GB2282653A

GB2282653A - Branch insert

Info

Publication number: GB2282653A
Application number: GB9419626A
Authority: GB
Inventors: Alan Rodriguez; John Arthur Rose
Original assignee: Angus Fire Armour Ltd
Current assignee: Angus Fire Armour Ltd
Priority date: 1993-10-05
Filing date: 1994-09-29
Publication date: 1995-04-12
Anticipated expiration: 2014-09-29
Also published as: GB9419626D0; DE4435653A1; GB9320486D0; GB2282653B

Description

1 2282653 This invention relates to an insert for a pipe providing a

branch conduit. The invention is particularly applicable to a branch insert for a lined renovated pipe.

is Renovation of a defective pipe by lining it with an inner plastics liner can be accomplished according to any one of a number of known methods. In the renovated state, the pipe comprises the outer main and the inner liner adhered to the main wall or closely fitting it. The liner is relatively rigid when it is in place, being made either of a rigid plastics material or being coated in a rigidising material, such as an epoxy resin.

Such pipeline renovation methods require a total operating system, which provides the lining materials to be used, the means for inserting them into the pipe requiring renovation, and the components and processes for fitting end connections and branch connections to the re-lined pipe.

An obvious requirement in fitting branch connections to a pipe which has been re-lined is that the said connection must be fitted entirely from the outside of the pipe, because the inside is generally inaccessible, unless robotic moles, operated by remote control, are used. Such systems are, highly skilled operators.

however expensive and need Secondly, the branch connection itself needs to provide a leak-proof joint with the liner which carries the fluid, and also needs to be rigidly fixed to the original pipe.

2 is Previous designs of branch connectors used with piperelining systems depend on the means of attachment to the pipe for both the subsequent leak-proofness of the joint and for the mechanical stability of the connection. In consequence, any further rusting or deterioration of the original pipe in the area of the branch connection can cause leaks at the branch connection.

It is an object of the present invention to provide a branch connection for a lined pipe, which can be inserted from the outside. and in which the connecting assembly retains its leak-proof properties, even when the original pipe becomes severely corroded at the location of the branchpipe connection.

According to the present invention there is provided a branch insert for a lined pipe comprising a hollow bolt, providing a branch conduit through branch apertures in the pipe and liner and having a pipe liner engaging seat engageable with the inner surface of the liner in the region surrounding its branch aperture, a deformable ring mounted on the hollow bolt and a clamp nut for tightening the ring against the pipe liner, such that it expands radially outwardly and engages the edge surface of the pipe defining its branch aperture.

Also according to the invention there is provided a method of forming a branch in a lined pipe, comprising forming a hole in the liner and a larger hole in the pipe, mounting a hollow bolt of a branch insert as defined above projecting through the apertures, assembling the ring on the hollow bolt so that the ring rests on the exposed surface of the liner within the larger hole in the pipe and tightening the clamp nut 3 against the ring so that it expands radially and engages the edge surface of the pipe defining the said larger hole.

Preferably, the ring comprises at least one outer washer. For example, the ring may have washers on either side to act as bearing plates.

Preferably, the ring is a cylindrical member which may include an internal taper. The washer or washers may be conically shaped to urge the ring radially outwardly as they are compressed by the clamp nut.

An alternative ring design comprises a cylindrical ring made f rom a tough but def ormable material which has annular ribs on its outer circumference. The ribs provide a maximum diameter of the ring which is slightly larger than the diameter of the reception hole drilled in the lined pipe at the branch connection point. A clamp nut forces the ring into the hole in the pipe at the same time as the pipe liner engaging seat is clamped against the inside surface of the liner. The castellations or ridges on the surface of the ring are deformed or distorted during this process to provide a tight fit between the branch assembly and the pipe to be lined. The compressive force between the clamp nut and the pipe liner engaging seat inhibits expansion and thus provides a permanent firm support protecting the branch assembly from damage by bending forces.

Branch connector assemblies may also incorporate a profiled washer which is positioned on the hollow bolt between the liner and the pipe and profiled to hold the liner f lat in the area around branch connection point 4 thus f orming the outer bearing surface on the liner matching the pipe liner engaging seat.

Preferably, the clamp nut includes locking means for locking it relative to the hollow bolt in an assembled position. The locking means may be a further lock nut or a grub screw threadedly received radially into the clamp nut to bear against the thread on the hollow bolt.

Preferably, the ring is made of nylon, rubber, polyethylene or any other polymeric compound able to withstand the force exerted by the clamp nut without disintegrating, while still expanding to fill, and fit tightly in, the larger hole in the pipe to hold the branch insert in place.

