GB2276925A - Pipe-tapping - Google Patents

Abstract

A fitting 1 for securing to a pipe to be tapped into, comprises a main body 4 having an end portion defining a pair of opposing U-shaped recesses 9 which provide a saddle-like arrangement for engaging one side of the pipe. A cap 12 having an associated formation 13 with a U-shaped recess 14 for engaging the opposite side of the pipe is screwable onto the end portion of the main body to clamp the fitting onto the pipe. A valve 6 in the main body is operable between valve open and valve closed positions with respect to a bore 5 extending through the main body 4. The main body 4 is adapted to facilitate releasable connection of a cutter assembly 2 thereto for tapping into the pipe via the bore. <IMAGE>

Description

PIPE TAPPING The present invention relates to pipe tapping and, more particularly, to a fitting for securing to a pipe and for use with a cutter means assembly to tap into the pipe. Our copending UK Patent Application No. 9101295.5, from which this application has been divided, relates to a method of and apparatus for tapping into pipes; and to a cutter means for use in the apparatus and method.

Applicants are primarily, although not exclusively, concerned with tapping into pipework carrying water, such as pipework in central heating systems. After such pipework has been installed it may be desired or necessary to tap into the pipework and secure thereto a connection piece or fitting.

Such a fitting may serve, for example, as a drain tap.

Alternatively, further equipment, such as an additional radiator, may be connected to the existing system via the fitting or connection piece. It would be convenient if the tapping of the pipework could be carried out under 'live' conditions, that is when the pipework is part of an operating or operative system containing fluid, so as to avoid having initially to drain the system or having to experience undesired leakage or spillage from the system.

Apparatus which has previously been proposed for tapping into pipes comprises a -cutter which moves through a bore in a fitting secured to the pipe and cuts out a disc or coupon from the pipe wall to leave a hole in the pipe wall over which the fitting was secured. In the case of pipework incorporated in a central heating system, it is important to remove the coupon completely because if the coupon were to fall into the pipe it could not only cause a partial or complete blockage but because the pipework is often made of copper and the radiators are often made of steel, could lead to corrosion at its points of contact with the radiator which could ultimately result in an undesired leakage hole in the system.

In the previously proposed apparatus the cutter has been described as being capable of retaining the cut coupon.

However, the cutter together with the retained cut coupon was not intended to be completely detached from the fitting under 'live' conditions. The cutter or the cutter together with the coupon served as a plug closing off passage of the fluid through the bore to an opening in the fitting. The removal of the cutter from the fitting through the opening in the fitting would allow undesired communication between the hole in the pipework and the opening in the fitting and thus flow of fluid through the fitting before further equipment can be connected to the opening.

The present invention provides a fitting for securing to a pipe and--f-rr-usé with a cutter means assembly to tap into the pipe, said fitting comprising a main body having a bore extending therethrough with one end of the bore opening at a main body end portion, and valve means in the main body operable between a valve open and a valve closed position with respect to the bore, the main body being adapted to facilitate releasable connection of the cutter means assembly thereto, and the said one end portion of the main body defining a pair of opposing generally U-shaped recesses which together form a saddle-like arrangement for engaging one side of the pipe to be tapped into, and said end portion being threaded to receive a complementary threaded cap having a projecting formation defining a generally U-shaped recess for engaging the opposite side of the pipe, and arranged such that the cap can be threaded onto the said main body end portion and tightened to clamp the fitting onto the pipe.

It will be appreciated that the apparatus should be substantially fluid tight under the conditions to which it is to be subjected. Thus, it may be necessary for the apparatus to incorporate gaskets or seals such as 0being seals to provide for positive sealing between the fitting and the cutter means and between other connected parts or relatively movable parts of the apparatus.

The valve means may comprise a valve member mounted on the main body for rotation about an axis which is transverse to the longitudinal axis of the bore, and an annular valve seating-wbich extends around the bore and which is engaged by an annular surface portion of the valve member in the valve closed position. In one embodiment of apparatus, the annular surface portion of the valve member which is engagable with the valve seating may be a portion of a part-spherical surface and the valve member may have an at least part tubular surface defining therethrough a hollow or slot through which, when the fitting is used with the cutter means, the cutting portion of the cutter means is movable past the valve member to and from the cutting position. The slot-defining surface of the valve member may be at least part cylindrical and may have a longitudinal axis which is substantially perpendicular to the axis of rotation of the valve member and co-axial with the bore through the main body of the fitting.

