GB2259124A

GB2259124A - Fitting a flow control valve into a service pipe

Info

Publication number: GB2259124A
Application number: GB9218026A
Authority: GB
Inventors: Robert William Jardine
Original assignee: E Peart and Co Ltd
Current assignee: E Peart and Co Ltd
Priority date: 1991-08-29
Filing date: 1992-08-25
Publication date: 1993-03-03
Also published as: DE4226882A1; GB9118461D0; FR2680857A1; GB9218026D0

Abstract

A flow control valve is fitted into a service pipe without interruption of the flow therein by attaching to the pipe (10) a sealed split tee (11) and placing over the tee branch a sandwich valve (15), attaching to the sandwich valve an under-pressure drilling machine (17) having a rotary cutter (18) with ports (19) therein to maintain flow, the cutter (16) removing an entire section of the pipe wall, replacing the drilling machine (17) with a sealed housing (20) containing a flow control valve (21) which is sealed against the tee branch (11) by an O-ring (22) and held in place by retaining studs (23). After removal of the housing (20) and sandwich valve (15), the flow control valve (21) is finally secured in place by bonnet studs (26, Fig 5 not shown). A sliding gate (24) within the valve (21) seals against a semi-circular invert surface (25) within the split tee (11). <IMAGE>

Description

2 2 1) 91 724 - 1 FITTING A FLOW CONTROL VALVE INTO A SERVICE PIPE THIS

INVENTION concerns a method of and system for fitting a flow control valve into an existing service pipe carrying, for example, a continuous flow of potable water under normal working pressure.

The invention is intended to meet the following requirements. The fitting of a valve into such a pipe must be as simple as possible, and must not cause interruption of the flbw nor require a significant reduction in pressure during the fitting operation. The finished valve must not reduce the flow capacity of the pipeline nor inhibit any of the normal pipeline operations such as cleaning. During the fitting operation there must not be excessive leakage, and local excavation must be minimal.

In a practical application a typical pipe diameter to which a flow control valve is to be fitted may be 150mm and the pipe may be of the kind carrying a working pressure of up to 16 bar. Many different pipe materials may b6 accommodated such as cast iron, asbestos cement, or plastics.

It is not hitherto been possible to carry out a retrofitting of a flow control valve into a water pipe without shutting off the water supply upstream of the valve site, and without utilising the pipe wall as a valve seat. Since the inner and outer surfaces of the 1 pipe wall may well be corroded, coated, cement lined or scaled, the surfaces are unlikely to be suitable for the valve seat. Similarly, drilling out of the pipe is unlikely to produce a sufficiently smooth fresh surface for seating.

According to the present invention there is provided a method of fitting a flow control valve into a service pipe, comprising the steps of placing a split tee around the pipe and clamping same thereto, attaching a shut- off valve to the tee branch, attaching an under-pressure drilling machine. to the shut-off valve and drilling out and removing, transversely to the pipe axis, a section of the pipe wall, subsequently closing the shut-off valve to seal the breached pipe, removing the drilling machine and, in place of the latter, attaching to the shut-off valve a scaled gear housing containing the flow control valve to be fitted, re-opening the shut-off valve and causing the flow control valve to pass through the gear housing into the split tee, attaching the flow control valve to the split tee in sealed engagement therewith, and finally removing the gear housing and shut-off valve therefrom to leave the flow control valve attached via the split tee to the drilled pipe.

Further according to. the present invention there is provided a system for fitting a flow control valve into a service pipe, comprising a split tee adapted to be placed around a pipe and clamped thereto, a shut-off valve adapted to be attached to the tee branch, an under-pressure drilling machine adapted to be attached to the shut-off valve to drill out and remove a section of the pipe wall, 1 - 3 a sealed gear housing adapted subsequently to be attached to the shutoff valve in place of the drilling machine and to contain the flow control valve, and means within the gear housing to cause sealed engagement of the flow control valve within the split tee thus to permit the gear housing and shut-off valve to be removed therefrom.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Fig. 1 is a vertical section through a split tee clamped around a pipe to which a valve is to be fitted.

Fig. 2 is a vertical section taken on line II-II of Fig. 1; Fig. 3 is a view similar to Fig. 1 with a sandwich valve and under- pressure drilling machine attached to the split tee; Fig., 4 is a view similar to Fig. 3 but with a gear housing attached to the sandwich valve in place of the drilling machine; and Fig. 5 is a vertical cross-section of the completed valve f itting.

Referring now to the drawings, in Fig. 1 there is shown a pipe 10 having clamped thereon a split tee 11. Fig. 2 illustrates how the split tee is clamped by bolts 12 and a gasket 13, onto the 4 - pipe. The bore of the split tee is sealed against the pipe by a pair of opposed gland rings 14. After fitting, the split tee may then be pressure tested to check the integrity of the seals.

