WO2013166559A1

WO2013166559A1 - Attachment for pipe laying

Info

Publication number: WO2013166559A1
Application number: PCT/AU2013/000485
Authority: WO
Inventors: Gerard O'brien; Matthew Graeme Dridan
Original assignee: Gerard O'brien; Matthew Graeme Dridan
Priority date: 2012-05-09
Filing date: 2013-05-09
Publication date: 2013-11-14
Also published as: AU2013205800A1; AU2013258881A1

Abstract

A guide arm (30) for a pipe laying assembly that includes a boom mountable vacuum plate operable between a suction pipe engaging mode and a pipe release mode, the guide arm comprising; a mount end (31) for mounting to the vacuum plate; and a guide end (38); wherein when in use and a pipe is engaged by the vacuum plate is brought into proximity to an end of a pipe installed in a pipeline, the guide end (38) guides the end of the engaged pipe into alignment with the end of the installed pipe.

Description

ATTACHMENT FOR PIPE LAYING

FIELD OF THE INVENTION

The present invention relates to an attachment for use in the laying of pipes in a pipe line. In particular, the present invention relates to an attachment for laying of pipes in a trench.

BACKGROUND OF THE INVENTION

The present invention will be described with particular reference to laying a pipe line in a trench. However, it will be appreciated that the attachment may also be used to lay above ground pipe lines and no limitation is intended thereby. Large diameter pipes are used in the mining, oil, utilities and gas industries.

Large diameter pipes are generally considered to be those of greater than about 100mm in diameter and which may be up to 1 .5m or more in diameter. Large diameter pipes are provided in pipe lengths, typically between 12m and 15m.

Laying of an underground pipe line is a labour intensive process. An excavator first digs a trench conforming to a specified line and length. The bottom of the trench is then covered with a bedding material to provide a base for the pipes. Lengths of pipe are lifted using a sling attached to a crane, excavator or other work machine and lowered into the trench. The slings are manually rigged about the pipe and care must be taken to rig the sling around the centre of the pipe length. The lifted pipe is lowered into a trench and manually guided into alignment with an installed pipe by workmen (pipe layers) in the trench. When the pipe is aligned, the pipe layer disengages the sling from the pipe. It will be appreciated that having workmen in a trench and working with heavy objects such as pipes is potentially hazardous. There are a number of different methods and pipe arrangements for joining pipes. One form of jointing uses pipes having a bell or socket end and a spigot end. The bell or spigot end may be machined to form a groove that receives an O ring or other rubber gasket. The pipe joint is assembled by pushing the spigot end into the bell end. These are commonly known as push on joints, as opposed to welded joints. The normal convention is to lay pipes starting from the downstream end with the socket end facing the upstream direction. The joint is typically assembled by placing the rubber ring on the end of the pipe, lubricating the joint surfaces of the pipes, aligning the pipes and pushing the two ends together. The present invention will be described with particular attention to pipes of the type having an O ring or other shaped gasket. However, it will be appreciated that the present invention may have other suitable applications and no limitation is intended thereby.

Methods of joining pipes depends upon the size of the pipe. For "small" large diameter pipes, a wooden block is placed across the end of the pipe so as to protect the pipe end from damage. A pipe layer wedges a crow bar against the wood block and applies pressure so as to push the pipe into position. For "medium" large diameter pipes, mechanical pipe pullers are anchored to an installed pipe several sections back and connected by a cross beam to a section to be installed. Generally two pipe layers apply force to the pipe puller to bring the pipe into the joined position.

For large pipes of over about 1 .5m in diameter, a block is installed inside a pipe several sections back that is connected by a pipe pulling device to a wooden cross beam placed across the end of the pipe to be joined. A pipe layer located inside the pipe moves the pipe puller to join the pipes.

