GB2472088A

GB2472088A - Improvements in pipe replacement

Info

Publication number: GB2472088A
Application number: GB0912896A
Authority: GB
Inventors: Keith Frederick Baylis
Original assignee: Scotia Gas Networks Ltd
Current assignee: Scotia Gas Networks Ltd
Priority date: 2009-07-23
Filing date: 2009-07-23
Publication date: 2011-01-26
Anticipated expiration: 2029-07-23
Also published as: GB2472088B; GB0912896D0

Abstract

A method of removing debris from a pipe which has two ends, the method comprising attaching an air supply to one end of the pipe so as to provide a jet of air to dislodge debris or dirt from the bore of the pipe, attaching a receptacle at the other end of the pipe to capture the debris or dirt dislodged by the air supply, venting excess air from the receptacle and supplying air to the pipe at a sufficient pressure to cause the debris or dirt to be blown towards the other end of the pipe and into the receptacle. Also disclosed is a pipe plug for closing the leading end of a flexible pipe to enable the pipe to be moved along the bore of an outer pipe over obstructions and around bends. Further disclosed is an apparatus for pushing or pulling an elongate member into a duct.

Description

Improvements in Pipe Replacement The present invention relates to a method of removing debris or dirt from an existing pipe, to a pipe plug for closing off the leading end of a flexible pipe and to apparatus for pushing or pulling an elongate member into a duct.

It is common to replace existing pipes particularly existing gas service pipes which as they are of steel may have developed leaks through corrosion and cracking. If the service pipe is located underground it is expensive to dig these pipes up and replace them with newer pipes which may be of plastic. On some occasions the existing service pipe may have to be removed and replaced as a result of changes in government legislation. Consequently when replacing existing pipes it is common to replace these pipes with a smaller external diameter replacement pipe so that the existing pipe does not have to be dug up. In order to replace the existing pipe effectively it is essential that the existing pipe is cleaned out to remove all the debris and dirt which may block the progress of the replacement pipe through the existing pipe.

It is an object of this aspect of the invention to provide a method for removing debris or dirt from an existing pipe efficiently In the use of the replacement pipe the pipe must be flexible enough to go round bends in the existing pipe and so this means that En general the pipe must be of plastic such as polyethylene. In order to prevent or at least reduce the possibility of the replacement pipe scooping up any extraneous debris or dirt through the open end of the replacement pipe whilst it is pushed up the pipe to be replaced the open end of the pipe is closed by a pipe * :. plug. The problem with the conventional existing pipe plugs is that their design tends to cause * them to snag on obstructions such as pipe flanges and fittings. *.**

It is therefore an object of this aspect of the invention to provide a pipe plug at least mitigating these disadvantages.

It is known to use apparatus for pushing a replacement service pipe into an existing service : * pipe and for retracting the replacement pipe from the existing pipe. In the existing machines jaws are provided to grip the replacement pipe and either push the replacement pipe into the existing pipe or remove the replacement pipe from the existing pipe depending on the mode in which the apparatus is being used. Because of the alignment of the jaws in the conventional apparatus frequently the flexible pipe is not pushed axially into the pipe. This may cause the replacement pipe to be crushed.

It is therefore an object of this aspect of the invention to provide apparatus overcoming this disadvantage.

According to one aspect of the present invention we provide a method of removing debris or dirt from an existing pipe which pipe has two ends, the method comprising attaching an air supply to one end of the pipe so as to provide a jet of air to dislodge debris or dirt from the bore of the pipe, attaching a receptacle at the other end of the pipe to capture the debris or dirt dislodged by the air supply, venting excess air from the receptacle and supplying air to the pipe at a sufficient pressure to cause the debris or dirt to be blown towards the other end of the pipe and into the receptacle.

Preferably where the pipe is of a ferrous material the debris may be rust and other forms of ferrous corrosion.

Suitably the receptacle is a flexible bag or plastic bottle.

Conveniently the bag is of a plastics material, paper or Hessian.

Preferably the bag is attached releasably to the pipe to allow it to be removed to discharge the debris.

Suitably the bag is releasably attached to the pipe by a velcro or bungy type strap.

According to another aspect of the invention, we provide a pipe plug for closing off the leading end of a flexible pipe to enable the pipe to be moved along the bore of an outer pipe over * obstructions and around bends, the plug comprising an annular portion terminating in a *: substantially flat end, means for connecting the annular portion to the end of the pipe and the plug being of a material which is sufficient flexible to permit the pipe to be moved over obstructions and around bends.

