GB2299386A - Electrofusion coupler with longitudinal strenghtening ribs - Google Patents

Electrofusion coupler with longitudinal strenghtening ribs Download PDF

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Publication number
GB2299386A
GB2299386A GB9506185A GB9506185A GB2299386A GB 2299386 A GB2299386 A GB 2299386A GB 9506185 A GB9506185 A GB 9506185A GB 9506185 A GB9506185 A GB 9506185A GB 2299386 A GB2299386 A GB 2299386A
Authority
GB
United Kingdom
Prior art keywords
electrofusion
coupler
electrofusion coupler
ribs
tubular sleeve
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.)
Withdrawn
Application number
GB9506185A
Other versions
GB9506185D0 (en
Inventor
Malcolm Raymond Barfield
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 Plastics Ltd
Original Assignee
Glynwed Plastics 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 Glynwed Plastics Ltd filed Critical Glynwed Plastics Ltd
Priority to GB9506185A priority Critical patent/GB2299386A/en
Publication of GB9506185D0 publication Critical patent/GB9506185D0/en
Publication of GB2299386A publication Critical patent/GB2299386A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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"
    • 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
    • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112—Single lapped joints
    • B29C66/1122—Single lap to lap joints, i.e. overlap joints
    • 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
    • B29C66/5221—Joining tubular articles for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
    • 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
    • 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
    • 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

Abstract

An electrofusion coupler or welding muff for connecting adjoining lengths of plastics pipe has longitudinally extending integral ribs 14. These strengthen the electrofusion coupler in axial tension without significantly adding to the overall amount of plastics used in the ion coupler.

Description

DESCRIPTION OF INVENTION Title: "Improved Electrofusion Coupler" THIS INVENTION relates to electrofusion couplers or welding muffs for use in connecting pipes of thermoplastics. Such electrofusion couplers typically comprise a body of thermoplastics in which is embedded an electrical resistance heating element whereby, once the coupler has been appropriately positioned in engagement with the thermoplastics pipe parts to be connected, an electrical current can be passed through the heating element to fuse together the regions of the coupler adjoining such pipe parts and the adjoining surface regions of the pipe parts thereby to weld the coupler to the pipe parts and thus effect a hermetic seal between the pipe parts.
Electrofusion couplers of this type are disclosed, for example, in GB2090558 and US-A-3062940.
Over the last two decades such electrofusion couplers have achieved a high level of acceptability by gas and water utilities throughout the world. Historically, electrofusion couplers, particularly in the larger sizes, were developed as an easy method for repairing for example polyethylene mains that had been damaged at some point or such electrofusion couplers were intended for use in extending existing polyethylene mains. In these circumstances, where there was an interruption to the main, traditional methods of joining together sections of polyethylene pipe, e.g. butt fusion, could no longer be applied. Thus the use of larger diameter electrofusion couplers was originally aimed predominantly at repair situations.
However, the use of larger diameter electrofusion couplers did not remain confined to repair situations for very long. Because of the ease of jointing, the reduced time of installation, and the increased performance benefits as compared with traditional pipe jointing methods, electrofusion quickly became adopted as a standard jointing technique for pipes of large diameter. Over the years the upper size limit for electrofusion couplers has increased steadily until at present, couplers as large as 400 mm in diameter have become available. However, extension of the use of electrofusion couplers to larger sizes has not been without its manufacturing problems.For example, as the physical size of electrofusion couplers increases so does the volume of plastics incorporated in such couplers, and ultimately the size of electrofusion coupler which can be produced by injection moulding is limited by the volumetric capacity of the moulding machine available. Some manufacturers have tried to overcome this limitation by manufacturing electrofusion couplers from thick wall pipe. This approach eliminates the need for large injection moulding machines by replacing injection moulding by a post-extrusion operation involving a high level machining process. This machining process is not only expensive and time-consuming, but is also susceptible to the problems associated with machining errors.
Because it makes it possible to maintain a truly reproducible product having consistent quality, the injection moulding method is much preferred. The main drawback with this method, as noted above, is the necessity to utilise large injection moulding machines.
It is current practice for all electrofusion fittings to have a diameter to wall section ratio of 11:1.
For PE80 type materials this means that the fittings are capable of containing a 10 bar operating pressure for 50 years. With the advent of new material development it is now possible for fittings manufactured from PE100 material to maintain the same level of performance with a reduced wall section, for example fittings having a diameter to wall section ratio as high as 17:1. Thus, by substituting PE100 material for PE80 material, the overall volume of material required can be reduced.However, whilst this expedient would allow the resistance to internal pressure of an electrofusion coupler to be met with a reduced wall section for a given diameter, the wall section reduction safely possible is in fact less marked than suggested by the above figures because of the design constraints imposed by the need for an electrofusion coupler, once fitted, to withstand substantial axial loads applied via the associated pipe parts i.e. to withstand forces tending to pull the associated pipe parts from the electrofusion coupler.
The applicants have found that the usual failure mechanism for electrofusion fittings subjected to axial tensile loads, i.e. where pipes welded into the electrofusion coupler are pulled axially from the electrofusion coupler until failure occurs, is for the mouth of the electrofusion coupler to expand, allowing the pipe to be torn from the inside of the fitting along the fitting fusion zone.
It is an object of the present invention to provide an electrofusion coupler which can be manufactured by injection moulding and in which the volume of plastics required for a given nominal diameter is reduced as compared with known electrofusion couplers.
According to the invention there is provided an electrofusion coupler comprising a tubular sleeve of thermoplastics material adapted to receive an end of a thermoplastics pipe and wherein said tubular sleeve is provided externally with a plurality of strengthening ribs each extending longitudinally with respect to said tubular sleeve.
It is an object of the invention to provide an electrofusion coupler which can be manufactured with small wall thickness in relation to the coupler diameter and is yet able adequately to withstand axial forces tending to pull plastics pipes connected by the coupler axially therefrom.
An embodiment of the invention is described below by way of example with reference to the accompanying drawings, wherein FIGURE 1 is a side elevation view of an electrofusion coupler embodying the invention, and FIGURE 2 is an end elevation view of the electrofusion coupler of Figure 1, looking along the longitudinal axis of the coupler.
The electrofusion coupler shown in Figures 1 and 2 is intended to receive respective ends of two axially aligned thermoplastics pipes, in manner known per se, and to be welded to such pipe ends in manner likewise known per se by passing current through an electrical resistance heating winding (not shown) embedded in the plastics body of the electrofusion coupler, such current being passed via terminals located within stubs 10, likewise in manner known per se. The features indicated at 12 are internal stops, known per se, within the bore 13 of the electrofusion coupler, which engage inverted pipe ends to limit insertion of the latter.The electrofusion coupler shown differs from known electrofusion couplers (a) in having relatively large ratio of internal diameter to wall thickness, for example in the region of 17:1 and (b) in having a plurality of longitudinally extending integral ribs 14 (four in the example shown) spaced equiangularly around the longitudinal axis 16 of the fitting.
Each rib 14 has a contoured profile having its greatest radial height (relative to the longitudinal axis of the coupler) adjacent the free open ends of the fitting, and its least radial height midway between the free ends of the fitting. Each rib 14 preferably extends over the regions where, in use, the welds between the electrofusion coupler and the inserted pipe ends are produced. It has been found, surprisingly, that the provision of the longitudinal ribs 14 substantially increases the capacity of the electrofusion coupler to withstand axial forces on the pipes connected thereby, tending to pull such pipes from the fitting without significantly adding to the overall amount of plastics used in the fitting.
That is to say, the ribs 14 make it possible to reduce the wall thickness of the fitting whilst maintaining the necessary strength of the fitting in axial tension, resulting in reduced consumption of plastics material and requiring a moulding machine of lesser capacity for a given electrofusion coupler diameter.