It will be appreciated that the individual steps of rigging the sling around the pipe, guiding the pipe into position, disconnecting the sling from the pipe and joining the pipes is a manually intensive process. Still further it is a dangerous occupation for the pipe layers. Vacuum pipe lift devices are known in the pipe laying arts. Such devices have a diesel motor and vacuum tank directly attached to a vacuum plate or shoe. The entire unit including the motor, vacuum tank and vacuum plates is mounted to a boom arm of a hydraulic work machine such as a crane, excavator, backhoe, pipe laying machine or the like. However, a disadvantage of conventional pipe vacuum lift devices is that the weight of the engine and vacuum tank adds to the load to be lifted. The lifting capacity of an excavator is primarily limited by tipping balance and not hydraulic capacity or boom strength. The tipping load decreases when the excavator load is to the side, at maximum reach and when the load is below ground level. Laying pipes in trenches requires all three positions. For this reason, conventional vacuum pipe lift attachments are not used for laying pipes in trenches, although they are of course suitable for laying pipes on the ground, in shallow trenches or the like. The present inventor has overcome this disadvantage of prior art vacuum lift devices by mounting a vacuum plate or shoe directly to the end of a boom arm and placing the vacuum pump and tank at a position on the work machine remote form the boom arm. Such a remote mounting of a vacuum pump is described in the co-applicant's earlier application AU2010202108. However, although the remote mounting provided significant advantages, alignment and joining of push- on pipes still needs to be done by pipe layers in the trench.

It is clearly desirable for safety reasons to be able to align and join pipes without having to have workmen in the trench. There may also be significant cost advantages by reducing the man hours required to install a pipe line. It is therefore an object of the present invention to provide an alternative method for lowering a pipe length into a trench and joining pipe ends.

SUMMARY OF THE INVENTION

According to a first broad form of the invention there is provided a guide arm for a pipe laying assembly that includes a boom mountable vacuum plate operable between a suction pipe engaging mode and a pipe release mode; the guide arm comprising: a mount end for mounting to the vacuum plate of a pipe lift device; and a guide end; wherein when in use and a pipe for joining is engaged by the vacuum plate is brought into proximity to an installed pipe, the guide end guides the respective pipe ends into alignment for joining.

The guide arm of the present invention may be mounted to the vacuum plate of known vacuum pipe lift devices. However, as discussed above, there are inherent disadvantages of using such machines to lay pipe in deep trenches. Accordingly, for laying pipe in trenches it is preferred that the vacuum plate to which the guide arm is mounted is remotely connected to the vacuum source and most preferably in a manner as taught in AU2010202108. The guide arm may be mounted to the vacuum plate by any suitable means. This may depend upon the type of vacuum plate, the size of the guide arm and vacuum shoe, the nature of the material form which the guide arm is constructed and the like.

The guide arm of the present invention is particularly applicable for use in joining together pipes of the type having a bell or spigot end and a socket end. In accordance with conventional pipe laying techniques the pipe end is a spigot end that is aligned with a socket end of an installed pipe.

The guide end of the guide arm serves to assist in aligning the end of the pipe being manoeuvred (the live end) with the end of the pipe installed in the pipe line (the dead end). The ability to guide the pipe into position means that it is not necessary for this to be done manually by pipe layers located on the ground or in a trench. The guide arm enables the excavator or other work machine operator to place the pipe in position.

The guide end may be provided with any suitable means, or combination thereof for guiding the pipe into position. It will be appreciated that in some cases, the live end of the pipe may not be visible to the work machine operator.

The guide end suitably has means for detecting the position of an end of the installed pipe. Such detection means may be any suitable means and may be physical in that there is some manner of physical cooperation between the installed pipe and the guide arm. In the case of a physical cooperation between the guide end and the end of the installed pipe, the guide arm is suitably dimensioned such that in use the guide end extends past the end of the engaged pipe so as to allow such physical cooperation.

The guide end suitably includes at least one pair of axially opposed guide members. In use, as the pipe is lowered into position in the trench, the pipe is lowered until the guides contact the upper surface of the installed pipe. If the guide members first contact the pipe in an off centre position, the force of the contact will cause the uppermost guide to follow the curvature of the pipe downwardly, thereby drawing the guide end to a centre position in which the ends of the pipes are aligned.

