Pipe fitting

A crimp ring fitting for connection to plastic or composite piping, the fitting including a spigot having one or more circumferentially extending ribs for engagement with the inner surface of the piping, a shoulder from which the spigot extends, a resilient sleeve extending coaxially with and spaced apart from the spigot, the sleeve terminating at one end in an inwardly directed flange adjacent the shoulder for retaining the sleeve about the spigot and at the other end in an outwardly directed flange, and a crimp ring slidably mounted over the sleeve for crimpable attachement of the fitting to the pipe, in use the outwardly directed flange preventing axial movement of the crimp ring along the pipe.

BACKGROUND OF THE INVENTION 
This invention relates to a crimp ring fitting for connection to plastic or 
composite piping and the like. 
The invention has been developed primarily for use with 
polyethylene/aluminium composite piping and will be described hereinafter 
with reference to this particular use. It will be appreciated, however, 
that the invention is not limited to this particular field of use. 
The principle of crimp ring pressure fittings has been established for many 
years and these are used extensively on hydraulic hoses and other plastic 
pipe fittings. However, it has been found that the existing crimp ring 
systems when used in particular on the composite pipes, tend to leak when 
subjected to cyclic temperature conditions. 
Another disadvantage of existing crimp ring fittings is that the copper 
crimp ring is often damaged or distorted during transport making on site 
assembly all the more difficult. Furthermore, there is a tendency for the 
crimp rings, after crimping, to cut into and damage the pipe, particularly 
at the leading edge of the ring. 
An object of the present invention is to provide a range of fittings which 
will overcome or at least ameliorate the discussed disadvantages of the 
prior art. 
SUMMARY OF THE INVENTION 
According to the invention there is provided a crimp ring fitting for 
connection to plastic or composite piping, the fitting including a spigot 
having one or more circumferentially extending ribs for engagement with 
the inner surface of the piping, a shoulder from which the spigot extends, 
a resilient sleeve extending coaxially with and spaced apart from said 
spigot, the sleeve terminating at one end in an inwardly directed flange 
adjacent the shoulder for retaining the sleeve about the spigot and at the 
other end in an outwardly directed flange, and a crimp ring slidably 
mounted over said sleeve for crimpable attachment of said fitting to said 
pipe, in use the outwardly directed flange preventing axial movement of 
the crimp ring along said pipe, particularly under cyclic temperature 
conditions. 
Preferably the ribs have a non-damaging rounded profile. 
In a preferred form the spigot also includes one or more tapered barbs for 
engagement with the inner surface of the piping. These barbs are 
preferably circumferentially extending with rounded extremities to prevent 
damage to the pipe. 
In a preferred embodiment the sleeve is made from polybutylene and the 
fitting made of copper or brass.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1 there is shown part of the fitting 1 adapted for 
connection to a composite pipe 2. The fitting 1 includes a spigot 3 
extending from a shoulder 4 surrounded by a captive resilient sleeve 5 
supporting a copper crimp ring 6. The shoulder is integral with the 
fitting body (not shown) which will vary according to its intended 
application. 
The spigot 3 is made predominatly from copper or brass and in some cases 
from plastics such as, for example, PVC and includes two spaced apart 
circumferentially extending rounded ribs 7. The sleeve 5 is made from 
moulded polybutylene and has at one end an inwardly directed flange 8 
which seats against the intersecting corner of shoulder 4 and spigot 3. An 
outwardly directed flange 9 extends from the distal end of sleeve 5 which 
serves to axially locate and retain the crimp ring 6. The external leading 
edge of the spigot 3 and the internal edges of sleeve 5 both have rounded 
lead-in portions 10 for ease of assembly to the pipe 2. 
Referring now to FIG. 2 there is shown a preferred second embodiment of the 
invention. Like reference numerals have been used to denote corresponding 
features. 
This embodiment is very similar to the first embodiment with the addition 
of two retaining ridges or annular barbs 11 disposed adjacent the leading 
edge of the spigot 3. The barbs taper inwardly toward the free end of the 
spigot 3 and may be blunted at their extremities to prevent damage to the 
pipe. 
In use both the crimp ring fittings are provided pre-assembled as shown in 
the drawings with the crimp ring captive on sleeve 4. The pipe 2 is then 
presented to the fitting and inserted until it can go no further. At this 
point the connection is self supporting and the ring 5 can be crimped 
about the pipe by means of a conventional crimping tool. 
In this way the rounded ribs 7 are forced into sealing engagement with the 
pipe wall whilst the polybutylene sleeve 5 ensures the pipe is gripped, 
but not damaged by the copper ring. 
With the second embodiment fitting, compression of the crimp ring causes 
the barbs 11 to exert a radial load on the piping material which under 
tensile axial loads will resist removal of the pipe. The barbs are tapered 
inwardly toward the free end of spigot 3 to facilitate easy connection to 
the pipe 2. This embodiment has been found to be extremely effective at 
providing a sealing connection that can withstand high axial tensile 
loads. 
If the connection is subjected to any form of thermal cycling, the 
resilience of the polybutylene sleeve prevents leaks from occurring. After 
crimping, the ring compresses the sleeve and another lip forms at the end 
adjacent the shoulder, which in conjunction with flange 9 holds the ring 
captive and prevents it creeping along the pipe, particularly under cyclic 
temperature conditions. 
In another embodiment the spigot extends beyond the distal end of the 
sleeve 5 to locate and if necessary re-round the pipe which may be 
distorted after cutting a coiling. 
One of the main advantages of the invention is that the fittings and copper 
crimp rings can be supplied as a single pre-assembled unit, thus 
simplifying assembly of the connections in the field. Furthermore, the 
sleeve serves to support the copper ring and help prevent damage or 
distortion of the ring during transport. 
It is also envisaged however, that the fitting be supplied as unassembled 
parts for use in repair work and cases where, for example, crimp rings of 
different materials may be selected. 
Another advantage of the invention is that the sleeve provides an 
electrically insulating barrier between the aluminium in the pipe and the 
brass or copper insert, thus reducing the likelihood of electrolytic 
corrosion. 
Although the foregoing describes two preferred embodiments of the 
invention, modifications can be made thereto without departing from the 
scope of the invention.