GB2298014A - Coupling for joining a plastics pipe to a fitting - Google Patents

Coupling for joining a plastics pipe to a fitting Download PDF

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Publication number
GB2298014A
GB2298014A GB9500477A GB9500477A GB2298014A GB 2298014 A GB2298014 A GB 2298014A GB 9500477 A GB9500477 A GB 9500477A GB 9500477 A GB9500477 A GB 9500477A GB 2298014 A GB2298014 A GB 2298014A
Authority
GB
United Kingdom
Prior art keywords
fitting
coupling
plastics
component
heating element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9500477A
Other versions
GB9500477D0 (en
GB2298014B (en
Inventor
Robert William Jardine
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Glynwed Pipe Systems Ltd
Original Assignee
Wask RMF Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wask RMF Ltd filed Critical Wask RMF Ltd
Priority to GB9500477A priority Critical patent/GB2298014B/en
Publication of GB9500477D0 publication Critical patent/GB9500477D0/en
Publication of GB2298014A publication Critical patent/GB2298014A/en
Application granted granted Critical
Publication of GB2298014B publication Critical patent/GB2298014B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L47/00—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics
    • F16L47/02—Welded joints; Adhesive joints
    • F16L47/03—Welded joints with an electrical resistance incorporated in the joint
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
    • B29C65/342—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint comprising at least a single wire, e.g. in the form of a winding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3468—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the means for supplying heat to said heated elements which remain in the join, e.g. special electrical connectors of windings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/56—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using mechanical means or mechanical connections, e.g. form-fits
    • B29C65/561—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using mechanical means or mechanical connections, e.g. form-fits using screw-threads being integral at least to one of the parts to be joined
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/56—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using mechanical means or mechanical connections, e.g. form-fits
    • B29C65/565—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor using mechanical means or mechanical connections, e.g. form-fits involving interference fits, e.g. force-fits or press-fits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/72—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by combined operations or combined techniques, e.g. welding and stitching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
    • B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
    • B29C66/1222—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least a lapped joint-segment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
    • B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
    • B29C66/1224—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least a butt joint-segment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52—Joining tubular articles, bars or profiled elements
    • B29C66/522—Joining tubular articles
    • B29C66/5229—Joining tubular articles involving the use of a socket
    • B29C66/52291—Joining tubular articles involving the use of a socket said socket comprising a stop
    • B29C66/52292—Joining tubular articles involving the use of a socket said socket comprising a stop said stop being internal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52—Joining tubular articles, bars or profiled elements
    • B29C66/522—Joining tubular articles
    • B29C66/5229—Joining tubular articles involving the use of a socket
    • B29C66/52297—Joining tubular articles involving the use of a socket said socket comprising slip-off prevention means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/53—Joining single elements to tubular articles, hollow articles or bars
    • B29C66/534—Joining single elements to open ends of tubular or hollow articles or to the ends of bars
    • B29C66/5344—Joining single elements to open ends of tubular or hollow articles or to the ends of bars said single elements being substantially annular, i.e. of finite length, e.g. joining flanges to tube ends
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
    • B29C66/712—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined the composition of one of the parts to be joined being different from the composition of the other part
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
    • B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
    • B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined

Abstract

The coupling comprises a first plastics component (5), for connection to the fitting (1), joined to a second plastics component (2) comprising an open-ended socket (8) for receiving the plastics pipe and which supports an electrical resistive heating element (9) for fusing the socket (8) to the pipe. One end of the heating element (9) terminates towards the open end of the socket (8), the termination (10) being connected to one terminal of a power supply. The opposite end of the heating element (9) has a connection(12)in the first component (5) to the fitting (1) after its coupling to the first component (5) so that the heating element (9) is energised by connecting a second terminal of the power supply to the fitting (1) by a termination (14). If the fitting (1) is non-conductive, a conductor connects the termination (14) to the connection (12).

