Pipe threading

Abstract

A pipe threading arrangement for connection to a service pipe (14) in a dwelling comprises a launch coupling (50) with a body portion (51) forming a chamber in which a parachute housing (60) is held. A stopper arrangement (30, 31) allows the coupling to be attached to the service pipe (14) whilst gas is present in both the service pipe and main. The housing includes a folded parachute-like device (62) attached to a line (66). A front portion of the parachute housing includes flexible guide (63) which allows the device to be manually lowered into a main pipe via the service pipe. A tube (65) is used to push the housing through the pipe. The tube is arranged to receive a jet of gas to separate the end with the guide attached and to inflate the parachute into the main where gas flow carries it along the main.

Description

[0001] The invention relates to pipe threading to allow a cable or similar line to pass between two locations in the pipe.

[0002] Typically in order to provide a cable between two locations in an existing main pipeline (e.g. gas main), it has been necessary to excavate each site and add large and expensive fittings to this pipeline.

[0003] In our copending patent application PCT/GB99/00168 an arrangement is described which allows a parachute-like device to be launched between two locations on the main pipe whilst keeping excavation to a minimum if access is not readily available.

[0004] The present invention is concerned with an alternative pipe threading configuration which can be carried out between a main pipe and an auxiliary pipe typically within a customer's premises.

[0005] According to the invention there is provided a method of threading a cable between a relatively small bore service pipe at a customer's premises at a first location and a second location on a main pipe, the method comprising providing an access point in the service pipe at the first location and an access point at the second location in the main pipe, providing a retrieval device at the second location, launching a parachute-like device carrying a threading cable from the service pipe, allowing the parachute to move to the second location by means of fluid flow through the main pipe and retrieving the parachute device or the cable attached at the second location to provide pipe threading between the two locations.

[0006] Further according to the invention there is provided a pipe threading apparatus including means for launching a parachute-like device attached to a cable from a relatively narrow bore service pipe in a dwelling at a first location to a second location in a main pipe under fluid pressure and means for retrieving the cable or parachute at the second location to provide pipe threading between the two locations.

[0007] Still further according to the invention there is provided a pipe threading apparatus for launching a parachute-like device including a closed parachute chamber containing a collapsed parachute, elongate guide means attached to the chamber to assist in moving the chamber through bends in a narrow bore pipe towards a junction with a main pipe and means for applying fluid pressure to the chamber to launch the parachute from the chamber into the main pipe.

[0008] The invention will now be described by way of example with reference to the accompanying drawings in which:

[0009] FIG. 1 shows an existing gas main with an auxiliary service pipe for supplying a gas service to a customer's premises;

[0010] FIG. 2 shows an arrangement for gaining access to the service pipe whilst gas is present in this pipe;

[0011] FIG. 3 shows the stoppered service pipe following removal of the service gas tap in one of a number of premises and the gas main access point;

[0012] FIG. 4 shows the launch coupling about to be attached to the service pipe;

[0013] FIG. 5 shows the introduction of the parachute arrangement into the service pipe following removal of the stopper;

[0014] FIG. 6 shows the parachute housing and guide in more detail together with the launch gas supply;

[0015] FIGS. 7A-7F show stages in gaining access to the main to form the gas main access point as well as retrieval of the parachute device;

[0016] FIG. 8 shows the retrieval rod and frame carrying a stopping mesh;

[0017] FIG. 9 shows an alternative retrieval arrangement; and

[0018] FIG. 10 shows the removal of the launch coupling following the pulling through of the optical fibre cable.

[0019] An existing gas pipe arrangement is shown in FIG. 1 and includes a service pipe 14 which terminates in a customer's premises 36 and the other end is connected at junction 17 to a main gas pipe 20 having an internal bore 21, the service pipe having a substantially smaller bore 11. The main pipe 20 as well as part of the service pipe 14 is buried beneath the ground 15. The service pipe has two bends 12 and 13 below ground, in this example, before it rises vertically to the meter 18 typically within a dwelling. A meter tap 16 is provided to shut off the supply for safety or isolation reasons. Gas will typically be flowing in both pipes and a governor adjacent the meter may typically also be present but it is omitted for the sake of simplicity.

[0020] The present configuration to be described allows for a line or cable to be passed between the small bore service pipe and the main whilst gas is present in the pipes without the need to excavate in the region of the service pipe.

[0021] In order to gain access for threading purposes through the service pipe, it is necessary to remove the meter whilst preventing inadvertent gas flow from the pipe which could be hazardous.

