GB2460470A

GB2460470A - Inclined access assembly for a pipeline

Info

Publication number: GB2460470A
Application number: GB0809946A
Authority: GB
Inventors: John Garton
Original assignee: P N DALY Ltd
Current assignee: P N DALY Ltd
Priority date: 2008-05-31
Filing date: 2008-05-31
Publication date: 2009-12-02
Also published as: GB0809946D0

Abstract

An access branch assembly 1 for a pipe such as a water main or sewer 13 has an angled guide conduit 5 that provides a guiding path for feeding an elongate member into the interior of the main 13 through an aperture in its wall. The guiding path is at an acute angle to the axis of the main when the access assembly is attached to the main. The elongate member, such as a fibre-optic inspection camera, or cleaning tool rod, is therefore less likely to jam or to be forced through a shall radius of curvature on entry into the main. The assembly may include further guide conduits to aid with cutting an access hole in the main or feeding elongate tools in either the forward or reverse direction to the main. The assembly may comprise a saddle clamp 2 or it may be screwed into a threaded (tapped) hole in the main pipe wall (figure 4).

Description

Access Assembly for a Main The present invention relates to access assemblies used to provide access for elongate members into pipes or mains such as water mains, gas mains, oil transport pipelines or sewage pipes. In particular, it relates to assemblies that allow for equipment, such as cleaning rods or elongate flexible fibre-optic inspection cameras, to be inserted into the main through the access assembly. It also relates to methods of attaching the assemblies to a main. In particular, the invention is suitable for use with mains of relatively small diameter, such as 20cm or less, for instance water distribution mains that carry water from the larger Mains or pipes, such as water mains, gas mains, sewage pipes and the like require inspection, either for regular maintenance purposes or prior to undertaking repairs. They may also require cleaning. Throughout this specification, the term "main" is used to mean a pipe, usually but not necessarily buried underground, and used for conveying fluids.

Conventionally, where a main is to be modified to allow the insertion of cleaning or inspection equipment, usually in the form of flexible rods, a hole is drilled in the pipe and a section of conduit fitted, using a fluid-tight connection, in or over the hole. The section of conduit is typically provided with a valve, such as a gate valve, in order to form an access assembly. Once the access assembly is in place, with the valve closed, fluid will not leak from the main. When it is necessary to gain access to the main, the valve may be opened and inspection equipment, cleaning equipment or the like may be inserted into the main through the open gate valve and the section of conduit. Conventionally, the section of conduit has its long axis at right angles to the long axis if the main, forming a T-section with the main.

Typically, the access assembly is fitted to the main in a small, buried inspection chamber, covered by a lid, and left in place for future inspections, cleaning operations or the like, with the valve closed to prevent leakage from the main. A problem with such access assemblies, particularly when used on mains of small diameter, such as 20 cm or less, 15 cm or less or even 10 cm or less, is that when rods, such as cleaning rods or optical fibre camera rods, are inserted into the arm of the 1-section, through a hole in one side of the main, they may jam against the opposite side of the main as an operator tries to push them into the main. Particularly with small diameter mains, it may be necessary for a rod-like tool to have to bend sharply in order for the tool to be pushed into the main. This means that there must be limitations on the rod-like tool, in that it must be sufficiently flexible along its entire length for it to be passed into the main through the required angle. However, if the tool is too flexible it may be difficult to push the tool far into the main, as frictional resistance has to be overcome by the rigidity of the tool allowing force to be transferred from the operator to push the head of the tool through the main. If it is too flexible, the tool may simple coil up on itself in the main rather than forcing the head along the main. Also, because of sharp edges at the hole in the wall of the main, which may have resulted from the drilling operation to fit the access assembly, the rod-like tool's outer surfaces may become damaged as they are forced past the edges of the hole into the main.

Furthermore, with repeated use of the rod-like tool, the bending of the tool to fit into mains may lead to fatigue-induced breakage.

Hence, there is a need for an access assembly adapted to allow rod-like flexible tools to be pushed into mains which overcomes some or all of these problems.

Until now, this had been addressed by optimising the flexibility/rigidity of the rod-like tools in order to allow them to pass around a small-radius bend whilst remaining sufficiently rigid to be pushed through a main. Modifying the access assembly in order to address the problem does not seem to have been considered: it has not been recognised that the shape of the access assembly itself is a problem that needs addressing. This is possibly because of the conventional means of drilling into a wall of a mains is at right angles to the main.

