Flexible conduit and method for forming the same

Abstract

A conduit defining a continuous conduit passage extending from a first opening to a second opening includes a plurality of flexible, tubular, corrugated sections, each defining at least a portion of the conduit passage therethrough. A plurality of tubular, non-corrugated sections are merged with at least one of the corrugated sections and define at least a portion of the conduit passage therethrough. The plurality of corrugated sections and the plurality of non-corrugated sections are arranged in alternating relation.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to conduits and pipes and, more particularly, to conduits and pipes for forming bends.

BACKGROUND OF THE INVENTION

[0002] Polymeric pipes are commonly used for transporting water and other fluids. Pipes formed of polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) may be preferred in many applications because of their performance characteristics and relatively low cost. PVC and CPVC pipes are rigid and typically are difficult to bend without kinking. As a result, typically fittings must be used to accommodate more than nominal bends. Alternatively, heat may be used to soften a pipe for bending. However, heat bending may reduce the performance characteristics (e.g., the pressure rating) of the pipe if the pipe wall on the outside of the bend is stretched thin. As a consequence of the foregoing problems, flexible piping material such as cross-linked polyethylene (PEX) and other polyolefin-based pipes have been employed in applications where PVC or CPVC piping might otherwise be preferred. Moreover, PEX and other polyolefin-based pipes may also suffer from insufficient flexibility.

SUMMARY OF THE INVENTION

[0003] According to embodiments of the present invention, a conduit defining a continuous conduit passage includes a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough. At least the corrugated section is formed of CPVC.

[0004] According to further embodiments of the present invention, a conduit defining a continuous conduit passage includes a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough. At least the corrugated section is formed of cross-linked polyethylene (PEX).

[0005] According to further embodiments of the present invention, a conduit defining a continuous conduit passage extending from a first opening to a second opening includes a plurality of flexible, tubular, corrugated sections, each defining at least a portion of the conduit passage therethrough. A plurality of tubular, non-corrugated sections is provided. Each of the non-corrugated sections merges with at least one of the corrugated sections and defines at least a portion of the conduit passage therethrough. The plurality of corrugated sections and the plurality of non-corrugated sections are arranged in alternating relation.

[0006] According to further embodiments of the present invention, a conduit system includes first and second substantially rigid conduits. A third conduit is interposed between the first and second conduits. The third conduit includes a flexible, tubular, corrugated section. At least the corrugated section is formed of CPVC.

[0007] According to further embodiments of the present invention, a conduit includes first and second substantially rigid conduits and a third conduit interposed between the first and second conduits. The third conduit includes a flexible, tubular, corrugated section. At least the corrugated section is formed of PEX.

[0008] According to method embodiments of the present invention, a method for forming a conduit includes extruding a tubular pre-form of PVC, CPVC, or PEX. Thereafter, a corrugated section is formed in the pre-form.

[0009] According to further method embodiments of the present invention, a method for forming a conduit includes extruding a tubular pre-form of a thermoplastic. A corrugated section is formed in the pre-form. A non-corrugated section is formed in the pre-form such that the non-corrugated section is merged with the corrugated section.

[0010] According to further method embodiments of the present invention, a method for forming a conduit system includes providing a first conduit including a flexible, tubular, corrugated section. At least the corrugated section is formed of CPVC. Second and third substantially rigid conduits are coupled to opposed ends of the first conduit. The corrugated section is bent to form a bend between the second and third conduits.

[0011] According to further method embodiments of the present invention, a method for forming a conduit system includes providing a first conduit including a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough, wherein at least the corrugated section is formed of PEX. Second and third substantially rigid conduits are coupled to opposed ends of the first conduit. The corrugated section is bent to form a bend between the second and third conduits.

[0012] According to further method embodiments of the present invention, a method for forming a conduit system includes providing a corrugated conduit defining a continuous conduit passage and including a flexible, tubular, corrugated section defining a first portion of the conduit passage therethrough. The corrugated section is formed of a thermoplastic. A tubular, non-corrugated section is merged with the corrugated section at an end of the corrugate section. The non-corrugated section defines a second portion of the conduit passage. The corrugated conduit is installed in a building structure such that the corrugated conduit provides fluid communication between a supply of potable water and a dispenser.

