GB2485350A

GB2485350A - Pipe coupling

Info

Publication number: GB2485350A
Application number: GB201018849A
Authority: GB
Inventors: Paul Anthony Davidson
Original assignee: COUPLING SOLUTIONS LLC
Current assignee: COUPLING SOLUTIONS LLC
Priority date: 2010-11-08
Filing date: 2010-11-08
Publication date: 2012-05-16
Also published as: WO2012064725A2; GB201018849D0; GB2488607A; WO2012064725A3; GB201107429D0

Abstract

A pipe coupling for connecting the ends of two tubular conduits 2 & 4 wherein each of the tubular conduits are provided with an annular groove 22. The pipe coupling comprises an annular gasket arrangement 6 for straddling and for forming a seal against two such conduit ends, a casing arrangement 8 & 10 for surrounding the gasket arrangement, which casing comprises a pair of radially inwardly extending projection arrangements, each projection arrangement for engaging the annular groove formed in each such conduit end, and a fixing sleeve 12 slidably mountable around the casing arrangement. The outer profile of the casing arrangement is tapered and an inner profile of the fixing sleeve is correspondingly tapered, such that the fixing sleeve may only be fitted to the casing arrangement in one direction. The fixing sleeve and casing arrangement comprise fixing means (30, fig. 3) to secure the fixing sleeve in position on the casing arrangement. The casing arrangement may be formed from a plurality of casing parts which cooperate together to form the casing arrangement.

Description

I

PIPE COUPLING

The present invention relates to a coupling for connecting tubular conduits, in particular for connecting lengths of pipe as part of a fluid transport system.

S

Fluid transport systems are known for conveying materials, such as liquids and gasses. The systems may include domestic plumbing systems installed in a building for conveying, for example, water or oil. These plumbing systems may include pipes for building heating systems, fire protection sprinkler systems and rising mains pipes and waste water pipes. The systems may also include oil and gas pipelines for conveying fuel over thousands of miles and pipe systems used in mining applications. The tubular conduits used in fluid transport of fuel may be made of different metals, including steel, iron, copper, aluminium and plastic.

For smaller diameter pipes, push fit couplings can be used, for example as described in IS 0B2,378,992. However, for pipe diameters above around 5cms, the force required to push the end of a pipe into such a push fit coupling becomes too high for manual connection. In addition, pipes connected by push fit couplings are able to rotate relative to each other, which can cause valve taps to move out of an optimum position.

For larger diameter pipes, welded joints can be used. However, welded joints have the disadvantage of requiring skilled workers as well as having negative health and safety and environmental implications. For example, the construction of a gas conveying pipeline made from 40 metre long lengths of steel pipe, and with a 1 metre diameter, conventionally use welded joints. Each joint can take a skilled team a whole day to make, when taking into consideration, the deployment of equipment at the joint location and inspection of the joint by X-ray equipment. Also, around 1 in 10 of such welded joints will have to be repaired after such an inspection. This makes pipelines expensive and time consuming to construct.

Where plastic pipes are used, heat fused joints may be used, in which the ends of the pipes to be connected are heated up and then fused together.

Push fit couplings, welded joints and fused joints are difficult to disconnect, for example for repair or maintenance, with such disconnection often causing damage to the pipes.

Victaulic (also known as victolic) pipe joints are known in the art, in which the pipe ends to be connected are formed with an annular groove in their external surface. An example of a Victaulic type pipe joint is shown in Figure 1. An annular resilient gasket (6), with a C-shaped longitudinal cross-section is placed over the pipe ends to be joined, so that the gasket straddles the two pipes. Typically, the gasket is stretched slightly to fit over the pipe ends so as to form a seal between the gasket and the pipes. The gasket is then encased by a rigid Victaulic type casing (108, 110), which engages the grooves formed in the pipe ends.

Generally the casing is formed in two halves (108, 110), formed with flanges (112) and the two halves are connected together by bolts (114) passing through the flanges. The casing S compresses the sealing gasket (6) to further improve the seal between the gasket and the pipe ends.

There are known problems with such Victaulic pipe joints. The first is that they are not well suited to high pressure pipe systems. In particular where one of the pipe elements coupled together by the joint comprises a pipe end cap, the joint has to withstand significant forces acting to pull the pipe ends connected by the joint apart. When fluid pressure builds up within the pipe joint of Figure 1, the pressure acts radially outwardly on the gasket, causing the gasket to inflate and apply a radially outwardly directed force to the casing halves (108, 110).