The main body may be fitted with or may incorporate a sealing means for engaging the surface of the pipe wall in a substantially fluid tight manner around the area from which the coupon is to be, or has been, cut.

Conveniently, the main body may have a threaded portion to facilitate releasably connecting the fitting to a complementary threaded portion on the cutter means.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of one embodiment of fitting accordtn-t-o-tWe invention shown in association with a cutter means assembly, Figure 2 is an elevational view of the apparatus as shown in Figure 1 with the fitting attached to a pipe, Figure 3 is a side view of the apparatus as shown in Figure 2 in the direction of arrow A, Figures 4 to 6 are essentially sectional views of the apparatus, with Figure 4 showing the cutter means prior to cutting a hole in the pipe, Figure 5 showing the cutter after cutting the hole, and Figure 6 showing the cutter with the retained coupon in a fully retracted position and showing the valve turned to the bore closed position, Figure 7 is a similar sectional view with the cutter assembly completely removed from the fitting, Figure 8 is a part sectional and part perspective view of the valve, Figure 9 shows partly in cross-section and on an enlarged scale a cutter means and its attachment to the assembly, Figures 10 and 11 show partly in cross-section alternative forms of cutter, Figure 32axis a Yiew of the cutter as shown in Figure 9, Figure 10 or Figure 11 in the direction of arrow B, and Figure 13 shows part of a radiator system comprising pipework to which a fitting remains secured after a hole has been cut in the pipework.

With reference to Figures 1 to 6 of the drawings, apparatus for tapping into a pipe comprises one embodiment of fitting 1 to be secured to the pipe and a cutter means assembly 2 including a cutter means 3.

The fitting 1 comprises a main body 4 of tubular form having a bore 5 extending therethrough, and valve means 6 located in the bore 5 of the tubular body 4.

One end 7 of the bore opens at a tubular body end portion which provides two opposing equivalent limbs 8 which define therebetween a pair of opposing generally U-shaped recesses or grooves 9 with part cylindrical bases 9a generally matching the curvature of the pipe 10 to which the fitting 1 is to be secured, together forming a saddle-like arrangement for receiving the pipe. The outer sides of the limbs 8 are threaded, as at 11. The fitting also comprises a threaded cap 12 and a projection piece 13 having an inner end 13a which fits into the cap. The other end of the projection piece defines a part cylindrical recess or groove 14.

A tubuSar-r-ubbe-r seal 15 having a central bore 16 is mounted in the bore of the tubular body 4. The innermost end portion of the seal is planar and fits over an annular stub 17 while the end face 18 of the seal abuts an annular shoulder 19 extending from the wall of the tubular body. The other end of the seal 15 has a pair of opposing part cylindrical portions 20, projecting beyond the bases 9a of the main body recesses 9, and bridging portions 21. With the projection piece fitted into the cap, the latter can be screwed onto the threaded end portion of the tubular body so that the part cylindrical recess 14 engages the lower side of the pipe (as viewed).

When the cap is tightened up the pipe is clamped between the projection piece 13 and the part cylindrical portions 20 of the seal 15 and the fitting is thereby secured to the pipe.

In the clamped position the part cylindrical portions 20 and bridging portions 21 engage the surface of the pipe to be tapped in a fluid tight manner around the area in which a hole is to be cut.

The valve means 6 comprises a valve member 22 and an annular valve seating 23. Viewed also with Figure 8 it can be seen that the valve member 22 is mounted on opposite sides of the tubular body 4 for rotation on pivot pins 24 disposed on an axis which is perpendicular to the longitudinal axis of the bore 5. The valve member has a part-spherical outer surface 25 which provides an annular surface portion 26 for engaging the valve seating 23 when the valve member is rotated to a closed position as will be described below. The valve member also has an winner part-cylindrical surface 27 defining therethrough a hollow or slot 28. The longitudinal axis about which the part cylindrical surface is described is substantially perpendicular to the axis of rotation of the valve member. The valve seating 23 is annular and externally threaded so as to screw into position in the bore 5 via threads 4a formed on the internal wall of the body 4. The valve member 22 is engageable with a valve seating member which is in the form of an O-ring 29 and located in an annular recess 30 provided in a mounting 31 formed by part of the valve seating 23 and extending about the bore of the main body above the valve member as viewed in the Figures.