This prevents the drill from slipping and provides the simplest manner for a main to be pierced to allow access. For a conventional fitting, where a tapped hole is drilled in the main, and then a piece of conduit screwed into the tapped hole (a so-called QuadrinaTM fitting), it is natural for the simplest method to be used, with a threaded section of conduit being screwed into the tapped hole at right angles to the long axis of the main.

It has now been realised, that by overcoming the prejudice in the prior art relating to drilling of mains, access assemblies can be provided which tackle some or all of the problems outlined above.

Hence, it is one object of the present invention, amongst others, to provide an access assembly for a main that allows a rod-like tool to be pushed into the main without requiring the tool to have to bend through a small radius curve. It is a further object of the invention to provide a means for fitting such an access assembly to a main in an easily achievable manner.

A first aspect of the invention provides an access assembly for a main, said main having forward and reverse directions parallel to its long axis, the access assembly comprising: an attachment means for attaching the access assembly to said main, and a first guide conduit configured or configurable to provide a first guiding path for feeding an elongate member into said interior of said main through an aperture in a wall of said main, wherein the first guiding path is at a first acute angle to the forward or the reverse direction of the main when the access assembly is attached to the main.

The long axis of the main is defined by the imaginary line along the length of the main which is defined by the centroids of the cross sectional areas of the aperture in the main, the cross sectional areas being defined at right angles to the walls of the main at any place along the length of the main. The direction of the main is any direction parallel to the long axis of the main, and it may be a forward direction (e.g. along which fluid flows) or a reverse direction (i.e. opposite to the direction along which fluid flows). The first guiding path of the first guide conduit is similarly defined by the long axis of the first guide conduit which is defined by the centroids of the cross sectional areas of the aperture in the first guide conduit, the cross sectional areas being defined at right angles to the walls of the first guide conduit at any place along the length of the first guide conduit.

The first guiding path is extrapolated as a linear continuation of the curve formed by the first guiding path where the first guide conduit terminates near the main.

The first guide conduit is suitably aligned with the aperture in the wall of the main such that the elongate member can be fed into the interior of the main without fouling against the edges of the aperture.

The elongate member is suitably a flexible elongate member with sufficient rigidity to allow it to be pushed into the main's interior through the first guide conduit and through the aperture. For instance, the elongate member may be a rod for a cleaning tool, or may be a guide cable for a camera system, such as a fibre-optic guide.

The angle between the first guiding path and the direction of the main is measured on the same side of the long axis of the main as the first guide conduit when the access assembly is attached to the main.

The first guiding path is at a first acute angle to the long axis of the main. The first acute angle is suitably 75° or less, preferably 65° or less, more preferably 500 or less, even more preferably 450 or less.

Preferably, the first guiding path and the long axis of the main intersect. In other words, the first guiding path and the long axis of the main lie in the same plane.

However, the first guiding path and the long axis of the main do not have to intersect. For instance, the first guiding path may intersect the interior distal wall of the main at a point which is not on the imaginary line parallel to the long axis of the main diametrically opposite the point where the guiding path would intersect the proximal interior wall of the main if the aperture was not formed in the wall. In this case, the acute angle is formed between the first guiding path and the axis parallel to the long axis of the main passing through the point where the first guiding path intersects the interior wall of the main (in other words, the first acute angle is formed between the first guiding path and the direction of the main at the wall, parallel to the long axis of the main). Preferably, the first guiding path is a straight line, but it may be a curved line.

The first acute angle, being an acute angle, gives the advantage that the head of any flexible, rod-like elongate tool, when pushed through the first guide conduit along the first guiding path, will intersect the far or distal wall of the main at an acute angle to both the wall itself and to the direction of the main, such that the passage of the head of the tool sliding along the wall and hence along the main will not be hindered by requiring the tool to be bent through an small radius of curvature. Nor will progress be blocked by the head meeting the wall at 900, such as may happen with a conventional T-shaped access assembly.

The attachment means for attaching the access assembly to the main may be any suitable attachment means. Preferably, it provides a fluid-tight seal between the access assembly and the mains, such that the interior of the first guide conduit is in fluid contact with the interior of the main through the aperture in the wall of the main, but such that the fluid in the main does not leak out to the exterior of the main at the attachment means.