The guide members may be of any suitable shape or configuration that will achieve the purpose. Guide for guiding conventional vacuum shoes onto a pipe are known and may be used in the present invention. Such guides are in the form of axially opposed rollers that guide the shoe onto the pipe. In practice, the rollers are subject to collecting dirt and grime that interferes with their action. Suitable guide members for use in the present invention are resilient rubber pads. In another form of the invention, the guide members are opposed guide plates aligned at an angle that is substantially tangential to a pipe to be joined. The guide plates are suitably lined or provided with a rubber or other resilient material that protects the pipe surface from being scratched or otherwise damaged by the plates.

Still further it is preferred that the guide members can accommodate pipes of different diameters. For example the angle of the plates referred to above may be adjustable to accommodate different pipe widths. Alternative methods for detecting the end of the dead pipe may be electronic such as laser, infra-red or acoustic guidance systems or videos cameras linked to screens within the cabin of the work machine.

It may be appreciated that any combination of guides may be used.

With many, if not all types of pipe, it is important that the pipe walls are protected from damage. It is therefore preferred that the guide arm further comprises at least one pair of opposed trench guides that may inhibit or otherwise protect the pipe walls from coming into contact with the trench walls. Suitable the trench guides are formed form a resilient material such as rubber. The trench guides are suitably mounted to the guide arm so that they have outer surfaces that are spaced from the pipe walls at a distance that compliments the distance between the trench walls.

Trenches are generally excavated to a predetermined width corresponding to the recommended fill width for a trench. In sufficient fill adversely affects the function of the pipe and there are strict guidelines regarding the minimum fill dimensions. An excess gap between the pipe and the trench wall reflect additional costs in terms of excavation and amount of fill required. An advantage of having the trench guides dimensioned in this way is that they can also assist in guiding the pipe vertically downwards into the trench. Usually an operator will not be able to directly see the pipe after it has been lowered below the top of the trench.

In order for the guide arm to be used with pipes of different diameter the distance between the outer surfaces of the trench guides may be varied in accordance with the different pipe diameters and recommended trench with for that diameter. In order to accommodate pipes of different lengths it is preferred that the length of the guide arm is adjustable. Methods of adjusting the lengths of arms are well known in the engineering field. One suitable method is to for the guide arm to have a main body portion that is adjustably connected to the guide end so that the guide is formed as a separate part from the main body and can be joined thereto. Suitably the guide end has members such as box sections that are telescopically received within complimentary members of the main body portion. The telescopic members may be fixed in place by know means such as by pins received within retaining holes.

Large diameter pipes of about 0.5 to about 1 /5m diameter and up to about 14m in length generally have a degree of flex. It is therefore preferred that the guide arm is able to accommodate this flex. This may be done by selecting a suitable material and/or introducing a means for modifying the tension experienced by the guide arm.

It will be appreciated that the arms are between about 4 to 5m in length and can have considerable weight when constructed of steel. Thus the components of the guide arm are subject to tension and compression. These forces change during operation of the assembly. In order to protect the guide arm from damage caused by the change in forces, the present inventors have introduced a tension modifying arrangement to the guide arm. Suitably the tension modifying arrangement is in the form of compressed rubber blocks proximate to the point at which the guide arm is connected to the shoe.

According to a further broad form of the invention there is provided a pipe laying assembly that comprises: a boom mountable vacuum plate of a vacuum pipe lift device that is operable between a suction pipe engaging mode and a pipe release mode and; a guide arm comprising; a mount end mountable to the vacuum plate of a pipe lift device; and a guide end; wherein when in use and a pipe for joining is engaged by vacuum plate is brought into proximity to an end of an installed pipe, the guide end guides the respective pipe ends into alignment for joining.

The vacuum plate to which the guide arm is mounted is remotely connected to the vacuum source and most preferably in a manner as taught in AU2010202108.

The guide arm is suitably the guide arm as defined in the above embodiment.

The pipe laying assembly is mountable to a boom member. A boom member refers to any hydraulically operable arm controlled by a heavy machinery such as a crane, excavator, back-hoe, pipe-laying machine or the like. The pipe laying assembly may be mounted to the boom member either directly or indirectly. An example of an indirect mounting is an excavator that has a stick mounted to a boom, in which case the pipe work attachment assembly may be mounted to the stick.

