IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0277334
(2002-10-22)
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발명자
/ 주소 |
- Schulte-Ladbeck, Bernd
- Jimenez, Oscar O.
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
6 인용 특허 :
9 |
초록
▼
A welded flange connection and methods and apparatus for producing the connection are disclosed. A weld insert is disposed between the flared ends of abutted plastic pipe or plastic-lined pipe sections. The weld insert includes an annular support disc having a resistance heating element disposed at
A welded flange connection and methods and apparatus for producing the connection are disclosed. A weld insert is disposed between the flared ends of abutted plastic pipe or plastic-lined pipe sections. The weld insert includes an annular support disc having a resistance heating element disposed at least about the inner circumference of the disc. When held tightly between the flared ends of abutted pipe sections power can be applied to the heating element to produce sufficient heat to temporarily raise the temperature of the adjacent surfaces of the flared sections of pipe above their melting point. When the weld is cooled, a strong, fluid-tight, thermoplastic weld is formed. A welded flange connection using the weld insert of the present invention effectively and efficiently produces high quality, fluid-tight connections in plastic pipe and plastic-lined piping systems. Further, by reapplying power to the insert which remains embedded in the weld, the method of the present invention permits the weld to be easily disassembled when necessary for repairs to the pipe system.
대표청구항
▼
1. A method for producing a thermowelded connection between two pipe members, said pipe members including opposed flanges comprised of a melt processable thermoplastic material, comprising:positioning an annular weld insert between the plastic flanges of each of two opposing pipe sections, such that
1. A method for producing a thermowelded connection between two pipe members, said pipe members including opposed flanges comprised of a melt processable thermoplastic material, comprising:positioning an annular weld insert between the plastic flanges of each of two opposing pipe sections, such that the weld insert is positioned between and against abutting surfaces of the flanges of the two opposed pipe members, said weld insert formed of a rigid material chemically compatible with the thermoplastic material of said flanges and having an inner and an outer circumference; urging the plastic flanges of the pipe sections into contact with each other and with the weld insert in between by applying and tightening a coupling about the abutting flanges of the opposed pipe members; passing electrical current through a resistance heating element symmetrically disposed about the inner circumference of the weld insert to produce sufficient heat to raise the temperature of the thermoplastic material of the opposed flanges adjacent and radially inwardly of the heating element to at least the melting point of the thermoplastic material; maintaining pressure longitudinally along the axes of the two opposed pipe members while heating the weld insert until the insert becomes embedded into the melting thermoplastic material; removing the electrical current once the weld insert is bonded with the thermoplastic material; and allowing the thermoplastic material to cool below its melting temperature in order to form a thermowelded flange connection. 2. The method of claim 1 comprising applying sufficient pressure to force the melt produced by the heating of the weld insert radially and outwardly towards the edges of the thermoplastic flanges resulting in a plastic flange thickness that meets the minimum flare thickness required by ASTM.3. The method of claim 1 wherein the weld insert is disposed near the outer periphery of the abutted flange surfaces and the heating element is disposed along an inner circumference of the weld insert.4. The method of claim 3 wherein the heating element is disposed not more than about 0.5 inches from the outer periphery of the abutted flange surfaces.5. The method of claim 1 wherein the pipe members are selected from the group consisting of plastic pipe members and plastic-lined pipe members.6. The method of claim 1 wherein the resistance heating element is heated by applying sufficient electrical power for a time not exceeding about 180 seconds to produce a watt-density of about 20-60 watt/square inch in an area defined by the heating element.7. A method for connecting two plastic or plastic-lined pipe members including opposed flanges comprised of a melt processable thermoplastic material, comprising:placing an annular weld insert between the opposed plastic flanges of two plastic or plastic-lined pipe members, said weld insert formed of a material having a melting point less than or equal to about the melting point of the thermoplastic material of said flanges and having an inner and an outer circumference; urging the pipe members and the weld insert into contact with each other, while the weld remains between the opposed flanges; heating a resistance heating element symmetrically disposed about the inner circumference of the weld insert to produce sufficient heat to temporarily melt the thermoplastic material of the flanges adjacent and radially inwardly of the heating element so that the weld insert becomes integrated with the flanges of the opposing pipe members; and forming a thermowelded connection by discontinuing the heating of the heating element and allowing the thermoplastic material to cool below its melting temperature. 