For example, the first guide conduit may be provided with an attachment means which is a threaded section adapted to screw into an aperture which is a tapped hole in the main. In this case the threaded section of the attachment means will suitably have an axis of rotation or screw axis which is at right angles to the long axis of the main when screwed into place. In other words, the screw axis is at an angle to the guiding path of 90° minus the first acute angle. For this arrangement, a fluid-tight seal between the attachment means and the main may be arranged by having a suitably shaped gasket or seal between the main's outer wall and a flange circumferentially located around the attachment means. Depending upon the thickness of the seal or gasket, the position of the first guide conduit may be configured so that the acute angle is formed either with the forward direction of the main or with the reverse direction of the main.

Hence, the assembly may be an access assembly according to the first aspect of the invention wherein said aperture is a tapped holed and the attachment means comprises a threaded section adapted to screw into said aperture by rotating about a screw axis whereby the first guide conduit and said interior of said main are placed in fluid connection through said aperture when the attachment means is screwed into said aperture.

In another embodiment of the first aspect of the invention, the attachment means may be a clamp adapted to attach the access assembly to said main and to provide a fluid-tight seal at said wall in said main around said aperture whereby the first guide conduit and said interior of said main are placed in fluid connection through said aperture when the access assembly is attached to said main.

For any embodiment of the first aspect of the invention, the first guide conduit suitably extends from an opening adapted to lie adjacent to said aperture in said main at a proximal end of the first guide conduit to a first port at a distal end of the first guide conduit, wherein the first guide conduit is provided with a first valve or closure means for the first port.

Preferably, the first valve or closure means is removably attached to the first guide conduit. This allows for greater adaptability of the access assembly, as different valves or closures may be fitted depending upon the use being made of the access assembly. The first valve or closure means is suitably a closure cap, or preferably a gate valve. When a closure cap is used, the cap may be left in place on the fitted access assembly until access to the main is needed. The closure cap may then be replaced by, for instance, a gate valve.

It is useful if the guide conduit is also provided with a valve such as a sandwich, shutter or spade valve (also known as a guillotine or plate valve) between the opening and the first port. Such a valve allows the first valve or closure means to be replaced or changed without the need for the main to be depressurised. Such a sandwich valve may also be used when using the first guide conduit as a guide for guiding a cutting tool head to cut the aperture in the wall of the main, whilst the main is still under pressure. This will be described in detail below.

The first guiding means may by rigidly attached to the attachment means, or it may be mounted to the attachment means by means of an adjustable mount, whereby the first guide conduit may be configured so that the acute angle is formed either with a forward direction of the main or with a reverse direction of the main. Preferably, the adjustable mount provides a fluid-tight seal whereby fluid does not leak from the main through the adjustable mount when the access assembly is in place on the main.

The adjustable mount may be adapted to allow the first guiding means to rotate about a rotation axis of the rotatable mount, the rotation axis being normal to the long axis of the main when the attachment means is attached to the main, or it may be adapted to allow the first guiding means to be configured such that the first acute angle is formed either with a forward direction of the main or with a reverse direction of the main. For instance, the adjustable mount may allow the first guiding means to by attached to the attachment means in one of two or more positions, including a first position where the first guiding means forms an acute angle with the forward direction of the main, and a second position where the first guiding means form an acute angle with the reverse direction of the main. This allows a single guiding means to be used for shoving a flexible tool in a forward direction along the main or in a reverse direction along the main.

In addition to the first guide conduit, the access assembly may optionally further comprise a second guide conduit configured to provide a second guiding path for feeding an elongate member into said interior of said main through said aperture in said wall of said main, wherein the second guiding path is at a second acute angle to the forward or reverse direction of the main and wherein the second acute angle is with the direction of the main that is not at an acute angle with the first guiding path. When the first guide conduit is configured to provide a guiding path with an acute angle with the forward direction of the main, the second guide conduit is then configured to provide a guiding path at a second acute angle to the reverse direction of the main (or vice versa). The second acute angle is measured between the second guiding path and the direction of the main on the same side of the long axis of the main as the second guiding conduit. The second guide conduit extends from the opening of the first guide conduit adapted to lie adjacent to the aperture in the main at the proximal end of the first guide conduit. This means that the same aperture in the main may be used for feeding a flexible tool into the main through either the first guide conduit or through the second guide conduit. The preferred features for the second guide conduit are as for the first guide conduit, and as detailed above for that first guide conduit, with the term "first" replaced by "second". The optional second conduit is particularly useful when the first guiding conduit is not adjustably mounted to the attachment means.

Typically the first guide conduit and the second, optional guide conduits are tubular pipes. The access assembly will typically be formed from a durable material such as metal or plastic, with elastomeric materials used to provide seals or gaskets.