Suitably the pipe work attachment assembly is mounted for controlled rotational movement such as being mounted to a hydraulic rotator. Hydraulic rotators are known in the heavy construction art for use with excavators to rotate grapples, hooks and the like. When the pipe laying assembly has engaged a pipe and collated into alignment with the end of a pipe to be installed, then the ends of the pipe may be joined together. Where the pipes are of the O ring type that can be pushed home to be joined, the operator may operate the boom member to move the engaged pipe towards the end of the installed pipe so as to push the pipe home. With normal conventional pipe manoeuvring procedures using a vacuum lift device, the vacuum lift device is generally located in the centre of the pipe so that the pipe is balanced as it is transported. It will be appreciated that this balance may be offset when a guide arm is mounted to the vacuum shoe. It will be appreciated that this may be offset may be overcome by providing a counter balance on the opposed side of the vacuum shoe or providing a counter balance on the shoe itself.

The further arm may be in the form of an arm mounted to the other side of the vacuum plate to which the guide arm is mounted. The arm may include trench guides of the types described above. In this way, the pipe may have at least two pairs of opposed trench guides spaced along its length.

The further arm arm may also include guide members for guiding the assembly onto a pipe to be engaged. The further arm may also include guide means for guiding the pipe into the trench. For example, the further arm may have a laser, infra-red or optical device that can alert an operator to the where the other end of the pipe is relative to the trench wall so that when the assembly is attached to a hydraulic rotator, the operator can make suitable adjustments.

Suitably the further arm is a push arm in that it has a push end that includes a push tab that abuts the end of the pipe. In use, this push tab assists in pushing the pipe home.

After insertion, the pipe is "pushed home" by manoeuvring the vacuum plate laterally. A considerable amount of force maybe required to push home the pipe, especially for large diameter pipes. The push arm and push tabs that bear on the free end of the pipe assist in distributing the lateral force from the vacuum plate that is located about the centre of the pipe towards the end of the pipe. The tab(s) also assist in holding the vacuum plate in its position on the top of the pipe so as to prevent slippage and possible loss of vacuum.

After the pipe has been pushed home, the pipe is disengaged from the vacuum plate and a fresh pipe can be prepared, lifted and installed. According to a further broad form of the invention, there is provided a method for joining a pipe to a pipe installed in a pipeline trench, the method comprising: providing a vacuum plate operable between a suction pipe engagement position and a pipe release position; mounting a guide arm to an end of the vacuum plate, where the guide arm is adapted to guide the end of the pipe to be joined to an end of the installed pipe; activating the suction on the vacuum plate and engaging the pipe to be joined; placing the engaged pipe into the trench such that the pipe to be joined is guided into alignment with the installed pipe and manipulating the vacuum plate so as to push the aligned ends of the pipe together.

Suitably the guide arm is as previously described in the aforementioned embodiments. Suitably, the method further includes providing a further arm as previously described in the aforementioned embodiments.

Suitably the vacuum plate is mounted on a boom arm of a heavy work machine wand connected to a remote vacuum source. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic perspective view of a preferred work attachment assembly of the present invention in use as seen from one direction;

Figure 2 is a schematic perspective view from the other direction;

Figure 3 is a guide end perspective view of a further preferred work attachment assembly of the present invention ;

Figure 4 is a push end perspective view of the assembly of Figure 3;

Figure 5 is plans view of the assembly of Figure 3;

Figure 6 is a side view of the assembly of Figure 3;

Figure 7 is a detail A from Figure 5; Figure 8 is a detail of the guide end of the assembly of Figure 3,

Figure 9 is a detail of the push end of the guide assembly of Figure 3;

Figure 10 is a detail of the rubber block assembly of the assembly of Figure 3 and

Figure 1 1 shows the assembly of Figure 3 in use.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic perspective view of a preferred attachment assembly 10 of the present invention in use. The attachment 10 is shown guiding a free or live pipe 12 towards an installed or dead pipe 14. The installed pipe 14 has a socket or bell end 16 with an internally machined groove with an O ring 17. The free pipe 12 has a spigot end 18 that is to be inserted into the bell end 16 of the installed pipe 14 and a bell end 20.

