GB2429252A - Tapping tee with spigot having metal insert - Google Patents

Abstract

A live access connection fitting comprises a branch saddle 2 with a spigot outlet 3. A metallic insert 4 is interference fit within the spigot and provides an external thread for connection to an equipment housing to be connected to the pipeline. A compression ring 5 is installed over the spigot 3 and forms a compression seal between spigot 3 and insert 4. This arrangement may allow a reduced overall height of the fitting. A sealing plug 13 may be provided, and the saddle may be connected to the pipeline by an electrofusion element 8.

Description

LIVE ACCESS CONNECTION

FIELD OF THE INVENTION

This invention relates to live access connections to pipelines, and more particularly to a fitting adapted to be mounted on a plastic pipeline for the provision of a live access connection.

BACKGROUND OF THE INVENTION

Within the gas industry there is a requirement to stop the flow of gas through a main when repair work or replacement is being carried out. Two methods are currently used to stop the flow of gas through a plastics main. In the first of these, commonly known as "squeeze off' the pipe is flattened using a 15 clamping tool in order to stop the flow of gas therethrough. This technique is suitable for small diameter pipes, but is not preferred for larger diameters * where very bulky clamping tools would need to be used. For larger diameters : the insertion of an inflatable bag flow stopper is preferred, since this enables a more compact excavation to be used, saving both time and the expense of * 20 moving excess spoil from the excavated hole. **** I. * * S S

* To enable the launch of an inflatable bag into the plastics main it is necessary to provide a fitting able to provide a live access connection. The fitting needs to include mounting means for mounting the fitting onto the plastics main, access for a cutter to cut an appropriately sized hole in the plastics main, access for the inflatable bag and mounting means for the bag launching unit.

In addition, the fitting needs to co-operate with sealing means to enable the hole in the plastics main to be sealed after the repair or renovation operation has been completed and the inflatable bag has been removed.

A typical inflatable bag flow stopping system is that supplied by WASKCRANE and used by National Grid Transco. This system requires the following features of a live access connection fitting: 1. A spigot having an external thread co-operable with an internal thread at the bottom of the WASK-CRANE bag launching unit; 2. An overall height of the fitting, measured from the crown of the pipe to the end face of the spigot not exceeding 69.0mm, to ensure that the full stroke of the bag launching equipment can be utilised; 3. A bore through the fitting to enable the passage of a 56.0mm cutter; and 4. A screw in plug to enable the hole to be sealed after the operation is finished and to permit extraction and removal of the inflatable bag.

The above requirements are particularly difficult to meet with conventional fittings, and in particular the overall height requirements are challenging, * :1:. 15 because a large part of the height of the fitting is accounted for by the external * : : : :* thread necessary for connection to the bottom of the bag launching unit. * I*

BRIEF SUMMARY OF THE DISCLOSURE S..

* 20 Throughout the description and claims of this specification, the words S...

*.: "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

rhe present invention provides a novel live access connection fithng having a low profile comprising a branch saddle and a metallic insert having a through bore, the saddle and insert being joined by a compression ring seal.

In a first aspect, the present invention provides a live access connection fitting for a plastics pipeline comprising: a branch saddle, adapted to be mounted on the pipeline; a spigot outlet integral with the branch saddle; a tubular metallic insert adapted to be an interference fit within the spigot outlet, the insert having an external threaded portion adapted to cooperate with an internal threaded portion on an equipment housing to be connected to :.:. 15 the pipeline; and

I S...

* * a compression ring adapted to encircle the spigot outlet and to make a compression seal between the spigot outlet and the tubular metallic insert. I.

* 20 In a further aspect the invention provides a method for assembling a live I...

* : access connection fitting of the first aspect of the invention.

In a still further aspect the invention provides a method of introducing an inflatable bag flow stopping device into a pipeline using a live access connection fitting in accordance with the first aspect of the invention.

Preferably the tubular metallic insert has a circumferential profiled ridge disposed on its external surface adapted to cooperate with the compression ring in order to form the compression seal.

Preferably the branch saddle and the integral spigot outlet are formed from a plastics material. Preferably the branch saddle is provided with a saddle shaped electrofusion element adapted to form an electrofusion joint between the branch saddle and the outer surface of the pipeline.

