GB2469640A

GB2469640A - Pipe stiffener

Info

Publication number: GB2469640A
Application number: GB0906785A
Authority: GB
Inventors: Michael Taylor; Keith Millward
Original assignee: Polypipe Building Products Ltd
Current assignee: Polypipe Building Products Ltd
Priority date: 2009-04-20
Filing date: 2009-04-20
Publication date: 2010-10-27
Anticipated expiration: 2029-04-20
Also published as: GB0906785D0; GB2469640B

Abstract

A stainless steel pipe stiffener 12 comprising a stem (34, figure 5) and a head, the stem extending from the head to a first free end of the pipe stiffener 12 and the head forming a second free end of the pipe stiffener 12. The pipe stiffener 12 has a thru-aperture extending all the way through both the stem and the head. The stem has provided thereon an annular groove containing an o-ring. The pipe stiffener 12 is provided in combination with connector 20 that comprises a collet 14 having multiple prongs 16, a main body and a cap 18. The cap 18 is either for securing the collet 14 within the main body, or else is to allow the collet 14 to secure itself to the main body by it passing through it.

Description

Pipe Stiffener The present invention relates to a pipe stiffener for inserting into a flexible pipe for providing a stiffened free end for that pipe. Such stiffened free ends are generally desirable where that free end is to be located onto or into a connector for that pipe, such as a connector utilising a collet and/or an 0-ring and/or ridges, which serve to compress down on that free end within or at the connector.

Pipe stiffeners per se are known. Such pipe stiffeners may be formed of a tube of plastic which has been injection moulded. They typically comprise a generally cylindrical member having a stem and a head, or flange, at an end thereof, with an open passageway extending axially through the coaxial head and stem.

The head is usually sized to match the thickness of the pipe into which the stiffener is to be inserted and the stem is generally sized to fit with a friction fit within the inner diameter of the pipe. The stem might also be provided with angulated ribbing for enhancing the friction fit and sealing effect of the stem within the free end of the pipe for resisting removal of the stiffener from the free end of the pipe and for preventing leakages.

The angular ribbing can have many different designs or shapes to enhance the fluidic seal between the stem and the pipe, and for resisting that removal of the pipe stiffener from the free end of the pipe. It would be desirable, however, to provide an improved pipe stiffener which can provide an improved fluidic seal between the stem and the pipe.

The present invention therefore provides a pipe stiffener as claimed in claim 1.

Preferably an 0-ring IS provided in each groove therein. The stem groove is in an outer surface of the stem.

The head and the free end of the stem therefore define two separated free ends of the pipe stiffener, with the stem extending therebetween.

The head groove is in an outer surface of the head. The second 0-ring is preferably larger than the first 0-ring, the second groove therefore being larger than the first in terms of the diameter of its inner depth, and a second 0-ring is preferably located in that second groove.

A tapering or rounding of either or both of the two free-ends might be provided. That taper is a tapering of the outer surface.

The pipe stiffener may be provided in combination with a collet. The collet may form part of a connector, the connector additionally comprising a main body and a cap for securing the coltet within the main body, or through which the collet may secure itself to the main body. The collet, having multiple prongs, is for clamping the free end of the pipe onto the stem of the pipe stiffener upon the engagement of its prongs against the outer surface of the pipe either or both through their resilience or upon receiving a biasing force there-towards, e.g. from an engagement against an inside surface of the cap.

The pipe stiffener may form part of the connector. A connector comprising a pipe stiffener according to the first aspect forms a second aspect of the invention.

The connector may have caps and collets at two or more free ends thereof for allowing two or more pipes to be connected thereto. For example, a T-coupler will have three free ends. Each pipe connection with these connectors may utilise a pipe stiffener as defined above. However, the second, or third etc, end of the connector may connect onto stiff pipes, such as copper pipes, and pipe stiffeners for those "stiff' pipes can be omitted since they are not needed. Further, the second, or third etc, end of the connector may feature alternative forms of connection, such as those that are known in the art of plumbing, e.g. olive arrangements or screw threads.

