Pipe coupling

The invention provides a pipe coupling (2) for connecting together a first pipe member (P1) having a liner pipe (L1) arranged in the bore thereof, to a second pipe member (P2); the pipe coupling comprising a first sleeve member (8) arranged to receive an end of the first pipe member (P1) whereby an end of the liner pipe (L1) can protrude axially therefrom; a second sleeve member (10) arranged to receive an end of the second pipe member (P2); a first annular sealing means (12) for disposal about the first pipe member (P1), the first annular sealing means (12) being arranged axially between a first annular collar (4) and the first sleeve member (8); second annular sealing means (14) and first gripping means (62) for disposal about an end of the liner pipe (l1), the second annular sealing means (14) being arranged axially between the first and second sleeve members (8,10); third annular sealing means (16) for disposal about the second pipe element (P2), the third annular sealing means (16) being arranged axially between a second annular collar (6) and the second annular sleeve member (10); and means (34,36,38) for drawing the first and second annular collars (4,6) axially together such that the first annular sealing means (12) is compressed axially between the first annular collar (4) and the first sleeve member (8) and is deformed radially inwardly to seal against the first pipe member (P1); the second annular sealing member (14) and first annular gripping means (62) are compressed axially between the first and second sleeve members (8,10) such that the second annular sealing member (14) is deformed radially inwardly into sealing contact with the end of the liner pipe (L1) and the first annular gripping member (62) is urged radially inwardly into gripping contact with the liner pipe (L1); and the third annular sealing member (16) is compressed axially between the second annular collar (6) and the second sleeve member (10) and is deformed radially inwardly into sealing contact with the second pipe member (P2).

BACKGROUND OF THE INVENTION 
This invention relates to a pipe coupling for coupling together a pipe 
having a liner pipe, hose or sleeve disposed therein to a second pipe 
member. 
Until recently, pipes made from ferrous materials have been used for 
pipelines, and in particular mains pipelines, for conveying services such 
as gas and water. A substantial problem with such ferrous pipes has been 
their tendency to corrode over a period of several years' use leading to 
loss of integrity of the pipe wall. One solution to this problem has to 
been to provide a liner pipe, hose or sleeve formed from a suitable 
material, for example a plastics material such as polyethylene, or an 
elastomeric material. In order to undertake a pipe lining operation, it is 
necessary to dig a trench at either end of the ferrous pipe section to be 
repaired, the liner being pulled through the host pipe bore such that 
eventually its end protrudes beyond the ferrous pipe end. In order to 
ensure that the joint is fluid tight, it is then necessary to provide a 
mechanical seal between the pressure-containing plastics liner and the 
pipe or fitting to which it is connected, and it is also necessary to 
provide a mechanical seal between the plastics liner pipe and the host 
pipe against the ingress of ground water, and a gripping means for 
preventing retraction of the liner pipe into the host pipe. 
It is an object of the present invention to provide such a pipe coupling. 
SUMMARY OF THE INVENTION 
Accordingly, in a first aspect, the invention provides a pipe coupling for 
connecting together a first pipe member having a liner pipe arranged in 
the bore thereof, to a second pipe member; the pipe coupling comprising a 
first sleeve member arranged to receive an end of the first pipe member 
whereby an end of the liner pipe can protrude axially therefrom; a second 
sleeve member arranged to receive an end of the second pipe member; a 
first annular collar disposed axially outwardly of the first sleeve member 
and being arranged in use to encircle the first pipe member; a second 
annular collar disposed axially outwardly of the second sleeve member and 
arranged in use to encircle an end of the second pipe member; a first 
annular sealing means for disposal about the first pipe member, the first 
annular sealing means being arranged axially between the first annular 
collar and the first sleeve member; second annular sealing means and first 
gripping means for disposal about an end of the liner pipe, the second 
annular sealing means being arranged axially between the first and second 
sleeve members; third annular sealing means for disposal about the second 
pipe element, the third annular sealing means being arranged axially 
between the second annular collar and the second annular sleeve member; 
and means for drawing the first and second annular collars axially 
together such that the first annular sealing means is compressed axially 
between the first annular collar and the first sleeve member and is 
deformed radially inwardly to seal against the first pipe member; the 
second annular sealing member and first annular gripping means are 
compressed axially between the first and second sleeve members such that 
the second annular sealing member is deformed radially inwardly into 
sealing contact with the end of the liner pipe and the first annular 
gripping member is urged radially inwardly into gripping contact with the 
liner pipe; and the third annular sealing member is compressed axially 
between the second annular collar and the second sleeve member and is 
deformed radially inwardly into sealing contact with the second pipe 
member. 