One of the pivot pins 24 has a slotted head 32 mounted in a housing 33 in the wall of the tubular body 4. The slotted head can be turned by a screw driver to rotate the valve member 22 via the non-circular bridging piece 34 which connects the pivot pin to the valve member. An O-ring seal 35 is located between the wall of housing 33 and the slotted head 32. The head 32 is provided with a projection 37 which engages spaced stop surfaces 38,39 on the housing which limit the rotation of the valve member in opposite directions. When the projection 37 abuts stop surface 38 the valve member 22 is in the closed position with the annular surface portion 26 engaging the O-ring 29 so as to close off or block off the bore 5. When the head 32 is turned about one quarter of a full revolution the projection 37 moves around and abuts the other stop surface 39 of the housing so that the valve member 22 robat-es- -to the valve open position in which the longitudinal axis of the part-cylindrical slot is coaxial with the longitudinal axis of the bore of the tubular body, with the slot 28 being coextensive with the portions of the bore on each side of the slot. Thus, in this orientation, the slot provides a path through the tubular body 4 to the pipe.

The internally threaded upper end portion 4a of the body 4 of the fitting facilitates attachment of the cutter means assembly 2 which will now be described.

The cutter means assembly comprises the cutter means 3, a supporting body 41 in which the cutter means is threadably mounted, and an outer body 42 in which the supporting body 41 is slidably mounted for longitudinal movement between limiting positions.

The cutter means 3 comprises a shaft 45 which carries at one end a replaceable cutting piece or tool 46 having a pair of cutting blades 47,48 spaced opposite each other. The cutting edges 49,50 of the blades are arcuate and, as viewed from the end of the tool, touch diametrically opposite sides of a common circle. The exterior surface 51 of the end portion of the cutting tool tapers to the cutting edges 49,50. Moreover, the inner sides 52 of the blades immediately adjacent the cutting edges have tapering or bevelled surfaces which merge with the cutting edges. In the. present embodiment the exterior taper angle is about 4" and the angle of the inner bevelled--surfaees is about 18 . These angles are not shown to scale in the drawings.

The cutting tool 46 also incorporates an externally threaded and pointed shaft or bradawl-like projection 53 which is coaxial with the circle on which the cutting edges lie and is for retaining the coupon on the tool when cut from the pipe.

The projection 53 projects centrally from the tool to a point just beyond (for example about 4mm) the cutting edges 49,50 of the blades. The threaded bradawl-like projection is a screw fit in the tool and thus is a fixed part of the tool (see Figure 11). The cutting tool may be screwed onto a threaded stub 54 provided at the end of the shaft (see Figure 9) or otherwise releasably secured to the cutter shaft.

A nut 55 is fixed to the other end of the shaft 45 and the shaft has an externally threaded portion 56 from the nut 55 to a position part way along its length. Between the threaded portion 56 of the shaft and the cutting tool 46, the shaft has a portion 57 of larger diameter.

The supporting body 41 in which the cutter means 3 is threadably mounted is generally of tubular form and has a central bore 60. The central bore comprises two bore portions 61 and 62. The upper bore portion 61, as viewed in the figures, is threaded. The thread 61a of the bore portion 61 is engaged by and cooperates with the threaded portion 56 on the shaft so that when the shaft 45 is rotated by the turning of a spanner--ot the like (not shown) applied to the nut 55, the shaft threadably moves along the supporting body 41. The thread 64 on the bradawl-like projection 53 starts from substantially the pointed end of the projection and is of the same hand and has substantially the same pitch and thread angle as the cooperating threads 56,61a on the exterior of the shaft 45 and on the wall of the bore portion 61 of the supporting body 41.

The lower bore portion 62 of the supporting body 41 has a plain cylindrical surface, is of larger diameter than upper bore portion 61 and is for accommodating movement of the larger diameter portion 57 of the shaft 45 as the shaft is threadably moved with respect to the supporting body. At the junction of the upper and lower bore portions 61 and 62 the supporting body provides a shoulder 63 against which the portion 57 can abut to prevent further movement of the shaft along the bore in one direction (that is the upward direction as viewed). The underside of the nut can abut the opposing end surface 65 of the supporting body 41 to prevent further movement of the shaft 45 in the opposite direction.