8. The method of claim 7 further comprising temporarily attaching the previously inserted weld insert to an external power source by use of electrical leads extending outwardly from the between the opposed flanges.9. The method of claim 7 wherein heating continues for a predetermined time and at a power level selected to raise the temperature of the thermoplastic material adjacent and radially inwardly of the heating element above its melting temperature in less than about 180 seconds.10. The method of claim 9 wherein power is applied at a voltage in a range of about 3-60 volts and a current in a range of about 3-10 amps.11. The method of claim 9 wherein power is applied to produce a watt-density in an area defined by the heating element in a range of about 20-60 watt/square inch.12. The method of claim 7 wherein the pipe members are urged together by applying force in longitudinal and circumferential directions along the axis of each flanged pipe member.13. The method of claim 7 further comprising disassembling the thermowelded connection produced between two opposed pipe members, comprising:re-applying electrical current to the weld insert embedded in the thermowelded flange connection; heating the resistance heating element disposed within the thermowelded connection to produce a temperature sufficient to temporarily melt the thermowelded plastic of the connection; applying force along the axes of the two opposed pipe sections forming the connection, said force applied to separate the pipe sections in order to aid in the breaking of the weld; and separating the previously welded opposing plastic flanges. 14. A weld insert adapted to produce a welded coupling connecting two opposed pipe members, said pipe members including opposed flanges of a melt processable thermoplastic material, comprising:an annular disc formed of a rigid material and having an inner and an outer circumference; a plurality of holes symmetrically disposed about the disc along a circular path between the inner and outer circumferences; at least one electrical conductor disposed around the disc and through the holes to form a resistance heating element; and a pair of electrical connectors disposed outwardly of the outer circumference of the disc and in electrical contact with the conductor, said connectors adapted for connection to a power source. 15. The weld insert of claim 14 wherein the electrical conductor is threaded alternately between the holes and inner circumference of the disc to produce a resistance heating element along an inner periphery of the disc defined by the inner circumference and holes of the disc.16. The weld insert of claim 15 wherein the outer circumference substantially corresponds to the diameter of the flanges of the pipe members to be welded.17. The weld insert of claim 14 wherein the annular disc is comprised of a plastic characterized by a melting temperature less than or equal to about the melting temperature of the thermoplastic material of the flanges of the pipe members and a chemical compatibility with that thermoplastic material.18. The weld insert of claim 14 wherein the annular disc is comprised of the thermoplastic material forming the flanges of the pipe members.19. The weld insert of claim 14 wherein the annular disc is comprised of a thermoplastic material selected from the group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), chlorotrifluoroethylene (CTFE), ethylene-tetrafluoro ethylene (ETFE), ethylene-chlorotrifluoro ethylene copolymer (E-CTFE), polypropylene (PP), perfluoro-ethylene-propylene copolymer (FEP), ethylene-propylene copolymer (EPM), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polyvinylidene chloride (PVDC), vinylidene fluoride (VDF), polyvinylidene fluoride (PVDF), perfluoromethoxy (MFA), perfluoroalkoxyalkanes (PFA) and polyamide (PA).20. The weld insert of claim 14 wherein the annular disc is not more than about 0.100 inch in thickness.21. The weld insert of claim 14 wherein the electrical conductor comprises a plurality of conductive wires, each having a diameter of at least about 0.010 inch.22. The weld insert of claim 14 further including an external power source connected to the electrical connectors, said power source including controls for adjusting voltage, current and time of the power applied to the heating element of the weld insert.23. The weld insert of claim 22 wherein the power source is capable of delivering a watt-density of about 20-60 watt/square inch in an area defined by the heating element.24. A method for forming a thermowelded connection between the abutted flared ends of two tubular members made from identical or compatible thermoplastic materials, said method comprising:positioning a weld insert between the facing surfaces of the flared ends of said tubular members, said weld insert comprising: an annular support disc having an inner and an outer circumference, said disc being formed of a rigid material having a melting point less than or equal to about the melting point of said thermoplastic materials and being chemically