NZ565917A - Flange connection system - Google Patents

Abstract

A connection system for joining a polyethylene pipe and fitting to a non-polyethylene pipe or other fluid handling equipment. The system includes a polyethylene stub enabling the substantial matching of the bore of the polyethylene pipe or fitting with the bore of the non-polyethylene pipe or other fluid handling equipment. The outer diameter of a clamping flange of the polyethylene stub substantially matches the outer diameter of a flange of the non-polyethylene pipe or fluid handling equipment. Clamping bolts clamping the clamping flange of the polyethylene stub to the flange of the non-polyethylene pipe or fluid handling equipment pass through the clamping flange.

Description

Patents Form # 5 *10055349872* NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION TITLE : Flange Connection System We, VINIDEX PTY LIMITED Address: PO Box 379, Sunnybank, QLD 4109, Australia Nationality: A State of Queensland, Australia company do hereby declare the invention for which we pray lhat 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: INTELLECTUAL PROPERTY - I . OFFICE OF N.Z 1 3 FEB 2008 RECEIVED l-.U00700\4007S9NZ\FiliisgJonns_200802n_EMM.doc FEECODE1050 1A FLANGE CONNECTION SYSTEM The present invention relates to joins between length of dissimilar pipes and between pipes and items of fluid handling equipment and, more particularly, to the joining of polyethylene pipes and fittings to other pipe types and equipment.

BACKGROUND The joining of pipes to pipes and pipes to other fluid handling equipment and fittings by means of flanges affixed at the respective ends of pipes or equipment is common throughout the fluid handling industry. Flange to flange joins where the respective flanges are bolted together, typically with a fluid proof gasket compressed between the flanges, forms an effective way of joining pipes and equipment.

It has long been accepted practice in the polyethylene pipe industry that flange joints are arranged by first butt-welding a "stub" to the end a length of pipe. An example of a stub is shown in Figure 1 where it can be seen that the stub 10 (shown sectioned) includes a short tubular section 16 matching in outer diameter and bore the polyethylene pipe 12 to which it is to be welded. The stub includes a rather narrow peripheral clamping flange 20. Fitted behind the rearward surface of the clamping flange 20 is a freely rotating ring or backing ring 22 which is predrilled with a series of bolt holes to match the array of bolt holes of the flange 26 of the pipe 14 (or item of equipment such as a pump or a fitting) to which the polyethylene pipe is to be joined.

In this example of a prior art stub, the clamping bolts 30 do not pass through the clamping flange 20. The free rotating backing ring 22 has the advantage that the backing ring 22 can be rotated to suit the orientation of the flange bolt holes of the pipe 14 (which typically will be a steel pipe already fixed in situ) and allows the alignment of the respective bolt holes.

This arrangement however, which forces the bolts to lie outside the periphery of the stub flange 2 0, has some major disadvantages. Firstly, (as can be readily seen in Figure 1), it forces a significant mismatch (up to some 20% depending on the pipe size and specification) between the bore of the polyethylene pipe and the bore of the steel pipe to which it is to be connected. The problem is exacerbated by the fact that the wall thickness of a steel pipe is considerably less than that required for a polyethylene pipe. This is particularly a problem in high pressure installations where the Standardised Dimensional Ratio (that is, the ratio defined by the outer diameter of the polyethylene pipe divided by its wall thickness is 13.6) or less. As a result, as can also be seen in Figure 1, the two pipes may have similar outer diameters but a large mismatch in bores.

For many fluid conducting installations, such a restriction of flow imposed by the mismatch in bores is 5 unacceptable. A particular example is the junction between pipes and water flow meters where accurate matching of the bore diameters is critical. Moreover in some situations the mismatch may produce a pocket allowing the trapping of gasses emanating from the conducted fluid. When such gasses 10 are subjected to rapid compression and decompression from hammerlock forces, destructive pressures can be created at the join and in the steel pipe.

