GB2167145A

GB2167145A - Pipe couplings

Info

Publication number: GB2167145A
Application number: GB08429347A
Authority: GB
Inventors: Paul Joseph Morrow; Francis Walter Davis
Original assignee: Victaulic Co PLC
Current assignee: Victaulic Co PLC
Priority date: 1984-11-21
Filing date: 1984-11-21
Publication date: 1986-05-21
Also published as: GB2167145B; GB8429347D0

Abstract

A pipe coupling comprises an annular sealing member 5 surrounding a pipe (1,2) to be coupled, first and second annular members, 3,8, adapted to surround the pipe, the first annular member being disposed axially inwards of the second member relative to the pipe coupling and the second annular member being axially movable such as to co-operate with the first annular member and the sealing member when moved axially inwards of the pipe coupling to cause the gasket to be compressed about the pipe. A plurality of hard gripping members 16 are disposed around and embedded in the seal member, each gripping member extending through the sealing member such that an axially outer end of the gripping member lies adjacent to, and in use is subject to pressure by, the second annular member 8. <IMAGE>

Description

SPECIFICATION Improvements in or relating to pipe couplings and pipe joints formed therewith This invention relates to pipe couplings and pipe joints formed therewith, and more particularly the invention relates to such couplings and joints for the end to end connection of plain ended pipe.

It is to be understood that by the word "pipe" as used herein is included any pipe-like member such as pipe, tube and hose and hollow pipe fittins used in pipe-work such as elbows, "T" junctions, end members and valves for example.

Pipe couplings have been known for many years for plain ended pipes, including an annular sleeve adapted to be fitted around the ends of the two pipes, to be connected, the sleeve having inwardly inclined end walls, an annular sealing member for encircling a pipe to be connected at each end of the sleeve and having a portion adapted for fitting within the space between the inclined portion of the end walls and the outer walls of the pipe such as to constitute a sealing wedge directed inwardly axially of the sleeve.Flange members are provided at each end of the sleeve, the flange members each having a cylindrical portion overlying the ends of the sleeve, and end wall portions extending radially inwardly and outwardly of the cylindrical portion, the inward wall portion providing support for an axially outer wall of the adjacent sealing member, and the outward wall portion receiving connecting means from the other flange member for linking the two flange members together so that they can be urged together in use to provide axial forces upon the two sealing members whereby the wedge portions of the sealing members are forced inwardly between the inclined rear walls of the sleeve and the outer peripheral walls of the pipes, thereby providing a compression seal with the pipes.

Couplings of the kind described in the foregoing paragraph are hereinafter referred t as "couplings of the kind referred to".

Couplings of the kind referred to have proved over many years to be of ease in assembly and great reliability in performance in providing a compression sealed joint between pipework of various kinds.

However, couplings of the kind referred to do suffer from the disadvantage that they are not intrinsically locked couplings, and can become disconnected in use if, for example, the pipes are subjected to outward axial forces of a magnitude greater than the frictional grip between the sealing member and the pipes.

It is an object of the present invention to overcome or at least substantially reduce the above mentioned problem.

According to one aspect of the invention there is provided a pipe coupling comprising an annular sealing gasket adapted to surround a pipe to be coupled, first and second annular members adapted to surround the pipe, the first annular member being disposed axially inwards of the second member relative to the pipe coupling and the second annular member being axially movable such as to co-operate with the first annular member and the sealing gasket when moved axially inwards of the pipe coupling to cause the gasket to be compressed about the pipe, and a plurality of hard gripping members disposed around and embedded in the gasket, each gripping member extending through the gasket such that an axially outer end of the gripping member lies adjacent to, in use is subject to pressure by, the second annular member, and such that an axially inner end of the gripping member has at least one toothlike portion located at or adjacent the radially inner wall of the sealing gasket.

According to another aspect of the invention, there is provided a pipe coupling of the kind referred to in which each annular sealing member is provided with a plurality of hard gripping members disposed therearound and embedded therein, each gripping member extending through the gasket such that an axially outer end of the gripping member lies closely adjacent to the angled junction (or corner) between the cylindrical portion and the inward will portion of the associated flange, and an axially inner end of the member has at least one toothlike portion located at or adjacent the radially inner wall of the sealing member axially inwardly of the sleeve.

It will be appreciated that in use with the arrangement as hereinabove defined, axial compression of the two flanges will, in the usual way, cause, through the inclined end face of the sleeve member, compression of the sealing member about the pipes to be joined. Additionally, such compression of the flanges will cause them to bear upon the axially outer ends of the gripping members, which in turn will cause the tooth or teeth of the gripping member, located at or adjacent the inner surface of the gasket, to bite into the wall of the pipe. Because of the axial displacement between the outer and inner ends of the gripping members, axial compression by the flanges causes the gripping members to turn about their points of engagement with the "corner" of the flange, reinforcing the engagement of the tooth or teeth with the pipe to be connected.It will also be appreciated that any attempt to move the pipes axially out from the coupling will also tend to turn the gripping members about their points of contact with the "corner" of the flange which, in turn, will increase the "bite" of the tooth or teeth of the gripping member with the pipe.

The gripping members may be formed of metal.

Each of the gripping members may comprise a toothed section at the inner end of two or more serrations, and a plain radiused or angled heel at the outer end for engagement with the angle or "corner" of the flange. Each insert may be positioned at the rear half of the sealing member with the toothed section flush with the radially inside surface of the sealing member and the gripping member as a whole angled back such that the heel is flush with the surfce of the sealing member adjacent to the angle or "corner" of the flange.

The invention includes within its scope joints formed with couplings as herein defined.

