NZ219289A - Compression pipe joint fitting. compression of seal deforms pipe - Google Patents

Description

2 19289 PATENTS FORM NO: 5 PATENTS ACT 1953 COMPLETE SPECIFICATION " COMPRESSION FITTING " WE, YORKSHIRE FITTINGS PTY. LIMITED, a Company incorporated under the laws of the State of Victoria, Commonwealth of Australia, of 144-154 Milperra Road, Revesby, New South Wales, Australia hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- , «... ; . . . ,| - --"rmrii ,i . ^ _ . ........ .. _.... . 2 19289 The present invention relates principally to the joining together of pipes or tubes, by means of fittings such as elbows and Tees, and to the joining of pipes or tubes to vessels, stopcocks and the like- The invention finds particular application in plumbing and gasfitting, or in other fields of endeavour where fluid-tight couplings are requited.

Compression fittings, employing a compressible sleeve or "olive" are in widespread use for making joints or 10 connections to tubes and pipes, such as copper pipes used for plumbing or stainless steel pipes used in the dairying and chemical process industries. A typical, conventional compression fitting is illustrated in Figures 1 and 2 herewith, each of which is a medial, half section of a prior art compression fitting. Figure 1 shows the parts of fitting loosely assembled, and Figure 2 shows those parts when engaged to form a fluid type joint.

As depicted, the prior art compression fitting consists of a tubular portion 12 of a body (not shown in 20 its entirety), terminating in a threaded end portion 16.

The body may take the form of any fitting to which a pipe is to be attached, such as an elbow, a Tee or a stopcock. Typically, prior art body portions are forged and then machined from a machinable metal such as brass, but may be constructed from other materials, depending on their intended use.

Tubular body portion 12 has a counterbore 13 able to receive the free end 14 of a pipe 15. 2 1928 The outer end of counterbore 13 has a bevelled or radius face 11 to engage with a ring-like olive 18 which, before assembly, fits slideably around pipe end 14.

A ring nut 19 also fits slideably over pipe 15, and is inwardly threaded to engage threaded portion 16 of body portion 12. The inner face 10 of the threaded counterbore of nut 19 is also bevelled to engage olive 18. Nut 19, like body 12, is typically forged and machined from brass, while olive 18 is usually machined from a more malleable material such as copper or nylon.

To make the joint, the parts are first assembled as shown in Figure 1, and ring nut 19 is screwed on to body portion 12 until olive 18 is compressed between the respective bevelled faces of the body and nut, and is forced radially inwardly, deforming pipe end 14 at area 20, and creating fluid-tight seal respectively between body portion 12, pipe 15, olive 18 and nut 19.

While compression fittings of the type described perform satisfactorily in a wide range of environments, the costs of manufacturing in particular the body portion are relatively high in comparison to soldered or capillary fittings. The cost disadvantages arise both from the relatively large amount of brass or other machinable material required, and from the number of manufacturing steps involved in forging and then machining in a series of separate operations. The shapes of elbow and Tee fittings do not allow the respective threaded portions to be produced in a single operation on an automatic lathe, ^ . . . - • 2 19289 and several machining steps are often required. In contrast, the production processes available for capillary fittings, for which elbow and Tee bodies are manufactured from bent tube and hydrostatically formed tube respectively, are much better adapted to mass production, and the fittings may be produced at a fraction of the cost.

Conventional compression fittings are unsuitable for use in certain applications, owing to the employment of 10 different metals in contact with the fluid flowing through the fitting. For example, in conventional plumbing fittings, the liquid flowing through the fitting comes into contact both with copper from the pipe itself and from the olive, and with brass from the body. The employment of different metals can give rise to galvanic effects, and it is known that certain brasses used for conventional compression fittings can be eroded by dissolved salts in some waters.

For other applications, such as in the dairy industry 20 or in chemical processing, it is necessary for all materials in contact with the fluid to be of particular, corrosion resistant alloys, such as stainless steel. The manufacture of the body from these materials can be particularly costly, owing to the poor workability of the alloy, and owing to its high cost.