Preferably the plug has a disc like top. S. ** * . S

* Suitably the edges of the disc are mitred or curved.

Conveniently the plug is flexible or deformable.

According to yet another aspect of the present invention, we provide apparatus for pushing or pulling an elongate member into a duct, the apparatus comprising a pair of jaws mounted for reciprocating movement in the apparatus for alternately gripping and releasing the member whereby during the gripping cycle the jaws move the member forwards or backwards, the jaws being arranged such that their ends terminate in the same plane at the end of the gripping cycle.

Preferably the jaws are movable by a handle which is pivotally connected to the jaws.

Suitably the handle is movable to one of two positions and is biassable into one or other of the two positions.

Conveniently the handle is movable against the bias from one position to the other, the arrangement being that in the biased position the jaws grip the member and when moved against the bias the jaws are released from the member.

Preferably the bias is applied by air pressure.

Suitably the bias is applied by means of a piston which is connected to a block and which is biased by the air pressure into one of the two positions.

Conveniently the block is also pivotally connected to the jaws to cause movement of the jaws on movement of the handle.

Preferably the piston forms part of a double acting piston-cylinder arrangement.

In one embodiment the piston forms with the cylinder two chambers in the cylinder, there being means for supplying air selectively to one or other of the chambers whereby the piston is biased into one or other of the two positions. *.I. * I S

*.. Suitably the means is a valve adapted selectively to supply air to a first outlet port for onward supply to one of the chambers and selectively to supply air to a second outlet port for onward supply to the other of the chambers and a first inlet port adapted selectively to supply air to *. : one or other of the outlet ports, the first outlet port also serving as a second inlet port for air returning from the chamber when the second inlet port is selectively serving as an outlet port and the second outlet port serving as a third inlet port for air returning from the chamber when : . the first outlet port is selectively serving as an outlet port.

Conveniently the valve has a third outlet port for selectively discharging air from the first outlet port and thence from the valve and a fourth outlet port for selectively discharging air from the second outlet port and thence from the valve.

Preferably the first inlet port is provided with means selectively to direct the air either to the first outlet port or to the second outlet port.

Embodiments of the inventions wilt now be particularly described with reference to the following in which: Figure 1 is a schematic view of the length of an elongate member in this case a gas service pipe from which debris or dirt is to be removed, Figure 2 is a further view of the service pipe of Figure 1 which has been separated from the main supply pipe at one end so that the service pipe can be cleaned, Figure 3 is a still further view of the service pipe in the process of being cleaned of debris or dirt, Figure 4 is a side view of a pipe plug, Figure 5 is a plan view of a section of the pipe plug shown in Figure 4, Figure 6 is an amplified side view of another embodiment of the plug, Figure 7 is a schematic view from the side of the apparatus, Figure 8 is a front view of the apparatus looking towards the right hand side of the apparatus, Figure 9 shows a side view of the jaws when released and * : :: : Figure 10 shows a side view of the jaws when gripping the service pipe. **. I

Referring to Figures ito 3, in Figure 1 a gas service pipe 1 which is to be cleaned out of debris and dirt prior to its being replaced by a smaller diameter replacement pipe is connected at one end to a high pressure gas main 2. The other end of the service pipe is connected to a customer control tap or valve 3. *I *S

In Figure 2 the service pipe I has been disconnected from the gas main 2 by cutting a smaU section out from it by conventional means near the end which is connected to the gas main 2 which is then capped off by a cap 4 to prevent the escape of gas. The other end of the service pipe 1 is disconnected from the customer tap and the resulting end is closed off by a cap 5 which has tubular inlet 6 for connection to a compressed air supply. A bag 7 of a plastics material such as polyethylene or Hessian or paper is then placed over the free end 8 of the service pipe 1 to capture any debris or dirt contained in the service pipe 2. Then a vent pipe 8 is placed inside the bag 7 to vent off to atmosphere excess air reaching the bag 7 from the end of the service pipe. The bag 7 and vent pipe B are then attached to the service pipe 2 by means of a Velcro or bungy type strap (not shown) in such a manner the bag 7 is air tight and all the air reaches the bag 7 and the excess air is vented to atmosphere by way of the vent pipe 8.