compatible with those materials; a resistance heating element symmetrically disposed about said inner circumference, said element upon passage of a current therethrough being capable of producing sufficient heat to raise the temperature of the abutting surfaces of said flared ends radially inwardly of said inner circumference above the melting point of said thermoplastic materials to produce an annular seal; and leads in electrical contact with said heating element for temporarily connecting said element with a source of electrical power; placing an annular flange around said tubular members; drawing the flared ends of said tubular member toward one another to form a mechanical seal between said abutting surfaces of said tubular members; and while maintaining said mechanical seal, applying a sufficient current to said resistance heating element for a sufficient time to raise the temperature of said thermoplastic materials radially inwardly of said inner circumference above their melting points for a time sufficient to form an annular weld; removing the electrical current once said annular weld has been formed; and allowing said thermoplastic material to cool below its melting temperature to form a fluid-tight, thermowelded connection. 25. The method of claim 24 wherein the resistance heating element is heated by applying sufficient electrical power for a time not exceeding about 180 seconds to produce a watt-density of about 20-60 watt/square inch in an area defined by the heating element.26. The method of claim 25 wherein power is applied at a voltage in a range of about 3-60 volts and a current in a range of about 3-10 amps.27. A welded joint connecting two tubular members in a fluid-tight manner, said joint comprising:first and second tubular members formed of identical or compatible thermoplastic materials; said tubular members each outwardly flared on at least one end, said outwardly flared ends positioned adjacent and abutting one another; a weld insert positioned between said abutting, flared ends, said insert comprising: an annular support disc having an inner and an outer circumference, said disc being formed of a rigid material having a melting point less than or equal to about the melting point of said thermoplastic materials and being chemically compatible with those materials; a resistance heating element symmetrically disposed about said inner circumference, said element upon passage of a current therethrough being capable of producing sufficient heat to raise the temperature of the abutting surfaces of said flared ends radially inwardly of said inner circumference above the melting point of said thermoplastic materials to produce an annular seal; leads in electrical contact with said heating element for temporarily connecting said element with a source of electrical power; and an annular flange surrounding said tubular members and including means for drawing said flared ends of said adjacent tubular members toward one another, wherein the abutted surfaces of said flared ends radially inwardly of said heating element have been melted together by power applied to said heating element to form an annular, fluid-tight seal. 28. A weld insert for use in forming a fluid-tight connection between the abutted flared ends of two tubular members made from identical or compatible thermoplastic materials, said weld insert comprising:an annular support disc having an inner and an outer circumference said disc being formed of a rigid material having a melting point less than or equal to about the melting point of said thermoplastic materials and being chemically compatible with those materials; a resistance heating element symmetrically disposed about at least said inner circumference, said element upon passage of a current therethrough being capable of producing sufficient heat to raise the temperature of the abutting surfaces of said flared ends radially inwardly of said inner circumference above the melting point of said thermoplastic materials to produce an annular, fluid-tight seal; and leads in electrical contact with said heating element for temporarily connecting said element with a source of electrical power. 29. The weld insert of claim 28 wherein said disc is formed of a rigid material having a melting point less than or equal to about the melting point of said thermoplastic materials and is chemically compatible with those materials.30. The weld insert of claim 28 wherein the annular disc is comprised of a thermoplastic material selected from the group consisting of high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), chlorotrifluoroethylene (CTFE), ethylene-tetrafluoro ethylene (ETFE), ethylene-chlorotrifluoro ethylene copolymer (E-CTFE), polypropylene (PP), perfluoro-ethylene-propylene copolymer (FEP), ethylene-propylene copolymer (EPM), polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polyvinylidene chloride (PVDC), vinylidene fluoride (VDF), polyvinylidene fluoride (PVDF), perfluoromethoxy (MFA), perfluoroalkoxyalkanes (PFA) and polyamide (PA).31. The weld insert of claim 28 wherein the annular disc is not more than about 0.100 inch in thickness.32. The weld insert of claim 28 wherein the electrical conductor comprises a plurality of conductive wires, each having a diameter of at least about 0.010 inch.
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