Referring now to Fig. 3, a sandwich valve 15 operated by a handwheel 16 is shown attached to the upper flange of the split tee 11. Then, an underpressure drilling machine 17 containing a descending rotary drill cutter 18 is attached to the sandwich valve 15, and the pipe is drilled by the cutter to remove a cylindrical section of the pipe. The cutter is designed to be of greater diameter than the pipe thus to ensure removal of a complete section thereof. It will be seen that the cutter 18 contains ports 19 to ensure that flow along the pipe is not interrupted during the cutting operation.

Once the cutter and pipe section are withdrawn within the casing 17, the sandwich valve 15 may be closed using the handwheel 16. The underpressure drilling machine may then be removed from the sandwich valve and replaced, as illustrated in Fig. 4, by a pressure tight insertion ge ar housing 20 containing a valve body 21. Once the housing 20 is firmly attached to the sandwich valve 15, the latter may be reopened so that the valve body 21 may be guided downwardly into the upper region of the split tee 11. An O-ring 22 provides a seal against the latter, and once it is in place a pair of retaining studs 23 are inserted radially through the tee branch wall to be located within aligned apertures of an annular groove in the wall of the valve, to fix the valve body in position.

As a final step in the fitting process, the gear housing 20 and sandwich valve 15 may be removed and a number of bonnet studs 26 applied as a permanent fixture of the valve body 21 to the upper flange of the split tee 11.

In Fig. 5, the finished valve is seen to include a rise and fall valve gate 24 slidable vertically within valve body 21, and shown in an operative position in which the flow through the pipe is fully interrupted. However, it will be seen that the valve gate 24 does not seal against the pipe wall but rather against the semi-circular invert surface 25 of the split tee 11.

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Claims

1. A method of fitting a flow control valve to a service pipe, comprising the steps of placing a split tee around the pipe and clamping same thereto, attaching a shut-off valve to said split tee, attaching a drilling machine to the shut-off valve and operating same to drill out and remove a cylindrical section of the pipe wall, subsequently closing the shut-off valve, removing the drilling machine and, in place of the latter, attaching to the shut-off valve a sealed gear housing containing the flow control valve to be fitted, re-opening the shut-off valve and causing the flow control valve to pass through the gear housing into the split tee, fixing the flow control valve within the split tee and finally removing the gear housing and shut-off valve therefrom to leave the flow control valve attached via the split tee to the drilled pipe.

2. A method according to Claim 1, wherein one or more ports are provided in the cutter of said drilling machine thus to ensure that flow along the pipe is not interrupted during the drilling and removal operation.

3. A method according to Claim 1 or Claim 2, wherein the cutter of the drilling machine is selected to be of a diameter greater than that of the pipe thus to ensure removal of a complete circumferential section of the pipe.

4.

t A method according to any preceding claim, wherein the 7 - flow control valve is fixed to the split tee in sealed engagement therewith by passing at least one retaining stud radially inwards through the wall of the tee branch to locate within an aligned aperture or groove in the wall of the flow control valve, an 0-ring providing a seal between the flow control valve and the tee branch.

5. A method according to any preceding claim, in which the flow control valve is finally secured to the tee branch by number of bonnet studs.

6. A method according to any preceding claim, wherein the flow control valve is placed in sealing engagement with a semi circular invert surface within the split tee.

7. A system for fitting a flow control valve into a service pipe, comprising a split tee adapted to be placed around a pipe and clamped thereto, a shut-off valve adapted to be attached to the split tee, a drilling machine adapted to be attached to the shut-off valve and having a rotary cutter to drill out and remove a cylindrical section of the pipe wall, a sealed gear housing adapted subsequently to be attached to the shut-off valve in place of the drilling machine and to contain the flow control valve, and means within the gear housing to cause sealed engagement of the flow control valve within the split tee thus to permit the gear housing and shut-off valve to be removed therefrom.

8.

A system according to Claim 7, wherein said shut-off valve is a sandwich valve operated by a handwheel and attached to an upper flange of the split tee.

9. A system according to Claim 7, wherein the cutter of said drilling machine includes at least one port to maintain flow along the pipe during the cutting operation.

10. A system according to Claim 7, wherein the cutter of said drilling machine is selected to be of a diameter greater than that of the pipe thus to ensure removal of a complete circumferential section thereof.

11. A system according to any of Claims 7 to 10, wherein said gear housing is sealed against the tee branch by an 0-ring and retained in place thereon by at least one retaining stud introduced radially through the tee branch wall to be located within an aligned aperture or groove in the wall of the flow control valve.

12. A system according to Claim 11, wherein said flow control valve is finally fixed to the tee branch by a plurality of bonnet studs to provide a permanen.t fixture.

13. A system according to any one of Claims 7 to 12, wherein the flow control valve includes a valve gate slidable transversely with respect to the pipe to seal against a semi-circular invert surface within the split tee such that the valve gate shall have no contact with the pipe during operation.

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14. A method of fitting a flow control valve into a service pipe, substantially as hereinbefore described.

15. A system for fitting a flow control valve into a service pipe, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.