Alternatively, the ring may be made of a more rigid material but which is split radially so that it can open out into engagement with the periphery of the main pipe defining the main pipe branch aperture.

The ring provides a simple means of securing the branch insert in the correct position at the same time as the clamp nut is tightened up to seal the hollow bolt against the lining. Thus, the one tightening operation serves both ends.

The seat may be removable from the bolt so that the bolt is more easily insertable into the apertures. In this case the bolt may be formed with a radially projecting portion for holding the seat. The seat is preferable discontiguous, the radially projecting portion on the bolt defining a segment which completes the seat.

The present invention can be put into practice in various ways some of which will now be described by way of example with reference to the accompanying drawings in which:

is Fig. 1 is an exploded cut-away prospective view of a lined pipe in which a branch insert according to the invention is arranged; and Figs. 2 to 7 are cross-sections of the pipe of Fig.1 illustrating the various stages in the assembly of a branch insert according to the invention; Fig.8 is an exploded view as in Fig.1 of a second embodiment of the invention; and Figs. 9 to 11 are cross-sections of the pipe in Fig.8 also illustrating the various stages in assembly.

Referring to Fig.1, a main pipe 10 is shown fitted with a liner 12. In this embodiment, the liner 12 is a composite of a thermoplastics outer layer, an intermediate fabric reinforcement layer and a thermoplastics fluid the pipe thermoplastics polythene which inner layer that is compatible with the is to carry. An example of a suitable material is high, medium or low density is commonly used in water pipes.

A first small circular hole 14 is formed in the liner 12 and a second, larger, coaxial circular hole 16 is formed in the main pipe 10. One of the main difficulties in connecting a branch insert to a lined pipe is the fact that it is most often the case that the insert must be applied to the main pipe 10 from the outside.

Referring now also to Fig.2, a hollow bolt 18 comprises a threaded portion 20 and a seat 22 at one end of the 6 bolt and separated from the threaded portion 20 by a smooth shank portion 24. The seat 22 has a semi-circular portion 26 coaxial with the threaded portion 20 and a more radially projecting foot portion 28 on the opposite side of the bolt to the semi-circular portion 26. The foot 28 bears an upwardly projecting arcuate segment 30 which is also coaxial with the threaded portion 20.

is A lever 32 is screwed into the hollow bolt 18 which has an internal thread for the purpose. The hollow bolt is then introduced into the main pipe 10 by engaging the segment 30 against the inside surface of the liner 12 close to the hole to gain purchase and then lever the less radially projecting semi-circular portion 26 of the seat 22 past the liner 12.

Referring to Fig.3, a C-shaped washer 34 is then slid over the lever 32 and introduced into the hole 14 in the liner. Again, the washer 34 is of a larger diameter than the hole 14, but it is slipped sideways so that the jaws of the washer are on either side of the liner so that it is then possible to push the major portion of the washer 34 past the liner 12. The washer is then seated on the seat 22 of the hollow bolt 18 such that the segment 30 completes the ring of the C-shaped washer 34 (see Fig.4).

The ring constituted by the C-shaped washer 34 and the projecting segment 30 has an inner annular recess which receives an 0-ring 36 for sealing against the inner surface of the liner 12 (see Fig.5) when the insert is assembled in the pipe. The washer 34 and the segment 30 define a series of coaxial circular grooves which bite on the inner surface of the liner as the insert is assembled.

3 7 When the hollow bolt 18 is raised into an upright position projecting radially outwardly from the lined pipe, a lower tapered washer 38 is passed over the lever 32. The tapered washer 38 has serrations on its lower surface which are intended to bite into the outer exposed surface of the liner within the perimeter of the larger hole 16. The maximum radius of the lower washer 38 is only slightly less than that of the larger hole 16 in the main pipe.

is A middle plastics washer 40 has a circular section cylindrical outer surface and is received over the hollow bolt 18 similarly to the lower tapered washer 38. The middle washer 40 also has an outer circumference that is only slightly less than that of the larger hole 16 in the main pipe 12. An internally tapered surface in the washer is complementary to that of the taper on the lower washer 38. A further upper plane tapered washer 42 is also received on the hollow bolt 18 outside the pipe liner 10. The taper on the upper washer 42 is opposite that of the lower washer 38 and sits in an oppositely arranged complementary recess in the middle washer 40.

