Method of manufacturing an overwrapped pressure vessel

• US 3,969,812 A
• Filed: 04/19/1974
• Issued: 07/20/1976
• Est. Priority Date: 04/19/1974
• Status: Expired due to Term

• Current Assignee: Martin Marietta Corporation
• Original Assignee: Martin Marietta Corporation
• Inventors: Beck, Emory J.
• Primary Examiner(s): Moon, Charlie T.
• Application Number:
  US05/462,356
• Time in Patent Office: 823 Days
• Field of Search: 29/446, 29/458, 29/452, 29/421, 242/2, 242/3, 220/3
• US Class Current: 29/421.1
• CPC Class Codes: B21D 51/24 high-pressure containers, e.g. boilers, bottles
• CPC Class Codes: B29C 53/605 by polar winding
• CPC Class Codes: B29L 2031/7156 Pressure vessels
• CPC Class Codes: B65D 23/08 Coverings or external coatings wrappers B65D65/00
• CPC Class Codes: F17C 1/16 constructed of plastics materials shaping of plastics B29C
• CPC Class Codes: F17C 2209/2154 Winding
• CPC Class Codes: Y10T 29/49805 Shaping by direct application of fluent pressure
• CPC Class Codes: Y10T 29/49863 with prestressing of part
• CPC Class Codes: Y10T 29/49874 Prestressing rod, filament or strand
• CPC Class Codes: Y10T 29/49885 with coating before or during assembling

Abstract

A pressure vessel of the type wherein a metallic liner in the shape of a cylindrical portion with a dome-shaped portion at each end thereof is overwrapped by a plurality of layers of resin coated, single fiberglass filaments. A four-step wrapping technique reinforces the vessel with overwrap material at the most likely areas for vessel failure. Overwrapping of the vessel is followed by a sizing pressurization cycle which induces a compressive prestress into the liner and thereby permits the liner to deform elastically through an increased strain range.

Claims

1. A method of manufacturing a pressure vessel including the steps of forming a liner in the shape of a cylindrical portion and a dome portion at each end thereof, overwrapping the liner by winding filament material thereabout in the following sequence:

a. wrapping filament material about the liner in the polar direction to form a first polar overwrap,

b. wrapping filament material over the first polar overwrap in a cylindrically oriented direction and of sufficient extent to cover the junctions of the cylindrical portion with the dome portions to form a first cylindrical overwrap, and

c. wrapping filament material over the first cylindrical overwrap in the polar direction to form a second polar overwrap which holds the cylindrical overwrap against movement relative to the liner.

2. A method as set forth in claim 1 further including the step of wrapping filament material over the second polar overwrap in the cylindrically oriented direction overlying the cylindrical portion of the liner, thereby forming a second cylindrical overwrap.

3. A method as set forth in claim 2 wherein the step of forming the second cylindrical overwrap includes the step of terminating the wrapping of the filament material adjacent to the junctions of the cylindrical portion with the dome portions.

4. A method as set forth in claim 1 wherein said step of forming a liner includes the step of integrally forming the dome and cylindrical portion of aluminum.

5. A method as set forth in claim 4 wherein said step of overwrapping the liner includes the step of providing filament material made of fiberglass, and further including the step of coating the fiberglass filament material with an epoxy resin prior to wrapping it around the liner.

6. A method as set forth in claim 5, and further including the step of heat curing the vessel after overwrapping the liner.

7. A method as set forth in claim 1, and further including the step of pressurizing the vessel beyond the elastic limit of the liner after overwrapping the liner, elastically unloading the liner by reducing the pressure, and compressing the liner with the filament overwrap.

8. A method as set forth in claim 1 wherein said step of overwrapping the liner includes the step of providing filament material made of graphite.

9. A method as set forth in claim 1 wherein said step of overwrapping the liner includes the step of providing filament material made of boron.

10. A method as set forth in claim 1 wherein said step of overwrapping the liner includes the step of providing filament material made of Kevlar.

11. A method of manufacturing a pressure vessel including the steps of forming a tubular blank of aluminum, forming the tubular blank into a liner in the shape of a cylindrical portion having a wall thickness and a dome portion of substantially equal wall thickness at each end thereof, completely overwrapping the liner by winding filament material in alternating polar oriented and cylindrically oriented winding patterns with at least part of a cylindrically wound winding pattern covering the junctions of the cylindrical portion and each dome portion, the filament material having a higher modulus of elasticity than the aluminum liner, pressurizing the vessel above the elastic limit of the metallic liner and then depressurizing the vessel, so that the metal liner unloads elastically, and a compressive stress is thereby applied to the metallic liner by the overwrap filaments.

12. A method of manufacturing a pressure vessel including the steps of forming a tubular blank of metallic material forming the tubular blank into a liner in the shape of a cylindrical portion having a wall thickness and a dome portion of substantially equal wall thickness at an end thereof, completely overwrapping the liner by winding filament material in alternating polar oriented and cylindrically oriented winding patterns with at least part of a cylindrically wound pattern covering the junction of the cylindrical portion with the dome portion, the filament material having a higher modulus of elasticity than the metallic liner, pressurizing the vessel above the elastic limit of the metallic liner and then depressurizing the vessel, so that the metal liner unloads elastically, and a compressive strength is thereby applied to the metallic liner by the overwrapped filaments.

13. A method of manufacturing a pressure vessel including the steps of forming a liner in the shape of a cylindrical portion and a dome portion at an end thereof, overwrapping the liner by winding filament material thereabout in the following sequence:

a. wrapping filament material about the liner in the polar direction to form a first polar overwrap;

b. wrapping filament material over the first polar overwrap in a cylindrically oriented direction and of sufficient extent to cover the junction of the cylindrical portion with the dome portion to form a first cylindrical overwrap;

c. wrapping filament material over the first cylinder overwrap in the polar direction to form a second polar overwrap which holds the cylindrical overwrap against movement relative to the liner;

d. wrapping filament material over the second polar overwrap in the cylindrically oriented direction overlying the cylindrical portion of the liner and terminating the wrapping of said wrapping of the filament material adjacent to the junction of the cylindrical portion with the dome portion.

14. A method of manufacturing a pressure vessel including the steps of forming a tubular blank of aluminum, forrming the tubular blank into a liner in the shape of a cylindrical portion having a wall thickness and a dome portion of substantially equal wall thickness at at least one end thereof, completely overwrapping the liner by winding filament material with the filament material covering both the cylindrical portion and the dome portion, the filament material having a higher modulus of elasticity than the aluminum liner, pressurizing the vessel above the elastic limit of the metallic liner and then depressurizing the vessel so that the metal liner unloads elastically and a compressive stress is thereby applied to the metallic liner by the overwrapped filaments.