WO1991019928A2

WO1991019928A2 - Pipe fittings

Info

Publication number: WO1991019928A2
Application number: PCT/GB1991/001000
Authority: WO
Inventors: John Proctor
Original assignee: Wask-Rmf Limited
Priority date: 1990-06-20
Filing date: 1991-06-20
Publication date: 1991-12-26
Also published as: GB9013795D0; GB2245943A; WO1991019928A3; AU7998991A

Abstract

A pipe fitting (32) has an inner tubular body (33) in screw threaded engagement (41) within an outer tapered bush (37). The bush (37) is adapted to locate into a hole (9) drilled in a pipe (1). The inner body (33) has a tapered seal (35) mounted on a flange (34). The outer bush (37) has an external seal (40). A pilot hole (9) is drilled under pressure into a lined pipe (1) which is connected in service. Retainer means (25) is inserted into said pipe (1) and a large hole is cut with the cut out portion retained. The pipe fitting (32) is inserted by locating the outer bush (37) into the hole such that the external seal (40) rests on the pipe surface. The inner body (33) is withdrawn away from the hole with the bush (37) stationary. The tapered seal (35) is deformed and acts to seal the interior of the pipe (1) to the fitting (32) and to trap the lining (23).

Description

PIPE FITTINGS

The present invention relates to pipe fittings and their insertion into and removal from a fluid conduit pipe particularly, but not exclusively, for application with conduit pipes used in the gas, oil and water industries.

A requirement that often arises in pipe line networks is to provide an additional service line connection to a mains pipe. It is often the case that this requirement was not anticipated at the time of installing the mains pipe and the provision of a fitting for that purpose was not made. Alternatively there may be a need to replace a faulty fitting already in place; in this case the fitting may or may not be connected to a service connection.

It is common practice in the industry to provide a conduit pipe with an interior lining fitted to the inside wall of a pipe. A lining has two functions: it serves as an anti-corrosion support and aids leak prevention. Known types of linings in use comprise fibres woven into a "sock" or tube and impregnated with a polymer to provide an impervious surface. The woven tube is fixed to the internal wall of the pipe by an appropriate adhesive resin.

Linings can provide problems when a new fitting is to be inserted into a pipe.A hole must be drilled through the pipe and the lining. Adhesion of the lining to the pipe wall is often not uniform across the whole length of the pipe. In some places pockets or annular regions may have developed between the lining and the pipe wall. If the lining is separated from the pipe wall at the point of drilling the hole there is the problem of having to pick up the lining when the fitting is inserted, such that it is sealed against the pipe wall. If this is not done fluid in the pipe can propagate along an annulus between the lining and the pipe wall, having potentially catastrophic consequences. Any such annulus must be sealed to prevent a build-up of gas. Effective sealing will also cure the problem of "wicking" whereby fluid is able to pass through fibres of the lining by virtue of the fact that the polymer resin may not be homogenous throughout the woven fibres. The existence of an above described annulus renders a pipe useless as a fitting cannot be installed without considerable effort and expense. Indeed, if during drilling the liner is left uncut because it has become separated from the

SUBSTITUTE SHEET pipe, it is virtually impossible to seal the lining to the pipe with the fitting.

All known methods for inserting a new fitting or replacing an existing fitting in a lined pipe involve isolating that particular section of mains pipe from the rest of the line thereby interrupting the supply to other subscribers on that line. This can cause considerable inconvenience, for example, in the case of gas or water supplies to households and may result in the subscriber being entitled to claim compensation for an excessive interruption of supply time.

One particular known pipe fitting designed for lined pipes involves cutting a hole in the pipe and inserting a flanged fitting defining two lugs. The fitting is inserted by locating one lug at a time under the lining and rotating the fitting in the process. The fitting is then held in place, trapping the lining between the flange thereof and the pipe wall, by for example, mole grips. A split washer is then threaded onto the body of the fitting followed by two jointing washers and a nut. The installation of such a fitting requires dexterous manipulation and can only be effected with the pipe out of service. If the pipe lining should be detached from the pipe wall in the area around the hole it is virtually impossible to guarantee the sealing of the lining between the pipe wall and the fitting.

