GB2247505A

GB2247505A - Pipe access equipment

Info

Publication number: GB2247505A
Application number: GB9018256A
Authority: GB
Inventors: Keith Johnston; Iain Knowles
Original assignee: British Gas PLC
Current assignee: British Gas PLC
Priority date: 1990-08-20
Filing date: 1990-08-20
Publication date: 1992-03-04
Anticipated expiration: 2010-08-20
Also published as: GB2247505B; GB9018256D0

Abstract

Non-destructive testing or inspection equipment eg. a closed circuit television camera 32 gains access to the interior of a pipe 12 such as a live gas main by means of a larger tube 18 secured to the end of a smaller tube 20. The camera 32 is contained initially in a launch tube 30 advanceable out of the larger tube 18 by a push rod 40. The camera 32 is connected to a GPP umbilical 36 passing out of the smaller tube 20 through a seal 26. The larger tube 18 is secured to a flange 22 having an aperture 24. The flange 22 is secured to a slide valve 16 supported by an underpressure clip 14 (following drilling of the main 12 full bore by a machine secured on the slide valve 16). Once the launch tube 30 is advanced the camera 32 is advanced along the main 12 by manual advance of the umbilical. An alternative allows the larger tube to be secured to a valve arranged on a cut out. No launch tube is used. <IMAGE>

Description

PIPZ ACCESS ZOUIPXENT The invention relates to pipe access equipment.

The invention particularly, though not exclusively relates to equipment by which a closed-circuit television camera can gain access to the interior of a live gas main. A live main is one carrying gas.

It is an object of the invention to provide equipment by which access to the interior of a pipe can be gained.

According to the invention, pipe access equipment comprises a larger tube coaxial with a smaller tube and joined to it end to end, the end of the larger tube remote from the smaller tube being secured to a flange having an aperture concentric with the larger tube and the end of the smaller tube remote from the larger tube having an annular seal assembly concentric with the smaller tube, the larger tube in use containing means, such as a closed circuit television camera, which means is connected to an umbilical which passes out of the smaller tube through the annular seal assembly.

In one form of the equipment the means is contained in a launch tube which is telescopically movable out of the larger tube through the aperture in the flange.

Equipment will now be described as an embodiment of the invention by way of example with reference to the accompanying drawings in which: Figures 1 and 2 are diagrammatic vertical sections through two forms of equipment in position to provide access to the interior of a gas main in order to provide inspection by a closed circuit television camera; and Figure 3 is a vertical section on a larger scale through the equipment shown in Figure 1.

Figures 1 and 3 show equipment 10 in position to provide access to the interior of a gas main 12 via an under pressure clip 14 and a slide valve 16. The equipment 10 comprises a larger tube 18 coaxial with a smaller tube 20 to which it is joined end to end. The lower end of the larger tube 18 is welded to a flange 22 having an aperture 24. The end of the smaller tube 20 remote from the larger tube 18 has a seal assembly 26 concentric with the smaller tube 20.

The larger tube 18 contains a launch tube 30 which in turn contains a close circuit television camera 32, which is mounted on brushes 34. The camera 32 is connected to a glass reinforced plastic rod 36, which forms an umbilical and which passes out of the smaller tube 20 through the seal assembly 26.

The launch tube 30 is secured to a push rod 40 which passes out of the larger tube 18 through a second seal assembly 42 (Figure 3).

Figure 3 shows the equipment in greater detail. The larger tube 18 has at its upper end a flange 44 adapted to receive a flange 46 on the lower end of the smaller tube 20. The flanges 44, 46 are secured together by bolts 48 and nuts 50 with a seal 52 between the two flanges 44 and 46 to make a gas-tight connection between the tubes 18, 20.

The seal assembly 26 comprises aluminium packing rings 60 and rubber packing rings 62 in a stack which can be compressed by the cap 64 screwed into the seal holder 66 and having a handle 68.

The seal assembly 42 is of similar construction to the seal assembly 26.

The lower end of the launch tube 30 has several apertures 70 to provide for gas flow when the launch tube 30 occupies its lowermost position within the main 12 as shown by broken lines in Figure 1.

The larger tube 18 has a vent aperture 72 controlled by a vent valve 74.