The attachment assembly 10 has a vacuum shoe 22 that is mounted to the stick 24 of an excavator (not shown). The vacuum shoe 22 is mounted to the stick 24 by a hydraulic rotator 26 that allows the shoe 22 and attached pipe 12 to be rotated in any direction.

The vacuum shoe 22 is remotely connected to a vacuum pump and tank that is mounted to the body of the excavator. The attachment assembly 10 has a guide arm 30 formed from a resilient and flexible rubber. The guide arm 30 has a mount end 31 that is mounted to the end of the vacuum shoe 22. The guide arm 30 has parallel side rails 32 and a centre rail 36. Lateral ribs 34 extend between the side rails 32. The ribs 34 contact the upper surface of pipe 12. The lower contact surface of the ribs 34 are curved so as to conform to the surface of the pipe 10. The guide end 38 of the guide arm extends past the end of pipe 10.

Opposed flexible and resilient rubber guide flaps 39 extend downwards from the extending guide end 38 of the guide arm 30. The flexible guide flaps 39 will deflect slightly as the pipe 12 is lowered towards and contacts the installed pipe 14. The resilience of the rubber urges the flaps 39 towards their original position which guides the pipe 12 into correct alignment with the installed pipe 14.

The attachment assembly 10 also has a push arm 40 mounted to the other end of the vacuum shoe 22 opposite to that of the guide arm 30. The push arm 40 also has parallel rails 42 and a centre rail 44. The push arm 40 has a push end 46 that has two push tabs 48 that extend over the bell end 20 of pipe 12. The tabs push tabs 48 are formed from a material that will not damage the pipe.

In use, when the pipe 12 has been properly aligned with pipe 14, the stick 24 moves the vacuum shoe 22 and pipe 12 towards the installed pipe 14 in the direction of arrow A as shown in Figure 1 . The push tabs 48 bear against the end of pipe 12 and assist in transferring some of the pushing forced to the end 20 of the pipe 12. The push arm 40 also holds the vacuum shoe 22 in place on the pipe 12 and resists slipping of the shoe 22 on the pipe surface.

Figure 3 is a schematic view of a further preferred work attachment assembly 50 of the present invention. The same reference numerals will be used to refer to the same features as shown in Figures 1 and 2. The attachment assembly 50 has a vacuum shoe 22, a guide arm 30 and a push arm 40 that each extend away from the vacuum shoe 22. The assembly 50 is shown engaged to a pipe 12 by the suction force of the shoe 22.

The pipe 12 is a ductile iron pipe of the type used for carrying water in water pipelines. It has a 1 m diameter and 12 - 14m in length. The pipe has a spigot end 18 and a socket end 20. In use the spigot end 18 is the live end in that it is joined to a pipe already installed in a pipe line (dead pipe). The spigot end has circumferential marker 15. The marker 15 is spaced from the end 18 of the pipe so as to indicate to an operator, the desired degree of insertion of the spigot end 18 into the socket end of a dead pipe.

The guide arm 30 and the push arm 40 are each made from steel and constructed from sub parts that are welded or bolted together. The respective arms 30, 40 are of similar construction in that they each have opposed rails 32, 42 and cross arms 52, 54. Each arm 30, 40 has a truss arrangement 56, 58 that comprises a central triangular support 60, 62 with an apex 64, 66. The apex 64, 66 of each support 60, 62 lies vertically above that point at which the respective arms 30, 40 are connected to the shoe 22. A truss 68, 70 connects the respective apexes 64, 66 shoe 22. A truss 72, 74 in the form of two truss arms extend between the respective apex 64, 66 to the arms 30, 40.

The truss arrangement provides support to the assembly. It will be appreciated that the arms are between about 4 to 5m in length can have considerable weight when constructed of steel. Thus the components of the truss are subject to tension and compression. These forces change during operation of the assembly. In order to protect the frame from damage caused by the change in forces, the present inventors have introduced a tension modifying arrangement to the assembly in the form of compressed rubber blocks proximate to the point at which the arms are connected to the shoe. This will be discussed in further detail below with reference to Figure 10. Each arm 30, 40 has a pair of opposed guide tubes 76, 80 that extend on either side of the arms 30, 40. The guide tubes 76, 80 are formed from HDPE tubes. The guide tubes 76, 80 serve to space the pipe from the sides of the trench so as to protect the pipe from damage. The guide tubes 76, 80 have a diameter selected to be slightly less than the distance between the trench edges and the pipe. The guide tubes 76, 80 are mounted to the respective arms 30, 40 by mounts 82, 84. The mounts 82, 84 are box sections telescopically received within a complimentary box section on the arms 30, 40. This allows the spacing between the guide tubes 60, 62 to be adjusted so as to conform to pipes of different diameters. The guide tubes 76, 80 are also adjustable vertically.

