Filament wound vessel with improved polar fitting

A fitting for use in a filament wound vessel which has a generally spherical portion including a polar opening defined by said fitting, and a plurality of layers of filaments forming a part of the thickness of the vessel and wound about the fitting, the improvement wherein said fitting comprises a polar boss having shoulder means defining a stepped configuration of decreasing diameters in a direction outwardly of the vessel whereby sequential layers of filaments lay against sequentially smaller diameters of said fitting, the wind angle of each layer being such as to lay adjacent to the largest unwound step diameter until the composite thickness reaches the extremity of the step where the wind angle of the wind pattern is changed such that the layers lay adjacent the next smaller unwound step diameter.

In a filament wound pressure vessel which has a generally spherical portion including a polar opening defined by a fitting, a composite comprising a plurality of layers of filaments forming part of the thickness of the vessel and wound about the fitting, each layer comprising a sequence of winding patterns with increasing wind angles away from the polar opening, said fitting comprising a polar boss having shoulder means defining a stepped configuration of decreasing diameters in a direction outwardly of the vessel whereby sequential layers of filaments lay against sequentially smaller diameters of said fitting, and wherein the wind angle of each layer is such as to lay adjacent to the largest unwound step diameter until the composite thickness reaches the extremity of the step where the wind angle of the wind pattern is changed such that the layers lay adjacent the next smaller unwound step diameter.

A method of fabricating at least a generally spherical portion of a filament wound pressure vessel wherein a plurality of layers of filaments form part of the thickness of the vessel, comprising:

• providing a fitting with a polar opening and with shoulder means defining a stepped configuration of decreasing diameters in a direction outwardly of the vessel, and
• winding said layers of filaments about said polar boss whereby sequenial layers of filaments lay against sequentially smaller diameters of said fitting, the wind angle of each layer being such as to lay adjacent to the largest unwound step diameter until the thickness reaches the extremity of the step, and changing the wind angle of the wind pattern such that the layers lay adjacent the next smaller unwound step diameter.