[0013] Objects of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments which follow, such description being merely illustrative of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a side view of a conduit according to embodiments of the present invention;

[0015] FIG. 2 is a cross-sectional view of the conduit of FIG. 1 taken along the line 2-2;

[0016] FIG. 3 is a side view of a conduit system including the conduit of FIG. 1;

[0017] FIG. 4 is a side view of a conduit assembly according to embodiments of the present invention;

[0018] FIG. 5 is a side view of a conduit system including a portion of the conduit assembly of FIG. 4;

[0019] FIG. 6 is a schematic view of an apparatus for forming and packaging a conduit assembly according to embodiments of the present invention; and

[0020] FIG. 7 is a block diagram representing method embodiments of the present invention for forming the conduit of FIG. 1 and the conduit assembly of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0022] With reference to FIGS. 1 and 2, a conduit 100 according to preferred embodiments of the present invention is shown therein. The conduit 100 may be used to form a conduit system 17 as shown in FIG. 3. As discussed in more detail below, two or more of the conduits 100 may be integrally formed and connected so as to form a conduit assembly 10 as shown in FIG. 4.

[0023] As best seen in FIG. 2, the conduit 100 includes a tubular, flexible corrugated section 130 and a pair of integral, relatively rigid, tubular, non-corrugated sections 112 and 114 merged with and extending from opposed ends of the corrugated section 130. The conduit 100 defines opposed end openings 140A and 140B and a through passage 140 extending between and fluidly connecting the openings 140A and 140B. Portions 142, 144 and 146 of the passage 140 are defined within the sections 112, 130 and 114, respectively. The overall length L1 of the conduit 100 is preferably between about 14 and 52 inches.

[0024] The non-corrugated sections 112, 114 are preferably adapted to engage conventional piping of common or standard dimensions. The length L2 of each of the non-corrugated sections 112 and 114 is preferably at least about 2 inches. The nominal inner diameter D1 of the sections 112 and 114 is preferably at least 0.489 inch, and more preferably between about 0.489 and 2.149 inches. Each of the non-corrugated sections 112, 114 preferably has a nominal thickness T1 of at least 0.068 inch, and more preferably between about 0.068 and 0.113 inch.

[0025] The corrugated section 130 includes a plurality of annular, concentric walls 135. Adjacent walls 135 are joined along upper folds 132 and lower folds 134 to form a series of corrugations.

[0026] The distance W1 of adjacent upper folds 132 is preferably between about 0.335 and 0.551 inch. The distance W2 between adjacent lower folds 134 is preferably between about 0.335 and 0.551 inch. The walls 135 preferably have a nominal thickness T2 of at least 0.068 inch, and more preferably between about 0.068 and 0.113 inch. The lower folds 134 preferably have a thickness T3 of at least 0.068 inch, and more preferably between about 0.068 and 0.113 inch. The upper folds 132 preferably have a thickness T4 at least 0.068 inch, and more preferably of between about 0.068 and 0.113 inch. The corrugations preferably have a height D2 (i.e., the radial distance from a given upper fold 132 to a given lower fold 134) of between about 0.281 and 0.469 inch. The nominal inner diameters of the lower folds 134 are preferably the same as the nominal inner diameter D1 of the non-corrugated sections 112, 114. Preferably, the wall thickness is substantially uniform along the full length L1 of the conduit 100. The length L3 of the corrugated section 130 is preferably between about 10 and 40 inches, and more preferably of between about 10 and 12 inches.

[0027] The conduit 100 may be formed of any suitable polymeric material. According to certain preferred embodiments, the conduit 100 is formed of CPVC. When formed of CPVC, the conduit 100 is particularly well suited for use in pressurized hot water piping. Preferably, the material of the conduit 100 has a modulus of elasticity of at least 360,000 psi and, more preferably, of between about 360,000 and 400,000 psi.

[0028] When formed of CPVC, the conduit 100 preferably has a burst pressure of at least 250 psi at 180° F. When formed of PVC, the conduit 100 preferably has a burst pressure of at least 630 psi at 73° F. Preferably, the conduit 100 is constructed so as to meet or exceed ASTM Standard F1970-01, revision 2001, when formed of CPVC. Preferably, the conduit 100 is constructed so as to meet or exceed ASTM Standard D2241-00, revision 2000, when formed of PVC. Preferably the conduit meets or exceeds ASTM Standard D1784-99A.

[0029] With reference to FIG. 3, the conduit 100 may be used in the following manner to form a conduit system 17. The non-corrugated sections 112 and 114 are inserted into the open ends of substantially rigid tubular conduits 12 and 14, respectively. The conduits 12, 14 may be of conventional construction and are preferably formed of PVC or CPVC. The corrugated section 130 is bent to form a bend 16 between the conduits 12 and 14. It will be appreciated that the conduits 12 and 14 may be coupled to the sections 112 and 114 by other techniques.

