AU2004101079A4 - Pipe coupling and coupling method - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Applicants: BLUESCOPE STEEL LIMITED Invention Title: PIPE COUPLING AND COUPLING METHOD The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 QPIPE COUPLING AND COUPLING METHOD TECHNICAL FIELD A pipe coupling is disclosed that is mountable to first and second pipes to facilitate their inter- A connection. Methods of coupling employing the pipe C coupling are also disclosed. The coupling has been Cdeveloped especially for use with steel pipes and is T herein described in that context. However, it is to be appreciated that the coupling can also be employed with pipes made from other materials, including other alloys and plastic materials.

BACKGROUND ART There are a wide range of potential applications for steel pipes as an alternative to concrete pipes. These applications include pipes for rainwater tanks, sewerage, stormwater, irrigation and culverts. Some steel pipes for use in these applications are formed from sheet steel strip and incorporate external ribs that extend along the length of the pipes to increase the strength of the pipe.

In one form, these ribs extend helically along the pipe, with the pipe being manufactured using a process of spiral winding the steel strip.

In a more specific form, multiple ribs are included in the steel strip and are separated by lands. These ribs terminate at an end of the pipe at locations which are radially spaced apart relative to the axis of the pipe thereby defining an arrangement similar to a multi-start thread.

In general it is beneficial if the pipes are adapted so that the ends of pipes can be coupled together quickly in a straightforward manner, and to form a watertight -3- Sseal. This issue is problematic particularly for steel Spipes that incorporate external ribs.

SUMMARY

In a first aspect, there is provided a pipe coupling C for coupling together first and second pipes at respective Cends thereof, the coupling having a wall that extends Cbetween opposing ends, the wall defining a bore through the coupling, wherein a protruding ridge extends at least part way around the wall in a manner such that, when the coupling is inserted into the first and second pipe ends, an end edge of each respective pipe can be brought into proximity of the ridge.

The capacity to bring into proximity each end edge to the ridge enables the edges of the first and second pipe ends to be sealed to the ridge (eg. by welding thereto, by adhesive etc). This can enable the ends of pipes to be coupled together quickly and in a straightforward manner, and can allow for a rapid and simple watertight seal to be formed.

In one form each pipe is of a type that has a plurality of external ribs terminating at a pipe end or adjacent thereto. The ribs enhance the torsional strength and improve the stiffness of each pipe.

Additionally, each pipe may be of a type that has a polymeric film or coating applied to at least one of the major surfaces thereof (eg. the external surface). This film/coating can provide a moisture barrier and/or can enhance the chemical resistance of the sheet metal and/or can enable a plastic weld to be employed between the first and second pipe ends and the ridge. Suitable polymeric films/coating may include low density or high density polyethylene, PVC and/or polypropylene.

-4- C Furthermore, each pipe may be made from sheet metal.

O In one form, the sheet metal may be a sheet steel which incorporates a corrosion resistant metal coating (eg. a Cl zinc or zinc/aluminium coating). Where each pipe comprises both a corrosion resistant metal coating and a polymer C film/coating, the coupling can enable a plastic weld to be Cemployed between the first and second pipe ends and the Cridge, without disturbing/effecting the corrosion T resistant metal coating. For example, a thermoplastic welding process can be employed to join the pipes via the coupling.

In one typical form the ridge extends peripherally right around the wall, to provide a positive stop to insertion of the coupling into each pipe. A peripheral ridge also enables a more comprehensive watertight seal to be readily formed (eg. via welding, adhesive etc). In another form, the ridge may be defined by a series of discrete protrusions extending peripherally right around the wall, again to provide a positive stop to insertion of the coupling into each pipe.

The coupling itself can be provided as a ribbed pipe to enhance its torsional strength and stiffness, however, when so provided typically the coupling ribs protrude inwardly of the coupling so as not to interfere with the first and second pipes when the coupling is inserted therein.

In one form the ridge or series of protrusions is located midway along the coupling wall between the coupling ends. In one form the coupling has a central axis, with the opposing coupling ends being spaced apart along the axis, and the wall being disposed about the axis so as to define the bore.

C In one form, the coupling is made from sheet metal.

O In one form, the sheet metal is a sheet steel which Sincorporates a corrosion resistant metal coating (eg. a CI zinc or zinc/aluminium coating).

Additionally, a polymeric film or coating may be C applied to at least one of the major surfaces of the Scoupling wall (eg. the external surface). Again, this film Ccan provide a moisture barrier and/or can enhance the Schemical resistance of the coupling sheet metal and/or can enable a plastic weld to be employed between the first and second pipe ends and the coupling. Suitable polymeric films/coatings may include low density or high density polyethylene, PVC and polypropylene.

In another form, the pipe coupling can be entirely formed from a polymeric material (eg. by rotation moulding).