OPERATION On completion of the fitting and testing of the underpressure clip 14 and the slide valve 16, the main 12 is drilled full bore by a machine (not shown) mounted on the slide valve 16. The slide valve is then closed and the equipment 10 is mounted on the slide valve 16 by means of the flange 22 which is bolted in place. The equipment purged to 100t G.I.A. at the vent valve 74 by means of a bleed facility (not shown) on the slide valve 16. The vent valve 74 is closed. The gas seal assembly 26 is now released by the handle 68 and the slide valve 16 is fully opened. The push rod 40 is pushed fully down allowing the launch tube 30 to enter the main 12. This prevents the camera 32 from dropping vertically and jamming on the base of the main.

The umbilical 36 is then manually pushed down further allowing the camera 32 to travel up to 100 metres along the main 12.

Upon completion of inspection, the camera 32 is withdrawn into the launch tube 30 and the tube 30 is pulled up into the larger tube 18. The slide valve 16 is closed and the vent valve 74 opened.

The procedure can be repeated, with the equipment 10 turned through 180 degrees upon the slide valve 16 (the flange 22 being released and bolted up again), to allow another 100 metres of main to be inspected in the opposite direction.

If the main 12 is lined after inspection, the hole drilled in the main 12 is made gas tight by the lining pipe. The underpressure clip 14 and the slide valve 14 are recoverable in that case.

Figure 2 shows the application of the equipment to a main 12 via a cut out. If it is a polyethylene main a squeeze off tool may be used at 100 to close the main. If it is a cast iron main a bag stop may be used at 100. A polyethylene flange is connected to the cut 102 by means of an electrofusion coupler 104. Alternatively, a mechanical coupling is used to enable a valve 106 to be secured t the main 12. The valve 106 is supported against end thrust produced by gas pressure.

Connected to the valve 106 is the flange 108 of the pipe access equipment 110. The flange 108 has an aperture (not shown) and is secured to a larger tube 112 (concentric with the aperture) which is itself secured to a smaller tube 114 in line with the larger tube 112. The larger tube 112 has a vent 116 and vent valve 118.

The closed circuit television camera 120 mounted on skids 122 is contained in the larger tube 112 and is connected to an umbilical 124. The free end of the smaller tube 114 carries a seal assembly 126 through which the umbilical 124 passes as it leaves the smaller tube 114.

The smaller tube 114 is, for example, a 2-inch tube with a 50 millimetre flange to connect it to the larger tube. The detailed construction is similar to that shown in Figure 3.

The larger tube 112 is of 80, 100, 150, 200, 250, 300 etc.

millimetres diameter to suit the main 12 being inspected.

OPERATION After completion of the cut and assembly of the valve 106, the latter is cracked open and the equipment interior is vented to 100% G.I.A. as before. The umbilical 124 is released by slackening off the seal assembly 126 (see Figure 3) and the valve 106 is fully opened. The umbilical 124 is then manually pushed inwards allowing the camera 120 to travel up to 100 metres along the main 12. Upon completion of inspection the camera is withdrawn into the larger tube 112. The valve 106 is closed and the vent valve 118 is opened. The equipment 110 can then be removed from the valve 106. The procedure can be repeated at the other cut 130. On completion of operations, a further squeeze off or bag is applied and the cut out is repaired using couplers to piece on a repair length of main 12.

The equipment described above can be applied to pipes generally e.g. water pipes or chemical pipes. The television camera may be replaced by another means to effect non-destructive inspection or testing or designed for some other purpose.

Claims

CLAIh8

1. Pipe access equipment comprising a larger tube coaxial with a smaller tube and joined to it end to end, the end of the larger tube remote from the smaller tube being secured to a flange having an aperture concentric with the larger tube and the end of the smaller tube remote from the larger tube having an annular seal assembly concentric with the smaller tube, the larger tube in use containing means, such as a closed circuit television camera which means is connected to an umbilical which passes out of the smaller tube through the annular seal assembly.

2. Equipment according to claim 1 the means being contained in a launch tube which is telescopically movable out of the larger tube through the aperture in the flange.

3. Equipment according to claim 2 the larger tube being inclined to the flange at an angle other than 90 degrees.

4. Equipment according to claim 2 or claim 3 the launch tube being connected to a push rod which passes out of the larger tube through a second seal assembly.

5. Equipment according to claim 1 substantially as herein described with reference to Figures 1 and 3 of the accompanying drawings.

6. Equipment according to claim 1 substantially as herein described with reference to Figure 2 of the accompanying drawing.