Yet another disadvantage of this reduced bore size of a polyethylene pipe arises where a polyethylene pipe is to 15 be connected at a butterfly . valve assembly. When fully opened the blade of the valve projects beyond its flanges and cannot be accommodated in the restricted bore of the adjoining polyethylene pipe. Such a join can then only be made with the use of a spacer with bore of sufficient size 20 to allow a full 90 degree rotation of the butterfly valve. The addition of the spacer adds cost as well as another join with potential leakage problems.

Secondly, it is very easy for installing personnel to over-torque the clamping bolts. With these bolts locating 25 beyond the periphery of the polyethylene flange, such over- torqueing can distort both the backing ring and the clamping flange and lead to leaking at the join.

Yet another disadvantage of a conventional stub and backing ring arrangement is that only one-piece backing rings can be used, whereas in some situations it would be an advantage to be able to use a split backing ring.

It is an object of the present invention to address the above disadvantages, or at least provide a useful alternative.

BRIEF DESCRIPTION OF INVENTION Accordingly, in a first broad form of the invention, there is provided a connection system for joining a polyethylene pipe and fitting to a non-polyethylene pipe or other fluid handling equipment; said system including a polyethylene stub enabling the substantial matching of the bore of a said polyethylene pipe or fitting with the bore of a said non-polyethylene pipe or other fluid handling equipment, and wherein the outer diameter of a clamping flange of said polyethylene stub substantially matches the outer diameter of a flange of said non-polyethylene pipe or fluid handling equipment.

Preferably, said stub conforms to a predetermined standardised dimensional ratio of said polyethylene pipe or fitting {that is, the outer diameter of said polyethylene pipe or fitting divided by the wall thickness of said polyethylene pipe or fitting); said predetermined standardised dimensional ratio being 13.6 or less.

Preferably, said polyethylene stub includes a separately provided backing ring; said backing ring having an outer diameter substantially equal to said outer diameter of said clamping flange of said stub.

Preferably, clamping bolts pass through bolt holes through said clamping flange of said polyethylene stub; said clamping bolts clamping together respective flanges of said stub and said non-polyethylene pipe or fluid handling equipment.

Preferably, said backing ring is provided with bolt holes at a pitch diameter and at radial separations according to standards for pitch diameter and radial separations for non-polyethylene pipes and other fluid handling equipment.

Preferably, said standards include DIN, ISO, ANSI and JSI standards.

Preferably, said backing ring is formed of metal.

Preferably, said backing ring is formed of polycarbonate or other mechanically suitable synthetic material.

Preferably, said backing ring is provided as single continuous ring.

Preferably, said backing ring is provided in two or more equal segments; each of said segments comprising a portion of a full circumferential backing ring.

Preferably, said clamping flange of said polyethylene stub is provided with pre-formed bolt holes; said bolt holes provided at a pitch diameter and radial separation equal to said pitch diameter and radial separation of said bolt holes provided in said backing ring.

Preferably, said clamping flange of said polyethylene stub is provided without bolt holes; a clamping face of said clamping flange inscribed with at least one pitch circle; said at least one pitch circle equal to a pitch circle of bolt holes of a standard flange of a non-polyethylene pipe or other fluid handling equipment for which said bore of said stub is substantially equal to said bore of said non-polyethylene pipe or other fluid handling equipment.

Preferably, said polyethylene stub is machined from a tubular section of polyethylene; said tubular section is formed by a polyethylene strip winding process.

Preferably, said polyethylene stub is machined from an extruded length of polyethylene tube.

Preferably, said polyethylene stub is produced by injection moulding.

Preferably, said polyethylene stub is produced by compression forming.

In another broad form of the invention, there is provided a backing ring for a polyethylene stub for a polyethylene pipe; said backing ring comprising a ring of material provided with a plurality of bolt holes; said bolt holes arranged at a pitch diameter and at a radial separation to suit bolt holes of at least one flange of a non-polyethylene pipe or other fluid handling equipment; said backing ring having an outer diameter approximately equal to an outer diameter of a clamping flange of said polyethylene stub with which said backing ring is supplied.

Preferably, said backing ring is of metal.

