Composite pressure vessel assembly and method

• US 20030111473A1
• Filed: 10/10/2002
• Published: 06/19/2003
• Est. Priority Date: 10/12/2001
• Status: Abandoned Application

• Current Assignee: Polymer & Steel Technologies Holding Company, LLC
• Original Assignee: Polymer & Steel Technologies Holding Company, LLC
• Inventors: Carter, Thomas G., Pristas, Robert J.
• Application Number:
  US10/268,823
• Publication Number:
  US 20030111473A1
• Time in Patent Office: Days
• US Class Current: 220/586
• CPC Class Codes: F17C 1/06 built-up from wound-on bands or filamentary material, e.g. wires
• CPC Class Codes: F17C 1/16 constructed of plastics materials shaping of plastics B29C
• CPC Class Codes: F17C 13/025 having the pressure as the parameter
• CPC Class Codes: F17C 2201/0109 with exteriorly curved end-piece
• CPC Class Codes: F17C 2201/054 medium (>1 m3)
• CPC Class Codes: F17C 2201/056 Small (<1 m3)
• CPC Class Codes: F17C 2203/0604 Liners
• CPC Class Codes: F17C 2203/0619 with two layers
• CPC Class Codes: F17C 2203/0621 with three layers
• CPC Class Codes: F17C 2203/066 Plastics
• CPC Class Codes: F17C 2203/0663 in form of fibers or filaments
• CPC Class Codes: F17C 2203/067 helically wound
• CPC Class Codes: F17C 2203/0673 Polymers
• CPC Class Codes: F17C 2205/0305 Bosses, e.g. boss collars
• CPC Class Codes: F17C 2205/051 by coating
• CPC Class Codes: F17C 2209/2109 Moulding
• CPC Class Codes: F17C 2209/2154 Winding
• CPC Class Codes: F17C 2209/221 Welding
• CPC Class Codes: F17C 2209/232 of walls
• CPC Class Codes: F17C 2209/234 of closing end pieces, e.g. caps
• CPC Class Codes: F17C 2270/05 : for industrial use

Abstract

A composite pressure vessel includes an endcap with first and second layers. The first layer is a thermoplastic layer and the second layer is a thermoplastic and glass fiber composite layer. A method for making the vessel includes placing commingled thermoplastic and glass fibers in a heated mold to melt the thermoplastic. The molten thermoplastic and the glass fibers are molded into the endcap shape. An outer surface of the pressure vessel is finished in accordance with another aspect of the invention. A pressurizable bladder with an inwardly facing surface is deflated. The outer surface of the vessel is heated to soften the thermoplastic. The pressure vessel is positioned in the bladder so that the inwardly facing surface of the bladder is adjacent to an outer surface of the pressure vessel. The bladder is pressurized to move the bladder inwardly into contact with the adjacent surfaces to each other.

Claims

1. A composite vessel, comprising:

an endcap comprising first and second layers, wherein the first layer is a thermoplastic layer and the second layer is a thermoplastic and glass fiber composite layer; and

a cylindrical liner defining an axis and having a first and a second end, and the endcap being secured to the liner first end.

2. The vessel as defined in claim 1, wherein the first layer is an inner layer facing an interior of the vessel and the second layer is an outer layer facing away from the vessel.

3. The vessel as defined in claim 1, wherein the first layer is formed of a thermoplastic material selected from the group consisting of polypropylene and polyethylene.

4. The vessel as defined in claim 1, wherein the second layer comprises a commingled fabric.

5. The vessel as defined in claim 1, wherein the second layer is a commingled thermoplastic and chopped glass fiber composite layer.

6. The vessel as defined in claim 5, wherein the chopped glass fibers have a length in a range of from about 1.25 centimeters to about 7.5 centimeters.

7. The vessel as defined in claim 1, wherein the endcap is a first one of a plurality of endcaps, and the vessel further comprises a second one of the plurality of endcaps secured to a second open end of the cylindrical liner so as to define a cavity.