[0030] When formed of CPVC, the corrugated section 130 is preferably adapted to bend at an angle of at least 90 degrees relative to straight while maintaining a burst pressure of at least 250 psi at 180° F. When formed of PVC, the corrugated section 130 is preferably adapted to bend at an angle of at least 90 degrees relative to straight while maintaining a burst pressure of at least 630 psi at 73° F.

[0031] With reference to FIG. 4, a plurality of the conduits 100 may be serially connected to form an integral conduit assembly 10. More particularly, the conduit assembly 10 includes a series of corrugated sections 130 and extended, non-corrugated sections 110 arranged in alternating relation. Each non-corrugated section 110 corresponds to the non-corrugated sections 112 and 114 of adjacent conduits 100.

[0032] A single conduit 100 may be provided by cutting the conduit 100 from the conduit assembly 10. Alternatively, two or more of the conduits 100 may be cut from the conduit assembly 10 such that the two or more conduits 100 are still connected or the conduit assembly 10 may be used as a whole. For example, with reference to FIG. 5, a conduit assembly 10A consisting of two conduits 100 joined at an extended non-corrugated section 110 is shown therein. The non-corrugated section 112 of the first conduit 100 and the non-corrugated section 114 of the second conduit 100 are coupled to the conduits 12 and 14, respectively. Each of the corrugated sections 130 is bent to form a combined bend 19. Conduit systems according to the present invention may be formed using conduit assemblies consisting of greater than two conduits 100, for example, to form sharper bends without overstressing the conduit assembly.

[0033] According to preferred methods of the present invention and with reference to FIGS. 6 and 7, the conduit 100 or conduit assembly 10 may be formed using the following methods and an apparatus 160. Suitable raw material (e.g., CPVC compound in pellet or powder form) is provided to an extruder 162. The extruder 162 is preferably a twin screw extruder. A continuous, tubular conduit pre-form 102 is extruded from the extruder 162 (Block 170). Preferably, the pre-form 102 has substantially the same inner and outer diameters as the non-corrugated sections 112 and 114. The pre-form 102 is preferably generated at a rate of at least 15 feet per minute.

[0034] The pre-form 102 is directed to a corrugator 166, which is preferably in-line with the extruder 162. Preferably, the pre-form 102 extends continuously from the extruder 162 to the corrugator 166. The corrugator 166 forms the corrugations of the corrugated section 130 in the pre-form 102 (Block 172). More particularly, the corrugator 166 intermittently engages the pre-form 102 to form the corrugated sections 130 at spaced apart locations along the length of the pre-form 102 such that uncorrugated sections corresponding to the sections 110 remain between the corrugated sections 130. Preferably, the pre-form 102 extends along substantially a single axis all the way from the exit of the extruder 162 to the downstream end of the portions of the corrugator 166 that engage the pre-form 102 (e.g., the mold dies). Preferably, the pre-form 102 is maintained at a temperature in the range of between about 350 and 450° F. from the extruder 162 to the corrugator 166.

[0035] The corrugated sections 130 are formed by the corrugator 166 while the pre-form 102 is heat-softened (i.e., in its plasticized condition). Preferably, the pre-form 102 is still heat softened (i.e., plasticized) from the heat of the extruder 162. Auxiliary heaters (e.g., in the corrugator 166) may be used to soften the pre-form 102 for the corrugating step. Preferably, the sections of the pre-form 102 in which the corrugations are formed are at a temperature of between about 350 and 450° F. during the step of molding the corrugations into the pre-form 102. Preferably, the pre-form is cooled in the corrugator 166 such that the exiting tube has a temperature of between about 125 and 175° F.

[0036] The corrugator 166 may form the corrugated sections 130 using a combination of a mold and a vacuum. The vacuum is provided in the mold to draw the pre-form 102 into the mold dies, the mold dies having the shape of the desired corrugated section 130.

[0037] The corrugator 166 may form the corrugated sections 130 using a combination of a mold and pressure or blow molding. A pressurized fluid, for example, air, is provided inside the pre-form 102 to prevent or limit collapse of the pre-form 102 as the mold dies are compressed about the pre-form 102. The mold dies have the shape of the desired corrugated section 130.

[0038] A continuous conduit assembly 10 is thereby produced from the corrugator 166. After cooling, the conduit assembly 10 may thereafter be packaged in desired fashion (Block 174). The conduit assembly 10 may be wound onto a roll 168 to form a package 11. Alternatively, the conduit assembly 10 may be cut to desired lengths including one or multiple conduits 100.