A further problem in known installation techniques is in the drilling process. In drilling a hole into the pipe and the lining the cut out disc or "slug" and swarf may be deposited in the mains pipe. This creates undesirable contamination of the fluid.

Machines used to drill unlined pipes and to remove and insert fittings under pressure, with the pipe connected in service, are well known in the art.

In accordance with the present invention there is provided a pipe fitting comprising an inner body moveable within and relative to an outer body, said outer body being adapted to locate into a pipe, first seal means supported on said inner body, second seal means supported on said outer body wherein one end of said outer body defines a taper and said first seal is adapted to receive said taper and undergo deformation whilst still in sealing contact with said inner body.

Preferably said outer body is moveable between a first position and a second position whereby in said first position said taper is clear

SUBSTITUTE SHEET of said first seal means and in said second position said taper is received between said first seal means and said inner body to elastically deform part of said first seal means away from said inner body whilst still in sealing contact with said inner body.

Preferably said outer body moves in screw threaded engagement with said inner body.

Preferably said outer body supports a screw thread on its exterior surface to locate into said pipe.

As a second aspect of the present invention there is provided a method for drilling a hole for a pipe fitting into a conduit pipe comprising the steps of: a) drilling a pilot hole in said conduit pipe b) locating retainer means within said pipe through said pilot hole, and c) drilling a full sized pipe fitting hole with said retainer means in position.

Preferably said conduit pipe is connected in service.

Preferably said conduit pipe is fitted with an interior lining.

Preferably the method comprises further steps of mounting a drilling machine into a chamber sealed on to part of said conduit pipe, sealing said drilling machine relative to said chamber, drilling a pilot hole through said conduit pipe and through said lining, withdrawing said drilling machine from said pipe, sealing said pipe from said chamber, removing the drilling machine from said chamber and inserting retainer means into said chamber, sealing said retainer means to said chamber, inserting retainer means through said pilot hole in said pipe and said lining, partially withdrawing said retainer means in an expanded condition such that it abuts the interior of said lining and said pipe wall, with retainer means in place locating said drilling machine into said chamber as before, drilling a full size hole in said pipe and said lining such that cut out material from said pipe and said lining is retained by said retainer means, withdrawing said retainer means and cut out material into said chamber, sealing said pipe from said chamber, venting said chamber, removing said retainer means and drilling machine, tapping said hole under pressure and sealing said pipe once again.

Preferably said drilling machine comprises a drilling head end, a drive end and a hollow spindle adapted to fit sealably into said chamber.

SUBSTITUTE SHEET Preferably said retainer means comprises a spindle adapted to fit with said hollow spindle of said drilling machine and a head adapted to pass through said pilot hole into said pipe and to expand within said pipe to prevent its withdrawal.

Preferably said head of said retainer means comprises two hinged wing portions moveable between a first position in which they are disposed substantially parallel to said spindle defining a relative small cross-sectional area and a second position in which the wing portions are disposed substantially at right angles to said spindle defining a relatively large cross sectional area.

Preferably said retainer means is biased, within said drilling spindle, away from said pipe.

Preferably a plunger is provided to move said retainer means into said pilot hole.

As a further aspect of the present invention there is provided a method of inserting a pipe fitting into a conduit pipe, said conduit pipe having been drilled and tapped to define a fitting hole, comprising the steps of: a) locating and fixing a main body of the pipe fitting into said fitting hole and sealing it to the external wall of said pipe, and b) withdrawing an inner body disposed within said outer body such that a fitting is sealed internally to said pipe.

Preferably said pipe is connected in service to a fluid mains and said fitting hole is initially sealed.

Preferably said pipe is fitted with an internal lining.