Preferably, said backing ring is of polycarbonate or other mechanically suitable synthetic material.

Preferably, said pitch diameter and radial separation of said bolt holes conform to international pipe flange standards.

In yet another broad form of the invention, there is provided a method of joining a polyethylene pipe to a non-polyethylene pipe or other fluid handling equipment; said method including the steps of: (a) butt welding a polyethylene stub to an end of said polyethylene pipe, (b) bolting a clamping flange of said polyethylene stub to a flange of said non-polyethylene pipe or other fluid handling equipment, and wherein bolts clamping respective said flanges together pass through bolt holes provided in said clamping flange of said polyethylene stub.

Preferably, said bolt holes are provided in said clamping flange of said polyethylene stub at manufacture of said stub; said bolt holes located at a pitch diameter and radial separation to align with bolt holes of a flange of at least one non-polyethylene pipe or other fluid handling equipment.

Preferably, said clamping flange is provided without bolt holes; a clamping face of said stub inscribed with at least one circle equal to a pitch diameter of bolt holes of a flange of a said non-polyethylene pipe or other fluid handling equipment.

Preferably, said bolt holes are drilled through said clamping flange of said polyethylene stub by a user prior to installation; radial spacing of said bolt holes indicated by bolt holes of a said backing ring provided with said stub.

In still another broad form of the invention, there is provided a method of substantially matching bores of polyethylene pipes with bores of non-polyethylene pipes or other fluid handling equipment according to flange tables for said non-polyethylene pipes and other fluid handling equipment; said method including the steps of: (a) forming polyethylene stubs for butt-welding to polyethylene pipes, (b) providing backing rims for said stubs, wherein outer diameters of clamping flanges of said stubs and bores of said stubs conform substantially to outer diameters and bores listed in said flange tables for said non-polyethylene pipes and other fluid handling equipment.

Preferably, outer diameters of said backing rings are substantially equal to outer diameters of said clamping flanges of said stubs.

Preferably, said backing rings are provided with bolt 5 holes through said backing rings; said bolt holes conforming in pitch diameter and radial separations to bolt holes of flanges listed in said flange tables.

BRIEF DESCRIPTION OF DRAWINGS Embodiments of the present invention will now be described with reference to the accompanying drawings wherein: Figure 1 (prior art) shows a conventional join between the flanges of a steel pipe and the polyethylene stub of a 15 polyethylene pipe, Figure 2 shows a join between the flange of a steel pipe and a polyethylene stub and backing ring according to a preferred embodiment of the invention, Figure 3 is a perspective exploded view of one 20 preferred embodiment of the stub and backing ring of Figure 2 ready for installation, Figure 4 is a perspective view of a further preferred embodiment of the stub and backing ring of Figure 2 after manufacture. - -11 - DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As noted above, Figure 1 shows a join 10 between a polyethylene pipe 12 and a non-polyethylene pipe 14 (for 5 example a steel pipe), according to conventional practice in the prior art.

A polyethylene stub 16, comprising of a short tubular section 18 and clamping flange 2 0, has been butt-welded 21 to the end of the section of polyethylene pipe 12. A 10 backing ring 22 is provided with a plurality of bolt holes 24. These holes are arranged at a pitch diameter and radial spacing to conform to a standard pitch diameter and spacing as laid down according to flange tables for, in this example, the flange 26 of steel pipe 14. Depending on 15 manufacture and application, flange tables may conform to any one of standards DIN, ISO, ANSI or JIS.

Again as noted above, in this arrangement according to the prior art, backing ring 22 is free turning about the tubular section 18 of stub 16, to allow the bolt holes 24 20 to align with the bolt holes 28 of steel pipe-flange 26. This feature of the free turning backing ring 22 which requires that the clamping bolts 30 lie outside the periphery of clamping flange 20, has the attendant disadvantages outlined above. It can be seen that, while 25 the outer diameter of the polyethylene pipe is approximately the same as the outer diameter of the steel pipe, there is a large mismatch between the bores of the pipes. As again noted above, this is a particular problem in high pressure installations in which the Standardised Dimensional Ratio is 13.6 or less.