The term pipe member as used herein refers to pipes as such, and also to 
pipe-like members such as elbows, bends, T-pieces, adaptors, valve bodies, 
and like members. The term liner pipe as used herein includes liner hoses 
and liner sleeves as well as liner pipes. 
The first pipe member is typically a ferrous pipe member, for example a 
cast iron mains pipe. 
The second pipe member can be formed from any pipeline material, but 
typically is formed from a ferrous material such as ductile iron or steel, 
or a plastics material such as a polyolefin or a polyvinylhalide material 
(e.g. polyvinylchloride). 
The liner pipe is usually formed from a suitable plastics material such as 
a polyolefin, e.g. polyethylene. Typically, the liner pipe will have a 
supporting element, for example a support sleeve, disposed in the end 
thereof to prevent the liner from collapsing radially inwardly when 
compressed. 
The first and second annular collars are preferably provided with radially 
extending flanges having an array of aligned holes through which flange 
bolts can be positioned, tightening of the flange bolts serving to draw 
the collars axially together. 
Alternatively, the annular collar(s) can be threaded to engage 
complementary threads on the respective sleeve members. 
The first and second sleeve members typically have radially outwardly 
inclined (i.e. flared) end portions at their axial outer ends. In use, the 
first and third annular sealing members are urged against the respective 
flared end portions as the annular collars are drawn together, the 
inclined surfaces of the flared portions assisting the sealing members to 
be deformed radially inwardly against the respective pipe members. 
The axially inner ends of the first and second sleeve members can be 
configured so that together they define an annular cavity within which is 
disposed the second sealing member and the first annular gripping member. 
One of the sleeve members can have an axially inner end (hereinafter 
referred to as the spigot portion) which is radially outwardly inclined 
(i.e. flared) and is of a size enabling it to be received within a socket 
portion of the axially inner end of the other sleeve member. The socket 
portion can comprise a generally cylindrical or slightly inclined region 
extending in a direction towards the axially outer end of the sleeve 
member into a radially inwardly inclined (i.e. tapering) abutment surface. 
The inner surface of the spigot portion, and the generally cylindrical or 
slightly inclined region and tapering abutment surface of the socket 
portion together can define the annular cavity. 
The annular cavity can contain only an annular sealing means, but 
preferably the cavity also contains the first annular gripping means for 
gripping the liner pipe. The first annular gripping means can be formed 
integrally with the sealing means or it can be a separate element. For 
example, the gripping means can take the form of gripping elements 
embedded in the sealing means. 
In a further aspect, the invention provides a pipe joint comprising first 
and second pipe members and a liner pipe disposed within the first pipe 
member; the first and second pipe members and liner member being coupled 
together by means of a pipe coupling as hereinbefore defined.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, the coupling 2 comprises first and second annular 
collars 4, 6, first and second sleeve members 8, 10, and first, second and 
third annular sealing members 12, 14, 16. 
First sleeve member 8 is generally cylindrical in form and is typically 
fabricated from ductile or malleable iron, or mild steel. Sleeve member 8 
has a flared axial end portion 18 and a radially inwardly oriented 
abutment portion 20. Abutment portion 20 has an axially outer surface 20a 
which is generally perpendicular to the axis of the coupling. The axially 
inner surface 20b of the abutment portion is inclined and forms a tapering 
abutment surface. 
The second sleeve member 10 has an enlarged bore portion 22 and a reduced 
bore portion 24, the enlarged and reduced bore portions 22, 24 being 
linked by a radially inclined portion 26. Both the reduced bore portion 
and the enlarged bore portion extend into radially outwardly flared 
portions 28, 30 respectively. 
At either end of the coupling are annular collars 4 and 6. In this 
embodiment, the annular collars are substantially identical in form, each 
having an array of aligned holes 32, 33 through which a flange bolt 34 is 
inserted. A nut 38 engages the threaded region 36 of the flange bolt 
enabling the two annular collars to be tightened together. 
Each of the annular collars 4, 6 have annular lip portions 40, 42 at their 
radially inner edges. 
Disposed axially between the first annular collar 4 and the first sleeve 
member 8 is the first annular sealing member 12. Annular sealing member 12 
has a generally cylindrical radially inner surface 44 configured to 
provide a plurality of annular gripping ribs 46. The sealing member 12 has 
a radially outwardly inclined surface 48 and an annular recess region 50. 
In use, the axially inner end of inclined surface 48 abuts against the 
flared portion 18 of the sealing member 8. 