In order that the invention may be more readily understood, one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a section through a coupling in use for joining two plain ended pipes in accordance with the invention; Figure 2 is an isometric view of a sealing ring having inserted toothed gripping members of the kind incorporated in the joint of Fig. 1; and Figure 3 is a front elevation of the ring of Fig. 2.

Referring now the the drawings, it will be seen that the joint is formed from two cast iron pipes 1,2 of plain ended configuration located closely adjacent in an end to end configuration. About the pipes is located a coupling comprising a cast iron sleeve 3 spanning the two pipes and having a radially inclined end face 4 at each end. Disposed at each end of the coupling and fitting within the radially inclined end face thereof is a resilient elastomeric sealing ring 5 having a wedge shaped axially inner portion 6, and an axially outer portion 7 adapted to receive and transmit to the wedge shaped portion compressive forces applied during make-up of the coupling and joint.Located about each end of the sleeve and sealing member is a cast iron flange 8 having a cylindrical portion 9 overlying radially the end of the sleeve and the sealing member, a radially inner portion 10 bearing upon the axially outer portion 7 of each of the sealing members, and a radially outer portion 11 carrying a plurality of apertures 12 therearound for the receipt of bolts 13 and nuts 14. It should be noticed that the pipes, sleeves and flanges can be of materials other than cast iron, such as of steel, for example.

As can be seen the sealing rings each incorporate, spaced around them a plurality of hard toothed gripping members 16 which may be formed of stainless steel for example. The gripping members are embedded in the axially outer portion 7 of each sealing ring 5 and have a double serrated toothed end 17 located at the radially inner wall 18 of the sealing ring, and a pointed axially outer end 19 terminating at the corner of an end wall 20 and outer radial wall 21 of the sealing gasket.

It is to be noted that in the disposition illustrated, the outer end of the gripping member is located in the "corner" formed between the cylindrical portion 9 of the frange and the inner radial portion 10 thereof. It is also to be noted that overall the gripping member is inclined to the axis of the coupling and pipes.

In operation, the coupling is assembled in the perfectly normal manner associated with this kind of coupling in that the flanges 8, sealing ring 5 and sleeve 3 are loosely located about the joint between the pipes, the bolts 13 inserted and then tightened. Upon tightening of the nuts 14 on the bolts 13 not only are the wedge portions of the sealing ring 5 forced into the wedge shaped spaces between the ends of the sleeves 4 and the pipes 12, creating a highly efficient compression seal, but also the flanges bear upon the outer corners 19 of the gripping members forcing them, because of their inclined disposition, axially along and radially inwardly so that the gripping member turns about the outermost point 19 thereof and the teech at the radial inner end 17 thereof bite and engage with the pipe forming a locked joint.By increasing the end load by further tightening the nuts 14 upon the bolts 13, the inserts are further forced into the pipe but with minimum movement.

The restraining properties achieved by means of the insert gripping members can be achieved of course on varying pipe outside diameters and offered angles. During assembly on varying pipe diameters the insert will be forced to take a new position by the action of rotation upon the outer angle thereof within the end flange. The position of the teeth on the radially inner surface 18 of the sealing ring 5 ensures constant tooth engagement into the pipe surface.

A further advantageous point to note is that if pipes are assembled in a deliberate flexed condition, so as to provide a slightly bent line to the pipework, the angled outer end of the inset will embed itself in the wall of the flange adjacent to the corner between the inward wall portion and the cylindrical portion thereby resisting bending moments, e.g. by internal pressure, that would tend to straighten the assembly. Thus, the arrangement can provide a lock both for a straight and a slightly angled joint.

Again, the freedom of positioning of the sealing ring allows the connection to be dismantled without the use of any special equipment and, depending on its condition, re-used on a new location.

Claims

1. A pipe coupling comprising an annular sealing member adapted to surround a pipe to be coupled, first and second annular members adapted to surround the pipe, the first annular member being disposed axially inwards of the second member relative to the pipe coupling and the second annular member being axially movable such as to co-operate with the first annular member and the sealing member when moved axially inwards of the pipe coupling to cause the member to be compressed about the pipe, and a plurality of hard gripping members disposed around and embedded in the member, each gripping member extending through the sealing member such that an axially outer end of the gripping member lies adjacent to, and in use is subject to pressure by, the second annular member, and such that an axially inner end of the gripping member has at least one toothlike portion located at or adjacent the radially inner wall of the sealing member axially inwardly of the sleeve.

2. A pipe coupling of the kind referred to in which each annular sealing member is provided with a plurality of hard gripping members disposed therearound and embedded therein, each gripping member extending through the gasket such that an axially outer end of the gripping member lies closely adjacent to the angled junction between the cylindrical portion and the inward wall portion of the associated flange, and an axially inner end of the member has at least one toothlike portion located at or adjacent the radially inner wall of the sealing member axially inwardly of the sleeve.

3. A pipe coupling as claimed in claim 1 or 2 wherein the gripping members are formed of metal.

4. A pipe coupling as claimed in any one of the preceeding claims wherein each of the gripping members comprises at the inner end a toothed section of two or more serrations, and a plain radiused or angled heel at the outer end for engagement with the angled junction of the associated flange between the cylindrical portion and the inward wall portion thereof.

5. A pipe coupling as clamed in claim 4 wherein each insert is positioned at the rear half of the sealing member with the toothed section flush with the radially inside surface of the sealing member, and the gripping member as a whole angled back such that the heel is flush with the surface of the sealing member adjacent said angled junction.

6. A pipe coupling substantially as shown in and as hereinbefore described with reference to the accompanying drawings.

7. A pipe joint formed with a pipe coupling as claimed in any one of the preceeding claims.