Description

A COUPLING The present invention relates to a coupling for joining a plastics pipe to a fitting, particularly, but not exclusively, a metal fitting.
Polyethylene (PE) pipes are now used within both the water and gas industries in preference to metal pipework.
Wherever such PE pipes need to be connected to existing metal pipework, or other ancillary equipment, couplings known as transition fittings must be used.
Currently available transition fittings rely on mechanical compression joints to connect PE pipes to metal pipes and/or fittings. Such transition fittings fall into two general types; fittings which are factory assembled and fittings which are designed to be assembled on site.
Between the two, factory assembled fittings are generally preferred as mechanical joints for site assembly tend to be expensive, require the use of special tools, and their effectiveness is often dependent upon the level of skill of the assembler.
However, factory assembled fittings leave a PE termination, or tail, which is a plain pipe which must be joined to a PE pipe on site. Thus a further connector, such as a conventional electrofusion coupler, must be used.
Two separate couplings are therefore required to join a single PE pipe to a metal fitting.
Conventional electrofusion couplers comprise a muff containing a heating element comprising two heating coils connected in series for joining together the ends of two plastics pipes. Within such couplings the terminals of the heating element are sited at each end of the heating element so as to be situated over the ends of each pipe away from the area of the join. This is to avoid the possibility of the heating element providing a leak path through which fluid may egress when the join is subjected to fluid pressure. Use of a bifilar heating element, which would permit both terminals to be situated at the same end of the heating element remote from the join, is not acceptable because during fusion of the coupling and pipe, adjacent opposite polarity windings can touch which reduces the heating effect of the element.
Thus, it has not been considered possible in the past to have a single metal to plastics coupling with a compression fitting at one end and a fusion coupling at the other because of the above restrictions with regard to the disposition of the heating element.
It is an object of the present invention to obviate or mitigate the above disadvantages.
According to the present invention there is provided a coupling for joining a plastics pipe to a fitting at least a part of which is electrically conductive, the coupling comprising a first plastics component adapted for connection to said fitting, joined to a second plastics component adapted for connection to said plastics pipe, wherein the second component comprises an open-ended socket for receiving said plastics pipe, the socket supporting an electrical resistive heating element for fusing the socket to the pipe, one end of the heating element terminating towards the open end of the socket and the termination being adapted for connection to one terminal of a power supply, and the opposite end of the heating element being supported by the first component so as to be electrically connected to said fitting after its connection to the first component, whereby the heating element may be energised by connecting a second terminal of the power supply to said fitting.
Where the fitting is metal the present invention enables the provision of a single metal to plastic coupling by using the body of the metal fitting itself as part of the electrical circuit to conduct current to the heating element.
In addition, the invention provides a coupling in which the plastics to metal joint may be factory made, avoiding the problems associated with site-assembled plastics to metal joints, but which can readily be joined to a plastics pipe on site by an electrofusion process without the requirement for a separate electrofusion coupler.
The coupling according to the present invention is not, however, limited to use with metal fittings. For instance, the fitting could be fabricated from a nonconductive material and provided with an electrical connection means for receiving said second terminal of the power supply and electrical contact means which electrically connects the connection means to the heating element when the fitting is connected to the first component of the coupling. For instance the fitting may be fabricated from a hard plastics material, such as acetal.
Such a hard plastics material could readily be configured for reliable screw-threaded connection to an existing metal fitting, which connection could readily be assembled on site.
Said termination of the heating element may be of a conventional type as found in standard electrofusion couplers, and the metal fitting may be provided with a similarly conventional terminal, to allow on-site use of a conventional electrofusion power supply.
The joint between the fitting and the first component is preferably a mechanical compression joint.
For example, the joint may comprise an internally ridged cylindrical socket supported by the fitting which receives, and is compressed around, a cylindrical portion of the first plastics component, a reinforcing sleeve being positioned within the cylindrical portion of the first plastics component.
Preferably said opposite end of the heating element is connected to an electrically conductive contact member which extends through the joint between the fitting and the first plastics component. With a compression joint of the type described above, the contact member preferably has a portion disposed between the cylindrical portion of the first plastics component and the reinforcing sleeve, and a portion disposed between the cylindrical portion and the ridged socket. This arrangement ensures that a good electrical contact is made between the contact member and the fitting as the joint between the fitting and the first plastic component is made.