The present invention seeks to overcome some of these disadvantages by providing compression fittings which are relatively cheap to manufacture, and by use of which, contact of the fluid with a plurality of materials can be avoided.

According to a first aspect the present invention provides a compression fitting assembly including a tube or pipe capable of deformation, a body having a tubular portion and a fitting for connecting said pipe or tube to said body, said fitting comprising; an internally threaded nut circumferentially fitted on said tubular portion, said tubular portion being formed outwardly at one end thereof to engage a conical back wall of said nut to prevent it being slid off said end of the tubular portion, an externally threaded bush adapted to threadingly engage said nut and fit slidably over said pipe or tube, an annular barrel seal or olive, having a pair of tapered faces adapted to fit circumferentially around said pipe or tube and within said formed one end of the tubular portion, said bush being provided with engagement means at its threaded end to engage said seal or olive, the assembly being so arranged that as said bush is initially screwed into said nut, the olive or seal is compressed between said engagement means and the inner face of said formed end of the tubular portion, and as the bush is further tightened the olive or seal deforms the pipe or tube to form an effective sealed joint between said pipe or tube and said body. 9 2 1 92a •> According to a further aspect the present invention provides compression fitting assembly including a tube or pipe capable of deformation, a body having a tubular portion and a fitting for connecting said pipe or tube to said body, said fitting comprising; an externally threaded bush circumferentially fitted on said tubular portion, said tubular portion being formed outwardly at one end thereof to engage a tapered inner surface of said bush at its threaded end to prevent it being slid off said end of the tubular portion; an internally threaded nut adapted to threadingly engage said bush and fit slidably over said pipe or tube, an annular barrel seal or olive, having a pair of tapered end faces, adapted to fit circumferentially around said pipe or tube and within said formed one end of the tubular portion, said nut being provided with engagement means at the 20 back wall thereof to engage said seal or olive, the assembly being so arrange that as said bush is initially screwed into said nut, the olive or seal is compressed between said engagement means and the inner face of said formed end of the tubular portion, and as the bush is further tightened the olive or seal deforms the pipe or tube to form an effective sealed joint between said pipe or tube and said body.

Particular embodiments of the present invention are 9.^ r- shown in Figures 3, 4 and 5 herewith, in which: Figure 3 is a medial, half sectional view, showing the parts of a compression fitting and a pipe loosely assembled; Figure 4 is a medial, half sectional view, showing the parts of Figure 3 assembled to form a fluid type joint Figure 5 is a medial, half sectional view, showing the parts of an alternative form of compression fitting, loosely assembled; and Figures 6 and 7 are medial, half sectional views showing how the body portions of fittings similar to the fitting of Figures 3 and 4 may be attached, via an adaptor, to a threaded pipe or another threaded fitting.

Referring firstly to Figures 3 and 4, the body portion 12 of Figures 1 and 2 is replaced by a tubular portion 31 (which is relatively thin walled in comparison to the forged and machined body portions of the prior art), and an internally threaded nut 32. Tubular portion 31, which desirably has a wall thickness no less than that of the pipe to be connected to it, is formed outwardly to engage the back wall of nut 32, and so to prevent nut 32 being slid off the end of the tubular portion.

Preferably, the formed end of tubular portion 31 engages a circumferential groove within the body of nut 32, substantially preventing axial movement in either direction. In alternative embodiments of the invention, the nut may be capable of axial movement away from the open end of tubular portion 31, being restrained from 2 1 removal by the shape of the body of which portion 31 is a part, and a satisfactory connection can still be made. Although relative axial movement between tubular portion 31 and nut 32 is largely prevented, rotation of nut 32 about its shared axis of which tubular portion 31 may sometimes be desirable, to facilitate use of the compression fitting in confined spaces.

