the shells including gripping formations at opposed respective ends of the shells which engage respectively with an outer surface of each pipe when compressive force is applied to the tubular body.

The tubular body is preferably of a material having a low modulus of elasticity, as hereinafter defined.

Use may also be made of first and second pairs of the shells, the f'irst pair of shells being located at one end of the tubular body, and the second pair of shells being 3 located at an opposing end of the tubular body.

The coupling may be adapted to constitute a flange adaptor and, in this case, the tubular body includes a retaining formation at a second end which opposes the first end, and the coupling includes an annular flange which abuts the retaining formation and which is adapted to be engaged with a second pipe.

Ai The pipe coupling, whilst comprising the aforelisted basic components and elements, may thus take a number of forms: i) Each described component or element may be made in one, two or more parts which are fixed together during manufacture or located together during assembly.

ii) The gripper means may form part of an enclosure ring element.

iii) The enclosure ring element may be of two separate rings situated one at each end of the tubular body and designed to grip or locate into the outside of the tubular body to prevent axial displacement during operation.

iv) The enclosure ring elemetut may be of two separate rings situated one at each end of the tubular body but joined together by tie members to prevent axial displacement during operation.

v) The gripper means may be enclosed within the ends of the tubular body and have external gripping edges or a shoulder which locates within the ends of the tubular body and cannot be axially displaced during operation.

vi) The means for applying the compressive force may be bolts and nuts, toggle clamps, or other means.

DESCRIPTION OF PREFERRED EMBODIMENTS Various embodiments of the invention are described by way of example only, with reference to the accompanying drawings in which: Figure 1 is a partially sectioned' side elevation of a pipe a

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F 4 cn errnbhiIe .,it coupling according to he invention, and pipe ends, showing the coupling in an untightened condition, Figure 2 is an end elevation of the pipe coupling of Figure 1 but in a tightened condition, Figure 3 is a partially sectioned side elevation of a pipe coupling and pipe ends showing the coupling in a tightened condition, Figure 4 is a partially sectioned side elevation of a pipe coupling according to a.second form of the invention, Figures 5 to 7 are similar views of three other pipe o(n eo Pmbo&eAneet% o 15 couplings according to the invention, and Figure 8 shows a pipe coupling according to a variation of the invention, of the 'flange adaptor' type.

DESCRIPTION OF PREFERRED EMBODIMENTS Figures 1, 2 and 3 show a pipe coupling according to a first form of the invention.

The coupling includes a tubular body 1 and, located in an annular groove within each end of the tubular body 1 and around the abutting ends of each pipe is an annular sealing ring 2 the shape of which ensures a seal between the body and the respective pipe when the coupling is tightened and under pressure.

The tubular body is made from a material with a modulus of elasticity which is sufficiently low to enable the material to deform to the required amount without exceeding its yield stress. As will become apparent hereinafter the body is deformed into contact with the -4 hereinafter I I' lI -6outer walls of the pipes. Initially there is a clearance of say 1,5% of pipe diameter between the bore of the body and the pipes. This facilitates assembly of the coupling.

The modulus of elasticity of the material of the body should have a low enough value to ensure that the body can deform, as required, without failure. One such suitable material is high density polyethylene which has a modulus of elasticity of the order of 0,9 GPa. Unplasticized polyvinylchloride may also be used and its modulus of elasticity being of the order of 3,0 GPa. By way of contrast the modulus of elasticity of steel is in the region of 209 GPa. It is to be understood though that other materials which deform to the required amount can be used, even though the yield stress is exceeded, provided the materials do not fail or fracture.

At each end of the tubular body and around the inner end of each pipe is an annular gripper ring element 3.

Enclosing the tubular body 1 and the gripper ring element 3 is an annular enclosure rii;q 4. As is apparent from Figure 2 the enclosure ring 4 consists of two shells with mating flanges which can be clamped, and drawn inwardly, by means of suitable fasteners. In this example fasteners in the form of bolts and nuts 5 achieve this purpose.

In use the coupling is assembled as shown with the clamping'fasteners 5 in the untightened position. Ends of two co-axial pipes are inserted into each end of the coupling and positioned centrally, abutting one another.

