WO2000055536A1

WO2000055536A1 - Pipe fitting

Info

Publication number: WO2000055536A1
Application number: PCT/ZA2000/000045
Authority: WO
Inventors: Hendrik Jakobus Van Wyk
Original assignee: Hendrik Jakobus Van Wyk
Priority date: 1999-03-16
Filing date: 2000-03-15
Publication date: 2000-09-21
Also published as: AU3775300A

Abstract

A pipe fitting is disclosed for connecting a pipe (20) to a body (10). The body (10) has an externally threaded flange (18.1) onto which an internally threaded, internally tapered clamping nut (28) is screwed. An O-ring (22), a split clamping member (24) of synthetic plastics material and a split metal spring clip (26) encircle the pipe (20). The member (24) has a frusto-conical outer surface (40). When the nut (28) is tightened, the frusto-conical surface (34) of the nut (28) bears on the surface (40) of the member (24) forcing the member (24) and clip (26) radially inwardly and closing up the gaps in these elements so that their internal diameters are decreased and the clip (26) grips the pipe end (20).

Description

-1-

PIPE FITTING

FIELD OF THE INVENTION

THIS INVENTION relates to a pipe fitting.

BACKGROUND TO THE INVENTION

When plumbing is being installed fittings are used to connect the pipes to

one another and to other components in the plumbing system. A plumbing fitting has to

make a leakproof connection to the pipe, and must prevent the pipe being withdrawn

from the fitting.

A seal, often an O-ring seal, within the fitting encircles the pipe and

prevents leaking between the pipe and the fitting.

A toothed metal ring within the fitting prevents the pipe being withdrawn

from the fitting, the ring encircling the pipe and its teeth being in the form of an array of

radially inwardly directed teeth around the hole in the ring. The pipe passes through the

hole in the ring and the inner peripheries of the teeth bite into the pipe.

In one form known to Applicant the teeth are angled. This permits the pipe

easily to be slid through the ring in one direction deflecting the teeth as it does so. -2-

However, the pipe cannot then be withdrawn and the fitting must be destroyed to get

the pipe out.

In another form known to Applicant the ring is crushed onto the pipe by

tightening a nut after the pipe has been passed through the ring. Crushing the ring

pushes the teeth into the pipe. The intention is that, when the nut is loosened, the

crushing action on the ring is released thus permitting the pipe to be withdrawn and the

fitting to be re-used. In practice, however, getting the pipe out is difficult and the ring is

often too badly damaged to be re-used.

As the nut of the type of prior art fitting known to applicant is tightened,

the ring is pushed along the pipe. Once the gripping force is sufficient the ring can no

longer move with respect to the pipe, and the pipe moves with the ring.

When the plumber is creating the joint, he cuts the pipe to length and

inserts the cut end into the fitting until it abuts a stop. Because pipe ends are rarely cut

"square", one part only of the periphery of the pipe contacts the stop. When the ring

pushes on the pipe during tightening of the nut, the pipe tends to pivot about the point

where it contacts the stop. This causes misalignment of the fitting and the pipe and

hence the potential for leaks past the seal. BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the present invention there is provided a pipe

fitting comprising a body defining a socket for receiving the end of a pipe, the socket

being encircled by a threaded flange, a clamping nut which can be screwed onto said

flange, said nut having an internal clamping surface, and a pipe clamp which is circular

in form and has a gap in the circumference thereof, the pipe clamp having an outwardly

facing clamping surface, the clamping surface of said nut bearing upon the clamping

surface of the pipe clamp when said pipe clamp is within the nut and the nut is

tightened onto said flange thereby to compress said pipe clamp and reduce its internal

diameter so that it grips a pipe which is in the socket, said gap closing up as said pipe

clamp is compressed.

Said pipe clamp preferably comprises an annular member and a metal

clip of generally annular form, the annular member having a bore which is stepped to

provide a smaller diameter part and a larger diameter part, the larger diameter part

constituting a recess which is open on one side, the recess receiving said metal clip

and said clip having a gap in the circumference thereof.

In one form the cylindrical face which forms the radially outer face of said

recess has a groove therein which receives the radially outer periphery of said clip.

To achieve the requisite clamping force the diameter of the inner periphery of said clip is less than the diameter of the inner periphery of said member

whereby the clip protrudes radially inwardly from the inner periphery of said member.

For sealing purposes said socket can be stepped to provide a smaller

diameter part for receiving said pipe end and a larger diameter part which is open on

one side, said larger diameter part serving to receiving a sealing ring which, in use, lies

between a radial surface which forms one end of said larger diameter socket part and a

radial surface of said pipe clamp member.