A cylindrical pipe 34 is slideably inserted into tubular portion 31. To ensure that the pipe is inserted to a sufficient depth, tubular portion 31 may be provided with a tube stop 33, which in the illustrated embodiment results 'from a reduction in internal diameter of tubular portion 31, at a predetermined axial distance from its open end. An olive 36 fits circumferentially around pipe 34 and inside the formed outer end 35 of tubular portion 31. Olive 36 may present a curved outer face, or may have a trapezoidal cross section, which can be either equiangled or alternatively angled more acutely at the fitting body end to maximize wedging/distortion when the fitting is assembled as described below. A threaded bush 37 fits slidably over pipe 34, and is provided with a counterbore and chamfer 38 at its threaded end to engage olive 36, while its thread mates with that of nut 32. As bush 37 is screwed into nut 32, olive 36 is compressed between bush 37 and the formed inner face of tubular portion 31. As the joint is tightened, olive 36 deforms pipe 34 to create a fluid tight joint.

In one embodiment of the invention, both pipe 34 and » 2 19^9 the body which terminates in tubular portion 31 are manufactured from copper, while nut 32 and bush 37 are manufactured from brass. The body may, for example, be a Tee or elbow, and can be formed relatively inexpensively from bent or hydrostatically formed copper tube. It can be attached to nut portion 33 by any suitable means, such as internal eccentric rolling, an axially moving punch, or a high speed reciprocating punch, producing a "peening" act ion.

An elbow will have two such tubular portions 31, while a Tee will have three such portions. The elbow or Tee manufactured according to the present invention will be considerably less expensive than an elbow or Tee manufactured by forging and machining of brass, according to the prior art.

Fluid within an assembled fitting will come into contact only with pipe 34, tubular portion 31, and (owing to the loose fit between those integers) olive 36. Each of these integers can be manufactured from the same 20 material, such as copper, avoiding the risk of galvanic action or of erosion as may occur with brass.

In alternative embodiments, those portions of the fitting coming into contact with fluid may be made from a corrosion resistant alloy such as stainless steel, while the machined and threaded components, nut 32 and bush 37 may be made from a different material such as mild steel, which need never come into contact with the fluid.

Fittings according to the invention may also be 1vl ' , ,„raii i.) .. • ... _ . .... —-*'■' 'adSMfhfc, ;© ;1 9289 ;constructed from mild steel, for use in the coupling of hydraulic pipes. ;Figure 5 shows the parts of an alternative compression fitting and pipe according to the present invention, wherein the body 41 carries a threaded bush 42, restrained from axial movement by an outwardly formed end of tubular body portion 41. A pipe 45 is inserted into the formed end of tubular body portion 41, and an olive 46 is held between the formed end of body portion 41 and the 10 inner chamfered face of a conventional ring nut 47. ;The fitting of Figure 6 does not employ an olive, but enables a body portion identical to the body portion of Figures 3 and 4 to be attached to an internally threaded pipe or to another fitting by means of an adaptor, generally designated 60. Tubular portion 31" is identical to the tubular body portion 31 of Figure 3, and is formed outwardly to engage a nut 32'. The inner face 35' of the outer end of tubular portion 31', instead of engaging an olive, engages a chamferred or radiused end face 61 of an 20 externally threaded bush 62 forming part of adaptor 60. ;Adaptor 60 is also provided with a hexagonal external """ portion 63 to facilitate tightening of nut 32' on to bush portion 62. ;The remote end of adaptor 60, as shown in Figure 6, also comprises a threaded bush portion 64, which in the embodiment shown is of greater diameter than bush portion 62. It will be appreciated that bush portion 64 may be of greater, equal or smaller diameter than bush portion 62, ;- 10 - ;2 1 9 2 8 ;and may carry a similar or a different thread. Thus, a wide variety of adaptors such as adaptor 63 may be provided, to allow the fitting of which body portion 31 forms a part to be attached to a variety of threaded members. In this way, substantial savings in inventory can be achieved. ;For example, a relatively small range of Tee-pieces may be used, through selection of appropriate adaptors at each of the three attachment positions, to attach to pipes of differing diameters, or to attach a fitting such as a stopcock at the junction of two pipes, which may be of different diameters. ;In another variation of adaptor 60, bush 64 may be internally threaded, to receive an externally threaded pipe. ;In the embodiment of Figure 7, body portion 31' is identical to that of Figures 3, 4 and 6, but the nut 72 is deeper than nuts 32 and 32', and receives a shortened bush 73, which is screwed up wholly within nut 72 so that a chamferred or radiused end face 74 engages the inner surface 35' of the outer end of end portion 31'. The inner bore of bush 73 may be hexagonal in shape, to receive an Allen key or similarly shaped tool, to facilitate assembly. The remaining inner threaded portion of nut 72 is then able to receive the externally threaded end of a pipe (not shown). ;- 11 - *