The annular collar 4, sealing member 12 and sleeve member 8 are shaped so 
as to be able to receive therein an end of a mains pipe P1, which may be 
for example a cast iron mains pipe. Mains pipe P1 has extending from the 
end thereof a link of liner pipe L1 which is formed from a suitable grade 
of polyethylene. Disposed within the protruding end of the liner pipe L1 
is a short length of a reinforcing liner R which may, for example, be 
formed from a plastics material such as polyethylene or a metal such as 
aluminium. 
The sleeve member 8 has, at its axially inner end, a socket portion 9 
defined by a generally cylindrical but slightly tapering region 9a and the 
tapering abutment surface 20b. The generally cylindrical region 9a and the 
abutment surface 20b, together with the inner surface of the flared end 28 
of the second sleeve member 10, form an annular cavity 60 within which are 
disposed the second annular sealing member 14 and a gripping member 62. 
Second annular sealing member 14 has a generally cylindrical radially 
inner surface provided with an array of annular ribs 61, and has a 
radially inclined surface 64 at its axially inner end. The radially 
inclined surface 64 rests against the radially inner surface of the flared 
portion 28 of the second sleeve member 10. Gripping member 62 typically is 
formed from a plastics material, e.g. an engineering plastics material 
such as Nylon or polyacetal, although it could be made instead from a 
metal such as steel, and has an array of annular gripping ribs or 
serrations 64 on its radially inner surface. Gripping ring 62 also has a 
radially inclined surface 66 which abuts against inclined surface 20b of 
the abutment portion 20 of the first sleeve member 8. 
Disposed between the second sleeve member 10 and the second annular collar 
6 is the third annular sealing member 16. As with the first and second 
annular sealing members, the third annular sealing member has an array of 
ribs 70 on its radially inner surface, and has a radially inclined surface 
72 which abuts against the radially inner surface of the flared end 
portion 30 of the second sleeve member. 
The second annular collar 6, the third sealing member 16 and the enlarged 
bore portion 22 of the second sleeve member are configured to receive 
therein an end of a second pipe member P2 which may be, for example, a 
short length of polyethylene or metal pipe. 
In use, the first and second pipe members P1 and P2 are inserted into the 
respective ends of the coupling, such that the liner pipe L1 protrudes 
from the end of the mains pipe P1, and the two annular collars 14 and 16 
are drawn axially together by tightening the flange bolt/nut arrangements 
34, 36, 38 as the two annular collars 14, 16 are drawn together, each of 
the annular sealing members are compressed and deformed radially inwardly 
into contact with their respective pipe members or liner pipe. 
Thus, first annular sealing member 12 is compressed axially between the 
flared end portion 18 of the first sleeve member 8 and an axially inner 
face 4a of the first annular collar 4. As the inclined surface 48 of the 
sealing member 12 is urged into engagement with the radially inner surface 
of flared portion 18, the effect is to compress the sealing member 12 
radially inwardly against the mains pipe P1, thereby to form a seal 
between the mains pipe P1 and the sleeve member 8. The resulting seal 
prevents, for example, entry of ground water into any annular space 
between the pipe P1 and the liner pipe L1. 
As the annular collars 4 and 6 are drawn together, the second sealing 
member 14 and the gripping member 62 are compressed between the first and 
second sealing members and are urged radially inwardly into sealing and 
gripping contact with the liner pipe L1. The gripping ribs or serrations 
66 of the gripping member bite into the outer surface of the liner to 
prevent it from being dislodged, whilst the sealing member provides a seal 
between the first sleeve member 8 and the liner pipe L1 and also between 
the second sleeve member 10 and the liner pipe L1. The support sleeve R 
disposed within the end of the liner prevents the liner from collapsing as 
it is subjected to compressive forces. 
A seal is formed in similar fashion between the second pipe member P2 and 
the sleeve member 10 by means of compression of the third annular sealing 
member 16. In this case, the third sealing member is compressed between an 
inner axially inner face 6a of the annular collar and the radially inner 
surface of the flared portion 30 of the second sleeve member 10. 
The arrangement shown in FIG. 1 has certain advantageous properties. Thus 
for example, it is easy to install and can be used to connect together 
pipes formed from a variety of different types of material and having 
different diameters. In particular, it can be used on essentially any type 
of pipe material P2 and can accommodate different lengths of pipe P2 to 
suit different trench conditions. 
The invention has been illustrated by reference to a single embodiment as 
shown in FIG. 1, but it will readily be appreciated that numerous 
modifications and alterations could be made to the embodiment shown in 
FIG. 1 without departing from the principles underlying the invention. All 
such modifications and alterations are intended to be embraced by this 
application.