The saddle of the live access connection fitting can be of any suitable shape, but is usually an annular disc or polygon (preferably a square or rectangle), curved to conform to the outer wall of the plastics pipeline. The saddle- shaped electrofusion element, can, if desired, be embedded in a fusible polymeric material in the form of a saddle-shaped electrofusion mat. The mat can be mounted on the saddle by screws or other connecting means, or can clip into a recess moulded into the saddle. Alternatively the electrofusion mat can be mounted on the saddle by the use of a hot melt adhesive as described in our pending UK application 0501453.5. In yet another alternative, where the saddle comprises a fusible polymeric material, the electrofusion element can be integrated with the saddle by over-moulding the saddle. In a still further embodiment, a wire for the electrofusion element of the saddle can be embedded within the premoulded body of the saddle by ploughing-in" the wire. I... * S..

* ,. The electrofusion element is preferably embedded in a fusible polymeric material. Suitable fusible polymeric materials include, for example, olefinically unsaturated polymeric materials such as polyethylene, polypropylene, * : 20 polybutylene, and higher olefinic polymers; copolymers of ethylene, propylene * : *. and butylenes with each other and with other olefinically unsaturated monomers, olefinically unsaturated aromatic polymers, such as polystyrene and styrene copolymers; and polymers and copolymers of vinyl monomers such as ethylene vinyl acetate copolymers, and such like materials. Block copolymers and polymer blends of polymerised monomers of any of the abovementioned polymers are also included. A particularly suitable polymeric material is polyethylene, and this is the preferred polymeric material for use in the present invention.

The electrofusion element is preferably a spirally wound electrofusion resistance wire forming a fusion coil. The fusion coil can be singly or doubly wound, although double winding is preferred. Examples of suitable saddle- shaped electrofusion elements and methods for their manufacture and use are described in US patents 4933037 and 5104468.

The spigot of the live access connection fitting is preferably moulded integrally with the saddle and can be formed from the same or different plastics material. Both the saddle and the spigot of the live access connection fitting can independently be formed from any suitable polymeric material and, for example, they can be formed from any of the fusible polymeric materials listed above. Preferably both the saddle and the spigot of the live access connection fitting are formed from a polyolefin polymer, more preferably from polyethylene. If desired, the polymeric material of the saddle and the spigot of the live access connection fitting can be cross-linked.

The spigot outlet is preferably upstanding such that its end face is not more than 39 mm from the crown of the pipe, in use. More preferably the end face of the spigot outlet is from 34.5 to 37.5 mm, most preferably about 34.5 mm :. 15 +/-0.2mmfromthecrownofthepipe a I...

* *. In accordance with one aspect of the invention, a tubular metallic insert is an interference fit within the spigot outlet and extends for a short distance beyond as.

the spigot outlet. Preferably the tubular metallic insert extends such that the * 20 end face of the insert is not more than 69 mm from the crown of the pipe, in use. More preferably the end face of the metallic insert is from 68 to 69 mm from the crown of the pipe. The bore of the insert is preferably of diameter from 57 mm to 58 mm, more preferably about 57 mm.

The distance measured from the end face of the metallic insert to the end face of the spigot outlet is preferably not more than 34 mm +1- 0.2 mm. More preferably the distance from the end face of the metallic insert to the end face of the spigot outlet is from 30 to 34 mm.

The metallic insert can be made from any suitable metal, including for example, stainless steel, coated mild steel, brass, and aluminium. The metallic insert has an externally threaded portion extending beyond the spigot outlet, adapted to co-operate with an internal threaded portion on an equipment housing to be connected to the pipeline, and preferably an internal threaded portion adapted to co-operate with an external threaded portion on a sealing plug or cap.

In a preferred embodiment, the tubular metallic insert is provided with an external circumferential profiled ridge adapted to co-operate with the compression ring to form a fluid tight seal between the internal wall of the spigot and the tubular metallic insert and to resist pull-out of the metallic insert from the spigot outlet. The profiled ridge is preferably shaped so as to complement the profile of the compression ring and to assist in preventing dislodgement of the insert by fluid pressure within the plastics main. For example, the profiled ridge can be provided with a lip or barb adapted to co- operate with the compression ring to resist any forces tending to push the insert off the spigot outlet. The lip or barb is preferably sized such that the spigot outlet would need to be expanded radially in order for the insert to be withdrawn from the spigot outlet. Preferably the lip or barb is sized such that the spigot outlet would need to be expanded radially by from 2 to 6%, for example, about 4.5%, to enable the metallic insert to be withdrawn.