Referring to Figure 3, an air hose 9 of a compressor (not shown) for supplying compressed air to the service pipe I is pushed onto the inlet 6 of the cap 5. Compressed air is then supplied at a pressure of 30 psi down the service pipe I transporting any debris or dirt contained in the pipe 2 into the bag 7 and excess air being vented to atmosphere. The process is continued for ten minutes. When the bag 7 is released from the pipe 2 it is found to contain a large amount of debris and dirt showing that the internal wall of the pipe 2 is now clean and ready for replacement by a smaller diameter replacement main.

Referring to Figures 4 and 5 the pipe plug comprises a hollow cylindrical body section 10 which is closed by a disc like flat top 11 with curved or mitred type edges 12, the plug being of a flexible and deformable plastics material such as polyethylene. The outer wall of the cylindrical section 10 is provided with a number of projecting ribs or vanes 13. The diameter of the plug with the ribs 13 is slightly greater than that of the replacement pipe (not shown) so that the plug can be force fitted into the replacement pipe (not shown) for use as a means of preventing any debris or dirt entering the replacement pipe during replacement, which dirt or debris has not already been removed in the method previously described.

Because the disc like top 11 of the plug has a generally flat upper surface and the edges 12 of the disc 11 are mitred the plug tends to slide over internal flanges and other projecting internal fittings without snagging or engaging with them when the replacement pipe is pushed * :. along the service pipe to be replaced. In addition the flexibility and deformablity of the plug assist in its surmounting obstacles like flanges and other projecting internal fittings. This means it can be inserted relatively quickly. *..

The plug in Figure 6 is similar to that in Figures 4 and 5 except the edges 12 are curved instead of being mitred. ** **

: * Referring to Figures 7 to 9 the apparatus comprises a pair of jaws 20 and 21 for pushing or pulling an elongate member such as a replacement service pipe into an existing service pipe, the jaws 20 and 21 being mounted for reciprocation in the apparatus for alternately gripping and releasing of the member whereby during the gripping cycle the jaws move the member forwards or backwards.

An uppermost block 22 is mounted above the jaw 20 and the jaws 20, 21 and block 22 are pivotally connected by pairs of bars 23 and 24 on either sides 25, 26, 27, 28, 29 and 30 of the jaws 20, 21 and block 22, a handle 29 is provided for movement between two positions where the handle is either in a forward or rearward position and is also pivotally connected to the jaws 20, 21 and block 22 to cause pivotal movement thereof. The handle 29 is biassable into one or other of the two positions where it is gripping the member either for forward movement or for rearward movement. Movement of the handle 29 against the bias causes the jaws 20 and 21 to be released from their grip on the member.

As shown in Figure 8 the jaws 20, 21 are each provided with a corresponding internal concave cavity 31, 32 forming a circular wall 33 to grip the member to be moved forwardly or rearwardly, the jaws 20, 21 being formed with adjoining edges 34, 35 and 36, 37 which when spaced apart as shown in Figure 8 release the jaws 20, 21 from the member and when closed together cause the jaws 20, 21 to grip the member and either move it forwardly or rearwardly.

The bias is applied by a double acting piston cylinder arrangement via a piston 38 which is connected to the uppermost block 22 to cause it to reciprocate by forward and backwards movement of the handle 29. The piston 38 has a cylindrical base 40 which is sealably slidable within the cylinder 41. The base 40 of the piston 38 forms with the cylinder 41 two chambers 42 and 43 which in use are selectively provided one or the other with air under pressure so as to move the piston 38 forwardly or backwardly whereby to provide a bias of the handle 29 into one or other of the positions.

The air is supplied to the cylinder 41 by means of a valve 44 which is shown schematically.

The valve 44 is provided with a first outlet port 45 for onward supply of air to the left hand chamber 42 whereby to bias the piston 38 towards the right. The air is also supplied selectively to the cylinder 41 by means of a second outlet port 46 for onward supply of the air to the right hand chamber 43 whereby to bias the piston 38 towards the left. There is a first inlet port 47 adapted to supply air selectively to one or other of the outlet ports 45 and 46. The first outlet port 45 also serves as a second inlet port 48 for air returning from the chamber 42.

The second outlet port 46 also serves as a third inlet port 49 for air returning from the chamber 43. Two further outlet ports 50 and 51 respectively serve to vent excess air from the the chamber 42 and the chamber 43.