Preferably the method comprises further steps of locating an insertion machine into a chamber sealed to said pipe around vicinity of said fitting hole, sealing said insertion machine to said chamber, unsealing said fitting hole, locating said outer body of said pipe fitting through said fitting hole and a hole in said lining such that a second seal means supported on said outer body locates onto the exterior of said pipe wall around the periphery of said fitting hole, moving said inner body relative to said outer body away from said fitting hole such that a first seal means supported on said inner body inside said pipe is deformed and abuts the interior of said lining sealing said lining

SUBSTITUTE SHEET between said first seal and said pipe wall, venting said chamber, removing said insertion machine and removing said chamber.

Preferably said first seal is deformed by a taper defined on said outer body wherein said inner body is moveable between a first position in which said taper is clear of said first seal means and a second position in which said taper is received between said first seal means and said inner body to elastically deform part of said first seal mans away from said inner body and in which said first seal means abuts the interior of said pipe sealing said lining thereto.

Preferably said inner body moves in screw threaded engagement relative to said outer body.

Preferably said outer body is screw threaded into said fitting hole.

Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a part sectioned view of a pipe and a machine base fitted thereto,

Fig. 2 is a part sectioned longitudinal view of a drilling machine fitted to a pipe in accordance with the present invention,

Fig. 3 is a part sectioned longitudinal view of a second embodiment of a drilling machine operating on a pipe in accordance with the present invention,

Fig. 4 shows in a part sectioned view the action of a retainer after drilling in accordance with the embodiment of Fig. 3,

Fig. 5 is a cross sectional longitudinal view of a pipe fitting, and Figs. 6 and 7 are cross-sectional longitudinal views of an insertion machine fitting the pipe fitting of Fig. 5 into a pipe.

Referring to the drawings, Fig. 1 shows the components which are common to all embodiments of machine assemblies (described below) used to operate on a fluid conduit pipe 1. Pipe 1 is fitted with a machine undercarriage 2 which is sealed to the pipe 1. The undercarriage 2 supports a machine base 3 which defines two annular grooves 4 on its upper face designed to receive a variety of machining assemblies. Disposed between the machine base 3 and the undercarriage 2 is a slideable valve plate 5 which is sealed on both faces by two seals 6, one fitted to the undercarriage 2 and the other to machine base 3. The assembly is mounted to the pipe wall using a known chain assembly 7. The abovedescribed equipment is well known in the field to which the

SUBSTITUTE SHEET present invention relates.

Fig. 2 shows a drilling machine mounted on the machine base 3 of Fig. 1. Such a machine is known and a detailed description of the machines is thus omitted.

The drilling machine comprises a hollow drilling spindle 8 to which a hole saw 9 is fitted at one end. The opposite end of the spindle 8 receives an end piece 10 welded to the spindle 8 having a flange 11 which seats on the spindle 8. The end piece is square to accept adaptor 12 which is used to drive spindle 8 and to provide location of feed screw 13.

The interior of the drill spindle 8 is fitted with a spindle 14 connected to a plunger head 15. The plunger head 15 is substantially the same diameter as the interior of the spindle and supports a ring seal 16. The spindle 14 is disposed coaxially with the spindle 8. The spindle 14 and plunger head 15 are free to move up and down axially within the drill spindle 8. The plunger head 15 is biased by a spring 17 coaxial with the spindle 14 between the plunger head 15 and the end wall of the drill spindle 8.

Machine base 3 supports a canopy 18 which is substantially frusto- conical in shape. The narrower neck end 19 receives the drilling spindle assembly and is of substantially the same diameter as the drill spindle 8. The canopy 18 is sealed at its wider end to the machine base 3 by seal 20 and is sealed at its neck end 19 to the drill spindle 8 by two ring seals 21 supported in two annular grooves in the neck portion 19. Drill spindle 8 is free to rotate and to move axially within the neck 19 of the canopy 18. The canopy 18 wall has a valve 22 through which pressure within the enclosed volume can be vented to atmosphere.

The procedure of inserting a pipe fitting into pipe 1 commences by drilling a relatively small pilot hole through the pipe wall 1 and a pipe lining 23. The drilling procedure is conducted as follows.