Both arms 30, 40 are also adjustable lengthwise so as to conform to different lengths of pipe. The respective rails at the ends 38, 46 of the arm are in the form of sections that are telescopically received within complimentary box sections of the arms. The ends have pin holes 82 to allow them to be fixed in place by pins as known in the art are fixed in place by pins as is known in the art.

Each arm end 38, 46 has a pair of opposed guide and support members 92, 94. The guide and support members 92, 94 serve to guide the assembly onto pipe 12 and also to space the respective arms from the pipe such that the steel arms do not contact the pipe which may damage the pipes' surface. The guide and support members 92, 94 each have a plate 96 set at an angle that is substantially tangential to the pipe. This may be seen more clearly with reference to Figure 8. The plates 96 are mounted to the arms in such a manner that the angle is adjustable to accommodate pipes of different diameters. Each guide and support member 92, 94 has a pair of rubber lugs 98 that protect the pipe 12 from contacting the steel plates.

The guide end 38 extends past the pipe 12. The guide end has a pair of guide members 100 that are the same as the guide and support members 92, 94. In use the guide members 100 align the guide arm relative to the dead end of the installed pipe. As there are two sets of guides on either side of the end of the pipe 12, when the dead end is aligned, the pipes will be accurately aligned without requiring any assistance from a worker in the trench.

The guide end 38 is fitted with a video camera 102 that is connected to a viewing screen in the cabin of the work machine. The camera 102 is mounted between the guide and support members 96 and the lens is directed towards the marker 15. This allows an operator in the work machine cabin to see when the spigot end 18 of pipe 12 has achieved the desired degree of insertion into the socket end of a dead pipe.

The push end 38 also extends past the end of the pipe and is more easily seen in figure 9. The push end 38 has a push tab 104 that abuts the end of the pipe 12. A video camera 106 is located on the push end 38 and is directed away from the pipe 12. The camera is linked to a screen in the cabin of such the camera can relay images to the operator. The lens of the camera 106 is directed away from the pipe and in use will assist the operator in lowering the pipe into a trench.

In use an operator will lift a pipe using the vacuum shoe as per conventional practice. This does not require slinging of the pipe which usually requires two pipe layers. The operator then places the pipe in the trench with the aid of the camera 14. As the pipe is lowered in the trench the guides at the guide end move the pipe into alignment with the dead pipe. Again, no manual intervention is required to align the pipes. After alignment the pipe is "pushed home". The operator is guided by the insert depth marker 15 and the video image of same that is transmitted into the cabin. Again, no manual intervention is required to drive home the pipe. When the pipe has been inserted to the desired extent, the pep is simply disengaged and the process is repeated. The only manual input other than the operator is preparation of the O ring by applying grease as is known in the pipe laying art.

Figure 10 is a detail showing the preload tension rubber blocks 1 10 that are located at the point at which the rails of the respective arms are bolted to the shoe 22. There are three rubber blocks that are compressed between plates 1 12, 1 14 that are connected by bolts 1 16. The rubber blocks maintain tension in the arms and prevent damage to the arms.

Figure 1 1 shows the present invention in use. The assembly 50 is mounted to a stick 24 of an excavator 120. A dead end 122 of a pipeline 124 may be seen at the base of a benched trench 126.

It may be appreciated that the attachment of the present invention can not only lay a pipe in a trench but can also push home a pipe without the need for a worker or workers to be present in the trench. It also does away with the use of a sling to lift the pipe. This not only increases safety but can significantly reduce the time taken to lay pipes.