[0039] The conduits and conduit assemblies of the present invention may be used to convey potable water. The conduit and conduit assemblies may convey the potable water from a suitable source of potable water such as a water storage container or a water supply pipe (e.g., a municipal water line) to a suitable dispenser such as a faucet. Preferably, such conduit formed of CPVC is installed in a building structure to convey potable pressurized hot water (i.e., water having a temperature in the range of between about 120 and 160° F.). Such conduit formed of PVC may be installed in the building structure to convey potable pressurized cold water (i.e., water having a temperature in the range of between about 40 and 80° F.). The building structure may be a residential or commercial structure.

[0040] According to further embodiments of the present invention, conduits and integral conduit assemblies as described above may be formed of suitable thermoplastic materials other than PVC or CPVC. Such conduits and conduit assemblies may be formed in the same manner and otherwise of the same construction as described above with regard to the conduit 100 and the conduit assembly 10. The selected thermoplastic material is preferably well-suited for use in pressurized water piping. It is particularly contemplated that conduits and conduit assemblies as described above may be formed of cross-linked polyethylene (PEX) in place of PVC or CPVC. While PEX may have significant inherent flexibility, the corrugated sections provide additional flexibility to facilitate installation and longevity.

[0041] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.

Claims

1. A conduit defining a continuous conduit passage and comprising: a) a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough; b) wherein at least the corrugated section is formed of CPVC.

2. The conduit of claim 1 further including: a) a tubular, non-corrugated section merged with the corrugated section at an end of the corrugated section; b) wherein the non-corrugated section defines a second portion of the conduit passage.

3. The conduit of claim 2 wherein the non-corrugated section is formed of CPVC.

4. The conduit of claim 2 wherein the non-corrugated section has a nominal wall thickness of at least 0.068 inch.

5. The conduit of claim 2 wherein the non-corrugated section has a nominal inner diameter of at least 0.489 inch.

6. The conduit of claim 2 wherein the non-corrugated section has a length of at least about 2 inches.

7. The conduit of claim 2 including: a) a second tubular, non-corrugated section merged with the corrugated section at a second end of the corrugated section; b) wherein the second non-corrugated section defines a third portion of the conduit passage.

8. The conduit of claim 7 including a second tubular, corrugated section merged with the second non-corrugated section at an end of the second non-corrugated section opposite the first corrugated section.

9. The conduit of claim 1 wherein the corrugated section has a nominal wall thickness of at least 0.068 inch.

10. The conduit of claim 1 wherein the corrugated section has a nominal inner diameter of at least 0.489 inch.

12. The conduit of claim 1 wherein the corrugated section has a length of between about 10 and 40 inches.

13. The conduit of claim 1 wherein the conduit has a burst pressure of at least 250 psi at 180° F.

14. The conduit of claim 1 wherein the conduit meets or exceeds ASTM F1970-01, revision 2001.

15. The conduit of claim 1 wherein the conduit is formed of CPVC having a modulus of elasticity of at least 360,000 psi.

16. A conduit defining a continuous conduit passage and comprising: a) a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough; b) wherein at least the corrugated section is formed of cross-linked polyethylene (PEX).

17. The conduit of claim 16 further including: a) a tubular, non-corrugated section merged with the corrugated section at an end of the corrugated section; b) wherein the non-corrugated section defines a second portion of the conduit passage.

18. The conduit of claim 17 wherein the non-corrugated section is formed of PEX.

19. The conduit of claim 17 wherein the non-corrugated section has a length of at least about 2 inches.

20. The conduit of claim 17 including: a) a second tubular, non-corrugated section merged with the corrugated section at a second end of the corrugated section; b) wherein the second non-corrugated section defines a third portion of the conduit passage.

21. The conduit of claim 20 including a second tubular, corrugated section merged with the second non-corrugated section at an end of the second non-corrugated section opposite the first corrugated section.

22. A conduit defining a continuous conduit passage extending from a first opening to a second opening and comprising: a) a plurality of flexible, tubular, corrugated sections each defining at least a portion of the conduit passage therethrough; and b) a plurality of tubular, non-corrugated sections each merged with at least one of the corrugated sections and defining at least a portion of the conduit passage therethrough; c) wherein the plurality of corrugated sections and the plurality of non-corrugated sections are arranged in alternating relation.

23. The conduit of claim 22 wherein each of the corrugated sections and the non-corrugated sections is formed of a thermoplastic.

24. The conduit of claim 23 wherein each of the corrugated sections and the non-corrugated sections is formed of CPVC.

25. The conduit of claim 24 wherein the conduit meets or exceeds ASTM F1970-01, revision 2001.

26. The conduit of claim 23 wherein each of the corrugated sections and the non-corrugated sections is formed of PVC.

27. The conduit of claim 26 wherein the conduit meets or exceeds ASTM D2241-00, revision 2000.

28. The conduit of claim 23 wherein each of the corrugated sections and the non-corrugated sections is formed of PEX.

29. The conduit of claim 22 wherein the conduit is formed of PVC or CPVC having a modulus of elasticity of at least 360,000 psi.