In a preferred version of the first aspect of the invention, the access assembly further comprises a cutting guide conduit adapted to guide a cutting tool head for cutting said aperture in said main along a cutting path wherein the cutting path is substantially at right angles to said long axis of said main when the access assembly is attached to said main. The cutting guide conduit extends from the opening at the proximal end of the first guide conduit to a cutting guide port at a distal end of the cutting guide conduit, and the cutting guide conduit is provided with a first valve or closure means for the cutting guide port. The cutting guide conduit comprises a valve or closure means in order to provide it with a fluid-tight seal. The valve or closure means is suitably removably attached to the cutting guide conduit. This allows for greater adaptability of the access assembly, as different valves or closures may be fitted to the cutting guide conduit, depending upon the use being made of the access assembly. The valve or closure means of the cutting guide conduit is suitably a gate valve, which may be used as a second access port, but more typically will be a closure cap. When a closure cap is used, the cap may be left in place closing the cutting guide conduit on the fitted access assembly. Typically, the cutting guide conduit is only used at the time that the access assembly is being fitted to the main and otherwise remains sealed.

However, it could be used, for instance, to fit a useful apparatus to the main, such as a fluid bleed valve or a hydrant valve.

The cutting path of the cutting guide conduit is defined by the long axis of the cutting guide conduit which is defined by the centroids of the cross sectional areas of the aperture in the second guide conduit, the cross sectional areas being defined at right angles to the walls of the second guide conduit at any place along the length of the guide conduit. Typically, the cutting guide conduit will be a cylindrical section of pipe.

Preferably, any valve or closure means for the cutting guide conduit is adaptable to allow the passage of a cutting or drilling tool into the cutting guide conduit along the cutting path when the valve or closure means is in an open configuration and to provide a fluid-tight seal when the second valve or closure means is in a closed configuration.

The cutting guide conduit shares the same opening as the first guide conduit and the optional second guide conduit. This ensures that the aperture formed by a cutting tool guided through the cutting guide conduit will be aligned with the opening.

It is also useful if the cutting guide conduit is provided with a valve such as a sandwich, shutter or spade valve (also known as a guillotine or plate valve) along its length between the opening and the cutting guide port. Such a valve allows the cutting guide conduit to be easily used as a guide for guiding a cutting tool head to cut the aperture in the wall of the main in a method where the main is maintained under pressure.

Suitably, the access assembly of the first aspect of the invention is for use with a main that is preferably a buried water main or sewage pipe. In these circumstances, the access assembly is typically located in a buried chamber beneath an access lid.

A second aspect of the invention provides a method for installation to a main of an access assembly according to the first aspect of the invention comprising the following steps: a) forming an aperture in a wall of the main, and b) attaching the access assembly to the main such that the first guide conduit is positioned to form a guiding path passing through the aperture into the main.

When the access assembly has an attachment means which is a clamp adapted to attach the access assembly to the main, the method of the second suitably comprises the steps: i) attaching the access assembly to the main prior to forming an aperture in the wall of the main, ii) cutting an aperture in a wall of the main by feeding an elongate cutting tool along the guiding path provided by the first guide conduit.

When the access assembly further comprises a second guide conduit, the method according to the second aspect of the invention suitably comprises the steps: i) attaching the access assembly to the main, ii) cutting an aperture in a wall of the main by feeding an elongate cutting tool along the cutting path provided by the second guide conduit.

Preferably, the aperture is cut in the wall of the main whilst the main interior contains a fluid at a pressure greater than atmospheric pressure (e.g. in a water main under pressure so that there is no need for the main to be emptied). This may be achieved by use of a cutting tool, such as a drill adapted for cutting into a pressurised main. In order to use such a tool, the tool is first attached, by a fluid-tight connection, to the first or second guide conduit of the access assembly, whilst the selected conduit is in a closed configuration. A valve in the conduit is then opened such that the cutting tool can be advanced through it and the cutting tool is advanced through the selected guide conduit in order to form an aperture in the wall of the main. This leads to the interior of the selected guide conduit and the tool interior being pressurised. The cutting tool is then withdrawn sufficiently that the valve in the selected guide can be closed, after which the fluid tight connection between the drilling tool and the access assembly may be broken and the tool removed without further leakage of fluid from the main. Preferably, any coupon arising from the cutting of the aperture is also removed as the cutting tool is withdrawn.

The method of the second aspect of the invention is particularly useful for use on a main which is a buried water main or sewage pipe.

