GB2247504A

GB2247504A - Pipe fitting

Info

Publication number: GB2247504A
Application number: GB9018255A
Authority: GB
Inventors: Ian Hetherington Mearns
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: GB2247504B; GB9018255D0

Abstract

The fitting 10 is used for launching pipe cleaning or treatment equipment, non-destructive test equipment or a camera 48 into a gas or other pipe 22. It comprises a split conduit 16 forming the lower part 12 and a hollow straight branch 26 with two integral straight hollow limbs 28, 30 forming the upper part 14. The upper portion 18 of the conduit 16 has an opening 24 which in a first mode of operation is closed by a plug 70 so that the conduit 16 can be permanently left on the pipe 22. In a second mode of operation the upper portion 18 receives the upper part 14 after removal of the plug through the opening 24. The upper portion 18 mates immediately above the opening 24 with the upper part 14 of the fitting 10. A machine mounted on the branch 26 cuts a hole 36 in the pipe 22 through which the camera 48 is launched using a tube 44. The tube 44 is pushed manually and a GRP rod 46 is then manually advanced to push the camera along the pipe 22. <IMAGE>

Description

PIPS ZITTIXA This invention relates to pipe fittings.

A particular use of the fitting to be described by way of example is to launch a camera into a gas pipe, particularly a pipe having a nominal diameter of four-inch (100 millimetres) of six-inch (150mm) pipe, for example.

However, the fitting with modification if necessary may have other uses, for example launching pipe treatment or cleaning equipment, such as a spray for concrete or resin, or non-destructive test equipment and the fitting can be used with pipes for other services, for example, water pipes or chemical plant pipes, and the fitting design is applicable to pipes of sizes different from 4 or 6-inch.

According to the invention, a pipe fitting comprises a lower part and an upper part, the lower part being a split conduit intended to be mounted on a pipe, the upper portion of the conduit having an opening intended in a first mode of use of the fitting to be closed by a plug so that the conduit can be permanently left on the pipe, the conduit being ready in a second mode of use to receive the upper part of the fitting after removal of the plug through the opening, the upper portion of the conduit mating immediately above the opening with the upper part of the fitting.

Preferably, the fitting when assembled for said second mode of use has an upper part comprising a hollow straight branch mating with the upper portion of the conduit and extending away from the conduit, and two hollow straight limbs integral with the branch and inclined to both the conduit and the branch with the branch lying between the two limbs, the branch carrying a valve at its free end and each limb having a valve.

Preferably a fitting assembled for said second mode of use, said upper part comprising a camera launch tube which can be reciprocatingly accomodated in either straight limb and which, when so accommodated just clears the edge of said opening in said upper portion of said conduit at one side and at the opposite side just clears the edge of the hole cut in the wall of the pipe on which said conduit is mounted said hole having been cut by a machine supported on said branch.

An embodiment of fitting will now be described by way of example with reference to the accompanying drawings: Figure 1 is a vertical section showing the assembled fitting mounted on a pipe; Figure 2 is a vertical section showing the lower part of the fitting mounted on a pipe in the first mode of use of the fitting; and Figure 3 is a plan of the part shown in Figure 2 with the blanking flange removed.

Figure 1 shows a pipe fitting 10 comprising a lower part 12 and an upper part 14. The lower part consists of a conduit 16, which is split longitudinally into an upper portion 18 and a lower portion 20, so that the conduit 16 can be mounted on a pipe 22 such as a gas main, for example.

The upper portion 18 has an opening 24.

The upper portion 18 mates with the lower end of a hollow straight branch 26 secured by bolts (not shown) to the upper portion 18. The branch 26 extends away from the conduit 16. Two hollow, straight limbs 28, 30 are integral with the branch 26 and are inclined to both the conduit 16 and the branch 26. The branch 26 lies between the limbs 28, 30 and carries a converter valve 32 at its free end.

An adaptor 34 is mounted on top of the converter valve 32 and enables a cutting machine to be used to cut a hole shown at 36 in the pipe 22.