Preferably the pipe stiffener is made of steel. Preferably, it is made of stainless steel, e.g. type S316 -Sil stainless steel. The pipe stiffener may also be made of copper, brass or other metal or metals.

The pipe stiffener may be produced using a forming process, comprising "deep-draw" pressing followed by a rolling process to produce the or each groove.

More than one groove may be provided along the stem.

More than one groove may be provided on the head.

The inside diameter of the thru-aperture through the stem and head may have a reduced diameter wherever a groove is located, i.e. reduced relative to the diameter of the thru-aperture immediately either side thereof. That reduced diameter may be a radial reduction equal to or less than, the depth of the respective groove.

The majority of the stem's length, i.e. at least 50% of the stem's length, may comprise a generally consistent wall thickness, although the free end of the stem and the free end at the head may have a tapered or rounded arrangement formed by reducing that wall thickness. That taper or rounding, however, may be produced by radially reducing the diameter of the thru-aperture at those locations.

Tapered or rounded ends facilitate insertion of the stiffener into the free end of a pipe or into the con nector/collet.

The stem of the pipe stiffener can also be referred to as the main body of the stiffener.

The head of the pipe stiffener may include a flange or wall extending outwardly from the stem or main body of the pipe stiffener. The free end of the pipe will abut that flange or wall. Preferably that flange or wall extends perpendicularly to the stem.

The head of the pipe stiffener may have a generally constant wall thickness. To form the head, the second free end of the pipe stiffener can be radially expanded, relative to the stem, during a forming or rolling process.

By forming the pipe stiffener from metal, an increased minimum bore (thru-aperture) diameter is generally achievable, compared to plastic equivalents, since the wall thickness of the pipe stiffener generally can be thinner when using metal rather than plastic. The advantage of that is particularly notable on small diameter pipe stiffeners, such as purely for example 7, 10 or 15 mm sizes or any other suitable size therebetween, above and below. For example, in a 10mm pipe stiffener, the minimum bore diameter, as located at a groove in the stem, may have a diameter of about 4.64mm. However, in an equivalent plastic pipe stiffener, i.e. one of sufficiently similar strength characteristics, the minimum bore at that same position would be about 3.48mm. That is due to the increased wall thickness of the plastic at that point. The larger minimum bore diameter has particular benefits when it conies to achievable fluid flow through the pipe stiffener since flow properties through the bore are proportional to the cross-sectional area of the bore. (With the above examples, the increased diameter of the minimum bore achievable with the metal pipe stiffener would provide an increase in potential flow through the pipe stiffener, at equal pressures, of about 75%).

Therefore, the present invention utilises metal as the preferred material of manufacture for the pipe stiffener, or at least the stem thereof.

The present invention also has the further advantage over the prior art pipe stiffeners of the 0-ring providing an improved seal between the stem and the pipe, compared to the

prior art ribbed stems.

These and other objects of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a connector connected to a pipe at one end and being arranged for connection to a second pipe at its other end; Figure 2 shows an alternative type of fitting in which a grab-ring is used to retain the pipe in the fitting, rather than a collet; Figures 3 to 5 illustrate an embodiment of pipe stiffener made from stainless steel that is 0.18mm thick and having a head with a 10mm outer diameter; Figures 6 to 8 shows an alternative embodiment of pipe stiffener where the majority of the internal thru-bore of the stiffener is of a uniform diameter.

Referring first of all to Figure 1 there is shown a free end of a flexible pipe 10, the pipe having an inside diameter sized to receive a pipe stiffener 12 therein. There is also shown a connector 20, a collet 14 having multiple resilient prongs 16 for clamping down on the outside surface of the pipe 10, and a cap 18 through which the collet retains itself in its clamping position, by its inter-engagement against an inside diameter 26 of the cap, as shown, or perhaps an inside wall of the connector 20 (not shown).

The connector 20 is also provided with an 0-ring 22 and two guides 24 for locating either side of the 0-ring 22, The 0-ring IS for ensuring a seal between the outside diameter of the pipe 10 and an inside diameter 44 of the connector 20.