That is, the pressure acts in the direction of the double headed arrow, labelled pressure' in IS Figure 1. This force acts to pull the casing halves apart, and so high fluid pressure within the pipe joint of Figure 1 is transferred to the bolts (114) holding the casing halves (108, 110) together. Such Victaulic type pipe joints are typically rated to fluid pressures of l5Opsi and have been know to fail around 200psi, typically by failure of the bolts (114).

In addition, pipes connected by a Victaulic type pipe joint, of the type shown in Figure 1, may be able to rotate with respect to each other and with respect to the casing (108, 110), which may cause problems of movement of pipe valves, etc. to inaccessible locations. Victaulic type pipe joints can also fail if the bolts come undone due to vibration of the pipe system.

It is an aim of embodiments of the present invention to address shortcomings in with prior art pipe coupling systems, whether mentioned herein or not.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent

claims, and the description which follows.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 shows a prior art Victaulic-type pipe coupling arrangement; Figure 2 shows a cross-sectional view of a pipe coupling according to an embodiment of the present invention; Figure 3 shows a cross-section through part of a casing arrangement forming part of a pipe coupling according to an embodiment of the present invention; Figure 4 shows a cross-section through part of a fixing sleeve forming part of a pipe coupling according to an embodiment of the present invention; and Figure 5 shows a cross-sectional view of an intermediate step in the assembly of the pipe coupling shown in Figure 2.

Figure 2 shows a cross-sectional view through a pipe coupling according to an embodiment of the present invention. The pipe coupling comprises a gasket 6 for sealing the ends of pipes 2, 4. It further comprises a pair of casing halves 8,10 which sit around the gasket and protrude into grooves 22 formed adjacent the end of each pipe 2, 4. Surrounding the casing arrangement is a fixing sleeve 12, which holds the casing halves 8, 10 together and compresses the joint formed between the pipe.

The gasket 6 is an annular gasket with a C-shaped longitudinal cross-section and may be of any kind known in the art for use in a Victaulic (or victolic) pipe joint. The gasket is made of resilient sealing material and may, for example, be moulded of natural or synthetic rubber.

Other material from which the gasket may be made include, ethylene propylene diene monomer (EFDM) (generally used where the transported fluid is water), a nitrile compound (generally used where the transported fluid is oil), fluoro-elastomer, neoprene, white nitrile and epichlorohydrin.

The casing halves 8, 10 are made of a rigid material and each are shaped generally as a half-annulus with a C-shaped longitudinal cross-section. Two end portions 18, 20 of the casing halves extend radially inwardly of a half-cylinder shaped main body 24 of the casing halves.

The end portions 18, 20 have a width and an internal diameter matching the width and the external diameter of the grooves 22 formed in the pipe ends 2, 4 so that the end portions fit into the grooves, when the casing halves 8, 10 are fitted over the gasket 6, as is shown in Figure 2. The half cylindrical inwardly facing faces of the end portions 18, 20 are formed with a set of longitudinally extending gripping teeth 26. The main body 24 of each casing half 8, 10 is formed with a central half-annular groove 28 in its inwardly facing surface dimensioned to fit over and abut the gasket 6 as is shown in Figure 2.

The end portions 18 and 20 are arranged to have different outer radii so that the outer profile of the casing half tapers from a larger radius at end portion 20 to a smaller radius at end portion 20. When the two casing halves 810 are assembled around the pipe ends 2, 4, the appearance of the casing arrangement is frusto-conical i.e. resembling a truncated cone.

In the embodiment shown in Figures 2 to 5, the change in radius from first end portion 18 to S second end portion 20 is linear. In alternative embodiments, the change in radius from first to second end portions may change in a non-linear manner.

The cylindrical fixing sleeve 12, shown in Figure 4, is made of a rigid material and is dimensioned to fit slideably over the two casing halves 8, 10 when the casing halves are mounted over the gasket 6, as shown in the intermediate step illustrated in Figure 5. In one embodiment, shown in Figure 2, the fixing sleeve 12 fits over the casing halves 8, 10. As the fixing sleeve is urged into position, which may require the use of a tool such as a hammer or mallet, the two casing halves 8, 10 are pushed inwardly so as to push up against the gasket and improve the sealing of the gasket to the pipes 2, 4. This also has the effect of improving IS the engagement between the toothed 26 end portions 18, 20 of the casing halves 8, 10 and the end portions of pipes 2, 4 so as to form a secure sealed coupling between the tubular conduits.