First Preferred Embodiment Turning now to a preferred embodiment of the present invention with reference to Figures 2 and 3, a polyethylene stub 116 has again been butt-welded to the end of a polyethylene pipe 112. The clamping flange 120 of stub 116 however, has an outer diameter substantially equal to the outer diameter of the flange 126 of the steel pipe 114 to which the polyethylene pipe is to be joined. The clamping flange is provided with bolt holes 127 at the pitch diameter and radial separation of both the steel pipe-flange 126 and backing ring 122.

This allows an appropriate wall section of stub 116 to be maintained for the size and specification of the polyethylene pipe, but which provides for the bore 123 to be substantially equal to the bore 125 of the steel pipe.

The. further immediate advantages which flow from the arrangement of Figure 2 are firstly, the backing ring 122 is now fully supported against the clamping flange 120 of the stub 116, and the clamping flange is in turn virtually wholly in contact with steel pipe-flange 126. As a result, no amount of over tightening of bolts 130 can cause any distortion of the clamping flange.

Secondly, the greater area of contact between the two 5 flanges 120 and 126 provides for a better sealing arrangement, allowing for a deeper gasket (not shown).

Thirdly, the thickness of the backing ring, which for large pipes is very considerable to prevent distortion, can be made both much thinner and with a considerably reduced 10 radial width. Conventional backing rings are of galvanized steel, are very heavy size for size and subject to corrosion. In one preferred form of the backing ring of the present invention, ring 120 is made of polycarbonate or other mechanically suitable synthetic material. 15 Polycarbonate for example, is of ample strength and, being fully supported, sa4 tests have shown virtually no distortion at the bolt holes even with bolts tightened close to stripping of their threads. It is of course also almost impervious to the corrosive environments in which 20 these flange joints are typically placed.

Second Preferred Embodiment For pipe lines which have been correctly laid according to standards in the industry, the bolt holes of a flange should be oriented according to the standard, that is with a line joining the uppermost pair of adjacent holes horizontal. Thus alignment between say a steel pipe or other fluid handling equipment already fixed in situ, the joining of a polyethylene pipe (or fitting made according to the principles of the stub of Figures 2 and 3) , should not present a problem. However where alignment problems do occur, polyethylene stubs according to the present invention may be provided blank; that is without preformed bolt holes.

With reference to Figure 4, in a second preferred form of a stub according to the invention, bolt holes may be drilled on site. By being provided without bolt holes through flange 220, a stub is not "locked in" to a particular flange specification and may be suited for two or more flange specifications. For example, where the pitch diameter of bolt holes of a metric DIN standard flange are relatively close to that of a US imperial ANSI flange and minor mismatches in bore sizes can be tolerated.

Thus a stub as shown in Figure 4 may be provided with the appropriate backing ring 222 for a DIN pipe-flange or an ANSI pipe-flange as required. Drilling of the holes 224 through the relatively soft polyethylene is readily accomplished with a spade bit. To ensure bolt holes are drilled at the correct pitch diameter, the sealing face 232 of the stub may be inscribed at manufacture with circles 234 and stamped with indicia to indicate the pipe-flange bolt hole pitch diameters. The radial spacing of the bolt holes can be marked before drilling by using the accompanying clamping ring as template.

For both the first and second embodiments, the backing ring may be provided in one piece or in two semi-circular sections 222A and 222B as shown in Figure 4A. This is possible with the stub of the invention since both sections of the clamping ring are fully supported against the clamping flange 220 of the stub 226. If desired, for larger diameter arrangements, the backing ring could be supplied in three or more equal segments.

Stub Manufacture Preferably, stubs are manufactured from a section of tubular polyethylene formed by winding a strip of polyethylene of the required width to a diameter at least equal to the outer diameter of the stub clamping flange. The strip is continuously heated aa it is wound, firstly onto a mandrel, subsequently building up layer by layer, with each layer melting onto the previous one to form a homogenous whole.