Insertion of the pipe ends into the coupling is achieved i with a minimum of resistance because there is a clearance between the gripper ring gripping edges and the outside of the pipes, and the sealing rings have a clearance between I their inner edges and the outside of the pipes, or at -7worst a light interference fit.

1 In the case where a damaged removed from a pipeline and slid completely over one of positioning.

section of pipe is to be replaced, the coupling can be the pipes before final Once the pipes and coupling are in the correct position the clamping fasteners 5 are progressively tightened. This tightening has two effects:

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1) The gripping edges of the gripper rings are deflected radially inwards towards the pipe surfaces and then into the pipe surfaces.

2) The tubular body is compressed and so deforms and deflects radially inwards towards the pipe surfaces until circumferential contact is made with the outer surfaces of the pipes.

During this deforming operation the sealing rings 2 which are captive within the grooves in the tubular body 1 press against the outside of the pipes to form fluid tight seals. ring seals are one example of the type of seal which can be used.

During operation it will be appreciated that the gripping action prevents axial separation of the pipe ends.

Figure 3 shows the position of the gripper ring elements and other components when the coupling is in an operational and pressurized condition.

Flexible sealing rings used in pipe couplings are subject to the problem of being extruded through the small gaps between the adjacent components or the components and the -8pipes themselves when subjected to very high pressures.

When the pipe coupling is used to connect pipes of a plastic type material, the pipes tend to increase in.

diameter as the pressure increases. In this invention by using a tubular body of material which has a sufficiently low modulus of elasticity, as hereinbefore described, and an enclosure ring of a much stronger material such as steel any small gaps remaining in the unpressurized condition reduce and finally disappear when the pipes and coupling are subjected to increased pressure. This feature ensures that each sealing ring is fully contained and minimizes the possibility of extrusion.

15 Also as the pipe diameters increase under pressure this causes each gripper ring, which is captive withi' the enclosure ring, to dig further into the respective pipe surface.

The second, third, fourth, fifth and sixth embodiments of the invention as shown respectively in Figures 4,5,6,7 and 8 operate on the same principle as the first but take differing physical forms.

Thus in Figure 4 opposing ends of the shells extend beyond the body 1 and carry gripping formations 6. The rings 3 are therefore dispensed with.

Figure 5 shows that two sets of shells, 7 and 8 respectively, are used. The shells include projections 9 which engage in recesses 10 in the body 1, and shoulders 11 which abut respective gripper rings 3, thereby to prevent axial separation of the pipes.

The Figure 6 arrangement is similar to that of Figure except that the gripper rings 3 are omitted and replaced -9by gripping formations 12 on the outer ends of the two sets of shells.

Figure 7 shows a modification to the coupling of Figure 6 wherein the projections 9 are omitted and the two sets of shells 7 and 8 are fixed to one another by tie members 13, ito prevent axial separation of the components when the 1pipes are pressurized.

Figure 8 shows a pipe coupling of the flange adaptor type according to the invention. The left hand half of this I coupling is substantially similar to a corresponding half t of the coupling shown in Figure 6 and consequently is not described in detail. Thus an end of pipe 17 is surrounded by an annular seal 2 which is formed within a tubular body 1 which in turn is contained within one pair of compression shells 7.

The tubular body 1 however extends from the shells and incorporates an annular shoulder 16. An annular flange 18 abuts the inner side of the shoulder which acts as a retaining formation.

The flange 18 can be secured to the flange of a seconid pipe or fitting, as required.

It iill be appreciated that in all the embodiments the material being conveyed in the pipes comes into contact only with the seals and the tubular body.

11 The couplings of the invention are suitable for use with plastic pipes or pipes of any other material which is softer than the gripper ring material. This allows the gripper rings to dig into the pipe outer surface and prevent axial separation.

b iG Furthermore, the couplings are simple to install and may easily and rapidly be installed where a damaged or perforated section has been removed from a pipeline and a new section replaced as is the case when a pipe develops a leak.

The gripper rings exert a compressiie force on the two pipes. On pipes having thin walls, to minimize the likelihood of the pipes collapsing under this force a liner may be inserted into each pipe. A single liner may be used, which extends into both pipes, or each pipe may have a liner, with a locating flange, as shown in dotted lines marked 15 on Figure 3.