[0022] To achieve this step a mechanism as shown in FIG. 2 is employed. With the gas tap 16 in the closed position the meter 18 connection (see FIG. 1) is removed and the FIG. 2 mechanism attached to the threaded portion 23 of tap 16.

[0023] The mechanism includes a housing 25 for a stopper 30 which comprises a flexible rod terminating in a number of rubber sealing discs 31. A nut 26 can be tightened to compress a gland seal 27 so as to effect a seal against the rod 30. The gland seal is typically formed of both metal and rubber discs. With this seal in place, the gas tap 16 can be opened and gas in the service pipe 14 cannot escape due to the seal.

[0024] The rod is then pushed downwards to cause the end with the seal discs 31 to move through the bore of tap 16 into the service pipe. Once in place, the checkpoint 28 allows for testing for any leakage. Assuming no leakage is present, the housing 25 can be removed. The stopper on the rod remains in the service pipe. The rod tap 16 can then be removed from threaded portion 24 to gain clearer access to the service pipe.

[0025] FIG. 3 shows the stopper 30 in the accessible end of the service pipe 14 within dwelling 36. Adjacent dwellings 37 and 38 will also have service pipes 40 and 41 respectively which can also be accessed in a similar manner.

[0026] The threading arrangement now described will allow access from any service pipe using the above technique to a convenient access point 45 on the gas main.

[0027] A launch coupling 50 (see FIG. 4) includes a tubular body portion 51 which can be coupled to portion 24 on the service pipe (e.g. compression fitting). Although the service pipe 14 is shown horizontally for illustrative purposes, it will in practice typically be vertical, with the body portion 51 correspondingly being in a vertical position. Within the body portion is located a flexible housing 60 in which is stowed a folded parachute-like device 62.

[0028] It can be seen that the launch coupling 50 also includes a second body portion 53 which extends at an angle from the main body portion and into which the stopper rod 30 of FIG. 3 has been inserted. Once the rod is inserted, the portion 52 can be coupled to portion 24 of the service pipe in preparation for the launch of the device 62. The rod 30 extends externally of the body 53 through a seal 54 surrounding an aperture in the cap 55.

[0029] The parachute housing 60 has a flexible guide 63 extending from a front face and an elongate tube 65 extending from its rear end which tube includes a thin flexible line 66 attached to the parachute. The tube 65 is in sealed relation to the housing 60 by means of end seal 67.

[0030] The stopper rod can then be withdrawn into the chamber within housing 53, as shown in FIG. 5, to open the passageway into the service pipe 14 without leakage of gas as the tube 65 abuts the seal 67A.

[0031] The mechanisms involved with the launch of the parachute are described in more detail in FIG. 6.

[0032] The parachute 62 is formed of a suitable lightweight fabric and is folded and stowed within housing 60. It is attached to the line 66 which extends from body 51 through flexible elongate tube 65. The tube 65 is of sufficient length that it can pass through the entire length of the service pipe 14 to a position adjacent the junction of the service and main pipe. The line or wire 66 attached to the parachute is of sufficient length to travel also along the main pipe to the retrieval point which could be 50 to 500 metres away, for example. Hence the line is held on a reel 70 which will automatically be played out as the parachute moves along the main pipe due to gas flow. Cable 66 passes through running seal 69 to prevent gas escaping.

[0033] The flexible housing 60 is typically of corrugated plastic construction, the corrugations being arranged to allow the desired degree of flexibility to be achieved. The housing terminates at the rear with an end piece 74 to which the plastic tube 65 is affixed. The end piece includes angle face 78 to assist in retrieval of the housing following launch.

[0034] The front end 75 of the housing is arranged to be a push fit with the body of the housing and has a curved face to assist in its movement through the pipe.

[0035] A guide extension 63 carries a weighted nose piece 73. The guide extension is formed from a helical spring which typically has a graduated resilience so that the end towards the nose piece is more flexible than the portion nearer the end 75. This assists in enabling the weighted nose piece to drop under gravity to ensure it will enter the junction with the main and move downwards to prevent jamming at this junction.

[0036] Hence, when required, the guide 63 is pushed through the service pipe by means of the external flexible tube 65 until it enters the junction with the main. Then a jet of fluid (e.g. fuel gas or nitrogen) is made available from source 80 via button 81 to coupling tube 82 and then to adaptor 83. This gas pressure separates end piece 75 and this falls away but is retained by cord 68 to prevent complete detachment. As this happens, the gas launches the parachute 62 and when it is in the main it is driven forward by the gas flow in the main 20.