A completed connection is shown to the right hand end of the connector 20 in Figure 1.

As shown therein, the collet 14 has its resilient prongs 16 passed through an end hole in the cap 18 whereupon they engage against the outer surface of the pipe 10 due to their resilient nature and due to compression acting thereon from the inside diameter 26 of that end hole in the cap 18.

The connector's collet 14 is also arranged such that any attempt to disengage that connection will cause the collet 14 to start to slide out of the end hole 26. However, it has an outer ridge 28 that will engage against an inner ridge 30 of the end hole, whereupon further removal of the collet 14 is resisted, with those further attempts simply resulting in additional compression of the resilient prongs 16 of the collet 14 against the outer surface of the pipe 10. This increases the grip on the pipe 10.

Figure 2 illustrates an alternative arrangement in which no collets are provided.

Instead, resilient flaps or members 32 are provided for engaging against the outer surface of the pipe 10. They operate like a ratchet. Common to the designs of Figures 1 and 2, however, is the pipe 10 and the pipe stiffener 12.

In these two illustrated designs the preferred size of the pipe is approximately 10mm, i.e. having an outside diameter of between 9.90mm and 10.10mm. Also it is preferred that the pipe has a maximum wall thickness of around 1.50 mm. The minimum inside diameter of the pipe is therefore around 7mm.

The pipe stiffener 12 of an embodiment of the invention has a stem 34 having its first groove 36 located towards the free end of that stem, away from the head, and it is for receiving an a-ring. In this embodiment, the 0-ring has an internal diameter and sectional diameter sized to provide a friction fit inside the inside diameter of the pipe 10 for sealing against the inside of the pipe once the shaft 34 has been fitted inside the free end of the pipe 10. The base of the groove 36 also seals with the 0-ring.

The head 38 of the pipe stiffener 12 is defined by a flange or wall that extends substantially perpendicularly from the stem 34. It defines a stop surface for the free end of the pipe 10, once the pipe stiffener 12 has been inserted into the free end of the pipe 10.

The head 38 is provided with a groove 40 for receiving a second 0-ring 42. That second 0-ring 42, in this example, is provided with an internal diameter of and a cross-sectional diameter sized to provide a friction fit inside a deeper aperture 48 provided within the connector 20. That deeper aperture 48, in this example, has a diameter of 10mm, whereby the a-ring fitted in the groove 40 is in a state of circumferential tension, whereby the 0-ring provides the above-mentioned friction fit inside the deeper aperture 48 of the connector 20. An alternative arrangement involves a slightly larger 0-ring. Standard sized a-rings, however, may be used.

The free end of the stem 34 is tapered 46. That taper 46 facilitates the insertion of the pipe stiffener 12 into the free end of the pipe 10. It might instead be rounded.

The free end of the head is also tapered or rounded. This likewise is to facilitate the insertion of that member into another member, in this case the internal diameter 44 of the connector 20. the cap 18, the 0-ring 22 and guides 44, the deeper aperture 48 and the collet 14.

In embodiments, the minimum internal diameter of the passage through the axis of the stern, at the location co-planar with the groove 36 in that stem 34 is referred to as the minimum bore position. It is desirable, however, to make that minimum bore position as large as possible without increasing the outer diameter of the stem 34 since that outer diameter of the stem 34 is predetermined by the internal diameter of the pipe 10. The minimum bore diameter, however, governs the potential flow rates through the pipe, pipe stiffener and connector arrangement. In the preferred embodiment of Figure 3 to 5, therefore, stainless steel is used. That stainless steel can be made much thinner -in this example 0.18mm thick. In the most preferred examples, that stainless steel is S316-S11, i.e. a molybdenum bearing austenitic stainless steel. Other metals and other steels, stainless or otherwise, might equally be used, however.

By use of the thinner material, the minimum bore diameter can be increased, as illustrated, to 4.64mm from for example 3.48mm in a plastics material in this example, without altering the outer diameter of the stem, or the appearance of the two grooves 36, 40 and the two tapers (on the head and the stem 34, respectively). As such, the external appearance of the pipe stiffener 12 in this preferred embodiment is effectively no different to a plastic version, albeit of a metal finish rather than a plastic finish. The increased internal diameter at the minimum bore position, however, allows greater flow rates through the pipe stiffener 12.

