GB2381054A

GB2381054A - A pipe fitting

Info

Publication number: GB2381054A
Application number: GB0124404A
Authority: GB
Inventors: Paul Davidson
Original assignee: POLYSLEEVE PRODUCTS Ltd
Current assignee: POLYSLEEVE PRODUCTS Ltd
Priority date: 2001-10-11
Filing date: 2001-10-11
Publication date: 2003-04-23
Also published as: GB0124404D0

Abstract

A pipe fitting includes a mouth portion for connection to a pipe end 17, the mouth portion including sealing means 9 for sealing between the fitting and the pie. Pipe engaging means, located rearwardly of the sealing means, comprise an internal recess 5,7 within the mouth portion and, located within the recess, a part annular pipe gripping element 11.

Description

PIPE FITTING This invention relates to pipe fittings and, in particular, to pipe fittings for attaching to one end of a plastic pipe. The invention is especially concerned, but not exclusively, with pipe fittings in the form of straight couplings for attaching together two plastic pipes in end to end relationship. Reference will be made hereinafter to such pipe fittings but it should be understood that the invention may be applied to other types of pipe fittings.

Straight couplings currently in use with plastic pipes are typically compression joints with a substantial number of parts some of which may be easily mislaid, particularly if work is being carried out at night or, generally, in poor light. Accordingly, there is a need for a simple straight coupling with few parts which can not easily be mislaid.

According to the present invention there is provided a pipe fitting including a mouth portion for connection to a pipe end, the mouth portion including sealing means for sealing between the fitting and the pipe and, located rearwardly of said sealing means, pipe engaging means comprising an internal recess within said mouth portion and, located within said recess, a part annular pipe gripping element.

The pipe gripping element preferably is a metal strip located within the recess and a plurality of integral teeth which extend from said strip radially inwardly and rearwardly out of the recess. Accordingly, when the pipe fitting is introduced over the end of a pipe, the teeth of the pipe gripping element do not impede this movement. However, movement in the opposite direction is impeded by the teeth and it is found that, in practice, the engagement between the pipe fitting and the pipe is extremely firm such that considerable force is required to remove the pipe fitting from the end of the pipe.

Preferably the sealing means comprises a further annular recess within which is located an O-ring or similar sealing element.

Preferably the pipe fitting is a straight coupling and is of generally tubular shape having an internal annular stop defining the extent of insertion of each pipe end into the fitting.

The present invention will now be described, by way of example only, and with reference to the following drawings, in which :- Figure 1 is a longitudinal section through a pipe fitting of the invention and located about two pipe ends; and Figure 2 shows a pipe gripping element of the pipe fitting of Figure 1.

Referring to the accompanying drawings, a pipe fitting of the invention is in the form of a straight coupling 1 made of plastics material and being of generally tubular shape. It has a generally smooth continuous outer surface which may be straight, as indicated in Figure 1 or it may have a gentle curvature, so that it is slightly thicker in the centre thereby giving it a pleasing appearance.

Internally the coupling has being machined to produce the profile indicated in Figure 1. As a result there is a central annular internal stop 3 and, symmetrically spaced from this stop 3, two pairs of internal recesses 5 and 7. Contained within each of the outer recesses is an O-ring 9 and within each inner recess is located a part annular pipe gripping element 11.

Element 11 is in the form of a part annular band or strip 13 which extends longitudinally within the recess. From that edge of band 13 which is closer to its neighbouring O-ring there extends a plurality of integral teeth 15, each of which extends radially inwardly and rearwardly (towards stop 3, the free end of each teeth lying radially inwardly of the normal internal surface of the coupling 1).

When pipe ends 17 are inserted into the coupling 1, no great resistance to this movement is encountered due to the presence of the teeth 15 of element 11 since the

teeth will move radially outwardly to accommodate the presence of the pipe end.

However these teeth are provided with quite sharp edges and they grip the external surface of the pipe end 17. Accordingly when an attempt is made to move the pipe end relatively away from the fitting, the teeth engage strongly with the pipe surface and resist such movement.

A particular feature of the present invention is the ease of assembly of the pipe coupling. The pipe gripping element, being of part annular structure rather than completely annular, may be easily compressed about its longitudinal axis and then inserted into the coupling and located in the appropriate recess 5. 0-rings may also be easily be inserted into their corresponding recesses.

A pipe coupling of the invention may be assembled at any location, for instance, at the manufacturing facility. It may be delivered to its point of use in a fully assembled condition thereby obviating any danger of losing parts of the coupling.

As described above, the coupling may be manufactured by machining the inside of a tubular length of plastics material. This process is much cheaper and simpler than producing the same item by means of a moulding operation. In particular, there is no need to manufacture an expensive moulding tool for this manufacturing operation.

It is particularly preferred that the pipe gripping element is located rearwardly of the 0-ring. If the pipe gripping element is located forwardly of the 0-ring, then there is the danger that the pipe coupling would not be inserted fully onto the pipe end and, in particularly, a sealing connection would not then be made. This is because the person effecting the coupling might feel that a positive engagement has been made before the coupling has been inserted to the point where the pipe end meets the integral internal stop. With the above described pipe coupling, there is no danger of this happening since by the time the pipe end engages with the pipe gripping element, it will already have passed beyond the sealing 0-ring.

In a modified pipe coupling according to the present invention a further O-ring may be provided on the other side of the gripping element to isolate the gripping element from, for instance, corrosive materials that might otherwise make contact with it in certain situations.

As indicated above, the main body of a pipe coupling in accordance with the present invention will typically be made of suitable tough plastics material. The pipe gripping elements are typically made of metal, for instance, aluminium or stainless steel and the 0-rings are made of suitable rubber or plastics resilient material.

Claims

CLAIMS 1. A pipe fitting including a mouth portion for connection to a pipe end, the mouth portion including sealing means for sealing between the fitting and the pipe and, located rearwardly of said sealing means, pipe engaging means comprising an internal recess within said mouth portion and, located within said recess, a part annular pipe gripping element.

1

2. A pipe fitting according to Claim I wherein the pipe gripping element is a metal strip located within the recess, the strip including a plurality of integral teeth which extend from said strip radially inwardly and rearwardly out of the recess.

3. A pipe fitting according to Claim 1 or Claim 2 wherein the sealing means comprises a further annular recess within which is located an O-ring or similar sealing element.

4. A pipe fitting according to any of the preceding claims in the form of a straight coupling of generally tubular shape having an internal annular stop defining the extent of insertion of each pipe end into the fitting.

5. A pipe fitting according to Claim 1 and substantially as herein defined.

6. A pipe fitting substantially as described herein with reference to the accompanying drawings.