8. The vessel as defined in claim 7, further comprising an overwrap layer disposed around and consolidated with the cylindrical liner.

9. The vessel as defined in claim 8, wherein the overwrap layer is a helically wound continuous glass filament and thermoplastic composite layer.

10. The vessel as defined in claim 8, wherein the overwrap layer has a predetermined outer surface texture selected from the group consisting of smooth, textured, patterned and embossed surface textures.

11. The vessel as defined in claim 8, further comprising an in-mold label secured to an outer surface of the overwrap layer.

12. The vessel as defined in claim 8, wherein the overwrap layer comprises a colorant.

13. The vessel as defined in claim 1, wherein the endcap comprises a colorant.

14. The vessel as defined in claim 1, further comprising a compression fitting extending through an aperture defined by the endcap, wherein the compression fitting is centered on the axis.

15. The vessel as defined in claim 1, wherein the endcap has a peripheral free edge, a lip extends from the peripheral free edge, the lip engages a circular end of the cylindrical liner such that the lip overlays a portion of the cylindrical liner to support an energy sealable seam between the endcap and the cylindrical liner.

16. The vessel as defined in claim 1, further comprising a structure disposed inside and secured to the vessel selected from the group consisting of a diffuser, rib, directional vane, water inlet tube, fitting, and combinations thereof.

17. The vessel as defined in claim 16, further comprising a perforated separator defining an aperture, and an access plate adapted to be received in the aperture, the separator being configured to divide an interior of the vessel into first and second compartments.

18. The vessel as defined in claim 17, further comprising a filter media disposed on a first side of the separator and within the first compartment.

19. The vessel as defined in claim 18, further comprising an additional filter media disposed on a second side of the separator and within the second compartment.

20. A method for making a pressure vessel, comprising the steps of:

placing commingled thermoplastic and glass fibers in a mold;

heating the mold to a temperature sufficient to melt the thermoplastic such that the thermoplastic flows around and encapsulates the glass fibers;

molding the thermoplastic and glass fibers into an endcap configured to secure to an end of a cylindrical liner; and

securing the endcap to the end of the liner.

21. The method as defined in claim 20, further comprising the step of chopping the commingled thermoplastic and glass fibers prior to the step of placing the commingled thermoplastic and glass fibers in the mold.

22. The method as defined in claim 21, further comprising the step of adding additional thermoplastic to the chopped commingled thermoplastic and glass fibers so as to adjust a glass to thermoplastic ratio.

23. The method as defined in claim 20, further comprising the step of adding a colorant to the commingled thermoplastic and glass fibers.

24. The method as defined in claim 20, further comprising the step of producing a preform of commingled fabric prior to the step of placing the commingled thermoplastic and glass fibers in the mold.

25. The method as defined in claim 24, further comprising the step of overmolding a layer of thermoplastic onto the preform in the mold.

26. The method as defined in claim 25, wherein the overmolding layer is on an inner side of the preform.

27. The method as defined in claim 24, further comprising the steps of providing a compression mold apparatus, laminating the consolidated commingled thermoplastic and glass fibers with a thermoplastic layer, and compression molding the laminated commingled thermoplastic and glass fibers into a dome shape.

28. The method as defined in claim 20, wherein the securing step is accomplished by spin welding, hot plate welding or laser welding

29. The method as defined in claim 20, wherein the endcap is a first endcap of a plurality of endcaps, and further comprising the step of securing a second endcap to a second open end of the cylindrical liner to define a cavity in the pressure vessel.

30. The method as defined in claim 29, further comprising the step of securing a permanent structural component to an inner wall surface of the cylindrical liner prior to securing at least one of the first and second endcaps to the liner.

31. The method as defined in claim 30, wherein the structural component is selected from the group consisting of a diffuser, rib, separator, directional vane, water inlet tube, fitting and combinations thereof, and further comprising the step of bonding the structural component to an inner surface of the liner or one of said endcaps.