* Air from the port 47 is supplied under pressure via a line 52 to the port 45 and thence via a line 53 to the chamber 42 in which case the piston 38 is biased to the right and moves the uppermost block 22 to the right. This then causes the bars 23, 24 to pivot forwardly and in this case excess air returns via the line 54 from the chamber 43 to the inlet port 49 and then via the line 55 to the outlet port 51 and finally to atmosphere. With the handle 29 biassed in the forward position as shown in Figure 7 the uppermost block 22 is caused to move the jaws 20 and 21 forwardly by a pivoting movement of the bars 23 and 24 forwardly to grip the member and with manually further forward movement of the handle 29 cause a portion of the member to move forward into the pipe to be replaced. When the handle 29 is moved manually backwardly against the bias, the piston 38 is retracted causing the block 22 also to be retracted and via backward movement of the bars 23 and 24 to cause the jaws 20, 21 to release their grip on the pipe ready for the handle 29 to be moved forwardly again so that the jaws 20, 21 grip the member and move a further portion of it forward. This process of alternate forwards and backwards movement of the handle 29 is continued until the entire member has been inserted into the pipe to be replaced.

In an alternative arrangement where it is desired to remove the member from the pipe for any reason, air from the port 47 is supplied under pressure via the line 55 which has been redirected (not shown) to the port 47 and thence via the line 54 to the chamber 43 in which case the piston 38 is now biased to the left and moves the uppermost jaw 22 to the left. This then causes the bars 23, 24 to pivot rearwardly and in this case excess air returns via the line 53, the port 48 and the line 52 which has been redirected (not shown) to the outlet port 50 and finally to atmosphere. With the handle 29 biassed in the rearward position (not shown) the uppermost block 22 is caused to move the jaws 20, 21 rearwardly by a pivoting movement of the bars 23, 24 rearwardly (not shown) to grip the member and with manually further rearward movement of the handle 29 cause a portion of the member to be moved rearwardly out of the pipe to be replaced. When the handle 29 is moved manually forwardly against the bias, the piston 38 is moved forwardly causing the block 22 also to be moved forwardly and via forward movement of the bars 23 and 24 to cause the jaws 20, 21 to release their grip on the pipe ready for the handle 29 to be moved rearwardly again so that the jaws 20, 21 grip the member and move a further portion of it rearwardly. This is continued until the entire member has been removed from the pipe to be replaced.

:. The direction of air lines 52 and 55 is changed by means of an on/off switch 56. In the off position the lines are arranged as shown. In the on position line 52 is connected to port 50 and line 55 is connected is connected to port 47.

Referring to Figure 7 a bottom guide plate 57 is provided beneath the lowermost jaw 21. This plate 57 is connected to the jaw 21 by a lever 58 which is held at one end in a recess in the plate 57 and at the other end in a recess in the lower part of the jaw 21. A spring 60 is located * between the lever 58 and the bottom surface 61 of the jaw 21. The arrangement serves to stabilise the jaw 21.

Referring to Figures 9 and 10 it will be seen that in this arrangement the jaws 20, 21 when they fully grip the pipe as shown in Figure 10 have their front faces 61,62 in the same plane and so the forces imparted to the pipe on the top and bottom jaws 20, 21 are substantially the same. They will not have the tendency as would be the case if the jaws were misaligned and their front faces were not in the same plane to impart a sideways force causing the pipe to collapse. If the pipe is not pushed axially as shown in Figure 10 the crushing forces on the pipe will tend to make the pipe collapse to one side and no further insertion can take place. If the force is applied axially the force transmitted to the pipe will be at a maximum before failure.

The apparatus has been designed so that when air is introduced into the air cylinder and with the handle oriented forwardly the forward movement of the handle will cause the jaws to grip the pipe tightly with the front faces of the jaws being in the same plane.

In conventional apparatuses of this type this feature is absent and so when there is an obstruction or significant resistance to insertion such machines may cause a collapse of the pipe.

In Figure 9 the jaws 20 and 21 have been moved apart to release the pipe and so the axial alignment of Figure 10 is not important.

The apparatus could also be used to push electrical cables into ducts or to pull into ducts such cables or fibre optic cables for telecommunication purposes. This would be effected by pulling on a previously inserted metal hawser which has been attached to the cable.