[0037] The parachute travels through the pipe to the access point 90 shown in FIG. 7A which will have been prepared prior to launch.

[0038] To form the access point 90, a drilling device 92 including a drill shaft 93 and drill bit/tap 96 is coupled to the pipe via a saddle valve 113 which includes clamp chains 91. The housing 95 is sealed by seal 125 with the shaft 93 to allow drilling with pressurised gas in the main. The saddle valve 113 is open as shown to allow the drill to be powered so as to drill through the wall of the main pipe and to form a tapped hole therein (e.g. 1 inch BSP).

[0039] The drill is then partially withdrawn and the valve 113 closed to seal any gas entering.

[0040] The housing 95 can then be uncoupled, the drill removed and a pipe holder 115 added with pipe 112 and placed over a stopper device 111. The valve 113 is opened once the housing 95 is affixed and then the pipe holder with attached pipe and stopper is lowered through the aperture in the valve. On rotation of the holder 115 the threaded pipe 112 is screwed into the main pipe wall. The pipe holder is sealed in relation to the housing 95 and the stopper 111 prevents gas flow through the bore of pipe.

[0041] After checking for any gas leaks after screwing in the pipe, the housing is removed to leave the pipe 112 with fitted stopper 111.

[0042] To this pipe, a special retrieval housing 110 is coupled as shown in FIG. 7C.

[0043] This accommodates the rod 114 in branch 130 and the main housing chamber 131 holds a retrieval mechanism comprising a rod portion 94 and head portion 97 formed as a resilient metal frame carrying a mesh 98.

[0044] To prepare for the launch of the parachute from the service pipe, the rod 114 on stopper 111 is pulled generally upwards to cause the discs 121 to move upwards into the branch chamber 130 so making the main pipe available to receive the retrieval device. The running seals 116 and 123 prevent any gas escape.

[0045] The lowering of the retrieval device, see FIG. 7D, is continued until it is within the bore of the main pipe 20.

[0046] The parachute 62 can then be launched via the service pipe and is stopped by the mesh 98 in head portion 97.

[0047] The rod 94 can then be pulled to withdraw the retrieval device and the parachute 62 therein together with the line 66 attached thereto.

[0048] As shown in FIG. 7E, once retrieved, the stopper is lowered and the discs seal the aperture once again, the line 66 being trapped against the pipe wall and the resilience of the discs providing an effective seal.

[0049] A cable, typically an optical fibre cable 99 can then be attached to line 66 utilising fitting 110 to allow the optical cable to be towed back along the main to the service pipe and along the service pipe inside the dwelling.

[0050] The running seal 116 within fitting 110 can be selected to ensure a tight fit with the optical cable.

[0051] On sealing once again by the stopper 111 a seal cap 118 is then added in replacement to form an additional seal for the cable 99 with seal element 117.

[0052] A more permanent fitting will then typically be provided dependant on requirements.

[0053] This method has the advantage of providing an additional service into the dwelling for TV, telephone, Internet, and other communications without the need to excavate anywhere within the customer's premises so offering a quick and inexpensive operation.

[0054] The retrieval mechanism is shown in more detail in FIGS. 8 and 9.

[0055] The rod 94 terminates in the retrieval mechanism which includes a resilient frame 97 which may be formed of a flat steel band which is sufficiently flexible to be compressed when within the retrieval chamber but will expand (shown expanded) when moved into the bore of the main.

[0056] In this first embodiment, the frame carries a flexible lightweight mesh 98 which will not block the flow of gas in the main pipe.

[0057] As explained above, in the extended position the parachute when reaching the retrieval position will impact against the mesh 98 and can be withdrawn through the special fitting 110 of FIG. 7E.

[0058] Although the retrieval mechanism of FIG. 8 employs a mesh, an alternative version shown in FIG. 9 has only the flexible band 97 which can be employed for example where more than one access point is desired in which case the intermediate access points would employ this rod with its band so that the parachute would pass through the band and move on to the next access point. During this operation the line or cable will have threaded through the eye of the band 97 so on retrieval the line can be pulled into the retrieval chambers of the intermediate access points, so that the launch of the parachute only has to be carried out once.

[0059] Once the optical fibre cable 99 has been pulled back through the service pipe using the line previously attached to the parachute, the stopper previously employed with the FIG. 4 arrangement is again utilised, as shown in FIG. 10.