Claims (4)

1. An electrofusion coupler comprising a tubular sleeve of thermoplastics material adapted to receive an end of a thermoplastics pipe and wherein said tubular sleeve is provided externally with a plurality of strengthening ribs each extending longitudinally with respect to said tubular sleeve.
2. An electrofusion coupler according to claim 1 wherein said ribs increase in radial height over a substantial part of said tubular sleeve, towards the free end thereof.
3. An electrofusion coupler substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
4. Any novel feature or combination of features described herein.
GB9506185A 1995-03-27 1995-03-27 Electrofusion coupler with longitudinal strenghtening ribs Withdrawn GB2299386A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9506185A GB2299386A (en) 1995-03-27 1995-03-27 Electrofusion coupler with longitudinal strenghtening ribs

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9506185A GB2299386A (en) 1995-03-27 1995-03-27 Electrofusion coupler with longitudinal strenghtening ribs

Publications (2)

Publication Number Publication Date
GB9506185D0 GB9506185D0 (en) 1995-05-17
GB2299386A true GB2299386A (en) 1996-10-02

Family

ID=10771944

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9506185A Withdrawn GB2299386A (en) 1995-03-27 1995-03-27 Electrofusion coupler with longitudinal strenghtening ribs

Country Status (1)

Country Link
GB (1) GB2299386A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2672162A1 (en) * 2012-06-08 2013-12-11 Georg Fischer Wavin AG Ribbed electric welding sleeve

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4429907A (en) * 1982-08-10 1984-02-07 Timmons Fred A Pipe coupler
EP0505083A1 (en) * 1991-03-20 1992-09-23 Victaulic Plc Weldable pipe fittings and pipe joints formed therewith
WO1994024477A1 (en) * 1993-04-17 1994-10-27 Fusion Group Plc Plastic pipe joints

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4429907A (en) * 1982-08-10 1984-02-07 Timmons Fred A Pipe coupler
EP0505083A1 (en) * 1991-03-20 1992-09-23 Victaulic Plc Weldable pipe fittings and pipe joints formed therewith
WO1994024477A1 (en) * 1993-04-17 1994-10-27 Fusion Group Plc Plastic pipe joints

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2672162A1 (en) * 2012-06-08 2013-12-11 Georg Fischer Wavin AG Ribbed electric welding sleeve

Also Published As

Publication number Publication date
GB9506185D0 (en) 1995-05-17

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)