* The compression ring is adapted to encircle the spigot outlet and to apply a * 20 compressive force thereto. The compression ring is preferably formed from a * .* metal, although certain engineering plastics, for example, cross- linked polyethylene, or acetal resins, may also be suitable. Suitable metals for the compression ring include, for example, stainless steel, coated mild steel, brass, and aluminium.

In assembling the fitting, the insert is first pushed into the spigot and the compression ring is then forced over the spigot so that it presses the wall of the spigot firmly against the metallic insert to form a fluid tight connection. If desired the compression ring can be expanded using a mandrel and then allowed to contract around the spigot outlet.

The sealing plug or cap can be of any suitable shape and material, and for example, it can be disc-shaped and formed from a suitable metal, for example, stainless steel, coated mild steel, brass, or aluminium, or from an engineering plastics material, for example, an acetal, for example Deirin. The sealing plug or cap can have an internally threaded section adapted to co- operate with the externally threaded section of the metallic insert, but preferably has an externally threaded section adapted to co-operate with an internally threaded section on the metallic insert. Preferably the plug or cap is provided with one or more elastomeric sealing rings, which can, for example, be seated in circumferential grooves in the periphery of the plug or cap, to provide sealing between the metallic insert and the plug or cap.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of a live access connection fitting in accordance with the invention will now be described, by way of example only, with reference to the accompanying Drawings, in which: S..

*... Figure 1 shows an exploded view of the live access connection fithng in * : :* sectional side elevation; Figure 2 shows the assembled live access connection fitting of Figure 1 in * 20 sectional side elevation; and *5** S. * * . * * S. Figure 3 shows the assembled live access connection fitting of Figure 1 in side elevation.

DETAILED DESCRIPTION

Referring firstly to Figure 1, there is shown a live access connection fitting illustrated generally at 1, comprising a saddle 2 with integral upstanding spigot outlet 3, metallic insert 4, compression ring 5, and sealing plug 6.

The saddle 2 is formed from P100 polyethylene material and is moulded integrally with the upstanding spigot outlet 3. The saddle 2 is provided with electrical terminals 7 that are connected to an electrofusion mat 8.

rhe tubular metallic insert 4 is formed from stainless steel and provided with an external threaded portion 9 and an internal threaded portion 10. In addition, the tubular metallic insert 4 has an external circumferential profiled ridge 11 encircling the insert and having a lip 12 adapted to co-operate with the compression ring 5.

The compression ring 5 is formed from stainless steel and dimensioned to be a tight fit around the upstanding spigot outlet 3.

The sealing plug 6 is formed from stainless steel, and provided with an external threaded portion 13 adapted to co-operate with the internal threaded portion 10 of the tubular metallic insert, two elastomeric sealing rings 14 seated in grooves around the periphery of the plug 6 and a square hole 15 adapted to receive a tool for rotating the plug. * . IS *

* *,.. Referring now to Figures 2 and 3, in assembling the fitting 1, the tubular * : :* metallic insert 4 is first pressed into the spigot outlet 3 until the profiled ridge ills disposed within the spigot outlet. The compression ring 5 is then placed S..

over the metallic insert 4 and forced down over the spigot outlet 3 until it * 20 arrives in register above the profiled ridge 11. The compression ring 5 is forced against the lip 12 in order to compress the spigot outlet wall and provide further resistance to dislodgement of the insert by fluid pressure within the plastics main.

In use, the live access connection fitting 1 is disposed on a plastics main and the terminals 7 are connected to a source of electric power (not shown). The electrofusion mat is thereby energised and forms a fusion joint between the saddle 2 and the plastics main. Next a cutter (not shown) is passed through the bore of the tubular metallic insert 4 and the spigot outlet 5 in order to cut a hole in the plastics main. The housing of an inflatable bag flow stopping system, for example, one supplied by WASK-CRANE and used by National Grid Transco, can then be connected to the tubular metallic insert 4 using the externally threaded portion 9 and the inflatable bag can be launched through the cut hole into the plastics main. The bag can then be inflated to seal off the plastics main whilst repairs or renovations are carried out. After the repair or renovation work has been completed the bag is deflated and removed from the plastics main together with the housing of the flow stopping system.

Finally the plug 6 is disposed within the tubular metallic insert 4 and rotated so that the threaded portions 10 and 13 and the sealing rings 14 co-operate to form a fluid tight seal.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the combination, except * : : ::* combinations where at least some of such features and/or steps are mutually exclusive.

S Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features S...

serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiments.

