GB2420603A

GB2420603A - Pipe fittings

Info

Publication number: GB2420603A
Application number: GB0426129A
Authority: GB
Inventors: David John Hill; Kevin Colin Surridge; Paul Quentin Oldbury
Original assignee: Glynwed Pipe Systems Ltd
Current assignee: Glynwed Pipe Systems Ltd
Priority date: 2004-11-29
Filing date: 2004-11-29
Publication date: 2006-05-31
Anticipated expiration: 2024-11-29
Also published as: GB2420603B; GB0426129D0

Abstract

A pipe fitting 1 comprising a female pipe part 3 for receiving a male pipe part 5, a resilient sealing ring 13 and a "grab" ring 17 located in respective undercut grooves 9, 15 within the wall thickness of the female pipe part, the "grab" ring 17 having a tapered eternal surface which engages a surface of complementary taper in the undercut recess 15 in which the ring is located, and auxiliary gripping ring 19 located, in the direction of pipe insertion, behind the "grab" ring 17, and in the same undercut recess as the "grab" ring 17, wherein the rings are arranged such that in use, when an initial withdrawal of the male part 5 occurs, (eg. reaction to internal fluid pressure) the auxiliary gripping ring 19 grips the male part 5 and as the withdrawal progresses, drives the "grab" ring 17 into contact with the complementary taper thereby forcing the "grab" ring 17 radially inwardly into the male part 5 so as to lock the male part 5 into position.

Description

Pipe Fittings The invention relates to pipe fittings, particularly but not

exclusively for use in water supply.

Various kinds of pipe fittings are know which comprise a female pipe part for receiving a male pipe part. Pipe fittings may be provided with means for retaining the male pipe part in the female pipe part in the form of a "grab" ring located within or at the end of the female pipe part. The "grab" ring being actuated by withdrawal of the pipe or pressurisation.

It is known to provide a pipe fitting wherein a "grab" ring and a female pipe part are driven together by friction, created when the female pipe part receives a male pipe part, which actuates the "grab" ring, for S...

example in a tapered interface, and blocks any further movement. S...

S *...

The present applicants have found several disadvantages with this, and other prior art mechanisms, for example the mechanism disclosed in British Patent Number 2166508. When the pipe is withdrawn slowly the friction may be too low to ensure that the "grab" ring and the female pipe part are driven together. If the "grab" ring is not actuated the pipe will skid across the "grab" ring. This is a significant problem if pressurisation or loading of the fitting is slow and consequent slow ejection of the inserted pipe generates insufficient friction to cause the grab ring to be driven against its tapered housing and fails to grip the pipe.

Furthermore, modification of a "grab" ring involves considerable moulding tool complexity and increased time, cost and difficulty to produce an improved pipe fitting.

The object of the invention is to provide an improved pipe fitting that overcomes the problems described above.

The invention provides a pipe fitting comprising a female pipe part for receiving a male pipe part, a resilient sealing ring and a so-called "grab" ring located in respective undercut recesses within the wall thickness of the female pipe part, the "grab" ring having a tapered external surface which engages a surface of complementary taper in the undercut recess in which the ring is located, an auxiliary gripping ring located, in the direction of insertion of the male part, behind the "grab" ring and in the same undercut recess as the "grab" ring, wherein the "grab" ring and auxiliary gripping ring are arranged such that in use, when an initial withdrawal of the male part occurs in reaction to internal fluid pressure or * some other action, the auxiliary gripping ring grips the male part firmly and as the withdrawal progresses, drives the "grab" ring into firm contact with the complementary taper thereby forcing the "grab" ring radially **..

inwardly into the male part so as to lock the male part into position. **** *

By providing an auxiliary gripping ring, the invention allows easy insertion of the pipe in one direction and a strong gripping action in the other direction even if the pipe is withdrawn or ejected slowly. The arrangement has the advantage that the auxiliary gripping ring can be added or retrofitted to a prior existing unused fitting.

Desirably, the auxiliary gripping ring is provided with a radially inwardly disposed toothed surface for indenting the periphery of the male pipe part.

Optionally, the toothed surface is angled in the direction of insertion of the male part so as to permit easy insertion of the male part but resistance to withdrawal of the male part.

Optionally, the "grab" ring is also provided with a radially inwardly disposed toothed surface.

Optionally, the tooth formations on one or both of the grab ring and auxiliary gripping ring are of a material which is harder than the material of the male part. Desirably, the tooth formations are metal.

Preferably, the auxiliary gripping ring is made from a metal pressing.

Alternatively, the auxiliary gripping ring is shaped from wire. S. * * S S

By providing an auxiliary gripping ring which is thin enough to fit into the s.

recess into which the "grab" ring is received, the cost and complexity of manufacture of the fitting are reduced. For example, the auxiliary gripping ring may comprise substantially of a flat annular ring or washer with a radially inner surface adapted for gripping the male pipe part. S.. . *S.*

Optionally, the female pipe part of the pipe fitting includes a spigot which is butt weldable to a pipe.

In another option, the female pipe part of the pipe fitting includes an electrofusion socket.

The female pipe part may include a butt weldable socket at a first end and an electrofusion socket at an opposing end.

If the female pipe part is welded to a pipe by electrofusion this allows for a more rapid assembly which is less equipment intensive and confers advantages in terms of productivity and cost. Additionally, an electrofusion fitting has an overall thinner section.

The invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which: - Figure 1 is a plan view showing a pipe fitting constructed in accordance with the invention; Figure 2 is a perspective view showing a "grab" ring constructed in accordance with the invention; Figure 3 shows a cross- sectional view of a gripping ring constructed in accordance with the invention; S. * * S * Figure 4 shows a view from above of a gripping ring constructed in..

accordance with the invention. * S

*....*

S

Referring to Figure 1, the pipe fitting 1 comprises a female pipe..

part 3 for receiving a male pipe part 5. The female pipe part 3 includes a *.S.

sleeve electrofusion welded to a length of pipe 7 of the same internal and " S...

external diameters as the male pipe part 5. At an opposing end of the *s.

female part, an undercut recess 9 is provided within a portion of the female pipe part 11 which has an increased wall thickness. A resilient sealing ring 13 is positioned within the recess 9 and is deflected outwards when the male pipe part 5 is inserted into the female pipe part 3.

A second undercut recess 15 is provided near to the first recess, between that first recess and the end through which the male part is received into the female pipe part 11. A "grab" ring 17 and an auxiliary gripping ring 19 are positioned within the same recess 15.

The location of the first 15 and second 9 undercut recesses may be reversed so that the sealing ring is nearer the mouth of the fitting than the grab ring.

As shown in Figure 2 the "grab" ring 17 is provided with angled internal surfaces. The external surface of the "grab" ring 17 is tapered and engages a surface of complementary taper in the recess 15. Optionally, one or both of the rings 17, 19 are split to allow them to be easily fitted within the recess 15.

As shown in Figures 3 and 4, the auxiliary gripping ring 19 has tooth formations 21 which are radially inwardly facing and axially outwardly splayed. In use, the male pipe part can be comfortably inserted through the gripping ring 19, however, any load on the male part tends to withdraw the male part and the tooth formations 21 act to grip the male pipe part * S 05....

S

In use, the male pipe part 5 is inserted into the pipe fitting 1 and passes through the "grab" ring 17 then the auxiliary gripping ring 19 and then the seal 13. Application of a load to the male pipe part 5 in the form 5I5* of internal pressurisation or tensile end load causes slight withdrawal of.

the male pipe part 5 out of the fitting 1. When the fitting encounters such a load, the auxiliary gripping ring 19 reacts to grip the male pipe part 5.

As the male part is further withdrawn from the female part (and in the absence of immediate gripping of the male part by the grab ring), the auxiliary ring 19 moves towards the grab ring 17, forcing it along the complementary taper of the recess and so radially inwardly to grab the male part. As such, the "grab" ring 17 takes over from the auxiliary gripping ring to firmly grip the male pipe part 5 and lock the pipe 5 in position.

The above described embodiment has been given by way of example only, and the skilled reader will naturally appreciate that many variations could be made thereto without departing from the scope of the present invention. *. . * * S * S. * . * * S * *. * S

* S....

S S. S * S S * .. S... * S S... S... S...

Claims

Claims 1. A pipe fitting comprising a female pipe part for receiving a

male pipe part, a resilient sealing ring and a so-called "grab" ring located in respective undercut recesses within the wall thickness of the female pipe part, the "grab" ring having a tapered external surface which engages a surface of complementary taper in the undercut recess in which the ring is located, an auxiliary gripping ring located, in the direction of insertion of the male part, behind the "grab" ring and in the same undercut recess as the "grab" ring, wherein the "grab" ring and auxiliary gripping ring are arranged such that in use, when an initial withdrawal of the male part occurs in reaction to internal fluid pressure or some other action, the auxiliary gripping ring grips the male part firmly and as the withdrawal progresses, drives ** the "grab" ring into firm contact with the complementary taper thereby forcing the "grab" ring radially inwardly into the male part so as to lock the male part into position. S..
2. A pipe fitting according to claim 1 wherein the auxiliary gripping ring is provided with a radially inwardly disposed toothed surface.
3. A pipe fitting according to claim 2 wherein the toothed surface is angled in the direction of insertion of the male part.
4. A pipe fitting according to any preceding claim wherein the auxiliary gripping ring comprises a flat annular ring with a radially inner surface adapted for gripping the male pipe part.
5. A pipe fitting according to any preceding claim wherein the "grab" ring is provided with a radially inwardly disposed toothed surface
6. A pipe fitting according to any preceding claim wherein the tooth formations on one or both of the grab ring and auxiliary gripping ring are of a material which is harder than the material of the male part.
7. A pipe fitting according to any preceding claim wherein the tooth formations are metal. * . I * **
8. A pipe fitting according to claim 7 wherein the auxiliary gripping *.: ring is made from a metal pressing.

lIs...

I
9. A pipe fitting according to any of claim 1 to claim 6 wherein the auxiliary gripping ring is shaped from wire. S...
10. A pipe fitting according to any preceding claim wherein the female pipe part further comprises a socket which is butt weldable to a pipe.
11. A pipe fitting according to any of claims 1 to 9 wherein the female pipe part further comprises an electrofusion socket.
12. A pipe fitting according to claims 1 to 9 wherein the female pipe part comprises a butt weldable socket at a first end and an electrofusion socket at an opposing end.
13. A pipe fitting substantially as described hereinbefore with reference to accompanying Figures 1, 3 and 4.