Said clamping surfaces are preferably both frusto-conical.

According to a further aspect of the present invention there is provided a

method of securing the end of a pipe to a pipe fitting which comprises placing a

clamping nut and an annular pipe clamp around said pipe so that the pipe passes

through the nut and the pipe clamp, the pipe clamp having a gap in the circumference

thereof, screwing the nut onto the flange so that axial movement of the nut with respect

to the flange causes a clamping surface of the nut to exert a radially inwardly directed

force on the pipe clamp to reduce its effective internal diameter and close up said gap,

and inhibiting said pipe clamp from performing any axial movement with respect to the

pipe whilst its internal diameter is being reduced and the gap in its periphery is being

closed up to clamp it onto the pipe. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the

same may be carried into effect, reference will now be made, by way of example, to the

accompanying drawings in which:-

Figure 1 is an axial cross-section of a pipe fitting body;

Figure 2 is a cross-sectional view of a pipe fitting in accordance with the present

invention;

Figure 3 is a pictorial view of an annular member of the pipe fitting of Figure 2;

Figure 4 is a pictorial view of a spring clip of the pipe fitting of Figure 2;

Figure 5 is a section through a modified form of the annular member of Figure 3,

and

Figure 6 is a section through another form of annular member.

DETAILED DESCRIPTION OF THE DRAWINGS

The body 10 shown in Figure 1 is in the form of a T-piece having stepped

sockets 12.1 , 12.2 and 12.3. The smaller diameter part 14.1 , 14.2, 14.3 of each socket

is for receiving a pipe (not shown in Figure 1 ). The larger diameter parts 16.1 , 16.2,

16.3 of the sockets receive O-rings (not shown in Figure 1 ). The sockets 12.1 , 12.2,

12.3 are bounded by externally threaded flanges 18.1 , 18.2, 18.3 respectively. The

flanges have end faces 19.1 , 19.2 and 19.3 respectively. It will be understood that, whilst a T-piece has been shown in Figure 1 , the

body could be for joining two co-axial pipe ends. In this event the socket 12.3 is

omitted. Alternatively the fitting could be in the form of an elbow to join two pipes which

are at right angles to one another, in which event one of the sockets 12.1 , 12.2 is

omitted.

Turning now to Figure 2, this shows the socket 12.1 , the flange 18.1 and

the parts associated therewith which serve to secure a pipe 20 to the body 10.

The end of the pipe 20 is in the smaller diameter part 14.1 of the socket

12.1 and there is an O-ring 22 in the larger diameter part 16.1. The O-ring 22 encircles

the pipe 20.

A member 24 (see also Figure 3) and a clip 26 (see also Figure 4)

together forming a pipe clamp encircle the pipe 20 externally of the socket 12.1.

A clamping nut 28 having an internally threaded cylindrical portion 30 is

screwed onto the flange 18.1. The nut 28, in addition to the cylindrical portion 30, has a

portion 32 bounded internally by a frusto-conical surface 34 and also has a collar 36

which extends inwardly from the portion 32.

The member 24 is generally annular (see Figure 3) but has a gap 38 therein. The member 24 has an external frusto-conical surface 40 which matches the

surface 34 in conical angle. The bore of the member 24 is stepped so as to provide

bore sections 42.1 and 42.2 of different diameters. The diameter of the smaller section

42.1 is slightly greater than the external diameter of the pipe 20. The bore section 42.2,

and the adjacent radially extending surface 42 of the member 24, define a recess for

the spring clip 26. The recess is open on one side.

The face of the member 24 opposite to the face 42 is designated 43 and

lies in a plane which is at right angles to the axis of the member. The face 43 abuts the

end face 19.1.

The spring clip 26 is also generally annular (see Figure 4) and has a gap

44 in its periphery. The radially inner periphery of the clip 26 is, apart from where it is

interrupted by the gap 44, circular in shape and devoid of any discontinuities or teeth.

The member 24 is preferably of a resiliently deformable synthetic plastics

material and the clip 26 is preferably of a metal such as spring steel.

In Figure 5 there is shown a modified annular member designated 24.1.

This member differs from that illustrated in Figures 1 to 3 in that there is a

circumferentially extending groove 46 in the cylindrical face which forms the radially

outer face of the recess which receives the clip 26. The radially outer periphery of the clip 26 fits in this groove. The radially inner peripheries of the member 24.1 and the clip

26 are designated 24.2 and 26.2 respectively in Figure 5. A surface of the pipe 20 is

also shown in Figure 5.