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (26)

1. A live access connection fitting for a plastics pipeline comprising: a branch saddle, adapted to be mounted on the pipeline; a spigot outlet integral with the branch saddle; a tubular metallic insert adapted to be an interference fit within the spigot outlet, the insert having an external threaded portion adapted to cooperate with an internal threaded portion on an equipment housing to be connected to the pipeline; and * : :* 15 a compression ring adapted to encircle the spigot outlet and to make a * S..

*... compression seal between the spigot outlet and the tubular metallic insert. * S.

:.

2. A fitting according to claim 1, wherein the tubular metallic insert has a circumferential profiled ridge disposed on its external surface adapted to 1: 20 cooperate with the compression ring in order to form the compression seal.

SS S S * * S.

3. A fitting according to claim I or 2, wherein the branch saddle and the integral spigot outlet are formed from a plastics material.

4. A fitting according to any one of the preceding claims, wherein the branch saddle is provided with a saddle shaped electrofusion element adapted in use to form an electrofusion joint between the branch saddle and the outer surface of the pipeline.

5. A fitting according to claim 4, wherein the electrofusion element is embedded in a fusible polymeric material.

6. A fitting according to claim 5, wherein the fusible polymeric material is polyethylene.

7. A fitting according to claim 5 or 6, wherein the electrofusion element is a spirally wound electrofusion resistance wire forming a fusion coil.

8. A fitting according to any one of the preceding claims, wherein the spigot of the live access connection fitting is moulded integrally with the saddle.

9. A fitting according to claim 8, wherein the saddle and the spigot of the live access connection fitting are formed from a polyolefin polymer.

10. A fitting according to any one of the preceding claims, wherein the spigot outlet is upstanding such that its end face is from 34.5 to 37.5 mm from the crown of the pipeline, in use.

* * 15 * S..

* a..'

11. A fitting according to any one of the preceding claims, wherein the *... tubular metallic insert is an interference fit within the spigot outlet and extends for a short distance beyond the spigot outlet.

12. A fitting according to claim 11, wherein the distance, measured from the end face of the metallic insert to the end face of the spigot outlet, is from 30 to 34 mm.

13. A fitting according to claim 11 or 12, wherein the tubular metallic insert extends such that the end face of the insert is from 68 to 69 mm from the crown of the pipeline, in use.

14. A fitting according to any one of the preceding claims, wherein the bore of the insert has a diameter of from 57mm to 58mm.

15. A fitting according to any one of the preceding claims, wherein the metallic insert is made from stainless steel, coated mild steel, brass, or aluminium.

16. A fitting according to any one of the preceding claims, wherein the metallic insert has an internal threaded portion adapted to co-operate with an external threaded portion on a sealing plug or cap.

17. A fitting according to claim 2, wherein the profiled ridge is shaped so as to complement the profile of the compression ring and to assist in preventing dislodgement of the insert by fluid pressure.

18. A fitting according to claim 17, wherein the profiled ridge is provided with a lip or barb adapted to co-operate with the compression ring to resist pull-out forces tending to withdraw the insert from the spigot outlet.

19. A fitting according to claim 18, wherein the lip or barb is sized such that the spigot outlet would need to be expanded radially by from 2 to 6% to enable the metallic insert to be withdrawn. * uS

S * SSS

19. A fitting according to any one of the preceding claims, wherein the compression ring is formed from stainless steel, coated mild steel, brass, or aluminium. * 20 ***

20. A fitting according to any one of the preceding claims, wherein the sealing plug or cap is disc-shaped and formed from stainless steel, coated mild steel, brass, or aluminium.

21. A fitting according to any one of the preceding claims, wherein the sealing plug or cap has an externally threaded section adapted to cooperate with an internally threaded section on the metallic insert.

22. A fitting according to any one of the preceding claims, wherein the sealing plug or cap is provided with one or more elastomeric sealing rings.

23. A fitting substantially as hereinbefore described with reference to and as illustrated in the accompanying Drawings.

24. A live access connection fitting for a plastics pipeline substantially as hereinbefore described.

25. A method for assembling a live access connection fitting according to claim 1, which comprises pressing the insert into the spigot outlet until the insert is disposed within the spigot outlet and forcing the compression ring over the spigot outlet in order to compress the wall of the spigot outlet between the compression ring and the insert.

26. A method of introducing an inflatable bag flow stopping device into a pipeline using a live access connection fitting in accordance with claim 1. * * * S I.. S. * S *

S *. ** . sq

I S * , S.