The coupling may be fabricated from any appropriate material such as polyethylene.
A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing, in which: Fig. 1 is an axial cross-section through a coupling according to the present invention connected to an initial fitting; and Fig. 2 is an end view of the fitting of Fig. 1 looking in the direction of arrow 2 of Fig. 1.
Referring to the drawings, the illustrated assembly comprises a metal fitting 1 mechanically joined to a polyethylene (PE) coupling 2, a central axial bore 3 extending through both the metal and PE components.
The fitting 1 is joined to the coupling 2 by a conventional factory assembled mechanical compression joint. That is, the fitting 1 defines at one end an internally ridged cylindrical socket 4 which receives, and is compressed around, a first component of the coupling in the form of a cylindrical end 5 of the PE component 2. An internal sleeve 6 is located within the cylindrical end 5 of the coupling 2 to support the compression of the joint.
The fitting 1 has a cylindrical end portion 7 remote from the PE component 2 which is externally screw threaded for connection in situ to a further fitting (not shown).
The PE coupling 2 defines a cylindrical socket 8 for receiving the end of a PE pipe (not shown) to which the coupling is in use to be fitted. An electric heating element 9 is coiled around the internal surface of the socket 8 in the manner of a conventional electrofusion coupling. One end of the heating element 9 is connected to a standard electrofusion terminal connection pin 10 which is situated adjacent the open end of the socket 8. The terminal pin 10 is housed within a conventional removable shroud 11.
The opposite end of the heating element 9 is welded to a conductive contact member 12, a portion of which lies between the cylindrical end portion 5 of the coupling 2 and the reinforcing sleeve 6, and a portion of which extends over the edge of the end portion 5 so as to lie between the end portion 5 and the socket 4. The positioning of the contact member 12 is such that good electrical contact will be made between the contact member 12 and the fitting 1 as the compression joint between the fitting 1 and the coupling 2 is formed.
The fitting 1 has an external flange 13 in which is provided a standard electrofusion terminal pin 14, again mounted within a conventional removable shroud 15.
In use, the assembly of the coupling and fitting is joined to the end of a PE pipe (not shown) by inserting the end -of the pipe into the socket 8 and connecting a conventional electrofusion power supply to the terminal pins 10 and 14. The body of the fitting 1 serves to conduct the current from the terminal pin 14 to the contact 12 and thus to the respective end of the heating element 9.
The end of the pipe is thus fused to the socket 8. Once the joint is complete the terminal pins 10 and 14, and the shrouds 11 and 15, may be removed.
The present invention thus provides a coupling for connecting a PE pipe to an existing metal fitting which has a reliable factory assembled metal to PE joint (thereby avoiding the problems associated with site assembled metal to PE joints), but which does not require a separate electrofusion coupling for connection to the PE pipe.
The arrangement of the terminal pins 10 and 14, in particular the positioning of the pin 14 and the use of the body of the metal fitting to conduct current from the pin 14 to the contact member 12, ensures that both terminal pins are situated well away from the region of both the compression joint between the metal and PE components and also.the fusion join of the PE pipe within the socket 8.
There is thus little possibility of the heater element providing a leak path via the terminal pins for fluid to escape from the coupling.
An alternative arrangement to that described above is illustrated in Figure 3. The assembly is substantially the same as that illustrated in Figure 1 (and thus the same reference numerals used in Figure 1 are used in Figure 3 where appropriate) but the fitting is fabricated from acetal as opposed to metal. Because the acetal is nonconductive it is provided with a contact strip 16 which extends between the terminal pin 14 and the socket 4 so as to electrically connect the pin 14 to the contact 12 when the fitting 1 is joined to the coupling 2.
It will be appreciated that the fitting 1 could be fabricated from a variety of non-metal materials. Acetal is useful as it is sufficiently hard to provide for a reliable threaded connection (via the threaded portion 7) to another fitting, which may be metal. The assembly of the coupling 2 and the fitting 1 could then be readily used on site to connect a plastics pipe to an existing metal fitting. It will be understood that there are other hard plastics materials which might also be used to fabricate the fitting.
It will be further appreciated that many other modifications could be made to the structure described above. For instance, the coupling 2 could be made of any suitable plastics material appropriate to the application to which the coupling is to be put. Similarly, depending on the intended application, the fitting 1 could have a variety of configurations.
In addition, it will be appreciated that alternative forms of connection may be used to join the fitting 1 to the PE coupling 2.