30. A conduit system comprising: a) first and second substantially rigid conduits; and b) a third conduit interposed between the first and second conduits, wherein: the third conduit includes a flexible, tubular, corrugated section; and at least the corrugated section is formed of CPVC.

31. A conduit system comprising: a) first and second substantially rigid conduits; and b) a third conduit interposed between the first and second conduits, wherein: the third conduit includes a flexible, tubular, corrugated section; and at least the corrugated section is formed of PEX.

32. A method for forming a conduit, the method comprising: a) extruding a tubular pre-form of PVC, CPVC, or PEX; and b) forming a corrugated section in the pre-form.

33. The method of claim 32 wherein the pre-form is formed of CPVC.

34. The method of claim 32 wherein the pre-form is formed of PVC.

35. The method of claim 32 wherein the pre-form is formed of PEX.

36. The method of claim 32 wherein the conduit is formed to meet or exceed ASTM D1794-99A.

37. The method of claim 32 wherein the step of forming the corrugated section is performed in-line with the step of extruding the pre-form.

38. The method of claim 32 wherein said step of forming a corrugated section includes forming corrugations in the pre-form while the pre-form is plasticized.

39. The method of claim 38 wherein said step of forming a corrugated section includes: a) compressing the pre-form with at least one mold adapted to form the corrugations; and b) pressurizing an interior passage of the pre-form with a pressurizing fluid while the mold is compressing the pre-form to limit displacement of walls of the pre-form into the interior passage.

40. The method of claim 38 wherein said step of forming a corrugated section includes: a) positioning at least one mold adjacent the pre-form, the mold being adapted to form the corrugations; and b) applying a vacuum to draw at least a portion of the pre-form into the mold to thereby form the corrugations.

41. A method for forming a conduit, the method comprising: a) extruding a tubular pre-form of a thermoplastic; b) forming a corrugated section in the pre-form; and c) forming a non-corrugated section in the pre-form such that the non-corrugated section is merged with the corrugated section.

42. The method of claim 41 wherein the pre-form is formed of CPVC.

43. The method of claim 41 wherein the pre-form is formed of PVC.

44. The method of claim 41 wherein the pre-form is formed of PEX.

45. A method for forming a conduit system, said method comprising: providing a first conduit including a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough, wherein at least the corrugated section is formed of CPVC; coupling second and third substantially rigid conduits to opposed ends of the first conduit; and bending the corrugated section to form a bend between the second and third conduits.

46. The method of claim 45 wherein the first conduit includes a second corrugated section connected to the first corrugated section by an integral non-corrugated section, and further including bending the second corrugated section to form the bend.

47. The method of claim 46 including cutting the first conduit from a conduit assembly including a third corrugated section, said step of cutting including separating the first conduit from the third corrugated section.

48. A method for forming a conduit system, said method comprising: providing a first conduit including a flexible, tubular, corrugated section defining at least a portion of the conduit passage therethrough, wherein at least the corrugated section is formed of PEX; coupling second and third substantially rigid conduits to opposed ends of the first conduit; and bending the corrugated section to form a bend between the second and third conduits.

49. The method of claim 48 wherein the first conduit includes a second corrugated section connected to the first corrugated section by an integral non-corrugated section, and further including bending the second corrugated section to form the bend.

50. The method of claim 49 including cutting the first conduit from a conduit assembly including a third corrugated section, said step of cutting including separating the first conduit from the third corrugated section.

51. A method for forming a conduit system, the method comprising: a) providing a corrugated conduit defining a continuous conduit passage and including: a flexible, tubular, corrugated section defining a first portion of the conduit passage therethrough, the corrugated section being formed of a thermoplastic; and a tubular, non-corrugated section merged with the corrugated section at an end of the corrugate section, the non-corrugated section defining a second portion of the conduit passage; and b) installing the corrugated conduit in a building structure such that the corrugated conduit provides fluid communication between a supply of potable water and a dispenser.

52. The method of claim 51 wherein the corrugated section is formed of CPVC.

53. The method of claim 51 wherein the corrugated section is formed of PVC.

54. The method of claim 51 wherein the corrugated section is formed of PEX.

55. The method of claim 51 wherein the step of installing includes bending the corrugated section to form a bend.

56. The method of claim 51 further including connecting at least one substantially rigid conduit to the corrugated conduit such that the rigid conduit also provides fluid communication between the supply of potable water and the dispenser.