32. The method as defined in claim 31, wherein the structural component includes the separator and the water inlet tube, and the separator defines both a first compartment and a second compartment in the cavity, and further comprising the steps of extending a fill tube around the water inlet tube from an area outside the cavity to the first compartment, and directing a filter media through the fill tube and outside of the water inlet tube into the first compartment.

33. The method as defined in claim 32, further comprising the steps of removing the fill tube, positioning an access plate in an aperture defined by the separator, and releasably securing the access plate to the separator so as to contain the filter media in the first compartment.

34. The method as defined in claim 33, further comprising the step of directing a second filter media into the second compartment.

35. The method as defined in claim 29, further comprising the step of filament winding a commingled continuous thermoplastic and glass fibers around the cylindrical liner to form an overwrap layer, and thereby to form a reinforced pressure vessel.

36. The method as defined in claim 35, wherein the winding step is a dry winding step, and further comprising the step of heating the overwrap layer to a temperature sufficient to melt the continuous thermoplastic fibers and to flow the melted thermoplastic around the continuous glass fibers.

37. The method as defined in claim 35, further comprising heating the continuous fibers prior to the winding step.

38. The method as defined in claim 35, further comprising the step of bathing the continuous fibers in a colorant prior to the winding step.

39. The method as defined in claim 35, further comprising the step of heating the outer surface of the overwrap layer to soften the thermoplastic of the overwrap layer.

40. The method as defined in claim 39, further comprising the step of controlling a pressurizable bladder having an inwardly facing surface to switch from an inflated condition to a deflated condition, whereby the bladder is deflated so as to move outwardly.

41. The method as defined in claim 40, further comprising the step of inserting the pressure vessel into the bladder, such that the inwardly facing surface of the bladder is adjacent to the softened outer surface of the overwrap layer of the pressure vessel.

42. The method as defined in claim 40, further comprising the step of controlling the bladder to switch to the inflated condition so as to move the bladder inwardly into contact with the outer surface of the overwrap layer to conform the outer surface of the vessel to the surface texture of the bladder.

43. A finishing device for use with a thermoplastic pressure vessel having an outer surface, comprising:

a pressurizable bladder having an inwardly facing surface with a surface texture; and

a pressure source operable to pressurize the bladder, the bladder responding to pressurization by moving inwardly and contacting an adjacent outer surface of the pressure vessel, and thereby altering the vessel outer surface.

44. The device as defined in claim 43, wherein the vessel is pressurizable, and the pressure source is further operable to pressurize the vessel so as to provide stability to the pressure vessel.

45. The device as defined in claim 43, wherein the surface texture of the bladder is selected from the group consisting of smooth, patterned, textured and embossed.

46. The device as defined in claim 44, wherein the pressure source is further operable to pressurize the bladder with water and the vessel with air.

47. A method of finishing an outer surface of a thermoplastic pressure vessel, comprising the steps of:

controlling a pressurizable bladder having an inwardly facing surface to switch between an inflated condition to a deflated condition;

heating the outer surface of the thermoplastic pressure vessel to soften the thermoplastic of the pressure vessel;

positioning the pressure vessel in the bladder so that the inwardly facing surface of the bladder is adjacent to the outer surface of the pressure vessel; and

pressurizing the bladder so as to inflate the bladder and move the inwardly facing surface into contact with the outer surface of the vessel, and to thereby conform the outer surface of the vessel to the surface texture of the bladder.

48. A composite vessel, comprising:

an injection molded endcap having a dome-shaped body, the body having a circular free end;

an insert having a threaded inner surface, an outer surface, and a radially extending flange, the endcap body overlaying the insert outer surface and flange; and

,

a cylindrical liner having a circular end that is attached to the free end of the endcap.

49. The vessel as defined in claim 48 wherein the insert has an open end and a closed end, and the closed end is configured to be cut from the insert so that the insert can define a threaded aperture extending through the endcap body.