The hot wound tubular section is allowed to cool in a cooling oven. When cooled the section is machined to the precise specifications for the required stub. Machining of polyethylene is very rapid and the process allows for the manufacture of a large range of stub sizes without the cost of expensive tooling as would be required by injection moulding.

Although the above is a preferred method of producing the stubs of the invention, it will be understood by those skilled in the art, that injection moulding, machining from extruded tube or compression forming, may also be employed.

Although the above description has referred primarily to joins between polyethylene pipes and non-polyethylene pipes, it will also be appreciated by those skilled in the art that the principles of the stub and backing ring of the invention may be applied to the joining of polyethylene pipes and fitting to a wide range of non-polyethylene fittings and equipment, such as gate valves, foot valves and pumps for example, as well as to polyethylene to polyethylene pipes or fittings.

The above describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.

Claims (27)

Received @ IPONZ 18 Dec 2008 - 17 -CLAIMS
1. A connection system for joining a polyethylene pipe and fitting to a non-polyethylene pipe or other fluid handling equipment; said system including a polyethylene stub enabling the substantial matching of the bore of a said polyethylene pipe or fitting with the bore of a said non-polyethylene pipe or other fluid handling equipment, and wherein the outer diameter of a clamping flange of said polyethylene stub substantially matches the outer diameter of a flange of said non-polyethylene pipe or fluid handling equipment, and wherein clamping bolts clamping said clamping flange of said polyethylene stub to said flange of said non-polyethylene pipe or fluid handling equipment pass through said clamping flange.
2. The system of claim 1 wherein said stub conforms to a predetermined standardised dimensional ratio of said polyethylene pipe or fitting (that is, the outer diameter of said polyethylene pipe or fitting divided by the wall thickness of said polyethylene pipe or fitting); said predetermined standardised dimensional ratio being 13.6 or less.
3. The system of claim 1 or 2 wherein said polyethylene stub includes a separately provided backing ring; said Received @ IPONZ 18 Dec 2008 - 18 - backing ring having an outer diameter substantially equal to said outer diameter of said clamping flange of said stub.
4. 4. The system of claim 1, 2 or 3 wherein clamping bolts 5 pass through bolt holes through said clamping flange of said polyethylene stub; said clamping bolts clamping together respective flanges of said stub and said non-polyethylene pipe or fluid handling equipment. 10
5. 5. The system of claim 3 or 4 wherein said backing ring is provided with bolt holes at a pitch diameter and at radial separations according to standards for pitch diameter and radial separations for non-polyethylene pipes and other fluid handling equipment. 15
6. 6. The system of claim 5 wherein said standards include DIN, ISO, ANSI and JSI standards.
7. 7. The system of any one of claims 3 to 6 wherein said backing ring is formed of metal.
8. 8. The system of any one of claims 3 to 6 wherein said 20 backing ring is formed of polycarbonate or other mechanically suitable synthetic material.
9. 9. The system of any one of claims 3 to 8 wherein said backing ring is provided as single continuous ring. Received @ IPONZ 18 Dec 2008 - 19 -
10. 10. The system of any one of claims 3 to 8 wherein said backing ring is provided in two or more equal segments; each of said segments comprising a portion of a full circumferential backing ring.
11. 11. The system of any one of claims 2 to 10 wherein said clamping flange of said polyethylene stub is provided with pre-formed bolt holes; said bolt holes provided at a pitch diameter and radial separation equal to said pitch diameter and radial separation of said bolt holes provided in said backing ring.
12. 12. The system of any one of claims 2 to 10 wherein said clamping flange of said polyethylene stub is provided without bolt holes; a clamping face of said clamping flange inscribed with at least one pitch circle; said at least one pitch circle equal to a pitch circle of bolt holes of a standard flange of a non-polyethylene pipe or other fluid handling equipment for which said bore of said stub is substantially equal to said bore of said non-polyethylene pipe or other fluid handling equipment.