Other advantages are that it is no longer a requirement to bench a trench. Benching refers to the process of providing the lower half of a trench with the desired clearance between the pipe and the edges of the trench to provide the requisite degree of fill. However, workers are unable to access the lower level of the trench as it is often too deep. This is addressed by providing a bench in the trench to allow workers access to the trench. Benching requires additional excavation which further adds to costs in pipe laying.

It will be appreciated that various changes and modifications may be made to the invention as described and claimed herein without departing from the spirit and scope thereof.

Claims

1 . A guide arm for a pipe laying assembly that includes a boom mountable vacuum plate operable between a suction pipe engaging mode and a pipe release mode, the guide arm comprising; a mount end for mounting to the vacuum plate; and a guide end; wherein when in use and a pipe is engaged by the vacuum plate is brought into proximity to an end of a pipe installed in a pipeline, the guide end guides the end of the engaged pipe into alignment with the end of the installed pipe.

2. The guide arm of claim 1 , wherein the guide end comprises means for detecting the position of the end of the installed pipe.

3. The guide arm of claim 2, wherein the position of the end of the installed pipe is detected by physical cooperation between the guide end and the end of the installed pipe.

4. The guide arm of claim 3, wherein the guide arm is suitable dimensioned such that in use the guide end extends past the end of the engaged pipe so as to allow such physical cooperation.

5. The guide arm of claim 4, wherein the guide end comprises at least one pair of axially opposed guide members.

6. The guide arm of claim 5, wherein the guide members are opposed guide plates aligned at an angle that is substantially tangential to the installed pipe.

7. The guide arm of claim 6, wherein the guide plates are provided with a resilient material that protects the pipe surface from being scratched or otherwise damaged by the plates.

8. The guide arm of claim 6 or claim 7, wherein the angle is adjustable so as to accommodate pipes of different diameters.

9. The guide arm of claim 2 wherein the end of the pipe is detected by a detection method selected from the group consisting of a laser, an infra-red acoustic guidance system, a videos, cameras or any two or more thereof.

10. The guide arm of any one of the preceding claims that further comprises at least one pair of opposed trench guides that may inhibit or otherwise protect the walls of the engaged pipe from coming into contact with the trench walls.

1 1 . The guide arm of claim 10, wherein the trench guides are mounted to the guide arm such that the distance between the trench facing surface of the trench guides is complimentary to the distance between the trench walls.

12. The guide arm of claim 1 1 , wherein the distance between the outer surfaces of the trench guides may be varied in accordance with the different pipe diameters and recommended trench with for that diameter.

13. The guide arm of any one of claims 1 to 12, wherein the length of the guide arm is adjustable.

14. The guide arm of any one of claims 1 to 13, wherein the guide arm has means for modifying the tension experienced by the guide arm.

15. A pipe laying assembly comprising; a boom mountable vacuum plate of a vacuum pipe lift device that is operable between a suction pipe engaging mode and a pipe release mode and; a guide arm comprising; a mount end mountable to the vacuum plate of a pipe lift device; and a guide end; wherein when in use and a pipe for joining is engaged by vacuum plate is brought into proximity to an end of an installed pipe.

16. The pipe laying assembly of claim, wherein the guide arm is the guide arm of any one of claims 2 to 14.

17. The assembly of claim 15 or claim 16, wherein the vacuum plate is remotely connected to the vacuum source.

18. The assembly of any one of claims 15 to 17, wherein the assembly further comprises a push arm mountable to an end of the vacuum plate opposite to that end to which the guide arm is mounted.

19. The assembly of claim 18, wherein the push arm comprises at least one pair of opposed trench guides that may inhibit or otherwise protect the pipe walls from coming into contact with the trench walls.

20. A method for joining a pipe to a pipe installed in a pipeline trench, the method comprising; providing a vacuum plate operable between a suction pipe engagement position and a pipe release position; mounting a guide arm to an end of the vacuum plate, where the guide arm is adapted to guide the end of an engaged pipe to an end of a pipe installed in the pipeline trench; activating the suction on the vacuum plate and engaging the pipe to be joined; placing the engaged pipe into the trench such that the pipe to be joined is guided into alignment with the installed pipe and manipulating the vacuum plate so as to push the aligned ends of the pipe together.