An O-ring seal 66 is located in the circumferential wall of the larger diameter portion 57 and engages and cooperates with the plain cylindrical surface of the bore portion 62 to provide a fluid tight seal between the shaft and the supporting body.

Towardsti-t-s-upper end the supporting body 41 is provided with two handles 70,71 which are fixed to opposite sides of the body and extend in diametrically opposite directions away therefrom. The lower end of the supporting body has an outwardly extending annular flange 72. Otherwise the outer surface of the supporting body is cylindrical.

The outer body 42 in which the supporting body 41 is slidably mounted is also of generally tubular form and has a central bore 73. The central bore comprises an upper bore portion 74 and a lower bore portion 75. The upper bore portion 74 is of a smaller diameter than the lower bore portion 75. In the wall of the outer body there are located two spaced O-ring seals 76,77 which extend around the smaller diameter bore portion 74 and engage and cooperate with the outer cylindrical surface of the supporting body to provide a fluid tight seal between the outer body 42 and the supporting body 41. The lower bore portion 75 of the outer body, which is of larger diameter than the upper bore, accommodates movement therealong of the flange 72 at the lower end of the supporting body as the latter is slid within the outer body. At the inner end of the bore portion 75 the outer body provides a shoulder 78 against which the flange 72 can abut to prevent withdrawal of the supporting body from the outer body in one direction, i.e.

the upward direction as viewed in the figures.

Starting from the top of the outer body 42 and opposite each other a pair of slots 80,81 are provided through the cylindrical wall of the outer body. Each slot extends downwardly and part way around the outer body in the same general direction as the threads 61a,56 extend on the supporting body 41 and on the shaft 45 of the cutter means.

Each slot has a mouth 82,83 at the upper end of the outer body and a stop surface 84,85 provided by the wall of the outer body at the other or inner end of the slot. The handle projections 70,71 on the supporting body 41 can be inserted into respective slots 80,81 via the mouths thereof and moved along the slots, whilst the supporting body rotates and slides further into the outer body 42, until the handles abut the stop surfaces 84,85. When the handles have been moved to these positions, the supporting body is considered to be releasably retained in a first limiting position, (as shown in Figures 4 and 5). The handles 70,71 can be moved from the releasably retained position back along the slots whilst the supporting body rotates and slides further out of the outer body until the handles emerge from the mouths 82,83 of the slots, whereafter the supporting body can be pulled even further out of the outer body until the flange 72 on the supporting body abuts the shoulder 78 on the outer body. In this position, the supporting body is considered to be in the second limiting position or retracted position (as shown in Figure 6). Thus, the supporting body is slidably movable in the outer body between limiting positions.

The outer body is externally threaded as at 86 over a lower end portion and has an outwardly extending annular flange 87 at theb i-nner nd of the threaded portion. The threaded portion 86 is fitted with an annular washer or gasket 88 and screws into the threaded upper end portion 4a of the tubular body 4 of the fitting 1. As the tubular body 4 and the outer body 42 are screwed together the annular washer 88 is engaged between the flange 87 and the upper end surface of the tubular body to provide for a fluid tight seal between the bodies.

With the two bodies screwed together, the outer body may be regarded as an extension of the tubular body or the two bodies may be regarded as two body portions providing an overall main body for the fitting when the apparatus is in use or in an operative condition for use, that is with the cutter assembly mounted on the fitting.

The pipe 10 can be tapped using the above described apparatus by following the method described below.

The fitting 1 is secured to the pipe 10 as described earlier and as shown with reference to Figures 2 to 6. It will be appreciated that the surface of the pipe may need to be cleaned before the fitting is clamped to the pipe. The supporting body 41 is slid relative to the outer body 42 to the second limiting position or retracted position (as shown in Figure 6). If necessary, a spanner is applied to the nut 55 on the end of the shaft 45 and turned so that the shaft attains a relatively withdrawn position relative to the supporting body 41 similar to that shown in Figures 2 to 4.