A clamp nut 44 is received on the hollow bolt 18 and brought into engagement with the upper washer 42. As the clamp nut 44 is tightened up, it both draws the ring comprising the C-shaped washer 34 and the segment 30 into engagement with the inner surface of the liner 10 and squeezes the plastics middle washer 40 between the two tapered washers. As a result, the middle washer 40 expands radially outwardly and into engagement with the edge of the main pipe defining the larger hole 16 (see Fig.7). In the assembled state of the insert, the clamp nut is secured relative to the hollow bolt 18 by a grub 8 screw 46 threadedly received in a radially extending bore in the nut. When the grub screw 46 is tightened up it bears against the threads of the bolt 18.

A coupling washer 50 is then placed in the clamp nut in preparation for connection of a branch pipe by means of the internal threading in the hollow bolt. The lever 32 can then be removed from the insert.

The clamp nut, acting on the middle washer, serves to draw up the hollow bolt into engagement with the liner so that the O-ring seals against the internal surface of the liner and simultaneously the middle washer expands radially outwardly to secure the insert in position, braced against the edge surface of the pipe defining the larger hole 16.

Referring to Fig.8 and Figs.9 to 11, a second embodiment of the invention is shown. The principle of assembly is the same as that of the f irst embodiment above. Thus, like numerals have been used for functionally similar parts. The initial assembly steps are as shown in Figs.2 to 4.

In this second embodiment the washers 381 and 42' are not tapered, but the circular washer 401 has a series of 3 circular ribs defined in it radially outer surface. The radially outer ribs provide an interference fit with the drilled hole in the pipe wall. Of course, more or less ribs over a greater or lesser axial extent of the washer 40' could be used. As with the first embodiment, tightening of the clamp nut 441 causes deformation of the washer 401, including radial bulging, resulting in frictional engagement with the periphery of the pipe T b 9 defining the hole.

A pair of radially oppositely projecting flanges 39 protrude from the annularly serrated portion of the washer 38'. The washer 38' is made of polythene on a similar deformable plastics material. It is pushed into the hole in the pipe by means of an insertion tool 41 to that the flanges are located between the pipe and the adjacent part of the liner (see Fig. 10). The serrated portion of the washer 381 provides the inner seat for the ribbed washer 401.

The invention provides branch connection a simple means of f ixing the to the relined pipe without access to The screw-clamping arrangements described provide leak-proof connections without dependence on the pipe for support, so that any subsequent damage or corrosion of the pipe in the area of the branch connection will not result in the development of leaks. on the other hand the system described gives good mechanical support to the branch connection and connected branch pipelines.

its interior

Claims

CLAIMS:

is 1. A branch insert for a lined pipe comprising an outer pipe and a liner, both defining generally aligned apertures for the branch insert, the insert comprising a hollow bolt, providing a branch conduit through the apertures in the pipe and liner, the bolt having a pipe liner engaging seat, having an annular sealing surface which is engageable with the inner surface of the liner in the region surrounding its aperture, a deformable ring mounted on the hollow bolt and a clamp nut for tightening the ring against the pipe liner, such that the ring deforms radially outwardly and engages the edge surface of the pipe defining its aperture.
2. An insert as claimed in claim 1 in which the ring has an outer washer providing a bearing surface for engagement by the clamp nut.
3. An insert as claimed in claim 1 or 2 in which the ring also has an inner washer providing a bearing surface for engagement by the liner in the region surrounding its aperture.
4. An insert as claimed in claim 2 or 3 in which the or each washer has a tapered surface, the taper urging the ring to deform radially outwardly as the clamping nut is tightened.
5. An insert as claimed in claim 3 in which the inner washer has a flange which is insertible between the pipe and the liner through the aperture in the pipe to hold the inner washer in place.

0 11
6. An insert as claimed in claim 1 or 2 in which the ring has a series of radial projections which engage the periphery of the pipe defining the aperture therein.
7. An insert as claimed'in claim 6 in which the radial projections are annular radially projecting ribs on the rings.
8. An insert as claimed in any of claims 1 to 7 in which the seat is removable from the bolt, the bolt defining a radially projecting portion for holding the seat.
9. An insert as claimed in claim 8 in which the seat is discontiguous.
10. An insert as claimed in claim 9 in which the radially projecting portion of the bolt defines a segment completing the annular seating surface.
11. An insert as claimed in any preceding claim in which the seat carries an annular seal for engagement with the liner around the edge defining its aperture.
12. A method of forming a branch in a comprising:

lined pipe, forming a hole in the liner and a larger hole in the pipe; mounting a hollow bolt of a branch insert as claimed in any preceding claim projecting through the apertures; assembling the ring on the hollow bolt so that the ring rests on the exposed surface of the liner within the larger hole in the pipe; and tightening the clamp nut against the ring so that it 12 deforms radially and engages the edged surface of the pipe defining the said larger holes.