With the appropriately dimensioned hole saw 9 fitted to the drill spindle 8 and the drill spindle 8 inserted into canopy 18, the canopy 18 is fitted to the machine base 3 and locked in position. The drill spindle 8 is pushed down towards the pipe 1 until the hole saw 9 locates on the pipe wall 1. With a driver (not shown) fitted to the square head 12 and the feed screw 13 in place, drilling is commenced. The feed screw 13 applies axial force on the drill spindle 8 as is known in the art. The

SUBSTITUTE SHEET feed screw 13 pressure will decrease rapidly as the hole saw 9 breaks through the pipe wall 1. The drill spindle 8 is still rotated a fraction at a time to cut through the pipe lining 23. When drilling is complete the feed screw 13 is backed off and the drill spindle 8 is withdrawn up above the valve plate 5 which is then closed. The pressure in the canopy 18 enclosure is then released through valve 22 and the canopy 18 can be removed.

In the drilling of the pilot hole some of the waste material may drop into the pipe 1 but this is relatively little compared to the waste material of the full size hole which is collected as described below. With the canopy 18 enclosure sealed and pressurised as described, drilling can be effected with the pipe 1 in service. Obviously this drilling operation could also be performed on a pipe which is not pressurised thus eliminating the requirement of sealing the volume around the drilling head.

The next stage is to cut out and tap the full size hole for a pipe fitting to be located. This is shown in Figs. 3 and 4. An appropriately dimensioned hole saw 9 is fitted in place of that used to drill the pilot hole. Fig. 3 shows the drilling machine assembled within the canopy 18 as before. In this embodiment the hollow interior of the drill spindle 8 is fitted with removable plunger rod 24. The plunger rod 24 locates coaxially inside the drill spindle 8 and passes from above the driven end of the drill spindle 8 down into the drill spindle 8 portion located inside the canopy 18, where it abuts the plunger head 15. The plunger head 15 is free to move axially within the drill spindle 8 operated by axial movement of the plunger rod 24. The plunger head 15 can move up and down within the drill spindle 8, biased upwards by the spring 17 and forced downwards against the spring 17 by application of force on the plunger rod 24. At the end opposite the plunger head 15 the spindle 14 is fitted with a liner retainer 25. The liner retainer 25 has two wing portions 26 which are fastened to the spindle 14 by a socket cap head screw 27 and a spacer 28. The wing portions 26 are hinged to the spindle 14 such that they can move between two positions. In a first position the wing portions 26 close up towards the spindle 14 such that they are approximately parallel to it, in a second position the wing portions 26 are each disposed at approximately right angles to the spindle 14 and at approximately 180° to each other. The wing portions

SUBSTITUTE SHEET 26 are spring loaded to the second position. It will be appreciated that a force applied to the lower surface 29 of the wing portions will cause them to deflect to the first position.

The procedure for drilling the full size hole is described below.

With the canopy 18 removed from the machine base 3 a large hole saw 9 is fitted to the drill spindle 8. The plunger rod 24 is depressed to move the plunger head 15 down to compress internal spring 17. Spindle 14 thus moves from within the drill spindle 8 through the hole saw 9 and protrudes beyond the latter. In this position the spindle 14 is retained in place against the force of the return spring 17 by, for example, a vice. The liner retainer 25 can then be fitted to the end of spindle 14 as described above and the spindle 14 is released from the vice. With the wing portions 26 extended, the spindle 14 is prevented from returning through the hole saw 9 into the drill spindle 8 (under the action of return spring 17) as the wing portions 26 abut the end of the drill spindle 8.

As described previously the drill spindle 8 and canopy 18 are fitted to the machine base 3 and the canopy 18 is locked in place. Valve plate 5 is opened and drill spindle 8 is pushed down until the hole saw 9 rests on the pipe wall 1. Using the plunger rod 24 the internal spring 17 is compressed by the plunger head 15 so that the liner retainer 25 is forced through the pilot hole in the pipe 1. The liner retainer 25 passes through the pilot hole by virtue of the pilot hole wall abutting the liner retainer wing portions 26 and biasing the liner retainer 25 into its closed position. The plunger rod 24 is pushed as far as is possible to fully compress the internal spring 17 so that the liner retainer 25 will have passed through the pilot hole in the pipe 1 and the lining 23, even if the lining 23 should be detached from the pipe wall 1. The plunger rod 24 is then released gradually until it stops. At this point the liner retainer 25 wing portions 26 are open and abut the interior of the pipe wall 1 and the pipe liner 23 around the vicinity of the pilot hole as shown in Fig. 3. Plunger rod 24 is then removed to allow the driver and feed screw to be attached as before and drilling proceeds as before.