In a typical form, the first and second pipes are each made from sheet metal which incorporates a polymeric film coating, and the pipe coupling also incorporates a polymeric outer surface to enable the first and second pipes and the coupling to be joined together using a thermoplastic welding process. The use of a thermoplastic welding process is beneficial as it maintains an integral corrosion resistant barrier between the first and second pipes and the coupling provided by the polymeric material.

As an additional watertight form of sealing, an Oring may be disposed between each of the first and second pipe edges and the ridge of the coupling, and each O-ring may be welded into the seal between the first and second pipe edges and the ridge of the coupling.

In a second aspect, there is provided a first pipe adapted for coupling to a second pipe at respective ends thereof, wherein the first pipe incorporates a polymeric -6- O film or coating, the adaptation of the first pipe Scomprising the positioning in the first pipe respective Send of a coupling that incorporates a polymeric outer R surface, the coupling having a wall that extends between opposing coupling ends and that defines a bore through the C coupling, wherein the coupling is inserted part way into Sthe first pipe end, and a plastic weld is formed between Sthe coupling outer surface and the first pipe end.

SThis first pipe may be pre-fabricated (eg. in a factory) and then supplied ready for use "in the field" with a second pipe.

In a typical form the second pipe also incorporates a polymeric film or coating whereby, when the coupling is inserted part way into the second pipe end, a plastic weld can formed between the coupling outer surface and the second pipe end. In this form the plastic weld formed between the coupling outer surface and the second pipe end may be adjacent to and/or overlap the plastic weld formed between the coupling outer surface and the first pipe end.

The first and second pipes and coupling of the second aspect may be otherwise as defined in the first aspect.

In a third aspect, there is provided a method for coupling together first and second pipes at respective ends thereof, the method comprising the steps of: inserting the coupling of the first aspect into the first pipe until an end of the first pipe is brought into proximity of the ridge; joining the first pipe end to the ridge; inserting the coupling into the second pipe until the second pipe end is brought into proximity of the ridge.

The method of the third aspect typically then comprises the further step of joining the second pipe end to the ridge.

-7- The joining steps typically involve the effecting of o a sealing between the first and second pipe ends and the Sridge.

CI The further joining step may comprise a specific joining (eg. sealing) procedure that takes place just C between the second pipe end and the ridge, or it may Ccomprise a joining procedure that takes place between the Cfirst and second pipe ends and the ridge (eg. an Soverarching joining procedure). In addition, the overarching joining procedure may take place after the specific joining procedure between the second pipe end and the ridge.

Once joined to the first pipe the coupling then facilitates easy connection of the first pipe to the second pipe.

Typically the first and second pipes and the coupling are joined by sealing them together using a thermoplastic welding process. In this regard, the first and second pipes may be as defined in the first or second aspects.

In a fourth aspect there is provided a method for coupling together first and second pipes at respective ends thereof, the method comprising the steps of: inserting a coupling into a first pipe as defined in the second aspect; joining the first pipe end to the coupling; inserting the coupling into the second pipe until the second pipe end is brought into proximity of the join between the first pipe end and the coupling.

In one typical form, the method of the fourth aspect comprises the further step of joining the second pipe end to the coupling.

In one form the joining step(s) involve the effecting of a sealing between the first and second pipe ends and -8- C the coupling. The first and second pipes and the coupling o can be joined by sealing them together using a Sthermoplastic welding process.

CI As in the second aspect, a plastic weld can be formed between the coupling outer surface and the first and C second pipe ends. Furthermore, the plastic weld formed Sbetween the coupling outer surface and the second pipe end CD may be adjacent to and/or overlap the plastic weld formed Sbetween the coupling outer surface and the first pipe end.

In a fifth aspect there is provided a pipe assembly incorporating the coupling of the first or second aspects and/or the first and second pipes as defined in the first or second aspects and/or as produced by the method of the third or fourth aspects.

BRIEF DESCRIPTION OF THE DRAWINGS It is convenient to hereinafter describe an embodiment of the coupling and coupling method with reference to the accompanying drawings. It is to be appreciated that the particularity of the drawings and the related description is to be understood as not superseding the generality of the preceding broad description. In the drawings: Figures 1A to lC show perspective views of a coupling positioned for interconnecting two pipes, with Figure 1A showing an assembled sectional view, Figure lB showing an exploded view and Figure IC showing an assembled view; Figure 2 is a schematic side sectional view of a coupling positioned in the end of a first pipe for eg.

stormwater applications; Figure 3 is a schematic side sectional view of a coupling positioned in the end of first and second pipes for eg. irrigation applications; 9 O Figure 4 is a schematic side sectional view of a O coupling positioned in the end of first and second pipes for eg. irrigation applications; Figure 5 shows a perspective view of a part of a pipe assembly of Figure 4 with a coupling interconnecting two pipes and welded into position; and Figure 6 shows a perspective view of a pipe assembly in a test facility with a series of couplings interconnecting a series of pipes, and each welded into position.