A specific embodiment of the present invention will now be described, by way of example only, with reference to an accompanying drawing in which: Figure 1 shows a cross sectional side view of a first embodiment of an access assemble according to the first aspect of the invention.

Figure 2 shows the embodiment of figure 1, attached to a water main. The view is a perspective view.

Figure 3 shows a cross sectional side view of a second embodiment of an access assembly according to the first aspect of the invention.

Figure 4 shows a cross sectional side view of a third embodiment of an access assembly according to the first aspect of the invention installed in a water main.

Figure 5 shows a perspective view of a fourth embodiment of the invention with both a first guide conduit and a second guide conduit.

Figure 6 shows a perspective view of a fifth embodiment of the invention, with a first guide conduit adjustably mounted to the attachment means.

Turning to the first embodiment of the invention as shown in figures 1 and 2, a clamp assembly 1 has a top part 2 and a bottom part 3 which are interconnectable via bolts 4. The top part of the clamp 2 has a first guide conduit which extends from an opening 6 to a first port 7. The port 7 is provided external screw threads 8. A second guide conduit 9 extends from the opening 6 to a second port 10. This second port 10 is provided with external screw threads 11. The first and second guide conduits are cylindrical in shape. An 0-ring seal 12 is provided around the opening 6.

Figure 2 shows the first embodiment of the first aspect of the invention attached to a water main 13. The top part 2 of the clamp 1 sits on the upper surface of the main 13 and is bolted via the bolts 4 to the bottom part 3 of the clamp 1.

The cutting guide conduit 9 is used as a cutting tool guide in order to form an aperture in the wall of the main 13. The aperture may be formed either by draining the main first or by drilling under pressure as explained in the description above. Necessary equipment may be attached to the first guide conduit by means of the threaded port 10. When not in use, the cutting guide conduit 9 maybe sealed by means of a closure cap threaded onto the cutting guide port 10 by means of the external threads 11. The first guide conduit 5 maybe terminated by a gate valve attached by the external threads 8 at the first port 7. When inspection of the main is required, the gate valve (not shown) may be opened to allow a flexible tool to be pushed into the interior of the main 13 via the first guide conduit 9 and through the opening 6 into the aperture formed in the wall of the main 13. After inspection or cleaning has been completed, the flexible tool may be withdrawn and the gate valve (not shown) closed.

Figure 3 shows a second embodiment of the invention. The assembly apparatus is in the form of a clamp I with an upper part 2 and a lower part 3. These are attached to each other by bolts 4 as in the first embodiment of the invention. The access assembly has only a first guide conduit 5 extending from an opening 6 to a first port 7 which is furnished with external threads 8.

In use, the clamp is fitted to a water main which may either have a pre-formed aperture in the wall of the main to align with the opening 6, or a cutting tool may be used, employing the first guide conduit 5 as a cutting guide, either using a pressurised drilling apparatus or by first emptying the main prior to drilling. The o-ring 12 provides a fluid tight seal around the opening 6 allowing fluid contact between the interior of the first guide conduit 5 and the interior of the main.

Typically, the first port 7 will be furnished with a gate valve (not shown) which may be opened to allow a flexible rod to be inserted into the main.

Figure 4 shows a third embodiment of the invention. A first guide conduit 15 has a first port 16 provided with external threads 17. At its other end, the guide conduit 15 is provided with an opening 6. This opening is provided with external threads 18 that mate with a tapped hole 19 in the water main 13. A shaped washer 20 forms a fluid tight seal between the external wall of the main 13 and a flange 21 provided on the exterior of the guide conduit 15 at the end with the opening 6.

In use, a tapped hole 19 is formed in the wall of the main 13 and the guide conduit 15 is screwed into the hole using the washer 20 to form a fluid tight seal against the external flange 21. The first port 16 is then closed with a gate valve (not shown). When access to the interior of the main 13 is required, the gate valve is opened and a flexible tool may be inserted into the interior of the main via the gate valve (not shown), the first port 16 and the hole 6 via the aperture 19 formed in the wall of the main 13.

Figure 5 shows a fourth embodiment of the invention with a fist guiding conduit 5 and a second guiding conduit 22 each attached to a clamp 1. The use of this embodiment is as for the second embodiment, except that two guiding means are present, allowing an elongate tool to be inserted either in the forward or in the reverse direction along the main, depending upon which guiding means 5,22 is selected.