In the form shown in Figures 6 the member and clip are combined into a

one piece pipe clamp 48 which is of any suitable material and provides the surface 40

as well as a radially inner edge 26.3 which contacts the pipe. The pipe clamp 48 has a

gap, equivalent to the gap 38, in its periphery.

To attach the pipe 20 to the body 10, the O-ring 22 is inserted into the

larger diameter part 16.1 of the socket 12.1. The clip 26 is pressed into the recess

provided therefor in the annular member 24. The gaps 38 and 44 can be aligned but

this is not essential. The pipe clamp constituted by the assembled member 24 and clip

26 is then dropped into the clamping nut 28 through the open end opposite to the collar

36. The surfaces 34 and 40 abut.

The easiest way of assembling the fitting is to slide the clamping nut 28,

member 24 and clip 26 onto the pipe 20. The end of the pipe 20 is then inserted into

the flange 18.1 until it abuts the end surface of the socket part 14.1. The nut 28 is then

screwed onto the flange 18.1 and tightened onto the flange 18.1. Because the face 43

of the member 24 is against the end face 19.1 by the time the surface 34 bears on the

surface 40, the pipe clamp cannot move to the left (as viewed in Figure 1 ) upon radially inward pressure being exerted on it by the nut 28. The only movement possible is

movement of the assembled pipe clamp's components radially inwardly to close up the

gaps 38, 44. The face 43 of the annular member 24, because it abuts the end face

19.1 of the flange 18.1 , does not exert any significant crushing forces on the O-ring 22.

It will be noted from Figure 2, and also from Figure 5, that the inner edge

of the clip 26 is radially inwardly of the inner edge of the member 24. These edges are

those designated 24.2 and 26.2 in Figure 5. The radially inner edge of the metal clip 26

thus engages the pipe 20 and the member 24, 24.1 acts firstly as a carrier for the clip

26 and secondly as the means through which the force required to deform the clip 26

and close up its gap 44 is transmitted. The member 24 is not intended to touch the

pipe 20.

Claims

CLAIMS:

1. A pipe fitting comprising a body defining a socket for receiving the end of

a pipe, the socket being encircled by a threaded flange, a clamping nut which can be

screwed onto said flange, said nut having an internal clamping surface, and a pipe

clamp which is circular in form and has a gap in the circumference thereof, the pipe

clamp having an outwardly facing clamping surface, the clamping surface of said nut

bearing upon the clamping surface of the pipe clamp when said pipe clamp is within the

nut and the nut is tightened onto said flange thereby to compress said pipe clamp and

reduce its internal diameter so that it grips a pipe which is in the socket, said gap

closing up as said pipe clamp is compressed.

2. A pipe fitting as claimed in claim 1 , wherein said pipe clamp comprises an

annular member and a metal clip of a generally circular form, the annular member

having a bore which is stepped to provide a smaller diameter part and a larger diameter

part, the larger diameter part constituting a recess which is open on one side, the

recess receiving said metal clip and said clip having a gap in the circumference thereof.

3. A pipe fitting as claimed in claim 2, wherein the cylindrical face which

forms the radially outer face of said recess has a groove therein which receives the

radially outer periphery of said clip.

4. A pipe fitting as claimed in claim 1 , 2 or 3, wherein the diameter of the

inner periphery of said clip is less than the diameter of the inner periphery of said

member whereby the clip protrudes radially inwardly from the inner periphery of said

member.

5. A pipe fitting as claimed in claim 1 , 2 or 3 wherein said socket is stepped

to provide a smaller diameter part for receiving said pipe end and a larger diameter part

which is open on one side, said larger diameter part serving to receive a sealing ring

which, in use, lies between a radial surface which forms one end of said larger diameter

socket part and a radial surface of said pipe clamp.

6. A pipe fitting as claimed in claim 1 , 2 or 3 wherein both said clamping

surfaces are frusto-conical.

7. A method of securing the end of a pipe to a pipe fitting which comprises

placing a clamping nut and an annular pipe clamp around said pipe so that the pipe

passes through the nut and the pipe clamp, the pipe clamp having a gap in the

circumference thereof, screwing the nut onto the flange so that axial movement of the

nut with respect to the flange causes a clamping surface of the nut to exert a radially

inwardly directed force on the pipe clamp to reduce its effective internal diameter and

close up said gap, and inhibiting said pipe clamp from performing any axial movement

with respect to the pipe whilst its internal diameter is being reduced and the gap in its periphery is being closed up to clamp it onto the pipe.