DETAILED DESCRIPTION OF THE DRAWINGS Referring firstly to Figures 1A to 1C, a coupling in the form of a squat cylindrical joiner 10 is depicted for interconnecting first and second host pipes 101, 102 at their ends 103, 104. The joiner 10 is inserted into an open end of each pipe 101, 102 until pipe edges at the pipe ends 103, 104 abut or locate in close proximity to a circumferentially extending protruding ridge 12 defined (eg. formed) in the joiner. The ridge 12 is typically located midway between opposing ends of the joiner. Once in this location (see Figures 1A and IC) the pipes can be fastened (eg. sealed) to the joiner, as described below.

In some forms the joiner 10 may not employ a protruding ridge 12, in which case the joiner 12 is typically inserted half-way into the first and then second host pipes 101, 102, as described below.

The joiner is formed from a polymer coated rollformed galvanised sheet steel, that is formed to incorporate internally protruding ribs 14. The ribs provide torsional strength and stiffness to the joiner and protrude inwardly so as not to interfere with the first and second pipes when the joiner is inserted therein. By 0 O comparison to the host pipes 101,102, the joiner 10 is o typically fabricated of relatively thin gauge polymer coated galvanised roll-formed steel sheet metal. As best depicted in Figure lB the joiner 10 is generally cylindrical, with the sheet metal forming a cylindrical wall.

The host pipes are also formed from a polymer coated roll-formed galvanised sheet steel, that is formed to incorporate external ribs 105, again to provide torsional strength and stiffness. Specifically, the host pipes are made up of interconnected sections, with each section incorporating three ribs 106, 107, 108 and a lock seam 109. The ribs and lock seam are separated by lands 110 and extend helically along the length of the respective pipes, terminating at the ends (eg. 103, 104) of each pipe section at angularly spaced locations. In this way, the ribs and lock seam form on the pipes an arrangement akin to a multi-start thread.

Each of the joiner and host pipes includes the polymer coating on its inner and outer surfaces. This polymer coating provides a further moisture and chemical barrier and also delivers resistance to abrasion thereby improving the performance over the life of the pipe.

One such pipe is manufactured and sold by the applicant under the trade mark HYRDORIB TM which incorporates a LD polyethylene film sold under the trade mark TRENCHCOAT T m LG which is a trade mark of the Dow Chemical Company. The joiner may also be formed of a squat pipe similar to HYRDORIB

M

Another suitable PVC coated steel sheet is sold by the applicant under the trade mark AQUAPLATE

M

Figure 2 illustrates the joiner 10 in side sectional detail for eg. a stormwater application. In this 11 O application the joiner 10 may be factory fitted to an end o of pipe 101 (eg. a HYRDORIB T M stormwater-rated pipe).

Firstly, the joiner 10 is inserted into pipe 101 until its end edge abuts the ridge 12. Then the pipe is sealed to the joiner. Where both the joiner and pipe are plastic coated, the pipe may be sealed to the joiner using a thermoplastic welding process (eg. by applying a polyethylene or "PE" weld to the join see Figure 2).

Where the joiner 10 does not employ a protruding ridge 12, the joiner 10 is typically inserted half-way into the first host pipe 101. Then, a PE weld is applied to join the end of pipe 101 to the outer surface of the joiner 10. In this case, the ridge 12 shown in Figure 2 may instead be considered as depicting a weld bead.

In either case, the pre-fitted pipe and joiner may now be employed in the field. In this regard, the next section of pipe can be push-fitted onto the exposed end of the joiner 10, typically either up to the ridge 12 or, where the ridge is not present, up to the weld bead. Then, it is optional as to whether a further PE weld is employed (ie. depending on the application). For example, in stormwater applications the further PE weld may not be required.

Figure 3 illustrates the joiner 10 in side sectional detail for eg. an irrigation application. In this application the joiner 10 is factory fitted to an end of pipe 101 for subsequent fitting to a pipe 102 (eg. both pipes being a HYRDORIB T M irrigation-rated pipe). Again, the joiner 10 is inserted into pipe 101 until its end edge abuts the ridge 12. Then the pipe is sealed to the joiner using a thermoplastic welding process, by applying a PE weld to the join (see PEl in Figure 3) 12 O The pre-fitted pipe and joiner may again be employed 0 in the field. In this regard, the next section of pipe is push-fitted onto the exposed end of the joiner typically either up to the ridge 12 or, where the ridge is not present, up to the weld bead. Then, a further PE weld is employed (see PE2 in Figure For irrigation applications the further PE weld is typically required because of the higher water pressures.

Figure 4 again illustrates the joiner 10 in side sectional detail, again for an irrigation application. In this application the joiner 10 is factory fitted to an end of pipe 101 for subsequent fitting to a pipe 102 (with both pipes again being a HYRDORIB T M irrigation-rated pipe).