Figure 6 shows a fifth embodiment of the invention. The guiding means 25 is bolted to a mount 27 on the clamp I via bolts 26. An o-ring gasket forms a fluid-tight seal between the mount 27 and the base of the guiding means 25. In use, the guiding means can be bolted onto the clamp so that the acute angle is formed either between the forward direction of the main, or the reverse direction of the main.

It will be appreciated that numerous modifications to the above described embodiment may be made without departing from the scope of the invention as defined in the appended claims. For example, the first guiding means may be mounted to a clamp by means of a fluid-tight rotatable mount.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as "preferable", "preferably", "preferred" or "more preferred" in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be contemplated as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

CLAIMS1. An access assembly for a main, said main having forward and reverse directions parallel to its long axis, the access assembly comprising: an attachment means for attaching the access assembly to said main, and a first guide conduit configured or configurable to provide a first guiding path for feeding an elongate member into said interior of said main through an aperture in a wall of said main, wherein the first guiding path is at a first acute angle to the forward or the reverse direction of the main when the access assembly is attached to the main.
2. An access assembly according to claim I wherein said aperture is a tapped holed and the attachment means comprises a threaded section adapted to screw into said aperture by rotating about a screw axis whereby the first guide conduit and said interior of said main are placed in fluid connection through said aperture when the attachment means is screwed into said aperture.
3. An access assembly according to claim 2 wherein the screw axis is at an angle to the first guiding path of 900 minus the acute angle.
4. An access assembly according to claim I wherein the attachment means is a clamp adapted to attach the access assembly to said main and to provide a fluid-tight seal at said wall in said main around said aperture whereby the first guide conduit and said interior of said main are placed in fluid connection through said aperture when the access assembly is attached to said main.
5. An access assembly according to any preceding claim wherein the first guide conduit extends from an opening adapted to lie adjacent to said aperture in said main at a proximal end of the first guide conduit to a first port at a distal end of the first guide conduit, wherein the first guide conduit is provided with a first valve or closure means for the first port.
6. An access assembly according to claim 5 wherein the first valve or closure means is removably attached to the first guide conduit.
7. An access assembly according to any preceding claim wherein the first guiding conduit is mounted to the attachment means by means of an adjustable mount, whereby the first guide conduit may be configured so that the first acute angle is formed either with a forward direction of the main or with a reverse direction of the main.
8. An access assembly according to any preceding claim wherein the first acute angle is 75° or less.
9. An access assembly according to any preceding claim further comprising a second guide conduit configured to provide a second guiding path for feeding an elongate member into said interior of said main through said aperture in said wall of said main, wherein the second guiding path is at a second acute angle to the forward or reverse direction of the main and wherein the second acute angle is with the direction of the main that is not at an acute angle with the first guiding path.
10. An access assembly according to any preceding claim further comprising a cutting guide conduit adapted to guide a cutting tool head for cutting said aperture in said main along a cutting path wherein the cutting path is substantially at right angles to said long axis of said main when the access assembly is attached to said main.
11. An access assembly according to claim 10 wherein cutting guide conduit is provided with a cutting guide valve or closure means is adapted to allow the passage of a drilling tool into the cutting guide conduit along the drilling path when the second valve or closure means is in an open configuration and to provide a fluid-tight seal when the cutting guide valve or closure means is in a closed configuration.
12. An access assembly according to any preceding claim wherein said main is a buried water main or sewage pipe.
13. A method for installation to a main of an access assembly according to any one of claims 1 to 9 comprising the following steps: a) forming an aperture in a wall of the main, b) attaching the access assembly to the main such that the first guide conduit is positioned to form a guiding path passing through the aperture into the main.
14. A method for installation to a main of an access assembly according to any one of claims 4 to 9 comprising the steps: i) attaching the access assembly to the main prior to forming an aperture in the wall of the main, ii) cutting an aperture in a wall of the main by feeding an elongate cutting tool along the first guiding path provided by the first guide conduit.
15. A method for installation to a main of an access assembly according to claim 10 or claim 11 comprising the steps: i) attaching the access assembly to the main, ii) cutting an aperture in a wall of the main by feeding a cutting tool along the cutting path provided by the cutting guide conduit.
16. A method according to claim 14 or claim 15 wherein the aperture is cut in the wall of the main whilst the main interior contains a fluid at a pressure greater than atmospheric pressure.
17. A method according to any one of claims 13 to 16 wherein the main is a buried water main or sewage pipe.
18. An access assembly or a method for installation of an access assembly assembly, substantially as hereinbefore described, with reference to and as shown in the accompanying figures.