GB2129080A

GB2129080A - Pipe fitting

Info

Publication number: GB2129080A
Application number: GB08229735A
Authority: GB
Inventors: Patrick Frawley
Original assignee: Plastiers Ltd
Current assignee: Plastiers Ltd
Priority date: 1982-10-18
Filing date: 1982-10-18
Publication date: 1984-05-10

Abstract

A pipe fitting comprises a body 1, a pipe engagement means 8 in the form of an annular member or ring which is adapted to deform into a ring of less internal diameter when axial pressure is applied thereto, and pressure-applying means e.g. threaded end cap 9 for applying axial pressure to the ring, the arrangement being such that, in use, a pipe can pass through the ring in its uncompressed state but will be engaged by the ring in its compressed state, thus to prevent or hinder accidental withdrawal of a said pipe from the fitting. <IMAGE>

Description

SPECIFICATION Pipe fitting This invention relates to a pipe fitting of the type provided with pipe engaging means for preventing or hindering accidental withdrawal of the pipe or pipes from the fitting.

A prior art pipe fitting employs an annular metal ring provided with radially inwardly projecting convergent teeth, the internal diameter of the ring being such that the teeth project into the path of a pipe inserted into the fitting. The teeth are arranged to converge in the direction of insertion of the pipe into the fitting and the arrangement is such that a pipe can be forced through the ring during insertion of the pipe into the fitting but the teeth will subsequently act to prevent withdrawal of the pipe from the fitting.

This known fitting has the disadvantage that the sharpened metal teeth can scar the surface of the pipe which can cause difficulties in sealing the pipe and fitting against egress of the pipe contents therefrom.

According to the present invention there is provided a pipe fitting which includes a pipe engagement means in the form of an annular member or ring which is adapted to deform into a ring of lesser internal diameter when axial pressure is applied thereto, and pressure-applying means for applying axial pressure to the ring, the arrangement being such that, in use, a pipe can pass through the ring in its uncompressed state but will be engaged by the ring in its compressed state, thus to prevent or hinder accidental withdrawal of a said pipe from the fitting.

The ring is composed of a material such that it will return substantially to its original diameter when said axial pressure is relaxed, thereby rendering the fitting re-usable, such as for example, spring steel or a suitable polymeric material such as an acetal resin.

The material of the pipe engagement should have a hardness at least equal to that of the material of the pipe with which the fitting is to be employed to ensure a sufficient engagement, e.g.

by annular deformation of the pipe wall, between the ring and the pipe.

To prevent too great a deformation of the pipe a reinforcing, flanged sleeve of suitable material, such as copper or stainless steel, may be provided for lining the interior of the end portion of the pipe.

Preferably the ring in its uncompressed state is frustoconical in shape and is provided with teeth on its inner periphery. It is envisaged however that not all of the circumference of the ring need be frustoconical; for example the ring could consist of one or more portions lying in a common frustoconical surface joined by one or more intermediate portions lying in a radially extending planar surface. Alternatively, it is envisaged that alternating circumferential portions of the ring could lie respectively in frustoconical surfaces of opposite handedness or that the ring has a Y-section.

The fitting will generally also include a seal for sealing the assembled pipe and fitting against accidental egress therefrom of the contents of the pipe and an annular spacer for locating the seal and/or pipe engagement ring. The seal may be a natural or synthetic elastomer such as rubber or neoprene whilst the spacer may be of an acetal resin.

The pressure applying means may be an annular threaded nut having a bore to receive a said pipe, cooperating with a suitable threaded portion on the exterior or interior of the body of the fitting. Preferably the thread pitch is selected such that sufficient pressure can be applied to the pipe engagement ring merely by hand-tightening.

It may alternatively press-fit or snap-fit into the body of the fitting to apply the necessary axial pressure to the pipe engagement ring. The pressure applying means is suitably composed of an acetal resin.

The body of the fitting may be composed of a synthetic plastics material such as polyethylene, polypropylene, polybutylene, polyvinyl chloride or chlorinated polyvinyl chloride, although it may be of a metal.

An embodiment of the present invention will now be described, by way of example, by reference to the accompanying drawings, in which: Fig. 1 is an axial section of an embodiment of a pipe fitting according to the present invention in a first state; Fig. 2 is similar of Fig. 1 but shows the fitting in a second state; Fig. 3 is a detail section showing the manner in which functions the pipe engagement of the fitting of Figs. 1 and 2; Fig. 4 is a perspective view of the pipe engagement means employed in the fitting of Figs.

1 and 3, and Fig. 5 is a detail section corresponding to Fig. 3 of a modification of the embodiment of Figs. 1 to4.

Referring to the drawings, a pipe fitting body 1 of chlorinated polyvinyl chloride is provided with a bore 2 for receiving a pipe 3 of polybutylene.

Surrounding the bore 2 are annular recesses 4 and 5 of enlarged diameter. Received within the recess 4 is an elastomeric sealing ring 6 which in this case is an O-ring of circular cross-section and, within the recess 5, a spacer ring 7 and a pipe engagement ring 8 each of an acetal resin. The spacer ring 7 is in this case provided with internal levelled edges. An annular end cap 9 having a bore for receiving a said pipe 3 is threaded at 10 and cooperates with corresponding threads 11 on the exterior surface of the fitting body 1. The cap also is made of an acetal resin. As may be seen from Fig. 4 pipe engagement ring 8 is provided with six or eight pipe engagement teeth 12 on its inner periphery and, in its uncompressed state, lies in a frustoconical surface.The inner diameter of the ring in its uncompressed state is selected such that a said pipe 3 can pass therethrough and be inserted into the fitting 1. The threads 10 and 1 1 are at a pitch of 1 5 to 20 threads per inch and have a square or buttress cross-section. The diameters of recesses 4 and 5 of the corresponding O-ring, spacer ring and pipe engagement ring are matched so that incorrect assembly of the fitting is rendered difficult or impossible.