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Claims

1. A coupling for a pipe which includes a tubular body which is formed with an annular groove on an inner surface, a sealing ring which is located in the annular groove, an end of the pipe being located within the tubular body with the sealing ring surrounding the pipe, at least a first pair of opposed shells which are located on an external surface of the tubular body and which overlie at least the annular groove, means for drawing the shells towards one another so that a compressive force is applied to the tubular body thereby to deform the tubular body so that its inner surface bears against an outer surface of the pipe, and so that a fluid tight seal is formed by the sealing ring within the confines of the annular groove and an outer surface of the pipe, the shells extending beyond a first end of the tubular body in the axial direction and including gripping formations at ends of the shells which are adapted to engage with an outer surface of the pipe when compressive force is applied to the tubular body.

2. A coupling according to claim 1, for use with two pipes, wherein the tubular body is formed with two of the annular grooves which are spaced from each other, two sealing rings are located respectively in the two annular grooves, opposing ends of the two pipes are located within the tubular body with each sealing ring surrounding a respective pipe, a fluid tight seal being formed by each sealing ring within the confines of the respective annular groove and an outer surface of the respective pipe, and the shells include gripping formations at opposed respective ends of the shells which engage respectively with an outer surface of each pipe when compressive force is applied to the tubular body. 1 i1 -12-

3. A pipe coupling according to claim 2 wherein the gripping formations are provided by two gripping rings located respectively at opposed ends of the tubular body, the shells being engaged with the gripper rings thereby to restrain relative axial separation of the gripping rings.

4. A pipe coupling according to claim 3 wherein gripping rings are located within the shells which have shoulders respectively abutting the gripping rings.

A pipe coupling according to claim 2 wherein the gripping formations are integral with the shells. 0o

6. A pipe coupling according to claim 2 which 15 includes first and second pairs of the shells, the first pair of shells being located at one end of the tubular .oo' body, and the second pair of shells being located at an opposing end of the tubular body.

7. A pipe coupling according to claim 6 wherein each pair of shells and the tubular body include inter-engaging formations.

8. A pipe coupling according to claim 7 wherein the inter-engaging formations comprise grooves or recesses in the tubular body and complementary projections on the shells.

9. A pipe coupling according to claim 6 which includes means securing shells of the first pair to respective shells of the second pair. A pipe coupling according to any one of claims 6 to 9 wherein the first pair of shells extends beyond one end of the tubular body and the second pair of shells extends beyond an opposing end of the tubular body.

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11. A pipe coupling according to claim 10 wherein the gripping means includes gripping formations on the two pairs of shells adjacent the respective ends of the tubular body.

12. A pipe coupling according to claim 10 wherein the gripping means includes two gripping rings located respectively at opposed ends of the tubular body and engaged respectively with the two pairs of shells.

13. A pipe coupling according to any one of claims 2 to 12 which includes liner means within the two pipes. 15

14. A pipe coupling according to claim 1 wherein the tubular body includes a retaining formation at a second end which opposes the first end, and which includes an annular flange which abuts the retaining formation and which is adapted to be engaged with a second pipe.

A pipe coupling according to any one of claims 1 to 14 wherein the tubular body is of a material which has a low modulus of elasticity, as hereinbefore defined.

16. A pipe coupling according to any one of claims 1 to 15 wherein the tubular body has a modulus of elasticity which is not greater than 3,0 GPa.

17. A pipe coupling according to any one of claims 1 to 16 wherein the tubular body is made from unplasticized polyvinylchloride or high density polyethylene. 9' I MK -14-

18. A pipe coupling substantially as hereinbefore described with reference to the accompanying drawings. S9--The steps, featur-s, eemCpos+to dconpounds- disclosed herein or referred to_ icated in the specification and/or ms of this application, individa o-ly collectively, and any and all combinations "rany two -o-more of said steps o-r ea-t-u-ces-- DATED this SEVENTEENTH day of NOVEMBER 1989 Stephen Lane by DAVIES COLLISON Patent Attorneys for the applicant(s) g