Again, the joiner 10 is inserted into pipe 101 until its end edge abuts the ridge 12. Now the pipe may or may not be sealed to the joiner with a PE weld to the join. For example, the push-fitting of the pipe 101 onto the joiner may be sufficient to hold it in place until sealing in the field takes place.

Where in this application the joiner does not employ a ridge 12, the joiner may be pre-welded to pipe 101, or it can be fabricated such that it requires some force to be inserted into each of the pipes 101, 102, so that it can be maintained partially inserted into pipe 101 and then later be partially inserted into pipe 102.

The pre-fitted pipe and joiner is again employed in the field. Again, the next section of pipe is push-fitted onto the exposed end of the joiner 10, and now a wide PE weld is applied right across the ridge 12 (or, where the joiner does not employ a ridge 12, across eg. a weld bead or small gap between the pipes) to join each pipe end 103,104 together and to the joiner (see weld PEW in Figures 13 C The wide PE weld bonds the joiner right across the 0 ridge 12 (or join)and thus provides extremely effective Ssealing. For irrigation applications the wide PE weld can 0 be employed where very high water pressures are encountered. The wide PEW weld may also replace each of h the specific PE, PE1 and/or PE2 welds, as appropriate.

CFigure 5 shows a pipe assembly 120 in which a wide CPEW weld has been pre-applied (eg. in the factory) to P first 121 and second 122 discrete sections of host pipe.

This assembly may be supplied to an end user, and then additional host pipe sections attached thereto in the field using eg. interconnected lock seams 109.

Figure 6 shows a test facility in which a 6.5 metre length of pipe assembly comprises a series of joiners interconnecting a series of pipes sections, and each welded into position. The pipe assembly is filled with water to test the effects of pressure on different weld configurations and locations, especially at joiner locations towards the lower end of the pipe assembly.

In use, the ridge 12 forms a pipe stop, to allow accurate location of the joiner 10 within the host pipes 101,102. The ridge 12 bears against the end edges of the pipes to prevent over-insertion of the joiner 10 within the bores of the host pipes. Where a weld bead replaces the ridge, it can perform the same function for pipe 102.

Whilst the ridge 12 usually extends peripherally right around the wall, the ridge may be defined by a series of discrete protrusions extending peripherally right around the wall. In either case, the ridge or protrusions will provide a positive stop to insertion of the coupling into each pipe. However, a continuous allows for a more comprehensive watertight seal to be readily formed.- 14 Circumferential groove(s) may also be provided in the U wall of the joiner 10 and/or in the interior of the host pipe walls, adjacent to the ridge 12, to accommodate an C additional sealing element, such as an O-ring. For example, the O-ring can form an additional fail-safe seal C between the joiner 10 and/or in the interior of the host Cpipe walls where the wide PEW weld configuration is CD employed.

SProviding the joiner 10 and the host pipes 101, 102 with a polymeric coating, enables them to be bonded together through a thermoplastic welding process such as a polyethylene welding process. An advantage of using a polyethylene welding process is that it provides a high tensile strength joint whist maintaining the integrity of the polymeric coating and of the corrosion resistant metal coating provided by the galvanising process.

Once the joiner is installed in between the respective host pipes, the resultant assembly allows externally ribbed pipes to be coupled together quickly in a straightforward manner and to form a watertight seal.

In this way, installation of the pipes inside can be easily effected.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments.

Variations and modifications may be made to the parts previously described without departing fromthe spirit or ambit of the disclosure.

Claims (3)

1. 2. A coupling according to claim 1, wherein the first and second pipes and the coupling are each made from sheet metal and each has a polymeric film or coating applied to at least one major surface thereof, such that a polymer-to-polymer bond between each of the pipes and the coupling can be formed in use.
2. 3. A coupling according to claim 2 wherein the polymeric film or coating is applied to each of the pipes and the coupling such that they can be joined together in use by a thermoplastic welding process.
3. 4. A coupling according to any one of the preceding claims, wherein the ridge extends peripherally right around the wall, or is provided as a series of discrete protrusions extending peripherally around the wall, and wherein the ridge or protrusions are located intermediately between the coupling ends. A first pipe adapted for coupling to a second pipe at respective ends thereof, wherein the first pipe incorporates a polymeric film or coating, the adaptation of the first pipe comprising the positioning in the first pipe respective end of a coupling that incorporates a polymeric outer surface, the coupling having a wall that extends between opposing coupling 16 ends and that defines a bore through the coupling, 0 wherein in use the coupling is inserted part way into the first pipe end, and a plastic weld is formed between C1 the coupling outer surface and the first pipe end. Dated this 22nd day of December 2004 BLUESCOPE STEEL LIMITED By its Patent Attorneys SGRIFFITH HACK