The O-ring 6 will form a seal with the exterior of the pipe 3. Thereafter the end cap 9 is screwed onto the fitting thus to compress the pipe engagement ring 8 between the end cap 9 and the spacer 7 (bearing against an end wall of recess 5).

Such compression of the pipe engagement ring 8 deforms it into a generally planar shape and, since it is constrained against increase in its outside diameter by the diameter of the recess 5, the~ internal diameter of the ring 8 diminishes causing the teeth 12 to engage and depress the wall of the pipe 3, thus to prevent accidental withdrawal of the pipe 3 from the coupling 1 when, e.g. internal hydrostatic pressure is applied.

When the end cap 9 is unscrewed the pipe engagement ring 8 will recover its original shape and permit withdrawal of the pipe 3 from the fitting 1.

In the embodiment described above the spacer ring 7 is provided with internal bevelled edges to accommodate the pipe engagement ring 8 in its uncompressed state. Alternatively, the spacer ring 7 may be of rectangular cross-section and the pipe engagement ring may be provided with a "flat" radial surface at its innermost periphery. Such an arrangement is shown in Fig. 5 of the drawings.

It is envisaged that in certain circumstances a permanently deformable ring could be employed if no provision for removal of a said pipe from the fitting is required.

The fitting of the present invention has the advantage that it does not scar any appreciable length of pipe and hence does not interfere with the sealing of the pipe and fitting. Moreover the fitting can be disassembled quickly and easily to remove the pipe from the coupling.

It will be appreciated that the term pipe fittings is intended to embrace not merely couplings for joining together two or more pipes but also such pipe fittings as blanking off caps, tap connectors etc. In other words the term embraces any fitting for coupling a pipe to another pipe or fitment.

Claims

1. A pipe fitting which comprises a body, a pipe engagement means in the form of an annular member or ring which is adapted to deform into a ring of less internal diameter when axial pressure is applied thereto, and pressure-applying means for applying axial pressure to the ring, the arrangement being such that, in use, a pipe can pass through the ring in its uncompressed state but will be engaged by the ring in its compressed state, thus to prevent or hinder accidental withdrawal of a said pipe from the fitting.

2. A pipe fitting according to Claim 1, wherein the annular member of ring is such that it will return substantially to its original internal diameter when said axial pressure is relaxed, thereby to render the fitting re-usable.

3. A pipe fitting according to Claim 2, wherein the annular member or ring is composed of a resilient material.

4. A pipe fitting according to Claim 3, wherein the annular member or ring comprises spring steel or an acetal resin.

5. A pipe fitting according to any one of the preceding claims, wherein the annular member or ring is frustoconical in shape.

6. A pipe fitting according to any of Claims 1 to 4, wherein the annular member or ring comprises one or more portions lying in a common frustoconical surface joined by one or more intermediate portions lying in a radially extending planar surface.

7. A pipe fitting according to any of Claims 1 to 4, wherein the annular member or ring comprises alternating circumferential portions lying respectively in frustoconical surfaces of opposite handedness.

8. A pipe fitting according to any of Claims 1 to 4, wherein the annular member or ring has a Y-section, the stem of the Y lying radially inwardly of the arms of the Y.

9. A pipe fitting according to any one of the preceding claims, wherein the annular member or ring is provided on its inner periphery with one or more teeth.

10. A pipe fitting according to any one of the preceding claims, which includes a seal.

11. A pipe fitting according to any one of the preceding claims, which includes a spacer for locating the annular member or ring and/or for locating the seal if present.

12. A pipe fitting according to any one of the preceding claims, wherein the pressure applying means comprises an annular threaded nut having a bore to receive a said pipe, and adapted to cooperate with a suitable threaded portion provided on the body of the fitting.

13. A pipe fitting according to any of claims 1 to 12, wherein the pressure applying means is adapted to press-fit or snap-fit into engagement with the body of the fitting.

14. A pipe fitting according to Claim 12 or 13, wherein the pressure applying means is composed of an acetal resin.

15. A pipe fitting substantially as hereinbefore described with reference to the accompanying drawings.

16. An annular member or ring adapted for use in a pipe fitting which annular member or ring is adapted to deform into a ring of lesser internal diameter when axial pressure is applied thereto.

17. An annular member or ring as claimed in Claim 16 and as defined in any one of claims 2 to 9.

18. An annular member or ring adapted for use in a pipe fitting and substantially as hereinbefore described with reference to the accompanying drawings.

19. The combination of a pipe fitting as claimed in any one of Claims 1 to 15, and a pipe, an end of the pipe being engaged by the annular member or ring in a compressed condition, and the annular member or ring having a hardness at least equal to that of the end of the pipe.

20. A combination according to Claim 19, which includes a reinforcing, flanged sleeve lining the interior of the end portion of the pipe.

21. A combination according to Claim 1 9 or 20, wherein the pipe is composed of a plastics material.

22. A combination according to Claim 19 and substantially as hereinbefore described with reference to Figs. 2 and 3 of the accompanying drawings.

23. The features hereinbefore disclosed, or their equivalents, in any novel selection.