Claims (8)

1. A coupling for joining a plastics pipe to a fitting at least a part of which is electrically conductive, the coupling comprising a first plastics component adapted for connection to said fitting, joined to a second plastics component adapted for connection to said plastics pipe, wherein the second component comprises an open-ended socket for receiving said plastics pipe, the socket supporting an electrical resistive heating element for fusing the socket to the pipe, one end of the heating element terminating towards the open end of the socket and the termination being adapted for connection to one terminal of a power supply, and the opposite end of the heating element being supported by the first component so as to be electrically connected to said fitting after its connection to the first component, whereby the heating element may be energised by connecting a second terminal of the power supply to said fitting.
2. A coupling according to claim 1, wherein the joint between the fitting and the first plastics component is a mechanical compression joint.
3. A coupling according to claim 2, wherein the joint comprises an internally ridged cylindrical socket supported by the fitting which receives, and is compressed around, a cylindrical portion of the first plastics component, a reinforcing sleeve being positioned within said cylindrical portion of the first plastics component.
4. A coupling according to any preceding claim, wherein said opposite end of the heating element is connected to an electrically conductive contact member which extends through the joint between the fitting and the first plastics component.
5. A coupling according to claim 4 when dependant from claim 3, wherein said contact member has a portion disposed between the cylindrical portion of the first plastics component and the reinforcing sleeve, and a portion disposed between said cylindrical portion and the ridged socket.
6. A coupling according to any preceding claim, wherein said termination is a conventional connecting pin for connection to a conventional electrofusion power supply.
7. A coupling according to any preceding claim, fabricated from polyethylene.
8. A coupling substantially as hereinbefore described, with reference to the accompanying drawings.
GB9500477A 1995-01-11 1995-01-11 A coupling Expired - Fee Related GB2298014B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9500477A GB2298014B (en) 1995-01-11 1995-01-11 A coupling

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9500477A GB2298014B (en) 1995-01-11 1995-01-11 A coupling

Publications (3)

Publication Number Publication Date
GB9500477D0 GB9500477D0 (en) 1995-03-01
GB2298014A true GB2298014A (en) 1996-08-21
GB2298014B GB2298014B (en) 1998-09-09

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9500477A Expired - Fee Related GB2298014B (en) 1995-01-11 1995-01-11 A coupling

Country Status (1)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003029717A1 (en) * 2001-10-04 2003-04-10 Petrotechnik Limited Improved couplings

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1514208A (en) * 1974-08-16 1978-06-14 Mannesmann Ag Pipe connections
EP0378406A2 (en) * 1989-01-11 1990-07-18 Osaka Gas Co., Ltd. Electrofusion joint and hot water supply header using the same
EP0493316A1 (en) * 1990-12-20 1992-07-01 Geberit AG Device for connecting a weldable plastic or composite tube to a further conduit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1514208A (en) * 1974-08-16 1978-06-14 Mannesmann Ag Pipe connections
EP0378406A2 (en) * 1989-01-11 1990-07-18 Osaka Gas Co., Ltd. Electrofusion joint and hot water supply header using the same
EP0493316A1 (en) * 1990-12-20 1992-07-01 Geberit AG Device for connecting a weldable plastic or composite tube to a further conduit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003029717A1 (en) * 2001-10-04 2003-04-10 Petrotechnik Limited Improved couplings
US7490861B2 (en) 2001-10-04 2009-02-17 Petro Technik, Ltd. Couplings

Also Published As

Publication number Publication date
GB9500477D0 (en) 1995-03-01
GB2298014B (en) 1998-09-09

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