Once the fixing sleeve 12 has been applied to the casing arrangement, noting that it can only be fitted one way, due to the tapering outer profile of the casing arrangement and corresponding tapering of the inner profile of the fixing sleeve, the point at which full engagement has been achieved will be noted by the fitter as the fixing sleeve clicks into position and is retained there by means of mutually interengaegable fixing means 30, 32.

First fixing means 30 is provided on edge of casing halved 8, 10 and takes the form of a resilient projection having a hook extending therefrom. When the fixing sleeve is positioned over the casing arrangement, it will ultimately reach a position where the hook of fixing means clicks into position in annular recess 32 provided at one end of fixing sleeve 32.

In this way, once the fixing sleeve has been properly fitted, it will not easily separate as the mutually co-operating fixing means 30, 32 act to hold the fixing sleeve firmly in position.

In the embodiment shown here, the fixing means 30, 32 are provided at the end of the casing arrangement having the smaller radius. However, the fixing means 30, 32 could equally be provided at the opposite end. As a further alternative, the resilient projection 30 could be provided midway along the outer profile of the casing halves 8, 10, and a corresponding groove 32 could be provided at a corresponding position on the inner surface of the fixing sleeve 12.

Advantageously, if the pipe coupling required disassembly at some future time, then the fixing means 30 may be deactivated by a tool such a screwdriver or chisel, and the fixing sleeve may simply be slid away, in a reversal of the fitting process. This, of course would not be possible if the fixing means 30, 32 are provided at a midway point as described previously, although such S a configuration could be used in secure environments where the pipe coupling cannot then be easily disassembled.

In a further advantageous development, once properly assembled, there are no protrusions from the completed coupling, as can be seen from Figure 2. This is particularly important when the coupling is used on large-scale pipelines, such as large-diameter oil pipelines, where the entire pipeline can move significantly in use, due to expansion/contraction effects caused by temperature differences. Protrusions from prior art pipe couplings which can become entangled with the ground or other structures can be torn off or damaged. The lack of any sudden discontinuity from pipe couplings according to embodiments of the present invention IS substantially obviates this problem.

Embodiments of the present invention find utility in a range of different pipe environments, ranging from small-bore pipes used in domestic situation up to large diameter pipes used in the transportation of oil, gas or water. Depending on the characteristics of the pipe, the materials used to manufacture the pipe coupling will vary. In some circumstances, the various components of the pipe coupling can be formed from a plastics material, such as glass-filled nylon. In other circumstances, the components can be formed from steel, another metal or an alloy.

The pipe coupling according to the present invention may be a coupling for connecting two lengths of pipe. Alternatively, the pipe coupling according to the present invention may be a coupling for connecting a length of pipe to a pipe joint assembly. Many types of pipe joint assemblies are known, for example pipe joint assemblies for connecting three lengths of pipe in a T-junction, pipe end caps and pipe joint assemblies incorporating valves or other elements known in the art.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A pipe coupling for connecting the ends of two tubular conduits comprising: an annular gasket arrangement for straddling and for forming a seal against two such conduit S ends; a casing arrangement for surrounding the gasket arrangement, which casing comprises a pair of radially inwardly extending projection arrangements, each projection arrangement for engaging an annular groove formed in each such conduit end; and a fixing sleeve slideably mountable around the casing arrangement, wherein an outer profile of the casing arrangement is tapered and an inner profile of the fixing sleeve is correspondingly tapered, such that the fixing sleeve may only be fitted to the casing arrangement in one direction and whereby the fixing sleeve and casing arrangement comprise fixing means to secure the fixing sleeve in position on the casing arrangement.
2. A pipe coupling according to claim I wherein the casing arrangement is formed from a plurality of casing parts which co-operate together to form the casing arrangement.
3. A pipe coupling according to claim 2 wherein the casing arrangement is formed from two casing halves.
4. A pipe coupling according to any one of claims I to 3 wherein each radially inwardly extending projection comprises an annular wall of the casing arrangement.
5. A pipe coupling according to any one of claims I to 4 wherein the casing arrangement comprises a substantially cylindrical main body.
6. A pipe coupling according to anyone of claims I to 5 wherein the casing arrangement is formed with a central annular recess on its inwardly facing surface for receiving the gasket arrangement.
7. A pipe coupling according to any one of claims I to 6 wherein an inwardly facing surface of each projection arrangement is formed with at least one gripping tooth arrangement.
8. A pipe coupling according to any one of claims I to 7 wherein the fixing sleeve has a substantially frusto-conical outer surface.