With drilling complete the cut-out pipe material 30 and the cut out lining 31 are retained in the hole saw 9 by the liner retainer 25 as shown in Fig. 4. The spindle assembly 8, 14 can now be withdrawn into canopy 18 together with the cut out material 30, 31.

SUBSTITUTE SHEET Valve plate 5 is closed and as previously described the equipment is disassembled. The hole saw 9 is then replaced by a tapping tool and the hole is tapped following the procedure outlined above for drilling. Fig. 5 shows a pipe fitting 32 to be inserted into the threaded hole in the pipe 1. The fitting 32 comprises a tubular main body 33, one end of which has an exterior flange 34. The flange 34 has an elastomeric ring seal 35 which fits snugly around the lower end of the main body 33. The ring seal 35 is substantially of the same diameter as the flange 34. At its end opposite the flange 34, the internal diameter of the seal 35 increases and departs from contact with the wall of the main body 33 forming a taper 36. The external diameter of the ring seal 35 remains constant throughout. At approximately the mid-point of the exterior of the main body 31 a bush 37 is coaxially in screw threaded engagement. The bush 37 is tubular and is approximately one third of the length of the main body 33. The end of the bush 37 nearest the seal 35 defines a tapered wall portion 38 which tapers in towards the main body 33 opposite to the tapered internal diameter 34 of the ring seal 35. In the initial condition the bush taper portion 38 is clear of the seal taper 36. The opposite end of the bush 37 has an external flange 39 to which is fitted an external ring seal 40 of approximately half the length of ring seal 35. The external seal 40 fits snugly around the bush 37 and is of substantially the same diameter as flange 39. The remaining exposed portion of the bush 37 between the external seal 40 and the bush taper 38 has a screw thread 41 which is designed to mate with the screw thread of the hole cut in the pipe 1. The face of flange 39 which is opposite that supporting external seal 40 abuts a lock nut 42, the function of which is described below. The lower end of the pipe fitting 32 is fitted, internally, with a stopper valve 54 which is well known in the art.

Figs. 6 and 7 illustrate the machine assembly employed to insert the fitting 32 into the pipe 1. Machine base 3 and machine undercarriage 2 will be in position from the preceding drilling operation.

The insertion machine comprises an internal spindle 43, internal and coaxial to a hollow external spindle 44. The spindles 43, 44 are rotatable relative to each other. The spindle assembly 43, 44 is inserted into a neck portion 45 of canopy 46 as described previously in the drilling machine embodiment. The free end of the neck portion 45 is

SUBSTITUTE SHEET fitted with a ring seal 47 in a groove. The ring seal 47 is held in place by means of a sealing nut 48 which screw engages with the neck portion 45 and extends over the seal 47 around the outer spindle 44. The spindles 43, 44 extend beyond the neck portion 45 outside the canopy 46. Outer spindle 44 is adapted to receive a known tommy bar arrangement 49 with arms extending radially from the spindle 44. The internal spindle 43 has a square head 50 suitable for mating with a square ratchet (not shown) by which the internal spindle 43 can be rotated relative to the external spindle 44.

At the end opposite the neck portion 45 of canopy 46 the outer spindle 44 is fitted to a tubular bush driver 51. Similarly the inner spindle 43, is fitted to a hollow cup shape 52. The external diameter of cup 52 is smaller than the interior diameter of bush driver 51 and the length of the cup 52 is approximately half the length of bush driver 51. The cup 52 is thus free to move axially and rotationally within the bush driver 51. The interior wall of the cup 52 is dimensioned to receive the top part of fitting 32 and is shaped to abut the lock nut 42 engaged with the wall of the main body 33 of the fitting 32.