Claims (8)

WHAT WE CLAIM IS:

1. A compression fitting assembly including a tube or pipe capable of deformation, a body having a tubular portion and a fitting for connecting said pipe or tube to said body, said fitting comprising; an internally threaded nut circumferentially fitted ori said tubular portion, said tubular poition being formed outwardly at one end thereof to engage a conical back wall of said nut to prevent it being slid off said end of the tubular portion, an externally threaded bush adapted to threadingly engage said nut and fit slidably over said pipe or tube, an annular barrel seal or olive, having a pair of tapered faces adapted to fit circumferentially around said pipe or tube and within said formed one end of the tubular portion, said bush being provided with engagement means at its threaded end to engage said seal or olive, the assembly being so arranged that as said bush is initially screwed into said nut, the olive or seal is compressed between said engagement means and the inner face of said formed end of the tubular portion, and as the bush is further tightened the olive or seal deforms the pipe or tube to form an effective sealed joint between said pipe or tube and said body.

2. A compression fitting assembly including a tube or pipe capable of deformation, a body having a tubular 2 1923 2 19: portion and a fitting for connecting said pipe or tube to said body, said fitting comprising; an externally threaded bush circumferentially fitted on said tubular portion, said tubular portion being formed outwardly at one end thereof to engage a tapered inner surface of said bush at its threaded end to prevent it being slid off said end of the tubular portion; an internally threaded nut adapted to threadingly engage said bush and fit slidably over said pipe or tube, an annular barrel seal or olive, having a pair of tapered end faces, adapted to fit circumferentially around said pipe or tube and within said formed one end of the tubular portion, said nut being provided with engagement means at the back wall thereof to engage said seal or olive, the assembly being so arranged that as said bush is initially screwed into said nut, the olive or seal is compressed between said engagement means and the inner face of said formed end of the tubular portion, and as the bush is further tightened the olive or seal deforms the pipe or tube to form an effective sealed joint between said pipe or tube and said body.

3. A compression fitting assembly according to claim 1 wherein said nut has an internal circumferential groove adapted to engage with said formed end of the tubular portion to substantially prevent axial movement - 13 - i ° 2 1 2 8 9 therebetween.

4. A compression fitting assembly according to claims 1, 2 or 3 wherein said tubular portion is provided with an internal tube stop at a predetermined axial distance from the said one end thereof, said stop ensuring the pipe or tube is inserted to a predetermined depth.

5. A compression fitting assembly according to any one of the preceding claims wherein said bush and nut are provided with hexagonal external portions to facilitate tightening.

6. A compression fitting assembly according to any one —' of the preceding claims wherein said olive is of trapezoidal cross-section and either equiangled or angled more acutely at its end adjacent to said tubular portion.

7. A compression fitting assembly according to claim 1 wherein said engagement means comprises a counterbore and chamfer.

8. A compression fitting assembly as hereinbefore described with reference to Figures 3 and 4 or Figure 5 of the accompanying drawings.. YORKSHIRE FITTINGS PTY. LIMITED by their authorised agents P-L. BERRY & ASSOCIATES per: *6 FEB 1987 -Sieved 14 -