13. 13. The system of any one of claims 2 to 12 wherein said polyethylene stub is machined from a tubular section of polyethylene; said tubular section is formed by a polyethylene strip winding process. Received @ IPONZ 18 Dec 2008 - 20 -
14. 14. The system of any one of claims 2 to 12 wherein said polyethylene stub is machined from an extruded length of polyethylene tube.
15. 15. The system of any one of claims 2 to 12 wherein said 5 polyethylene stub is produced by injection moulding.
16. 16. The system of any one of claims 2 to 12 wherein said polyethylene stub is produced by compression forming.
17. 17. A connection system for joining a polyethylene pipe and fitting to a non-polyethylene pipe or other fluid 10 handling equipment; said system including a polyethylene stub enabling the substantial matching of the bore of a said polyethylene pipe or fitting with the bore of a said non-polyethylene pipe or other fluid handling equipment, said polyethylene stub 15 having a clamping flange with an outer diameter substantially matching an outer diameter of the flange of said non-polyethylene pipe or other fluid handling equipment; said stub provided with a backing ring having an outer diameter approximately equal to said 20 clamping flange of said polyethylene stub with which said backing ring is supplied; said backing ring comprising a ring of material provided with a plurality of bolt holes; said bolt holes arranged at a pitch diameter and at a radial separation to suit bolt Received @ IPONZ 18 Dec 2008 - 21 - holes of at least one flange of a non-polyethylene pipe or other fluid handling equipment.
18. 18. The system of claim 17 wherein said backing ring is of metal. 5
19. 19. The system of claim 17 wherein said backing ring is of polycarbonate or other mechanically suitable synthetic material.
20. 20, The system of any one of claims 17 to 19 wherein said pitch diameter and radial separation of said bolt 10 holes conform to international pipe flange standards.
21. 21. A method of joining a polyethylene pipe to a non-polyethylene pipe or other fluid handling equipment; said method including the steps of: (a) butt welding a polyethylene stub to an end of 15 said polyethylene pipe, (b) bolting a clamping flange of said polyethylene stub to a flange of said non-polyethylene pipe or other fluid handling equipment, wherein the diameter of said clamping flange of said 20 polyethylene stub substantially matches the outer diameter of a flange of said non-polyethylene pipe or other fluid handling equipment, and wherein bolts Received @ IPONZ 18 Dec 2008 - 22 - clamping respective said flanges together pass through bolt holes provided in said clamping flange of said polyethylene stub,
22. 22. The method of claim 21 wherein said bolt holes are provided in said clamping flange of said polyethylene stub at manufacture of said stub; said bolt holes located at a pitch diameter and radial separation to align with bolt holes of a flange of at least one non-polyethylene pipe or other fluid handling equipment.
23. 23. The method of claim 21 wherein said clamping flange is provided without bolt holes; a clamping face of said stub inscribed with at least one circle equal to a pitch diameter of bolt holes of a flange of a said non-polyethylene pipe or other fluid handling equipment.
24. 24. The method of claim 23 wherein said bolt holes are drilled through said clamping flange of said polyethylene stub by a user prior to installation; radial spacing of said bolt holes indicated by bolt holes of a said backing ring provided with said stub.
25. 25. A method of substantially matching bores of polyethylene pipes with bores of non-polyethylene pipes or other fluid handling equipment according to flange tables for said non-polyethylene pipes and Received @ IPONZ 18 Dec 2008 - 23 - other fluid handling equipment; said method including the steps of: (c) forming polyethylene stubs for butt-welding to polyethylene pipes, (d) providing backing rims for said stubs, wherein outer diameters of clamping flanges of said stubs and bores of said stubs conform substantially to outer diameters and bores listed in said flange tables for said non-polyethylene pipes and other fluid handling equipment.
26. 26. The method of claim 25 wherein outer diameters of said backing rings are substantially equal to outer diameters of said clamping flanges of said stubs.
27. 27. The method of claim 25 or 26 wherein said backing rings are provided with bolt holes through said backing rings; said bolt holes conforming in pitch diameter and radial separations to bolt holes of flanges listed in said flange tables.