To insert the pipe fitting 32 into pipe 1 the procedure described below is followed. Initially the spindle assembly 43, 44 is separate from the canopy 46.

The top portion of the fitting which extends above lock nut 42 is received in the cup 52 such that the rim of the cup 52 abuts the lock nut 42 of the fitting 32. The bush driver 51 is slide fitted over the fitting 32 and fastened to the bush 37 by means of two counter sunk screws 53 which pass through the wall of the bush driver 51 and abut the bush 37. The spindle assembly 43, 44 is then inserted into canopy 46 with the fitting 32 fitted in place in the bush driver 51. Sealing gland 48 is tightened on to the outer spindle 44, canopy 46 is locked and sealed to machine base 3, valve plate 5 opened, as previously described. Spindle assembly 43, 44 is then pushed down until the fitting 32 rests on the pipe wall 1. Using the tommy bar 49 the outer spindle 44 is rotated clockwise so that the bush 37 of fitting 32 is screw threaded into the hole in the pipe carrying the main body 33 of the fitting 32 with it until the external seal 40 rests on the pipe 1, a further revolution of the tommy bar 49 will then lock the fitting 32 to the pipe wall 1 (see Fig. 6). A square ratchet (not shown) is used to rotate the inner spindle 43

SUBSTITUTE SHEET anticlockwise whilst the tommy bars 49 are held stationary. The main body 33 of the fitting 32 is thus rotated relative to the stationary bush 37 and this has the effect of withdrawing the main body 33 upwards relative to the bush 37. In so doing the elastomeric ring seal 35 is forced to ride up and over the bush taper 38 by virtue of the seal taper 36 mating with the bush taper 38. The ring seal 35 is deformed elastically such that complete withdrawal of the main body 33 from the pipe 1 is prevented by the outward deformation of the seal 35 which now abuts the pipe wall 1 and liner 23 around the hole as shown in Fig. 7. The fitting 32 is now sealed internally by seal 35 and externally by seal 40. The pipe 1 is now fully sealed from the surrounding atmosphere. The liner 23 being trapped between the fitting 32 and the pipe wall 1 is sealed, preventing any propagation of fluid along an annulus between the pipes and the liner 23.

As previously described the canopy 46 is vented and removed. The machine base 3 is filled with a known leak detecting fluid to check for any escaping gas. The machine base 3 is then removed with the spindle assembly 43, 44 in position. The counter sunk screws 53 are removed from the bush driver 51 allowing the spindle assembly 43, 44 to be removed. The locknut 42 is then tightened down onto bush 37.

It may be necessary to remove a fitting 32 from the pipe 1, for example if the fitting 32 was faulty or leaking the above operation of rotating the spindles 43, 44 is reversed. With the tooling located the inner spindle 43 is rotated clockwise whilst holding the tommy bars 49 stationary. The tommy cars 49 are then rotated anti clockwise until fitting 32 is felt to have disengaged from the threads in the pipe wall 1. The fitting 32 is lifted out and clear of the valve plate 5 using the tommy bars 49, valve plate 5 is closed and canopy 46 vented and removed as before.

SUBSTITUTE SHEET

Claims

1. A pipe fitting comprising an inner body moveable within and relative to an outer body, said outer body being adapted to locate into a pipe, first seal means on said inner body, second seal means on said outer body wherein one end of said outer body has a taper and said first seal is adapted to receive said taper and undergo deformation whilst still in sealing contact with said inner body.

2. A pipe fitting according to claim 1 where in said outer body is moveable between a first position and a second position whereby in said first position said taper is clear of said first seal means and in said second position said taper is received between said first seal means and said inner body to elastically deform part of said first seal means away from said inner body whilst still in sealing contact with said inner body.

3. A pipe fitting according to claim 2 wherein said outer body moves in screw threaded engagement with said inner body.

4. A pipe fitting according to any preceding claim wherein said outer body has a screw thread on its exterior surface to locate into said pipe.

5. A pipe fitting according to any preceding claim wherein said first seal means is mounted on a flange of said inner body.

