GB2223550A - Pipe tapping - Google Patents

Abstract

The fluid-tightness of a tapping in the wall of a pipe 1, such as a water main, is improved by providing within the pipe an annular cup-shaped seal member 17 to prevent fluid leaking out of the pipe at the tapping. The seal member can advantageously be mounted on a tubular support 10 which is clamped to a ferrule 4 located in the tapped hole 3, to keep the seal member 17 pressed against the inner wall of the pipe. The inside of the pipe 1 around the hole 3 can be cleaned by scraping with an expandible tool with a scrape blade (42) (Fig 6) which is passed through the hole 3. <IMAGE>

Description

PIPE TAPPING This invention relates generally to pipe tapping and is particularly concerned with the provision of a fluidtight tapping on a pipe.

It is, of course, well known to tap a pipe and there are various procedures for doing so depending, for example, on the nature of the material of the pipe, the position of the pipe (eg. above soil level or subterranean) and the intended purpose of the tapping. In general, however, all these techniques involve cutting a hole in the wall of the pipe and fixing a connector to the pipe at the hole. In some cases, it has proved possible to achieve a good fluid-tight connection, but in other cases, especially where the fluid contents of the pipe are normally under significant pressure, leakage can occur.

We have now found a way of improving the fluid tightness of a tapping connection. Broadly, in accordance with the invention, after cutting a hole in the pipe wall, a seal member is inserted into the pipe through the hole to surround the hole, and pressed against the inner wall of the pipe to provide a seal.

The invention also includes a device for use in tapping a pipe which comprises a resilient seal member mounted on an elongate support, the seal member being insertable through a hole cut in the wall of the pipe to lie within the pipe and surround the hole, the elongate support means extending out of the pipe through the hole, and means for clamping the support with respect to the pipe to press the seal member directly or indirectly against the inner wall surface of the pipe to provide a seal.

Preferably, the seal member is generally ring-like and cup-shaped, and made of a resilient material, to achieve a close fit around the periphery of the hole in the pipe wall. The support member may be of any suitable shape. For most purposes, we prefer it to be tubular so that fluid from within the pipe can flow out through the support member.

The width of the support member must be small enough for it to pass into the pipe through the hole, but the seal member must be of greater size (or capable of becoming of greater size) so that it will seat directly or indirectly on the inner pipe surface around the hole. Thus, the seal will normally extend radially outwardly of the support member, and be temporarily deformable upon its insertion through the hole into the pipe, where it resumes its normal shape.

In order to provide a sealing effect, the seal member is pressed in a direction radially outwardly of the pipe towards the inner surface of the pipe around the hole.

This can be achieved, for example, by biasing the elongate support in a direction radially outwardly of the pipe and clamping (or otherwise fixing) it in position. For example, the support member can be screw-threaded to engage a complementarily threaded orifice fixed in relation to the pipe. Such an orifice can be provided in a ferrule, for example, as will be described in more detail hereafter. It is not essential that the support member be screw-threaded: other means of achieving and holding it under tension can be used.

The method and apparatus of the invention are of general utility, but they have a special importance for tapping water mains, and the invention will hereafter be described principally with reference to this use.

In the water industry, a large proportion of water mains are of ferrous metal. Conventionally, these are tapped by cutting a hole in the pipe wall, tapping a screw thread in the hole, and then screwing a ferrule tightly into the tapped hole. Various problems can arise.

Firstly, some cast iron water mains have in recent years been renovated to improve their water-tightness by providing therein an internal water-proof lining. One way in which this is done is to spray a resinous material in situ onto the inner surface of the pipe, and allow the material to cure to form a water-tight lining. When such a lined pipe is subjected to the conventional tapping procedure described above, we have found that the internal lining is not always cut cleanly, and also its integrity around the hole can be damaged. In the result, when the tapping is complete and the conventional ferrule in position, there is the danger of mains water getting behind the lining (i.e. seeping between the lining and the pipe surface), thus rendering the lining non-water-tight.In accordance with the present invention, this problem can be overcome by ensuring that the seal member covers the cut edge of the lining around the hole. In this way, entry of water behind the lining is prevented, and the integrity of the lining and its water-tightness are preserved.

This is a very important aspect of the present invention, namely the provision of a method and means to reliably overcome a problem associated with tapping such lined water mains.