It is preferred that the finished article is free from burrs. This can be achieved by adapting the manufacturing process accordingly to include a deburring step where necessary. Likewise, with plastic embodiments it is preferred that any sharp corners are removed by the provision of a nominal radius of perhaps 0.2mm. This can also be achieved during the manufacturing process, for example when injection molding or otherwise forming the pipe stiffeners.

Other embodiments of pipe stiffener and their use in straight-connectors, may be provided with various pipe sizes, for example dimensions for 10, 15, 22 and 28 mm pipes, i.e. various pipe sizes. Non-straight pipe connectors cane likewise be used.

The present invention has been described above purely by way of example.

Modification in detail may be made within the scope of the invention as defined in the claims appended hereto.

Claims

CLAIMS: 1 A metal pipe stiffener comprising: a stem and a head, the stem extending from the head to a first free end of the pipe stiffener and the head being provided at a second free end of the pipe stiffener; and a thru-aperture extending all the way through both the stem and the head, wherein the stem and head each have provided thereon an annular groove for locating a respective 0-ring therein.
2. A pipe stiffener according to any one of the preceding claims, for fitting within a free end of a standard plumber's 10mm outside diameter flexible pipe, wherein the minimum bore diameter of the pipe stiffener's thru-aperture is greater than 3.48mm.
3. The pipe stiffener of claim 1 or claim 2, wherein a tapering or rounding of either or both of the two free-ends is provided.
4. The pipe stiffener of claim 3, wherein the tapering or rounding is formed by a reduced wall thickness for the pipe stiffener at that or those locations.
5. The pipe stiffener of claim 3, wherein the tapering or rounding is formed by providing a radially reduced diameter of the thru-aperture at that or those locations.
6. The pipe stiffener of any one of the preceding claims, wherein the metal is stainless steel.
7. The pipe stiffener of any one of the preceding claims, wherein the inside diameter of the thru-aperture through the stem and head has a diameter wherever a groove is located that is reduced relative to the diameter of the thru-aperture immediately either side thereof.
8. The pipe stiffener of claim 7, wherein that reduced diameter is a radial reduction equal to, or less than, the depth of the respective groove.
9. The pipe stiffener of any one of the preceding claims, wherein the majority of the stem's length comprises a generally consistent wall thickness.
10. The pipe stiffener of any one of the preceding claims, wherein the head includes a flange or wall extending outwardly from the stem of the pipe stiffener for the free end of a pipe to abut against.
11. The pipe stiffener of any one of the preceding claims, wherein the head of the pipe stiffener has a generally constant wall thickness, but a varying inside diameter.
12. The pipe stiffener of any one of the preceding claims, provided in combination with a collet having multiple prongs.
13. The pipe stiffener of claim 12, wherein the collet forms part of a connector, the connector additionally comprising a main body and a cap either for securing the collet within the main body, or through which the collet may secure itself to the main body.
14. The pipe stiffener of claim 13, wherein the connector has caps and collets at two or more free ends thereof.
15. The pipe stiffener of any of claims 1 to 11, in combination with a pressed stainless steel grab-ring.
16. A pipe stiffener according to any one of the preceding claims, formed by a forming process, comprising "deep-draw" pressing followed by a rolling process to produce the or each groove.
17. A pipe stiffener according to any one of the preceding claims, formed by a forming process, comprising forming the head by radially expanding the second free end of the pipe stiffener relative to the stem.
18. A kit of parts comprising multiple pipe stiffeners according to any one of the preceding claims.
19. A connector, comprising a pipe stiffener according to any one of claims 1 to 17.
20. A pipe stiffener substantially as hereinbefore described with reference to any one or more of the accompanying drawings.
21. A kit of parts comprising a selection of pipe stiffeners substantially as hereinbefore described with reference to any one or more of the accompanying drawings.