6. A method for drilling a hole for a pipe fitting into a conduit pipe comprising the steps of: a)drilling a pilot hole in said conduit pipe b)locating retainer means within said pipe through said pilot h5e, and c)drilling a full sized pipe fitting hole with said retainer means in position.

7. A method according to claim 6 wherein said conduit pipe is connected in service.

SUBSTITUTE SHEET

8. A method according to claim 6 or 7 wherein said conduit pipe is fitted with an interior lining.

9. A method according to claim 8 wherein the method comprises further steps of mounting a drilling machine into a chamber sealed on to part of said conduit pipe, sealing said drilling machine relative to said chamber, drilling a pilot hole through said conduit pipe and through said lining, withdrawing said drilling machine from said pipe, sealing said pipe from said chamber, removing the drilling machine from said chamber and inserting retainer means into said chamber, sealing said retainer means to said chamber, inserting retainer means through said pilot hole in said pipe and said lining, partially withdrawing said retainer means in an expanded condition such that it abuts the interior of said lining and said pipe wall, with retainer means in place locating said drilling machine into said chamber as before, drilling a full size hole in said pipe and said lining such that cut out material from said pipe and said lining is retained by said retainer means, withdrawing said retainer means and cut out material into said chamber, sealing said pipe from said chamber, venting said chamber, removing said retainer means and drilling machine, tapping said hole under pressure and sealing said pipe once again.

10. A method according to claim 9 wherein said drilling machine comprises a drilling head end, a drive end and a hollow spindle adapted to fit sealably into said chamber.

11. A method according to claims 6, 7, 8, 9 or 10 wherein said retainer means comprises a spindle and a head adapted to pass through said pilot hole into said pipe and to expand within said pipe to prevent its withdrawal.

12. A method according to claim 11 wherein said head of said retainer means comprises two hinged wing portions moveable between a first position in which they are disposed substantially parallel to said spindle defining a relative small cross-sectional area and a second position in which the wing portions are disposed substantially at right angles to

SUBSTITUTE SHEET said spindle defining a relatively large cross-sectional area.

13. A method according to claim 11 or 12 wherein said retainer means is biased, within said drilling spindle away from said pipe.

14. A method according to claim 11, 12 or 13 wherein a plunger is provided to move said retainer means into said pilot hole.

15. A method of inserting a pipe fitting into a conduit pipe, said conduit pipe having been drilled and tapped to define a fitting hole, comprising the steps of: a)locating and fixing a main body of the pipe fitting into s a i d fitting hole and sealing it to the external wall of said pipe, and b)withdrawing an inner body disposed within outer said body such that a fitting is sealed internally to said pipe.

16. A method according to claim 15 wherein said pipe is connected in service to a fluid mains and said fitting hole is initially sealed.

17. A method according to claim 15 or 16 wherein said pipe is fitted with an internal lining.

18. A method according to claim 17 wherein the method comprises further steps of locating an insertion machine into a chamber sealed to said pipe around vicinity of said fitting hole, sealing said insertion machine to said chamber, unsealing said fitting hole, locating said outer body of said pipe fitting through said fitting hole and a hole in said lining such that a second seal means supported on said outer body locates onto the exterior of said pipe wall around the periphery of said fitting hole, moving said inner body relative to said outer body away from said fitting hole such that a first seal means supported on said inner body inside said pipe is deformed and abuts the interior of said lining sealing and said lining between said first seal and said pipe wall, venting said chamber, removing said insertion machine and removing said chamber.

19. A method according to claim 18 wherein said first seal is deformed

SUBSTITUTE SHEET by a taper defined on said outer body wherein said inner body is moveable between a first position in which said taper is clear of said first seal means and a second position in which said taper is received between said first seal means and said inner body to elastically deform part of said first seal means away from said inner body and in which said first seal means abuts the interior of said pipe sealing said lining thereto.

20. A method according to claim 19 wherein said inner body moves in screw threaded engagement relative to said outer body.

21. A method according to claim 20 wherein said outer body is screw threaded into said fitting hole.

SUBSTITUTE SHEET