Each limb 28, 30 has a ball-valve 38, 40 respectively.

The fitting 10 is intended for use with a buried pipe 22 such as a 'live' gas main and the conduit 16 is split longitudinally to allow the conduit 16 to be fitted over the pipe 22 once it has been exposed at an excavation. A 'live' gas main is a main carrying gas under pressure.

When the fitting has been fitted as shown, a cutting machine is fitted to the top of the adaptor 34 and the converter valve 32 is opened. The ball valves 38, 40 are closed at this time. The cutting machine cuts a hole 36 through the sidewall of the pipe 22. In the case of a 4inch main, as illustrated, the cutting machine is mounted with its working stem eccentric to the centre line of the branch 26. It first of all cuts a first hole. Then, the machine is turned through 180 degrees and the machine cuts a second hole overlapping the first hole. The result is an elongated hole 36 in the pipe 22, which has a minimum width which just allows the camera 48 to enter the pipe 22.

For a 6-inch pipe the cutting machine is mounted with its working stem coincident with the centre line of the branch 26 and a single hole is cut in the pipe 22.

After cutting the hole, the converter valve 32 is closed and the cutting machine removed.

A camera outer launch tube 41 is then fitted to one end of one of the limbs, say 30, after the blanking flange has been removed. The outer tube 41 has a seal arrangement 42 at its free end and receives an inner launch tube 44.

Before the tube 41 is fitted, a camera rod 46 of glass reinforced plastic is fed through the tube 44 through its leading end. The rod 46 passes through a running seal 49.

A camera 48 is attached to the rod 46 is eventually housed within the inner launch tube 44.

The inner launch tube 44 has an enlarged-diameter lower end and has an opening in its lowermost sidewall to facilitate rotation of the camera 48 as it approaches the tube lowermost sidewall. A radius or roller may be provided at 52 to afford protection for the rod 46 at that point.

After the outer tube 41, with the camera and inner tube 44 retained in it, has been fitted to the limb 30, the ball valve 40 is opened. The seal 42 and the seal 62 (see below) are released and the launch tube 44 is manually pushed inwardly against the gas pressure.

The lower end of the inner tube 44 passes through the ball valve 40, through the hole 36 and reaches the lower wall of the pipe 22. The seals 42 and 62 are tightened up and the camera 48 is then advanced by manually feeding the rod 46 through the inner tube 44. Eventually, the camera 48 enters the pipe 22 and can be advanced along the pipe 22 to make a full inspection, the camera view being displayed on a monitor connected to the rod 46, which acts as an umbilical connection to the camera 48. The camera 48 has a flexible connection at 54 to allow, for example, 90 degrees of articulation relative to the rod 46. The length of the camera 48 and the length of the opening 50 are carefully chosen to ensure that the camera 48 smoothly crosses the opening 50 in both directions of travel.

The outer launch tube 41 carries at its end a threaded collar 58 which contains the seal 42. The seal 42 can be tightened against the inner launch tube 44 by a threaded cup 60 carried on the collar 58. The cup 60 is threaded at its other end and contains a primary seal 62, which can be tightened against the inner launch tube 44. This can be done by a threaded cup 64 carried on the cup 60.

During launch, both the seals - 42 and 62 are released, though the seal 42 prevents gas leakage except for a minute amount. When the camera 48 is launched into the pipe 22, the seals are both tightened against the inner launch tube 44 by rotation of the cups 60 and 64. This gives a virtually perfect seal.

When inspection has been completed and another inspection, if necessary, carried out using the other limb 28, the camera launch assembly is removed and the ball valve 38 is closed (the valve 40 having already been closed).

Blanking flanges are fitted to the ends of the limbs 28, 30. The converter valve 32 is closed and the machine adaptor 32 is removed and the blanking flange (not shown) can be fitted.

Another machine, for example a cutting machine, with a special device (not shown) to receive a plug 70 (Figure 2) is then fitted to a normal adaptor (i.e. non-eccentric) on top of the converter valve 32. The valve 32 is opened and the plug 70 is lowered until it locates in the opening 24.