It is also known to renovate a leaking water main by feeding into the main a smaller integral plastics tube through which the mains water is thereafter conveyed. This sort of lining is not adhered to the inner surface of the mains pipe. The method and apparatus of the invention are also useful in tapping a main which has been lined in this way. It is to be noted here that conventional tapping procedures would be unsatisfactory because they would not preserve the water-tightness of the liner. In accordance with a feature of the present invention, the seal member would lie inside the plastics liner and would be biased radially outwardly to press the liner directly on to the pipe surface around the hole, and to thus provide the necessary sealing effect.

Secondly, the invention is also utilisable with unlined ferrous metal water mains. Here, however, a further problem can arise in that such water mains (particularly after some years of use) suffer from tuberculation. The presence of tubercles in the region of the hole can prevent a seal member of the invention seating properly with respect to the inner wall surface of the pipe. We have found a way of overcoming this problem. In particular, in accordance with a feature of the present invention, we have found that the inner wall surface around the hole can be prepared, eg.

by removal of any tubercles of the like, by using a tool inserted into the pipe through the hole. Thus, by operating in accordance with the invention, excellent water-tight tappings can be made on old cast iron pipes which are difficult to tap efficiently by conventional techniques.

The tool for preparing the inner wall surface of the pipe must be such as can be inserted through the hole and be operable to clear away tubercles and the like from the pipe surface. We have devised one such tool which includes a cleaning head mounted on an elongate drive member, the cleaning head being insertable through the hole into the pipe in a retracted condition, and then expandable and driveable to engage the pipe inner surface around the periphery of the hole to clean it. The cleaning head can for example be a drill member. It may be necessary to control the position of the cleaning head in dependence on the angle of driven rotation, and for this purpose one or more cams can be provided for example, so that the cleaning head closely follows the profile of the surface being cleaned.

Whilst most water mains of size up to about 6 inches (15cm) have in the past been made of cast iron, in recent years the use of plastics piping has become more common. The invention is also useful for tapping such plastics mains.

In order that the invention may be more fully understood, reference is made to the accompanying drawings, wherein: Fig. 1 is a schematic sectional view of a mains pipe wall with a hole cut therein and a ferrule in position in the hole; Fig. 2 shows the arrangement of Fig. 1 but with an embodiment of seal arrangement of the present invention; Fig. 3 shows in longitudinal section an embodiment of seal device of the invention; Fig. 4 is similar to Fig. 2 except that the mains pipe has a water-proof lining on its internal wall; Fig. 5 is similar to Fig. 2 except that the mains pipe has a plastics liner tube therein; and Fig, 6 is a schematic longitudinal sectional view of an embodiment of scraper tool of the invention in position in a mains pipe.

In all the Figures like numerals indicate like parts.

Referring to Fig. 1, there is shown part of a mains pipe 1 which may, for example, be a water or gas pipe.

In the wall of pipe 1, a circular hole 2 has been cut by conventional means. The internal wall surface 3 of the hole has been tapped, i.e. a screw thread has been cut therein.

Ferrule member 4 having a through bore 5 has been screwed tightly into hole 2. Bore 5 opens into pipe 1. Ferrule 4 has a screw thread 6 formed on the upper region of the wall 7 of bore 5. The ferrule 4 has an integral lock nut 8.

As will be understood, various items (eg. valves) can be attached to ferrule 4 as desired in the art, and no further description of these items is given here.

There are a number of problems associated with tappings of the type shown in Fig. 1. In particular, the screw-fitting between the ferrule and the pipe 1 is often not completely water-tight, and water (or other fluid from pipe 1) tends to leak. Leaks are very undesirable and can even cause deterioration of fittings etc. in the vicinity.

Fig. 3 shows a device of the present invention especially suited for use with a ferrule 4 of Fig. 1, and Fig. 2 shows the Fig. 3 device in working position in the ferrule of Fig. 1. Referring to Fig. 3, the device comprises a tubular support member 10 with a through bore 11, and a screw thread 12 externally on an intermediate portion 13 thereof. Attached at the lower end 14 of member 10 is an annular support plate or flange 15, on which is seated an annular elastomeric cup-seal 16. The cup seal comprises a flexible upstanding annular wall 17 around a base 18. In use, the cup seal has Boss Blue" or a similar plumbing sealant 19 therein.