The apparatus might also be used to replace or renew lead water pipes by inserting the lead pipe again by means of a hawser to which the pipe is attached and providing a cutter to split the pipe so that the lead pipe splits as the new polyethylene water pipe is inserted. IS.. * . S S. I S... * . I... *55* * S * S. S ** I. * I S

I

Claims

Claims 1. A method of removing debris from an existing pipe which pipe has two ends, the method comprising attaching an air supply to one end of the pipe so as to provide a jet of air to dislodge debris or dirt from the bore of the pipe, attaching a receptacle at the other end of the pipe to capture the debris or dirt dislodged by the air supply, venting excess air from the receptacle and supplying air to the pipe at a sufficient pressure to cause the debris or dirt to be blown towards the other end of the pipe and into the receptacle.
2. A method as claimed in claim 1 in which where the pipe is of a ferrous material the debris may be rust and other forms of ferrous corrosion.
3. A method as claimed in claim I or claim 2 in which the receptacle is a flexible bag or plastic bottle.
4. A method as claimed in claim 4 in which the bag is of a plastics material, paper or Hessian.
5. A method as claimed in claim 3 or claim 4 in which the bag is attached releasably to the pipe to allow it to be removed to discharge the debris.
6. A method as claimed in claim 5 in which the bag is releasably attached to the pipe by a velcro or bungy type strap.
7. A pipe plug for closing the leading end of a flexible pipe to enable the pipe to be moved along the bore of an outer pipe over obstructions and around bends, the pipe : plug comprising an annular portion terminating in a substantially flat end, means for *::: * connecting the annular portion to the end of the pipe and the pipe plug being of a material which is sufficient flexible to permit the pipe to be moved over obstructions and around bends. * * S. S
8. A pipe plug as claimed in claim 8 in which the plug has a disc like top.
9. A pipe plug as claimed in clam 8 in which the edges of the disc are mitred or curved.
10. A pipe plug as claimed in either of claims 7 to 9 in which the plug is flexible or deformable.
11. Apparatus for pushing or pulling an elongate member into a duct, the apparatus comprising a pair of jaws mounted for reciprocating movement in the apparatus for alternately gripping and releasing the member whereby during the gripping cycle the jaws move the member forwards or backwards, the jaws being arranged such that their ends terminate in the same plane at the end of the gripping cycle.
12. Apparatus as claimed in claim 11 in which the jaws are movable by a handle which is pivotally connected to the jaws.
13. Apparatus as claimed in claim 12 in which the handle is movable to one of two positions and is biassable into one or other of the two positions.
14. Apparatus as claimed in claim 13 in which the handle is movable against the bias from one position to the other, the arrangement being that in the biased position the jaws grip the member and when moved against the bias the jaws are released from the member.
15. Apparatus as claimed in claim 14 in which the bias is applied by air pressure.
16. Apparatus as claimed in claim 16 in which the bias is applied by means of a piston which is connected to a block and which is biased by the air pressure into one of the two positions.
17. Apparatus as claimed in clam 16 in which the block is also pivotally connected to the jaws to cause movement of the jaws when the handle is moved.
18. Apparatus as claimed in claim 17 in which the piston forms part of a double acting piston-cylinder arrangement.
19. Apparatus as claimed in claim 18 in which the piston forms with the cylinder two chambers in the cylinder, there being means for supplying air selectively to one or other of the chambers whereby the piston is biased into one or other of the two positions. * * .

::..:
20. Apparatus as claimed in claim 19 in which the means is a valve adapted selectively to eS supply air to a first outlet port for onward supply to one of the chambers and selectively to * supply air to a second outlet port for onward supply to the other of the chambers and a first inlet port adapted selectively to supply air to one or other of the outlet ports, the first outlet port also serving as a second inlet port for air returning from the chamber when the second inlet port is selectively serving as an outlet port and the second outlet port serving as a third inlet port for air returning from the chamber when the first outlet port is selectively serving as an outlet port.
21. Apparatus as claimed in claim 20 in which the valve has a third outlet port for selectively discharging air from the first outlet port and thence from the valve and a fourth outlet port for selectively discharging air from the second outlet port and thence from the valve.
22. Apparatus as claimed in claim 20 or claim 21 in which the first inlet port is provided with means selectively to direct the air either to the first outlet port or to the second outlet port.
23. A method substantially as hereinbefore described with reference to the drawings.
24. A pipe plug substantially as hereinbefore described with reference to the drawings.
25. Apparatus substantially as hereinbefore described with reference to the drawings. **1 * . . *. * S.. * * * . * * * , * I. * *I I