An inwardly-directed flange 71 is provided to act as a stop for the plug 70 at the inner edge of the opening 24.

The plug 70 is mechanically retained by means not shown.

The machine retracts the device and the converter valve 32 is closed. The upper part 14 of the fitting 10 is then removed. The plug 70 has a seal 72 which seals against the wall of the opening 24.

Finally, a gasket 74 and a blanking flange 76 are fitted to the conduit 16 above the plug 70 blanking off the opening 24. The blanking flange 76 is retained by studs 78 and nuts 80.

The lower part 12 of the fitting 10 can thus be permanently left fitted to the pipe 22. However, by using the method set out immediately above in reverse the upper part 14 can at any time be fitted to the lower part 12 and camera inspection (or other process) re-applied to the pipe 22 as required.

As mentioned above, the example shown in the drawings is a fitting for a 4-inch main. Apart from the use of eccentric cutting of two holes by the cutting machine, the method used for a 6-inch main is virtually the same. In both cases, it is important to keep the dimension X shown in Figure 2 as small as possible. For a 4-inch main it is preferred that X be llOmm maximum. The main 22 has a range of outside diameters between 116mm and 124mm. For a 6-inch main, the dimension X is preferred to be 138mm.

The 6-inch pipe has a range of outside diameters between 167mm and 179mm. This minimises the size of the equipment left on the main after an inspection.

It is also important for the tube 44, when it is advanced towards the pipe 22, just to clear the edge 81 of the opening 24 at one side and, at the other side, just to clear the edge 82 of the hole 36 in the pipe wall.

The invention is applicable to pipe fittings for use in other than gas systems. For example, it is applicable to water systems or to systems above ground or sub-sea containing pressurised gas or water or a pressurised fluid.

Claims

CLLIKS

1. A pipe fitting comprising a lower part and an upper part, the lower part being a split conduit intended to be mounted on a pipe, the upper portion of the conduit having an opening intended in a first mode of use of the fitting to be closed by a plug so that the conduit can be permanently left on the pipe, the conduit being ready in a second mode of use to receive the upper part of the fitting after removal of the plug through the opening, the upper portion of the conduit mating immediately above the opening with the upper part of the fitting.

2. A fitting according to claim 1 assembled for said second mode of use, said upper part comprising a hollow straight branch mating with the upper portion of the conduit and extending away from the conduit, and two hollow straight limbs integral with the branch and inclined to both the conduit and the branch with the branch lying between the two limbs, the branch carrying a valve at its free end and each limb having a valve.

3. A fitting according to claim 2, having a camera launch tube which can be reciprocatingly accommodated in either straight limb and which when so accommodated just clears the edge of said opening in said upper portion of said conduit at one side and at the opposite side just clears the edge of the hole cut in the wall of the pipe on which said conduit is mounted said hole having been cut by a machine supported on said branch.

4. The lower part of the fitting according to claim 1 mounted on a pipe with said opening closed by said plug and with a blanking flange fitted to the conduit above the plug and blanking off the opening.

5. A fitting according to claim 2, the branch supporting a machine operable to cut a hole through the pipe received in said conduit.

6. A fitting according to claim 5, the machine being mounted eccentrically on the branch so that two overlapping holes can be cut at two positions of the machine 180 degrees apart.

7. A fitting according to claim 3, one limb having connected to its free end one end of an outer straight hollow launch tube having a seal arrangement at its other end and receiving an inner launch tube (forming said camera launch tube) passing through the seal arrangement, a camera being contained in the inner tube and being attached to a flexible rod extending through the inner tube, the inner tube being advanceable through the outer tube, through the open valve of the limb, and through the hole in the pipe after which the rod can be advanced to advance the camera into the pipe.

8. A fitting according to claim 1 substantially as herein before described with reference to Figure 1 of the accompanying drawings.

9. The lower part of the fitting according to claim 1 substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.