Fig. 2 shows the sealing device in position in ferrule 4 and pipe 1. This arrangement is achieved by first inserting member 10 from below into bore 5 of a ferrule 4 (the ferrule not at this stage being screwed into pipe 1).

Screw thread 12 on member 10 engages in thread 6 in bore 5 of ferrule 4, so the seal device and ferrule are attached together. The lower end 14 of the seal device is now inserted through hole 2 into pipe 1. The diameter of plate or flange 15 is just smaller than the diameter of hole 2.

The wall 17 of cup-seal 16 is temporarily deflected inwardly upon insertion in pipe 1, since the normal diameter of the seal is greater than that of hole 2.

The ferrule (which is already joined to the seal device) is now screwed into thread 3 on hole 2. When the ferrule is in position (as in Fig. 1), the cup seal is initially well below hole 2 within pipe 1. Member 10 is then rotated to draw the cup seal up and, finally, press it against the inside wall of pipe 1 as shown in Fig. 2. The sealant 19 assists the seal wall 17 in forming a fluid-tight seal around the hole 2.

We have illustrated one particular shape of seal 16, but as will be clear, many other different shapes and types of seal can be used. Also, in the illustrated embodiment, the sealing device is held with the seal under compression, by engagement of member 10 with ferrule 4.

Screw-threaded engagement is shown, but other types of engagement can be used. Indeed, the presence of a ferrule is not essential, provided some other means is provided to hold the seal device in sealing position. Of course, if no ferrule 4 were used in Fig. 2, the arrangement would also be modified to make member 10 a closer fit in hole 2. However, tapping of hole 2 is not essential. The present invention merely requires some means of holding the seal under compression around the periphery of the hole 2 in pipe 1, to effect a fluid-tight seal. Thus, if pipe 1 were a plastics material pipe, the hole 2 would not normally be "tapped" i.e. screw threaded. In such a case, member 10 could for example be provided with an external locking nut which, by bearing engagement with the outer surface of pipe 1, could hold seal 16 in sealing compression.It will be clear to those in the art that many different arrangements are possible.

Referring now to Fig. 4, the arrangement is essentially the same as in Fig. 2. However, in Fig. 4, the pipe 1 has been lined on its inner wall surface 20 with a water-tight resinous lining 21. This has fallen away slightly adjacent the periphery of hole 2, and Fig. 4 illustrates how a sealing device of the invention overcomes the potential leakage problems resulting from damage to the resinous lining 21. Thus, cup seal wall 17 extends over the edge 22 of the lining 21, and the sealant assists in plugging the area to ensure water-tightness.

Fig. 5 shows a sealing device of the invention in use in a pipe 1 which contains a liner tube 30. When hole 2 was cut in pipe 1, a similar hole was cut in liner 30. The sealing device of the invention is inserted into pipe 1 and into liner 30, and then upon compressing the cup seal 16 against the inner wall surface 20, the liner is drawn against surface 20 and a seal made by the cup seal 16 and sealant 19. Thus, the bore 11 of member 10 communicates directly with the inside of line 30, and fluids cannot get between liner 30 and pipe surface 20.

Fig. 6 illustrates the working end of a tool, in accordance with a feature of the invention for preparing the internal surface 20 of pipe 1 in order to remove tuburcles and any other irregularities, to ensure the formation of a good seal. Essentially, the tool comprises a tubular casing 40 which is insertable into pipe 1 through hole 2. At the lower end 41 of casing 40 is mounted a scraper blade 42 having a scraping edge 43. The blade is pivoted about an axle 44 mounted in the casing 40. Spring 45 is in compression and bears upon a face 45' of blade 42 to bias it to urn about axle 44 so that the blade is biased normally to lie wholly within casing 40. Casing 40 includes a window 46 through which blade 42 can in part protrude, with scraping edge 43 lying essentially parallel to surface 20 of pipe 1. The tool further comprises a wedge member 50 longitudinally movable in casing 40, and including a cam surface 51 bearing against one side 52 of blade 42.

Downwards movement of wedge 50 causes blade 42 to pivot to extend scraping edge 43 out of window 46. Upon upwards movement of wedge 50, blade 42 is retracted into casing 40 under the influence of spring 45.