[0060] This stopper is pushed into place into the service pipe as in the FIG. 4 arrangement and the discs 31 are sufficiently resilient to hold the cable 99 in sealed relationship to the inner wall of the service pipe 14. At this stage the launch coupling 50 can be removed and a suitable adaptor for the service pipe and optical fibre cable added prior to the replacement of the gas tap 16 and meter 18 of FIG. 1.

[0061] Although the stopper has been described in terms of a rod with a number of sealing discs, the discs could be replaced by an inflatable device to effect the sealing; the rod being hollow to provide the inflatable source in such an arrangement.

[0062] The above method allows the addition of the cable to be made in the dwelling without interrupting the supply of gas to other customers as the main continues to carry gas. The arrangement can cope with bends in the narrow bore service pipe as well as the junction in the service pipe and access requirements at the second location downstream. The interruption of availability of gas to an individual customer is kept to the minimum as no excavation is required.

Claims

1. A method of threading a cable between a relatively small bore service pipe at a customer's premises at a first location and a second location on a main pipe, the method comprising providing an access point in the service pipe at the first location and an access point at the second location in the main pipe, providing a retrieval device at the second location, launching a parachute-like device carrying a threading cable from the service pipe, allowing the parachute to move to the second location by means of fluid flow through the main pipe and retrieving the parachute device or the cable attached at the second location to provide pipe threading between the two locations.

2. A method as claimed in claim 1 wherein the launch step includes moving the parachute device through the service pipe using guiding means from the access point to a position adjacent a junction with the main pipe prior to launch.

3. A method as claimed in claim 1 or 2 including the step of applying a fluid to a closed parachute chamber containing the parachute to open the chamber and to launch the parachute into the flowing fluid in the main pipe.

4. A method as claimed in claim 3 wherein the method includes providing a sealable housing for holding the parachute chamber and a pipe stopper device for selectively sealing the service pipe.

5. A method as claimed in claim 4 including the step of providing a optical fibre cable for attachment to the threaded cable at the second location and pulling the optical cable through the main pipe into the service pipe.

6. A method as claimed in claim 5 including the step of sealing the optical cable in the service pipe by means of a portion of the stopper device.

7. A method as claimed in any preceding claim including the step of removing a gas meter attached to the service pipe to provide the access point in the service pipe.

8. A method as claimed in any preceding claim wherein an access point to the second location is provided by forming an aperture in the main pipe and permanently fixing a duct thereto to allow a stopping mechanism and a retrieval mechanism to be utilised to access the main and retrieve the cable.

9. A method as claimed in claim 8 including the step of pulling an optical cable via the access point utilising a sealed entry device.

10. A pipe threading apparatus including means for launching a parachute-like device attached to a cable from a relatively narrow bore service pipe in a dwelling at a first location to a second location in a main pipe under fluid pressure and means for retrieving the cable or parachute at the second location to provide pipe threading between the two locations.

11. Apparatus as claimed in claim 10 wherein the launching means includes container means for the parachute and elongate guiding means for assisting the passage of the parachute to a position adjacent a junction with the main pipe prior to launch.

12. Apparatus as claimed in claim 11 wherein the elongate guide means is resilient and includes weighted termination means for ensuring the guide means has a tendency to extend downwards.

13. Apparatus as claimed in claim 11 or 12 wherein the container means includes a closed parachute chamber and means attached thereto for opening the chamber and releasing the parachute in response to fluid pressure applied to the container.

14. Apparatus as claimed in claim 11, 12 or 13 including a sealable housing for holding the container means and a pipe stopper device for selectively sealing the service pipe.

15. Apparatus as claimed in any one of claims 10 to 14 including housing means attachable to an entry point at the second location in the main pipe, the housing means including means for holding a moveable stopping device and means for holding a moveable retrieval device.

16. Apparatus as claimed in claim 15 including seal means attachable to the housing means to allow an optical cable to pass through the entry point in sealed relationship with the housing means.

17. A pipe threading apparatus for launching a parachute-like device including a closed parachute chamber containing a collapsed parachute, elongate guide means attached to the chamber to assist in moving the chamber through bends in a narrow bore pipe towards a junction with a main pipe and means for applying fluid pressure to the chamber to launch the parachute from the chamber into the main pipe.

18. Apparatus as claimed in claim 17 wherein the elongate means is configured to be biased so as to tend to angle downwards.

19. A method of threading a cable substantially as described herein.

20. Pipe threading apparatus substantially as described herein with reference to the accompanying drawings.