Then the outer body is screwed onto the main body 4. With the valve Member 22 turned to the bore open position the handles 70,71 are inserted in and moved all the way along the slots 80,81 in the outer body 42 so that the supporting body 41 slides down the outer body to the first limiting position (as shown in Figure 4) relatively close to the pipe where the supporting body is releasably retained as a result of the cooperating engagement between the handles and the slots. A spanner is then applied to the nut 55 and turned so the cutting tool 46, from a position in the slot 28 in the valve member 22, moves through the slot 28 and through the bore 16 (forming part of the bore 5 of the fitting 1) of the tubular rubber seal 15 towards a cutting position whereat the cutting edges of the blades contact and start to cut into the pipe wall. First, the tip or pointed end of the bradawl-like projection engages the centre of the area from which the coupon is to be cut. Continued turning of the nut causes the projection to penetrate the pipe wall and, via its thread, tap a corresponding thread through the thickness of the pipe wall, and then the blades engage the pipe wall and proceed to cut through the pipe wall to form the hole 90 and produce the cut coupon 91 (see Figure 5). The common pitch of the threads on the bradawl-like projection 53, on the cutter shaft 45 and on the supporting body 41 may, for example, be 0.5mm or 2mm. By virtue of the small pitch of the threads, the cutting blades 47,48 can readily be advanced slowly to cut the pipe wall to provide for a smooth and even cutting operation.

As the exterior tapered portion 51 at the end of the cutter tool moves--through the pipe wall it very slightly increases the size of the hole 90. The cut coupon 91 occupies the space between the cutting blades 47,48 and is retained on the cutter tool 46 primarily by virtue of the threaded interengagement of the thread on the projection 53 and the thread (not shown) which has been cut or tapped in the hole in the coupon 91.

The supporting body 41 is then released from the first limiting position by turning the handles 70,71 and moving them back along the slots 80,81 and out of the slot mouths 82,83 so that the supporting body 41 slides in the outer body 42 away from the cut pipe to the position where the flange 72 abuts the shoulder 78. Thus, the cutter tool 46 and retained coupon 91 are withdrawn back from the position shown in Figure 5 through the hole 90, through the tubular seal 15, and through the slot 31 in the valve member 22 to a retracted position such that the valve member can be turned so as to engage the valve seating member 29 and thus close off the bore 5 of the tubular body 4 (see Figure 6) and thereby prevent leakage of water from the pipe 10, via the hole 90, through the fitting 1.

The outer body 42 can then be unscrewed from the main body 4 to leave the fitting 1 secured to the pipe as a drain tap or as a connection point (see Figure 7) via which further equipment can be connected to the system. The cutter tool together with the retained coupon is then removed from the end of the shaft. A fresh cutter tool may then be fitted to the shaft so that the cutter assembly is ready for use with anothe?:fittin. When further equipment has been connected the valve member can be turned to the open position to provide for communication with the tapped pipe.

Figures 9 to 11 show different embodiments of cutter means 3.

In Figure 9, the bradawl-like retaining projection 53 is secured to one end of a rod-like member 95 which is a slide fit in a bore 96 extending into the threaded stub 54 and shaft 45 from the lower end thereof. The member 95 is secured in position by means of a grub screw 97 which is screwed into the shaft and engages a flat 98 provided adjacent the other end of the member 95. With this embodiment, the cutter tool 46 and bradawl-like retaining projection 53 are separate from each other and thus can independently be removed from or secured to the shaft 45. In Figure 10, the bradawl-like projection 53 is secured to one end of a rod 100 which is fixed centrally in the cutter tool 46 iteself. In Figure 11, the bradawl-like projection 53 is again fixed to the cutter tool itself; this time it is screwed by means of the threads 64 into the cutter tool (as mentioned in the above description of the overall apparatus) and fixed in position by welding as at 101.

In Figures 10 and 11, although not shown, the cutter tool 46 screws onto a threaded stub as shown in Figure 9. It will be appreciated that with the Figure 10 and 11 embodiments, the cutter tools and bradawl-like retaining projections can only be removed and replaced as combined units.

The appearance of each of the embodiments of cutter tool in the diEestion*6 in Figures 9, 10 and 11 is the same and is shown in Figure 12.