In use of the tool, wedge 40 is firstly in an upper retracted position so that blade 42 lies wholly within casing 40 with no part of the blade protruding through window 46. In this condition, the lower end 41 of the tool is inserted into pipe 1 through hole 2. Next, the wedge 50 is lowered and its cam surface 51 bears on edge 52 of blade 42, causing the blade to turn about axle 44 and scraping edge 43 to protrude through window 46. The tool is now rotated about its longitudinal axis so that scraping edge 43 sweeps around over the surface 20 of the pipe 1, engaging and (in due course) removing any projections.

During this rotation, wedge 50 moves up and down under control of a cam (not shown) so that the degree of protrusion of the blade varies to ensure that edge 43 is always lying substantially parallel to the adjacent surface 20. Initially, when there are large projections on surface 20, edge 43 may be substantially spaced from surface 20 but, as the projections are gradually removed, the tool is raised until finally scraping edge 43 engages surface 20 to ensure its smoothness ready to receive a seal of the invention.

After preparing the surface 20, wedge 50 is retracted to allow blade 42 to pivot to its normal position wholly within casing 40, and the tool is then removed from pipe 1.

Claims (17)

CLAIMS:

1. A method of providing a tapping on a pipe which comprises cutting a hole in the pipe wall, inserting a seal member into the pipe through the said hole, and pressing the seal member directly or indirectly against the inner wall of the pipe around the hole to provide a seal to prevent or reduce fluid leakage at the tapping.

2. A method according to claim 1, wherein the seal is mounted on an elongate support, and the support is arranged to extend out of the pipe through the said hole and to be clamped with respect to the pipe to hold the seal member pressed directly or indirectly against the inner wall surface of the pipe.

3. A method according to claim 2, wherein the seal member is a close fit around the periphery of the hole.

4. A method according to claim 2 or 3, wherein the support member is tubular so that fluid can flow therethrough, and wherein said seal member provides a seal between the said support member ard the wall of the pipe.

5. A method according to claim 1,2,3 or 4, wherein the seal member is cup-shaped and of resilient material.

6. A method according to any of claims 1 to 5, wherein the pipe contains a non-metal liner, a hole is also cut in the liner, and the seal is inserted into the liner and biased radially outwardly to press the liner directly on to the inner pipe surface around the hole to provide a seal.

7. A method according to any preceding claim, wherein the pipe is a water main.

8. A method according to claim 7, wherein the pipe is a cast iron water main and wherein, after cutting said hole in the wall thereof, tubercles and the like on the inside of the pipe around the hole are removed or reduced in size before inserting said seal member.

9. A method according to claim 7 or 8, wherein said hole is tapped in the pipe wall and a ferrule is located in the tapped hole, and wherein the said seal member provides a seal between the support member and the ferrule and between the ferrule and the pipe, to prevent or reduce water leakage at the tapping.

10. A method according to claim 9, wherein the support member is clamped to the ferrule to maintain the seal pressed against the inner wall of the pipe.

11. A method of providing a tapping on a pipe substantially as herein described with reference to Figures 2,4 or 5 of the accompanying drawings.

12. A seal device for use in the method of claim 2, which comprises a resilient seal member mounted at one end of an elongate support to extend radially outwardly thereof, the seal member on the support being insertable through a hole cut in the wall of the pipe to lie within the pipe and surround the hole, the elongate support means extending out of the pipe through the hole; and means for clamping the support with respect to the pipe to press the seal member directly or indirectly against the inner wall surface of the pipe to provide a seal.

13. A device according to claim 12, wherein the seal member is annular and cup-shaped.

14. A device according to claim 12 or 13, wherein the support member is tubular.

15. A seal device substantially as herein described with reference to Figure 3 of the accompanying drawings.

16. A tool for use in the method of claim 8, for removal of tubercles or the like from the inner wall surface region of a pipe around a hole cut therein, which tool comprises a cleaning head mounted on an elongate drive member, the cleaning head being insertable through the hole into the pipe in a retracted condition, and then expandible and driveable to engage the said inner wall surface region to remove tubercles or the like therefrom.

17. A tool according to claim 16 substantially as herein described with reference to Figure 6 of the accompanying drawings