Figure 13 shows part of a radiator system comprising two radiators 105,106, connected together by a hot water carrying pipe 107 which has secured thereto a fitting 1 which has been fitted to the pipe 107 by means of the method and apparatus as described with reference to Figures 1 to 8.

Applicants investigations using the above described apparatus have mainly involved tapping into copper pipe having an external diameter of 15mm or 22mm and a wall thickness of about lmm. Substantially swarf free cuts have been obtained.

As regards the sizes of the holes which can be cut out from these diameter pipes, cutting tools have been used in which the cutting edges of the blades lie on a circle having a diameter of approximately 10mm (for 15mm pipe) or 15mm (for 22mm pipe). Thus holes of approximately these sizes are produced. However, it will be appreciated that the tool may be used on pipes of other diameters and different size holes may be cut out. Apparatus according to the invention has been used successfully on such pipes carrying hot water. For example, the pipes may form part of a central heating system in which the water temperature may be up to llO"C and the pressure may be up to 5 Bar. Applicants have found that the various O-ring seals used in the apparatus to provide for fluid tightness may conveniently be made from suitable ethylene ----propylene rubber, for example a type which is suitable where temperatures may be up to 1200C.

The tubular body may be made of non-dezincifying brass; the valve member may be made of a stainless steel; the seals may be made from suitable rubber; the cutter tool including the bradawl-like projection may be made from a carbon steel; and the remainder of the cutter assembly may be made of stainless steel. Applicants have found that cutter tools having cutting edges which have a hardness value of about 370 (Vickers) are suitable for use with the copper pipe.

Whilst a particular embodiment has been described above with reference to Figures 1 to 8; it will be appreciated that various modifications may be made without departing from the scope of the invention. For example, the tubular body 4 of the fitting 1 may be lengthened and provided with a tubular branch connection which is connected to the tubular body at a point on the side of the valve seal remote from the clamping end of the fitting. Thus, when the cutter portion is withdrawn to a retracted position beyond the opening of the branch connection into the tubular body, closing of the valve member will close off the bore and thus communication between a cut hole in the pipe and the branch connection.

Furthermore, the outer body 42 may be a permanent connection to the tubular body 4 and form a single tubular body which may be designed to releasably mount therein the supporting body, which carries the cutter means, for sliding movement between required -first( and second limiting positions. When the supporting body together with the cutter means is removed after the coupon has been cut, the single tubular body and the incorporated valve means are left secured to the tapped pipe.

Moreover, the cutter means may comprise a threaded portion and the tubular body itself may have an internally threaded bore so that the threaded portion of the cutter means is releasably insertable therein and threadably movable therealong, so that the cutting tool can be moved to and from the cutting position. It will also be appreciated that the apparatus may be used to tap into pipes carrying other fluids, such as gas carrying pipes.

Claims (6)

1. A fitting for securing to a pipe and for use with a cutter means assembly to tap into the pipe, said fitting comprising a main body having a bore extending therethrough with one end of the bore opening at a main body end portion, and valve means in the main body operable between a valve open and a valve closed position with respect to the bore, the main body being adapted to facilitate releasable connection of the cutter means assembly thereto, and the said one end portion of the main body defining a pair of opposing generally U-shaped recesses which together form a saddle-like arrangement for engaging one side of the pipe to be tapped into, and said end portion being threaded to receive a complementary threaded cap having a projecting formation defining a generally U-shaped recess for engaging the opposite side of the pipe, and arranged such that the cap can be threaded onto the said main body end portion and tightened to clamp the fitting onto the pipe.

2. A fitting as claimed in claim 1, in which the main body incorporates a sealing means for engaging the surface of the pipe wall in a substantially fluid tight manner around the area to be, or which has been, tapped.

3. A fitting substantially as hereinbefore described with reference to Figures 1 to 7 of the accompanying drawings.

4. Fluid-carrying pipework comprising pipe which has secured thereto a fitting as claimed in any of claims 1 to 3, the pipe having previously been tapped so as to have a hole or opening in an area of the pipe wall about which the fitting is mounted with the hole or opening providing communication between the interior of the pipe and the bore of the main body of the fitting.

5. Pipework and associated fitting as claimed in claim 4, in which the pipe is for carrying hot water.

6. A radiator system comprising pipework and associated fitting as claimed in claim 5.